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Title: The Cambridge Natural History, Vol. 06 (of 10)
Author: Sharp, David
Language: English
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* * * * *
THE
CAMBRIDGE NATURAL HISTORY
EDITED BY
S. F. HARMER, Sc.D., F.R.S., Fellow of King's College, Cambridge;
Superintendent of the University Museum of Zoology
AND
A. E. SHIPLEY, M.A., Fellow of Christ's College, Cambridge; University
Lecturer on the Morphology of Invertebrates
VOLUME VI
[Illustration]
INSECTS
PART II. Hymenoptera _continued_ (Tubulifera and Aculeata), Coleoptera,
Strepsiptera, Lepidoptera, Diptera, Aphaniptera, Thysanoptera, Hemiptera,
Anoplura.
By David Sharp, M.A. (Cantab.), M.B. (Edinb.), F.R.S.
London
MACMILLAN AND CO., Limited
NEW YORK: THE MACMILLAN COMPANY
1899
_All rights reserved_
"Men are poor things; I don't know why the world thinks so
much of them."—_Mrs. Bee_, by L. & M. Wintle.
{v}CONTENTS
PAGE
SCHEME OF THE CLASSIFICATION ADOPTED IN THIS BOOK vii
CHAPTER I
HYMENOPTERA PETIOLATA _CONTINUED_—SERIES 2. TUBULIFERA OR
CHRYSIDIDAE.—SERIES 3. ACULEATA—GENERAL—CLASSIFICATION—
DIVISION I. ANTHOPHILA OR BEES 1
CHAPTER II
HYMENOPTERA ACULEATA _CONTINUED_—DIVISION II. DIPLOPTERA OR WASPS—
EUMENIDAE, SOLITARY TRUE WASPS—VESPIDAE, SOCIAL WASPS—MASARIDAE 71
CHAPTER III
HYMENOPTERA ACULEATA _CONTINUED_—DIVISION III. FOSSORES OR FOSSORIAL
SOLITARY WASPS—FAMILY SCOLIIDAE OR SUBTERRANEAN FOSSORES—FAMILY
POMPILIDAE OR RUNNERS—FAMILY SPHEGIDAE OR PERFECT-STINGERS 90
CHAPTER IV
HYMENOPTERA ACULEATA _CONTINUED_—DIVISION IV. FORMICIDAE OR ANTS 131
CHAPTER V
COLEOPTERA OR BEETLES—STREPSIPTERA 184
CHAPTER VI
LEPIDOPTERA, OR BUTTERFLIES AND MOTHS 304
CHAPTER VII {vi}
DIPTERA, OR FLIES—APHANIPTERA, OR FLEAS—THYSANOPTERA, OR THRIPS 438
CHAPTER VIII
HEMIPTERA, OR BUGS—ANOPLURA 532
NOTES AND CORRIGENDA TO VOLUME VI. AND TO INSECTA OF VOLUME V. 602
INDEX 603
{vii}SCHEME OF THE CLASSIFICATION ADOPTED IN THIS BOOK
Order. Sub-order, Family. Sub-Family Group.
Division, or Tribe.
or Series.
HYMENOPTERA (_continued from Vol. V_).
PETIOLATA. (_continued from Vol. V_).
TUBULIFERA (p. 1)
CHRYSIDIDAE (p. 1).
ACULEATA (p. 4)
_ANTHOPHILA_ (p. 10)
APIDAE (p. 10)
Archiapides (p. 21).
Obtusilingues (p. 22).
Andrenides (p. 23).
Denudatae (p. 29).
Scopulipedes (p. 32).
Dasygastres (p. 35).
Sociales (p. 53).
_DIPLOPTERA_ (p. 71)
EUMENIDAE (p. 72).
VESPIDAE (p. 78).
MASARIDAE (p. 88).
_FOSSORES_ (p. 90)
SCOLIIDAE (p. 94)
Mutillides (p. 94).
Thynnides (p. 96).
Scoliides (p. 97).
Sapygides (p. 99).
Rhopalosomides (p. 100).
POMPILIDAE (p. 101).
SPHEGIDAE (p. 107)
Sphegides (p. 107).
Ampulicides (p. 114).
Larrides (p. 116).
Trypoxylonides (p. 118).
Astatides (p. 119).
Bembecides (p. 119).
Nyssonides (p. 123).
Philanthides (p. 124).
Mimesides (p. 127).
Crabronides (p. 128).
_HETEROGYNA_ (p. 131)
FORMICIDAE (p. 131)
Camponotides (p. 144).
Dolichoderides (p. 157).
Myrmicides (p. 158)
Myrmicini (p. 159).
Attini (p. 165).
Pseudomyrmini (p. 168).
Cryptocerini (p. 169).
Ponerides (p. 170).
Dorylides (p. 174)
Ecitonini (p. 175).
Dorylini (p. 177).
Amblyoponides (p. 180).
Order. Sub-Order, Family. Sub-Family or
Division, Tribe.
or Series.
COLEOPTERA (p. 184)
LAMELLICORNIA (p. 190)
PASSALIDAE (p. 192).
LUCANIDAE (p. 193).
SCARABAEIDAE (p. 194)
Coprides (p. 195).
Melolonthides (p. 198).
Rutelides (p. 198).
Dynastides (p. 199).
Cetoniides (p. 199).
ADEPHAGA OR CARABOIDEA (p. 200)
CICINDELIDAE (p. 201).
CARABIDAE (p. 204)
Carabides (p. 206).
Harpalides (p. 206).
Pseudomorphides (p. 206).
Mormolycides (p. 206).
AMPHIZOIDAE (p. 207).
PELOBIIDAE (p. 207).
HALIPLIDAE (p. 209).
DYTISCIDAE (p. 210).
POLYMORPHA (p. 213)
PAUSSIDAE (p. 213).
GYRINIDAE (p. 215).
HYDROPHILIDAE (p. 216).
PLATYPSYLLIDAE (p. 219).
LEPTINIDAE (p. 220).
SILPHIDAE (p. 221).
SCYDMAENIDAE (p. 223).
GNOSTIDAE (p. 223).
PSELAPHIDAE (p. 223).
STAPHYLINIDAE (p. 224).
SPHAERIIDAE (p. 227).
TRICHOPTERYGIDAE (p. 227).
HYDROSCAPHIDAE (p. 228).
CORYLOPHIDAE (p. 228).
SCAPHIDIIDAE (p. 229).
SYNTELIIDAE (p. 229).
HISTERIDAE (p. 230).
PHALACRIDAE (p. 231).
NITIDULIDAE (p. 231).
TROGOSITIDAE (p. 232).
COLYDIIDAE (p. 233).
RHYSODIDAE (p. 234).
CUCUJIDAE (p. 234).
CRYPTOPHAGIDAE (p. 235).
HELOTIDAE (p. 235).
THORICTIDAE (p. 236).
EROTYLIDAE (p. 236).
MYCETOPHAGIDAE (p. 237).
COCCINELLIDAE (p. 237).
ENDOMYCHIDAE (p. 239).
MYCETAEIDAE (p. 239).
LATRIDIIDAE (p. 240).
ADIMERIDAE (p. 240).
DERMESTIDAE (p. 241).
BYRRHIDAE (p. 242).
CYATHOCERIDAE (p. 243).
GEORYSSIDAE (p. 243).
HETEROCERIDAE (p. 243).
PARNIDAE (p. 243).
DERODONTIDAE (p. 244).
CIOIDAE (p. 245).
SPHINDIDAE (p. 245).
BOSTRICHIDAE (p. 246).
PTINIDAE (p. 246)
Ptinides (p. 246).
Anobiides (p. 246).
MALACODERMIDAE (p. 248)
Lycides (p. 248).
Drilides (p. 248).
Lampyrides (p. 248).
Telephorides (p. 248).
MELYRIDAE (p. 252).
CLERIDAE (p. 253).
LYMEXYLONIDAE (p. 254).
DASCILLIDAE (p. 255).
RHIPICERIDAE (p. 256).
ELATERIDAE (p. 256)
Throscides (p. 260).
Eucnemides (p. 260).
Elaterides (p. 260).
Cebrionides (p. 260).
Perothopides (p. 260).
Cerophytides (p. 260).
BUPRESTIDAE (p. 261).
HETEROMERA (p. 262)
TENEBRIONIDAE (p. 263).
CISTELIDAE (p. 264).
LAGRIIDAE (p. 264).
OTHNIIDAE (p. 265).
AEGIALITIDAE (p. 265).
MONOMMIDAE (p. 265).
NILIONIDAE (p. 265).
MELANDRYIDAE (p. 265).
PYTHIDAE (p. 265).
PYROCHROIDAE (p. 266).
ANTHICIDAE (p. 266).
OEDEMERIDAE (p. 266).
MORDELLIDAE (p. 267).
CANTHARIDAE (p. 269).
TRICTENOTOMIDAE (p. 275).
PHYTOPHAGA (p. 276)
BRUCHIDAE (p. 276)
CHRYSOMELIDAE (p. 278)
Eupoda (p. 280).
Camptosomes (p. 281).
Cyclica (p. 282).
Cryptostomes (p. 282).
CERAMBYCIDAE (p. 285)
Prionides (p. 287).
Cerambycides (p. 287).
Lamiides (p. 287).
RHYNCHOPHORA (p. 288)
ANTHRIBIDAE (p. 290).
CURCULIONIDAE (p. 290).
SCOLYTIDAE (p. 294).
BRENTHIDAE (p. 295).
AGLYCYDERIDAE (p. 297).
PROTORHINIDAE (p. 298).
STREPSIPTERA (p. 298)
STYLOPIDAE (p. 298).
LEPIDOPTERA (p. 304)
RHOPALOCERA (p. 341)
NYMPHALIDAE (p. 343)
Danaides (p. 344).
Ithomiides (p. 346).
Satyrides (p. 347).
Morphides (p. 348).
Brassolides (p. 349).
Acraeides (p. 350).
Heliconiides (p. 351).
Nymphalides (p. 352).
ERYCINIDAE (p. 354)
Erycinides (p. 355).
Libytheides (p. 355).
LYCAENIDAE (p. 356).
PIERIDAE (p. 357).
PAPILIONIDAE (p. 359).
HESPERIIDAE (p. 363).
HETEROCERA (p. 366)
CASTNIIDAE (p. 371).
NEOCASTNIIDAE (p. 372).
SATURNIIDAE (p. 372).
BRAHMAEIDAE (p. 374).
CERATOCAMPIDAE (p. 375).
BOMBYCIDAE (p. 375).
EUPTEROTIDAE (p. 376).
PEROPHORIDAE (p. 377).
SPHINGIDAE (p. 380).
COCYTIIDAE (p. 382).
NOTODONTIDAE (p. 383).
CYMATOPHORIDAE (p. 386).
SESIIDAE (p. 386).
TINAEGERIIDAE (p. 387).
SYNTOMIDAE (p. 388).
ZYGAENIDAE (p. 390).
HIMANTOPTERIDAE (p. 392).
HETEROGYNIDAE (p. 392).
PSYCHIDAE (p. 392).
COSSIDAE (p. 395).
ARBELIDAE (p. 396).
CHRYSOPOLOMIDAE (p. 396).
HEPIALIDAE (p. 396).
CALLIDULIDAE (p. 400).
DREPANIDAE (p. 400).
LIMACODIDAE (p. 401).
MEGALOPYOGIDAE (p. 404).
THYRIDIDAE (p. 404).
LASIOCAMPIDAE (p. 405).
ENDROMIDAE (p. 406).
PTEROTHYSANIDAE (p. 406).
LYMANTRIIDAE (p. 406).
HYPSIDAE (p. 408).
ARCTIIDAE (p. 408).
AGARISTIDAE (p. 410).
GEOMETRIDAE (p. 411).
NOCTUIDAE (p. 414).
EPICOPEIIDAE (p. 418).
URANIIDAE (p. 419).
EPIPLEMIDAE (p. 420).
PYRALIDAE (p. 420).
PTEROPHORIDAE (p. 426).
ALUCITIDAE (p. 426).
TORTRICIDAE (p. 427).
TINEIDAE (p. 428).
ERIOCEPHALIDAE (p. 433).
MICROPTERYGIDAE (p. 435).
DIPTERA (p. 438)
ORTHORRHAPHA NEMOCERA (p. 455)
CECIDOMYIIDAE (p. 458).
MYCETOPHILIDAE (p. 462).
BLEPHAROCERIDAE (p. 464).
CULICIDAE (p. 466).
CHIRONOMIDAE (p. 468).
ORPHNEPHILIDAE (p. 470).
PSYCHODIDAE (p. 470).
DIXIDAE (p. 471).
TIPULIDAE (p. 471)
Ptychopterinae (p. 472).
Limnobiinae (p. 473).
Tipulinae (p. 475).
BIBIONIDAE (p. 475).
SIMULIIDAE (p. 477).
RHYPHIDAE (p. 478).
ORTHORRHAPHA BRACHYCERA (pp. 455, 478)
STRATIOMYIDAE (p. 478).
LEPTIDAE (p. 479).
TABANIDAE (p. 481).
ACANTHOMERIDAE (p. 483).
THEREVIDAE (p. 484).
SCENOPINIDAE (p. 484).
NEMESTRINIDAE (p. 484).
BOMBYLIIDAE (p. 485).
ACROCERIDAE (p. 489).
LONCHOPTERIDAE (p. 490).
MYDAIDAE (p. 491).
ASILIDAE (p. 491).
APIOCERIDAE (p. 492).
EMPIDAE (p. 492).
DOLICHOPIDAE (p. 493).
CYCLORRHAPHA ASCIZA (pp. 455, 494)
PHORIDAE (p. 494).
PLATYPEZIDAE (p. 496).
PIPUNCULIDAE (p. 496).
CONOPIDAE (p. 497).
SYRPHIDAE (p. 498).
CYCLORRHAPHA SCHIZOPHORA (pp. 456, 503)
MUSCIDAE ACALYPTRATAE (p. 503).
ANTHOMYIIDAE (p. 506).
TACHINIDAE (p. 507).
DEXIIDAE (p. 510).
SARCOPHAGIDAE (p. 510).
MUSCIDAE (p. 511).
OESTRIDAE (p. 514).
PUPIPARA (pp. 456, 517)
HIPPOBOSCIDAE (p. 518).
BRAULIDAE (p. 520).
STREBLIDAE (p. 521).
NYCTERIBIIDAE (p. 521).
APHANIPTERA (pp. 456, 522)
PULICIDAE (p. 522).
THYSANOPTERA (p. 526)
TEREBRANTIA (p. 531).
TUBULIFERA (p. 531).
Order. Sub-Order. Series. Family.
HEMIPTERA (p. 532)
HETEROPTERA (pp. 543, 544)
GYMNOCERATA (p. 544)
PENTATOMIDAE (p. 545).
COREIDAE (p. 546).
BERYTIDAE (p. 548).
LYGAEIDAE (p. 548).
PYRRHOCORIDAE (p. 549).
TINGIDAE (p. 549).
ARADIDAE (p. 550).
HEBRIDAE (p. 551).
HYDROMETRIDAE (p. 551).
HENICOCEPHALIDAE (p. 554).
PHYMATIDAE (p. 554).
REDUVIIDAE (p. 555).
AËPOPHILIDAE (p. 559).
CERATOCOMBIDAE (p. 559).
CIMICIDAE (p. 559).
ANTHOCORIDAE (p. 560).
POLYCTENIDAE (p. 560).
CAPSIDAE (p. 561).
SALDIDAE (p. 562).
CRYPTOCERATA (p. 562)
GALGULIDAE (p. 562).
NEPIDAE (p. 563).
NAUCORIDAE (p. 565).
BELOSTOMIDAE (p. 565).
NOTONECTIDAE (p. 567).
CORIXIDAE (p. 567).
HOMOPTERA (pp. 543, 568)
TRIMERA (p. 544)
CICADIDAE (p. 568).
FULGORIDAE (p. 574).
MEMBRACIDAE (p. 576).
CERCOPIDAE (p. 577).
JASSIDAE (p. 578).
DIMERA (p. 544)
PSYLLIDAE (p. 578).
APHIDAE (p. 581).
ALEURODIDAE (p. 591).
MONOMERA (p. 544)
COCCIDAE (p. 592).
ANOPLURA (p. 599)
PEDICULIDAE (p. 599).
{1}CHAPTER I
HYMENOPTERA PETIOLATA _CONTINUED_
SERIES 2. TUBULIFERA OR CHRYSIDIDAE—SERIES 3. ACULEATA—GENERAL—
CLASSIFICATION—DIVISION I. ANTHOPHILA OR BEES
The First Series—Parasitica—of the Sub-Order Hymenoptera Petiolata was
discussed in the previous volume. We now pass to the Second Series.
SERIES 2. HYMENOPTERA TUBULIFERA.
_Trochanters undivided; the hind-body consisting of from three to five
visible segments; the female with an ovipositor, usually retracted,
transversely segmented, enveloping a fine, pointed style. The larvae
usually live in the cells of other Hymenoptera._
The Tubulifera form but a small group in comparison with Parasitica and
Aculeata, the other two Series of the Sub-Order. Though of parasitic
habits, they do not appear to be closely allied to any of the families of
Hymenoptera Parasitica, though M. du Buysson suggests that they have some
affinity with Proctotrypidae; their morphology and classification have
been, however, but little discussed, and have not been the subject of any
profound investigation. At present it is only necessary to recognise one
family, viz. Chrysididae or Ruby-wasps.[1] These Insects are usually of
glowing, metallic colours, with a very hard, coarsely-sculptured
integument. Their antennae are abruptly elbowed, the joints not being
numerous, usually about thirteen, and frequently so {2}connected that it is
not easy to count them. The abdomen is, in the great majority, of very
peculiar construction, and allows the Insect to curl it completely under
the anterior parts, so as to roll up into a little ball; the dorsal plates
are very strongly arched, and seen from beneath form a free edge, while the
ventral plates are of less hard consistence, and are connected with the
dorsal plates at some distance from the free edge, so that the abdomen
appears concave beneath. In the anomalous genus _Cleptes_ the abdomen is,
however, similar in form to that of the Aculeate Hymenoptera, and has four
or five visible segments, instead of the three or four that are all that
can be seen in the normal Chrysididae. The larvae of the Ruby-flies have
the same number of segments as other Hymenoptera Petiolata. The difference
in this respect of the perfect Chrysididae from other Petiolata is due to a
greater number of the terminal segments being indrawn so as to form the
tube, or telescope-like structure from which the series obtains its name.
This tube is shown partially extruded in Fig. 1; when fully thrust out it
is seen to be segmented, and three or four segments may be distinguished.
The ovipositor proper is concealed within this tube; it appears to be of
the nature of an imperfect sting; there being a very sharply pointed style,
and a pair of enveloping sheaths; the style really consists of a
trough-like plate and two fine rods or spiculae. There are no poison
glands, except in _Cleptes_, which form appears to come very near to the
Aculeate series. Some of the Chrysididae on occasions use the ovipositor as
a sting, though it is only capable of inflicting a very minute and almost
innocuous wound.
[Illustration: Fig. 1.—_Chrysis ignita_, ♀. England.]
Although none of the Ruby-flies attain a large size, they are usually very
conspicuous on account of their gaudy or brilliant colours. They are
amongst the most restless and rapid of Insects; {3}they love the hot
sunshine, and are difficult of capture. Though not anywhere numerous in
species, they are found in most parts of the world. In Britain we have
about twenty species. They usually frequent old wood or masonry, in which
the nests of Aculeate Hymenoptera exist, or fly rapidly to and fro about
the banks of earth where bees nest. Dr. Chapman has observed the habits of
some of our British species.[2] He noticed _Chrysis ignita_ flying about
the cell of _Odynerus parietum_, a solitary wasp that provisions its nest
with caterpillars; in this cell the _Chrysis_ deposited an egg, and in less
than an hour the wasp had sealed the cell. Two days afterwards this was
opened and was found to contain a larva of _Chrysis_ a quarter of an inch
long, as well as the Lepidopterous larvae stored up by the wasp, but there
was no trace of egg or young of the wasp. Six days after the egg was laid
the _Chrysis_ had eaten all the food and was full-grown, having moulted
three or four times. Afterwards it formed a cocoon in which to complete its
metamorphosis. It is, however, more usual for the species of _Chrysis_ to
live on the larva of the wasp and not on the food; indeed, it has recently
been positively stated that _Chrysis_ never eats the food in the wasp's
cell, but there is no ground whatever for rejecting the evidence of so
careful an observer as Dr. Chapman. According to M. du Buysson the larva of
_Chrysis_ will not eat the lepidopterous larvae, but will die in their
midst if the _Odynerus_ larva does not develop; but this observation
probably relates only to such species as habitually live on _Odynerus_
itself. The mother-wasp of _Chrysis bidentata_ searches for a cell of
_Odynerus spinipes_ that has not been properly closed, and that contains a
full-grown larva of that wasp enclosed in its cocoon. Having succeeded in
its search the _Chrysis_ deposits several eggs—from six to ten; for some
reason that is not apparent all but one of these eggs fail to produce
young; in two or three days this one hatches, the others shrivelling up.
The young _Chrysis_ larva seizes with its mouth a fold of the skin of the
helpless larva of the _Odynerus_, and sucks it without inflicting any
visible wound. In about eleven days the _Chrysis_ has changed its skin four
times, has consumed all the larva and is full-fed; it spins its own cocoon
inside that of its victim, and remains therein till the following spring,
when it changes to a pupa, and in less than three weeks {4}thereafter
emerges a perfect _Chrysis_ of the most brilliant colour, and if it be a
female indefatigable in activity. It is remarkable that the larva of
_Chrysis_ is so much like that of _Odynerus_ that the two can only be
distinguished externally by the colour, the _Odynerus_ being yellow and the
_Chrysis_ white; but this is only one of the many cases in which host and
parasite are extremely similar to the eye. _Chrysis shanghaiensis_ has been
reared from the cocoons of a Lepidopterous Insect—_Monema flavescens_,
family Limacodidae—and it has been presumed that it eats the larva therein
contained. All other Chrysids, so far as known, live at the expense of
Hymenoptera (usually, as we have seen, actually consuming their bodies),
and it is not impossible that _C. shanghaiensis_ really lives on a
Hymenopterous parasite in the cocoon of the Lepidopteron.
_Parnopes carnea_ frequents the nests of _Bembex rostrata_, a solitary wasp
that has the unusual habit of bringing from time to time a supply of food
to its young larva; for this purpose it has to open the nest in which its
young is enclosed, and the _Parnopes_ takes advantage of this habit by
entering the cell and depositing there an egg which produces a larva that
devours that of the _Bembex_. The species of the anomalous genus _Cleptes_
live, it is believed, at the expense of Tenthredinidae, and in all
probability oviposit in their cocoons which are placed in the earth.
SERIES 3. HYMENOPTERA ACULEATA.
_The females (whether workers or true females) provided with a sting:
trochanters usually undivided (monotrochous). Usually the antennae of the
males with thirteen, of the females with twelve, joints (exceptions in
ants numerous)._
These characters only define this series in a very unsatisfactory manner,
as no means of distinguishing the "sting" from the homologous structures
found in Tubulifera, and in the Proctotrypid division of Hymenoptera
Parasitica, have been pointed out. As the structure of the trochanters is
subject to numerous exceptions, the classification at present existing is
an arbitrary one. It would probably be more satisfactory to separate the
Proctotrypidae (or a considerable part thereof) from the Parasitica, and
unite them with the Tubulifera and Aculeata in a great series,
characterised by the fact that the ovipositor is {5}withdrawn into the body
in a direct manner so as to be entirely internal, whereas in the Parasitica
it is not withdrawn in this manner, but remains truly an external organ,
though in numerous cases concealed by a process of torsion of the terminal
segments. If this were done it might be found possible to divide the great
group thus formed into two divisions characterised by the fact that the
ovipositor in one retains its function, the egg passing through it
(Proctotrypidae and Tubulifera), while in the other the organ in question
serves as a weapon of offence and defence, and does not act as a true
ovipositor, the egg escaping at its base. It would, however, be premature
to adopt so revolutionary a course until the comparative anatomy of the
organs concerned shall have received a much greater share of attention; a
detailed scrutiny of Prototrypidae being particularly desired.
[Illustration: Fig. 2.—Diagram of upper surface of _Priocnemis affinis_ ♀,
Pompilidae. _o_, ocelli; _B^1_, pronotum; _B^2_, mesonotum; _B^3_,
scutellum of mesonotum; _B^4_, post-scutellum or middle part of metanotum;
_B^5_, propodeum or median segment (see vol. v. p. 491); _B^6_, combing
hairs, pecten, of front foot: _C^1_, first segment of abdomen, here not
forming a pedicel or stalk: _D^1_, coxa; _D^2_, trochanter; _D^3_, femur;
_D^6_, calcaria or spurs of hind leg: 1 to 15, nervures of wings, viz. 1,
costal; 2, post-costal; 3, median; 4, posterior; 5, stigma; 6, marginal; 7,
upper basal; 8, lower basal; 9, 9, cubital; 10, the three sub-marginal; 11,
first recurrent; 12, second recurrent; 13, anterior of hind wing; 14,
median; 15, posterior: I to XI, the cells, viz. I, upper basal; II, lower
basal; III, marginal; IV, V, VI, first, second and third sub-marginal; VII,
first discoidal; VIII, third discoidal; IX, second discoidal; X, first
apical; XI, second apical.]
We have dealt with the external anatomy of Hymenoptera in {6}Vol. V.; so
that here it is only necessary to give a diagram to explain the terms used
in the descriptions of the families and sub-families of Aculeata, and to
discuss briefly their characteristic structures.
[Illustration: Fig. 3—Sting of bee. A, One of the needles separated; _a_,
the barbed point; _b_, piston; _c_, arm. B, Transverse section of the
sting: _dd_, the two needles; _e_, bead for guiding the needles; _f_,
director; _g_, channel of poison. (After Carlet.)]
The Sting of the bee has been described in detail by Kraepelin, Sollmann,
Carlet[3] and others. It is an extremely perfect mechanical arrangement.
The sting itself—independent of the sheaths and adjuncts—consists of three
elongate pieces, one of them a gouge-like director, the other two pointed
and barbed needles; the director is provided with a bead for each of the
needles to run on, these latter having a corresponding groove; the entrance
to the groove is narrower than its subsequent diameter, so that the needles
play up and down on the director with facility, but cannot be dragged away
from it; each needle is provided with an arm at the base to which are
attached the muscles for its movement. This simple manner of describing the
mechanical arrangement is, however, incomplete, inasmuch as it includes no
account of the means by which the poison is conveyed. This is done by a
very complex set of modifications of all the parts; firstly, the director
is enlarged at the anterior part to form a chamber, through which the
needles play; the needles are each provided with a projecting piece, which,
as the needle moves, plays in the chamber of the director, and forces
downwards any liquid that may be therein; the poison-glands open into the
chamber, and the projections on the needles, acting after the manner of a
piston, carry the poison before them. The needles are so arranged on {7}the
director that they enclose between themselves and it a space that forms the
channel along which the poison flows, as it is carried forwards by the
movement of the pistons attached to the needles. If the needles be thrust
into an object quite as far as, or beyond, the point of the director much
poison may be introduced into a wound, as the barbs are provided with small
orifices placed one above the other, while if this be not the case much of
the liquid will flow on the outside of the object.
According to Carlet the poison of the bee is formed by the mixture of the
secretions of two glands, one of which is acid and the other alkaline; it
is very deadly in its effects on other Insects. We shall see, however, that
the Fossorial Hymenoptera, which catch and sting living prey for their
young, frequently do not kill but only stupefy it, and Carlet states that
in this group the alkaline gland is absent or atrophied, so that the poison
consists only of the acid; it is thus, he thinks, deprived of its lethal
power. Moreover, in the Fossoria the needles are destitute of barbs, so
that the sting does not remain in the wound. Bordas, however, states[4]
that in all the numerous Hymenoptera he has examined, both acid and
alkaline glands exist, but exhibit considerable differences of form in the
various groups. He gives no explanation of the variety of effects of the
poison of different Aculeata.
The larvae (for figure of larva of _Bombus_, see Vol. V. p. 488) are,
without known exception, legless grubs, of soft consistence, living
entirely under cover, being protected either in cells, or, in the case of
social Hymenoptera, in the abodes of the parents. The larvae of Ants and
fossorial Hymenoptera have the anterior parts of the body long and narrow
and abruptly flexed, so that their heads hang down in a helpless manner.
All the larvae of Aculeates, so far as known, are remarkable from the fact
that the posterior part of the alimentary canal does not connect with the
stomach till the larval instar is more or less advanced; hence the food
amongst which they live cannot be sullied by faecal matter. The pupa is
invariably soft, and assumes gradually the colour of the perfect Insect.
Almost nothing is known as to the intimate details of the metamorphosis,
and very little as to the changes of external form. According to Packard a
period intervenes between the stadium of the full-grown larva and that of
the pupa, in which a series of changes he speaks of as semi-pupal {8}are
passed through; these, however, have not been followed out in the case of
any individual, and it is not possible to form any final idea about them,
but it seems probable that they are largely changes of external shape, in
conformity with the great changes going on in the internal organs. Owing to
the fragmentary nature of observations, much obscurity and difference of
opinion have existed as to the metamorphosis of Aculeate Hymenoptera. Sir
S. Saunders gives the following statement as to the larva of a wasp of the
genus _Psiliglossa_,[5] just before it assumes the pupal form: "The
respective segments, which are very distinctly indicated, may be defined as
follows:—The five anterior, including the head, are compactly welded
together, and incapable of separate action in the pseudo-pupa state; the
third, fourth, and fifth bearing a spiracle on either side. The thoracical
region terminating here, the two anterior segments are assignable to the
development of the imago head, as pointed out by Ratzeburg." This inference
is not, however, correct. We have seen that in the perfect Insect of
Petiolate Hymenoptera the first abdominal segment is fixed to the thorax,
and Saunders' statement is interesting as showing that this assignment of
parts already exists in the larva, but it in no way proves that the head of
the imago is formed from the thorax of the larva. It has been stated that
the larvae of the Aculeata have a different number of segments according to
the sex, but this also is incorrect. The difference that exists in the
perfect Insects in this respect is due to the withdrawal of the terminal
three segments to the interior in the female, and of two only in the male.
The larva consists of fourteen segments, and we find this number
distributed in the female perfect Insect as follows: one constitutes the
head, four segments the thorax and propodeum, followed by six external
segments of the restricted abdomen, and three for the internal structures
of the abdomen. This agrees with Forel's statement that in the ants the
sting is placed in a chamber formed by three segments.
The development of the sting of the common bee has been studied by
Dewitz.[6] It takes place in the last larval stage. Although nothing of the
organ is visible externally in the adult larva, yet if such a larva be
placed in spirit, there can be seen within the skin certain small
appendages on the ventral surface of the penultimate and antepenultimate
abdominal segments {9}(Fig. 4, A) placed two on the one, four on the other;
these are the rudiments of the sting. In the course of development the
terminal three segments are taken into the body, and the external pair of
the appendages of the twelfth body segment (the ninth abdominal) become the
sheaths of the sting, and the middle pair become the director; the pair of
appendages on the eleventh segment give rise to the needles or spiculae.
The sting-rudiments at an earlier stage (Fig. 4, C) are masses of
hypodermis connected with tracheae; there is then but one pair on the
twelfth segment, and this pair coalesce to form a single mass; the
rudiments of the pair that form the director are differentiated secondarily
from the primary pair of these masses of hypodermis. A good deal of
discussion has taken place as to whether the component parts of the
sting—gonapophyses—are to be considered as modifications of abdominal
extremities (_i.e._ abdominal legs such as exist in Myriapods). Heymons is
of opinion that this is not the case, but that the leg-rudiments and
gonapophysal rudiments are quite distinct.[7] The origin of the sting of
Hymenoptera (and of the ovipositor of parasitic Hymenoptera) is very
similar to that of the ovipositor of _Locusta_ (Vol. V. p. 315 of this
work), but there is much difference in the history of the development of
the rudiments.
[Illustration: Fig. 4—Development of sting of the bee: A and C, ventral; B,
side view. A, End of abdomen of adult larva: _a_, _b_, _c_, _d_, the last
four segments, _c_ being the eleventh body segment, 11; _b_ bearing two
pairs, and _c_ one pair, of rudiments. B, Tip of abdomen of adult bee: 9,
the ninth, _d_, the tenth body segment. C, Rudiments in the early condition
as seen within the body: _c_, first pair; _b_, the second pair not yet
divided into two pairs; _b″_, _c′_, commencement of external growths from
the internal projections. (After Dewitz.)]
Dewitz has also traced the development of the thoracic appendages in
Hymenoptera.[8] Although no legs are visible in the adult larva, they
really arise very early in the larval life from masses of hypodermis, and
grow in the interior of the body, so that when the larva is adult the legs
exist in a segmented though rudimentary condition in the interior of the
body. Dewitz's study of the wing-development is less complete.
{10}Four primary divisions of Aculeates are generally recognised, viz.
Anthophila (Bees), Diploptera (Wasps), Fossores (Solitary Wasps),
Heterogyna (Ants). Though apparently they are natural, it is impossible to
define them by characters that are without some exceptions, especially in
the case of the males. Ashmead has recently proposed[9] to divide the
Fossores; thus making five divisions as follows:—
Body with more or less of the hairs on it plumose 1. Anthophila.
Hairs of body not plumose.
Pronotum not reaching back to tegulae 2. Entomophila
[= Fossores part].
Pronotum reaching back to tegulae.
Petiole (articulating segment of abdomen) simple without
scales or nodes.
Front wings in repose with a fold making them narrow
3. Diploptera.
Front wings not folded 4. Fossores [part].
Petiole with a scale or node (an irregular elevation
on the upper side) 5. Heterogyna.
We shall here follow the usual method of treating all the fossorial wasps
as forming a single group, uniting Ashmead's Entomophila and Fossores, as
we think their separation is only valid for the purposes of a table; the
Pompilidae placed by the American savant in Fossores being as much allied
to Entomophila as they are to the other Fossores with which Ashmead
associates them.
DIVISION I. ANTHOPHILA OR APIDAE—BEES.
_Some of the hairs of the body plumose; parts of the mouth elongated,
sometimes to a great extent, so as to form a protrusible apparatus,
usually tubular with a very flexible tip. Basal joint of hind foot
elongate. No wingless adult forms; in some cases societies are formed,
and then barren females called workers exist in great numbers, and carry
on the industrial operations of the community. Food always derived from
the vegetable kingdom, or from other Bees._
There are about 150 genera and 1500 species of bees at present known. Some
call the division Mellifera instead of Anthophila. The term Apidae is used
by some authorities to denote all the bees, while others limit this term to
one of the families {11}or sub-divisions. The bees are, as a rule,
distinguished from other Hymenoptera by the hairs, by the great development
of the mouth parts to form a proboscis (usually, but not correctly, called
tongue), and by the modification of the hind-legs; but these distinctive
characters are in some of the species exhibited in so minor a degree of
perfection that it is not easy to recognise these primitive forms as
Anthophila. A few general remarks on the three points mentioned will enable
the student to better appreciate the importance of certain points we shall
subsequently deal with.
[Illustration: Fig. 5—Hairs of Bees: A, simple hair from abdomen of
_Osmia_; B, spiral hair from abdomen of _Megachile_; C, plumose hair from
thorax of _Megachile_; D, from thorax of _Andrena dorsata_; E, from thorax
of _Prosopis_.]
The bees are, as a rule, much more covered with hair than any other of the
Hymenoptera. Saunders[10] states that he has examined the structure of the
hairs in all the genera of British Aculeata, and that in none but the
Anthophila do branched and plumose hairs occur. The function of this kind
of hairs is unknown; Saunders suggests[10] that they may be instrumental in
the gathering of pollen, but they occur in the parasitic bees as well as in
the males, neither of which gather pollen. The variety of the positions
they occupy on the body seems to offer but little support to the
suggestion. Not all the hairs of the bee's body are plumose, some are
simple, as shown in Fig. 5, A, and this is specially the case with the
hairs that are placed at the edges of the dilated plates for carrying
pollen. In some forms there is an extensive system of simple hairs all over
the body, and the "feathers" are distributed between these; and we do not
see any reason for assuming that the feathered are superior to the simple
hairs for gathering and carrying pollen. Some bees, _e.g._ _Prosopis_,
_Ceratina_, have very little hair on the body, but nevertheless some
plumose hairs are always present even though they be very short.
{12}[Illustration: Fig. 6—A, Worker of the honey-bee (_Apis mellifica_),
with pollen plates laden; B, basal portions of a middle-leg (trochanter
with part of coxa and of femur) with plumose hairs and grains of pollen; C,
one hair bearing pollen-grains.]
The hind-legs of bees are very largely used in the industrial occupations
of these indefatigable creatures; one of their chief functions in the
female being to act as receptacles for carrying pollen to the nest: they
exhibit, however, considerable diversity. The parts most modified are the
tibia and the first joint of the hind-foot. Pollen is carried by other
parts of the body in many bees, and even the hind-leg itself is used in
different ways for the purpose: sometimes the outer face of the tibia is
highly polished and its margins surrounded by hair, in which case pollen
plates are said to exist (Fig. 6, A); sometimes the first joint of the
tarsus is analogous to the tibia both in structure and function; in other
cases the hind-legs are thick and densely covered with hair that retains
the pollen between the separate hairs. In this case the pollen is carried
home in a dry state, while, in the species with pollen plates, the pollen
is made into a mass of a clay-like consistence.[11] The legs also assist in
arranging the pollen on the other parts of the body. The males do not carry
pollen, and though their hind-legs are also highly modified, yet the
modifications do not agree with those of the female, and their functions
are in all probability sexual. The parasitic bees also do not carry pollen,
and exhibit another series of structures. The most interesting case in this
series of modifications is that found in the genus _Apis_, where the
hind-leg of male, female, and worker are all different (Fig. 25); the limb
in the worker being highly modified for industrial purposes. This case has
been frequently referred to, in consequence of the difficulty that exists
in connection with its heredity, for the {13}structure exists in neither of
the parents. It is, in fact, a case of a very special adaptation appearing
in the majority of the individuals of each generation, though nothing of
the sort occurs in either parent.
The proboscis of the bee[12] is a very complex organ, and in its extremely
developed forms exhibits a complication of details and a delicacy of
structure that elicit the admiration of all who study it. In the lower
bees, however, especially in _Prosopis_, it exists in a comparatively
simple form (Fig. 9, B, C), that differs but little from what is seen in
some Vespidae or Fossores. The upper lip and the mandibles do not take any
part in the formation of the bee's proboscis, which is consequently
entirely made up from the lower lip and the maxillae, the former of these
two organs exhibiting the greatest modifications. The proboscis is situate
on the lower part of the head, and in repose is not visible; a portion, and
that by no means an inconsiderable one, of its modifications being for the
purpose of its withdrawal and protection when not in use. For this object
the under side of the head is provided with a very deep groove, in which
the whole organ is, in bees with a short proboscis, withdrawn; in the
Apidae with a long proboscis this groove also exists, and the basal part of
the proboscis is buried in it during repose, while the other parts of the
elongate organ are doubled on the basal part, so that they extend backwards
under the body, and the front end or tip of the tongue is, when in repose,
its most posterior part.
For the extrusion of the proboscis there exists a special apparatus that
comes into play after the mandibles are unlocked and the labrum lifted.
This extensive apparatus cannot be satisfactorily illustrated by a drawing,
as the parts composing it are placed in different planes; but it may be
described by saying that the cardo, or basal hinge of the maxilla, changes
from an oblique to a vertical position, and thrusts the base of the
proboscis out of the groove. The maxillae form the outer sheath of the
proboscis, the lower lip its medial part (see Figs. 7 and 9); the base of
the lower lip is attached to the submentum, which rises with the cardo so
that labium and maxillae are lifted together; the co-operation of these two
parts is effected by an angular piece called the lorum, in which the base
of the submentum rests; the submentum is articulated with the mentum in
such a manner that the two can either be placed in planes at a right angle
to one another, or can be brought into one continuous plane, and by this
change of plane the basal part of the tongue can also be thrust forwards.
{14}[Illustration: Fig. 7.—Side view of basal portions of proboscis of
_Bombus_. _a_, Epipharyngeal sclerites; _b_, arrow indicating the position
of the entrance to pharynx, which is concealed by the epipharynx, _c_; _d_,
hypopharyngeal sclerites; _e_, vacant space between the scales of the
maxillae through which the nectar comes: _f_, lobe; _f′_, stipes; _g_,
cardo of maxilla: _h_, encephalic pillar on which the cardo swings; _i_,
angle of junction of lores and submentum lorum; _k_, mentum; _l_, base of
labial palp; _m_, maxillary palp.]
There is considerable variety in the lengths of these parts in different
genera, and the lorum varies in shape in accordance with the length of the
submentum. The lorum is a peculiar piece, and its mechanical adaptations
are very remarkable; usually the base of the submentum rests in the angle
formed by the junction of the two sides of the lorum, but in _Xylocopa_,
where the submentum is unusually short, this part reposes in a groove on
the back of the lorum, this latter having a very broad truncated apex
instead of an angular one; in the condition of repose the apex of the lorum
rests in a notch on the middle of the back of the oral groove, and in some
of the forms with elongate submentum, this depression is transformed into a
deep hole, or even a sort of tunnel, so as to permit the complete stowing
away of the base of the tongue, which would otherwise be prevented by the
long submentum; another function of the lorum appears to be that, as it
extends, its arms have an outward thrust, and so separate the maxillae from
the labium. In addition to these parts there are also four elongate,
slender sclerites that are only brought into view on dissection, and that
no doubt assist in correlating the movements of the parts of the mouth and
{15}hypopharynx; one pair of these strap-like pieces extends backwards from
the two sides of the base of the epipharynx; Huxley called them sclerites
of the oesophagus; a better name would be epipharyngeal sclerites (Fig. 7,
_a_): the other pair pass from the terminations of the epipharyngeal
sclerites, along the front face of the hypopharynx, down to the mentum,
their lower parts being concealed by the stipites of the maxillae; these
are the hypopharyngeal sclerites, and we believe it will prove that they
play a highly important part in deglutition. When the labrum of a bee is
raised and the proboscis depressed, the epipharynx is seen hanging like a
curtain from the roof of the head; this structure plays an important part
in the act of deglutition. The entrance to the pharynx, or commencement of
the alimentary canal, is placed below the base of the epipharynx. As we are
not aware of any good delineations of the basal parts of the proboscis we
give a figure thereof (Fig. 7). The maxillae in the higher bees are
extremely modified so as to form a sheath, and their palpi are minute; in
the lower bees the palpi have the structure usual in mandibulate Insects.
Returning to the consideration of the lower lip, we find that there is
attached to the mentum a pair of elongate organs that extend forwards and
form a tube or sheath, enclosed by the maxillary sheath we have previously
mentioned; these are the greatly modified labial palpi, their distal parts
still retaining the palpar form; and in the lower bees the labial palpi
are, like the maxillary, of the form usual in mandibulate Insects. Between
the labial palps and the central organ of the lip there is attached a pair
of delicate organs, the paraglossae.
There remains for consideration the most remarkable part of the proboscis,
the long, delicate, hairy organ which the bee thrusts out from the tip of
the shining tube formed by the labial palps and the maxillae, described
above, and which looks like a prolongation of the mentum. This organ is
variously called ligula, lingua, or tongue.[13] We prefer the first of
these names.
According to Breithaupt and Cheshire the structure of the ligula is highly
remarkable; it is a tube (filled with fluid from the body cavity), and with
a groove underneath caused by a large part of the circumference of the tube
being invaginated; the {16}invaginated part can be thrust out by increase
of the pressure of the fluid in the tube. A portion of the wall of the
invaginate part is thickened so as to form a chitinous rod.
This description will suffice for present purposes, as the other parts of
the mouth will be readily recognised by the aid of figure 9, A, B, C. In
the exquisitely endowed South American genus _Euglossa_ (Fig. 18), the
proboscis is somewhat longer than the whole of the body, so that its tip in
repose projects behind the body like a sting.
[Illustration: Fig. 8.—Transverse section of ligula of honey-bee,
diagramatic. A, With the long sac invaginate. B, evaginate: _a_, chitinous
envelope with the bases of the hairs; _b_, rod; _c_, groove of rod; _d_,
lumen due in A to invagination of the rod, in B to its evagination; _n_,
nerve; _tr_, trachea.]
The correct nomenclature of the parts connected with the lower lip is not
definitely settled, authorities not being agreed on several points. The
whole of the proboscis is usually called the tongue; this, however, is
admittedly an erroneous application of this term. The terminal delicate,
elongate, flexible organ is by some called the tongue; but this again is
wrong: the lingua in Insects is the hypopharynx; this part is developed in
a peculiar manner in bees, but as it is not tongue-like in shape, the term
lingua is not suitable for it, and should be dismissed altogether from the
nomenclature of the bee's trophi; it is used at present in two different
senses, both of which are erroneous. We see no objection to describing the
flexible apical portion of the proboscis as the ligula. The lorum is
probably a special part peculiar to the higher bees; according to Saunders
it is not present as a specialised part in some of the primitive forms.[14]
The application of the terms mentum, submentum and hypoglottis is open to
the same doubts that exist with regard to them in so many other
{17}Insects, and we have omitted the term hypoglottis altogether, though
some may think the mentum entitled to that name.
[Illustration: Fig. 9.—A, Proboscis of a "long-tongued" bee, _Anthophora
pilipes_; B, lower, C, upper view of proboscis of an "obtuse-tongued" bee,
_Prosopis pubescens_. _a_, Labrum; _b_, stipes; _c_, palpiger; _d_, scale:
_f_, lobe; _g_, palpus; _h_, cardo, of maxilla: _i_, lorum; _k_, submentum;
_l_, mentum; _m_, labial palp; _n_, paraglossa; _o_, ligula; _p_, tip of
ligula (with "spoon" at tip and some of the hairs more magnified); _q_,
hypopharyngeal sclerites.]
The way in which the proboscis of the bee acts has been very largely
discussed, with special reference to the question as to whether it is a
sucking or a licking action. It is impossible to consider either of these
terms as applicable. The foundation of the action is capillary attraction,
by which, and by slight movements of increase and contraction of the
capacity of various parts, the fluid travels to the cavity in front of the
hypopharynx: here the scales of the maxillae leave a vacant space, (Fig. 7,
_e_) so that a cup or cavity is formed, the fluid in which is within reach
of the tip of the dependent epipharynx (_c_), which hangs down over the
front of the hypopharynx (and is so shaped that its tip covers the cup); it
is between these two parts that the fluid passes to reach the pharynx. It
is no doubt to slight movements of the membranous parts of the hypopharynx
and of the epipharynx that the further progress of the nectar is due, aided
by contraction and expansion of the pharynx, induced by muscles attached to
it. It should be recollected that in addition to the movements of the head
itself, the hypopharynx is constantly changing its dimensions slightly by
the impulses of the fluid of the general body cavity; also that the head
changes its position, {18}and that the proboscis is directed downwards as
well as forwards. Those who wish to pursue this subject should refer to the
works of Breithaupt[15] and Cheshire.
The other external characters of the Bees call for little remark. The
pronotum is never very large or much prolonged in front, and its hind
angles never repose on the tegulae as they do in the wasps,[16] but extend
backwards below the tegulae. The hind body is never narrowed at the base
into an elongate pedicel, as it so frequently is in the Wasps and in the
Fossors; and the propodeum (the posterior part of the thorax) is more
perpendicular and rarely so largely developed as it is in the Fossors; this
last character will as a rule permit a bee to be recognised at a glance
from the fossorial Hymenoptera.
Bees, as every one knows, frequent flowers, and it is usually incorrectly
said that they extract honey. They really gather nectar, swallow it, so
that it goes as far as the crop of their alimentary canal, called in
English the honey-sac, and is regurgitated as honey. Bertrand states that
the nectar when gathered is almost entirely pure saccharose, and that when
regurgitated it is found to consist of dextrose and levulose:[17] this
change appears to be practically the conversion of cane- into grape-sugar.
A small quantity of the products of the salivary glands is added, and this
probably causes the change alluded to; so that honey and nectar are by no
means synonymous. According to Cheshire the glandular matter is added while
the nectar is being sucked, and is passing over the middle parts of the
lower lip, so that the nectar may be honey when swallowed by the bee. In
addition to gathering nectar the female bees are largely occupied in
collecting pollen, which, mixed with honey, is to serve as food for the
colony. Many, if not all, bees eat pollen while collecting it. The mode in
which they accumulate the pollen, and the mechanism of its conveyance from
hair to hair till it reaches the part of the body it must attain in order
to be removed for packing in the cells, is not fully understood, but it
appears to be accomplished by complex correlative actions of various parts;
the head and the front legs scratch up the pollen, the legs move with great
rapidity, and the pollen ultimately reaches its destination. The workers of
the genus _Apis_, and of some other social {19}bees, have the basal joint
of the hind foot specially adapted to deal with pollen (Fig. 25, 2). We
have already mentioned the modifications of the legs used for its
conveyance, and need here only add that numerous bees—the Dasygastres—carry
the pollen by aid of a special and dense clothing of hairs on the underside
of the abdomen.
The buzzing of bees (and other Insects) has been for long a subject of
controversy: some having maintained that it is partially or wholly due to
the vibration of parts connected with the spiracles, while others have
found its cause in the vibrations of the wings. According to the
observations of Pérez and Bellesme,[18] two distinct sounds are to be
distinguished. One, a deep noise, is due to the vibration of the wings, and
is produced whenever a certain rapidity is attained; the other is an acute
sound, and is said to be produced by the vibrations of the walls of the
thorax, to which muscles are attached; this sound is specially evident in
Diptera and Hymenoptera, because the integument is of the right consistence
for vibration. Both of these observers agree that the spiracles are not
concerned in the matter.
The young of bees are invariably reared in cells. These (except in the case
of the parasitical bees) are constructed by the mothers, or by the
transformed females called workers. The solitary bees store the cells with
food, and close up each cell after having laid an egg in it, so that in
these cases each larva consumes a special store previously provided for it.
The social bees do not close the cells in which the larvae are placed, and
the workers act as foster-mothers, feeding the young larvae after the same
fashion as birds feed their nestling young. The food is a mixture of honey
and pollen, the mixing being effected in various ways and proportions
according to the species; the honey seems to be particularly suitable to
the digestive organs of the young larvae, and those bees that make closed
cells, place on the outside of the mass of food a layer more thickly
saturated with honey, and this layer the young grub consumes before
attacking the drier parts of the provisions. The active life of the larva
is quite short, but after the larva is full-grown it usually passes a more
or less prolonged period in a state of quiescence before assuming the pupal
form. The pupa shows the limbs and other parts of the perfect Insect in a
very distinct manner, and the {20}development of the imago takes place
gradually though quickly. Some larvae spin cocoons, others do not.
A very large number of bees are parasitic in their habits, laying an egg,
or sometimes more than one, in the cell of a working bee of some species
other than their own; in such cases the resulting larvae eat and grow more
quickly than the progeny of the host bee, and so cause it to die of
starvation. It has been observed that some of these parasitic larvae, after
eating all the store of food, then devour the larva they have robbed. In
other cases it is possible that the first care of the parasitic larva,
after hatching, is to eat the rival egg.
The taxonomy of bees is in a very unsatisfactory state. The earlier
Hymenopterists were divided into two schools, one of which proposed to
classify the bees according to their habits, while the other adopted an
arrangement depending on the length of the parts of the mouth, the
development of the palpi, and the form and positions of the organs for
carrying pollen. Neither of these arrangements was at all satisfactory, and
some entomologists endeavoured to combine them, the result being a
classification founded partly on habits and partly on certain minor
structural characters. This course has also proved unsatisfactory; this is
especially the case with exotic bees, which have been placed in groups that
are defined by habits, although very little observation has actually been
made on this point. Efforts have recently been made to establish an
improved classification, but as they relate solely to the European bees
they are insufficient for general purposes.
The more important of the groups that have been recognised are—(1) the
Obtusilingues, short-tongued bees, with the tip of the lingua bifid or
broad; (2) Acutilingues, short-tongued bees, with acute tip to the tongue;
these two groups being frequently treated of as forming the Andrenidae.
Coming to the Apidae, or the bees with long and folded tongues, there have
been distinguished (3) Scopulipedes, bees carrying pollen with their feet,
and (4) Dasygastres, those that carry it under the abdomen; some of the
parasitic and other forms have been separated as (5) Denudatae (or
Cuculinae); the Bombi and the more perfectly social bees forming another
group, viz. (6) Sociales. A group Andrenoides, or Panurgides, was also
proposed for certain bees considered to belong to the Apidae though
exhibiting many points of {21}resemblance with the Andrenidae. This
arrangement is by no means satisfactory, but as the tropical bees have been
but little collected, and are only very imperfectly known, it is clear that
we cannot hope for a better classification till collections have been very
much increased and improved. The arrangement adopted in Dalla Torre's
recent valuable catalogue of bees[19] recognises no less than fourteen
primary divisions, but is far from satisfactory.
[Illustration: Fig. 10—_Prosopis signata._ Cambridge. A, Female; B, front
of head of female; C, of male.]
The two genera _Prosopis_ and _Sphecodes_ have been recently formed into a
special family, Archiapidae, by Friese,[20] who, however, admits that the
association is not a natural one. The term should be limited to _Prosopis_
and the genera into which it has been, or shortly will be, divided. The
primitive nature of the members of this genus is exhibited in all the
external characters that are most distinctive of bees; the proboscis (Fig.
9, B, C), is quite short, its ligula being very short, and instead of being
pointed having a concave front margin. The body is almost bare, though
there is some very short feathered plumage. The hind legs are destitute of
modifications for industrial purposes. Owing to these peculiarities it was
for long assumed that the species of _Prosopis_ must be parasites. This is,
however, known not to be the case so far as many of the species are
concerned. They form cells lined with a silken membrane in the stems of
brambles and other plants that are suitable, or in burrows in the earth, or
in the mortar of walls; individuals of the same species varying much as to
the nidus they select. The food they store in these cells is much more
liquid than usual, and has been supposed to be entirely honey, since they
have no apparatus for carrying pollen. Mr. R. C. L. Perkins has, however,
observed that they swallow both pollen and nectar, brushing the first-named
substance to the mouth by aid of the front legs. He {22}has ascertained
that a few of the very numerous Hawaiian species of the genus are really
parasitic on their congeners: these parasites are destitute of a peculiar
arrangement of hairs on the front legs of the female, the possession of
which, by some of the non-parasitic forms, enables the bee to sweep the
pollen towards its mouth. These observations show that the structural
peculiarities of _Prosopis_ are correlative with the habits of forming a
peculiar lining to the cell, and of gathering pollen by the mouth and
conveying it by the alimentary canal instead of by external parts of the
body. _Prosopis_ is a very widely distributed genus, and very numerous in
species. We have ten in Britain; several of them occur in the grounds of
our Museum at Cambridge.
The species of the genus _Colletes_ are hairy bees of moderate size, with a
good development of hair on the middle and posterior femora for carrying
pollen. They have a short, bilobed ligula like that of wasps, and therein
differ from the Andrenae, which they much resemble. With _Prosopis_ they
form the group Obtusilingues of some taxonomists. They have a manner of
nesting peculiar to themselves; they dig cylindrical burrows in the earth,
line them with a sort of slime, that dries to a substance like
gold-beater's skin, and then by partitions arrange the burrow as six to ten
separate cells, each of which is filled with food that is more liquid than
usual in bees. Except in regard to the ligula and the nature of the
cell-lining, _Colletes_ has but little resemblance to _Prosopis_; but the
term Obtusilingues may be applied to _Colletes_ if _Prosopis_ be separated
as Archiapidae. We have six species of _Colletes_ in Britain.
_Sphecodes_ is a genus that has been the subject of prolonged difference of
opinion. The species are rather small shining bees, with a red, or red and
black, abdomen, almost without pollen-collecting apparatus, and with a
short but pointed ligula. These characters led to the belief that the
Insects are parasitic, or, as they are sometimes called, cuckoo-bees. But
evidence could not be obtained of the fact, and as they were seen to make
burrows it was decided that we have in _Sphecodes_ examples of industrial
bees extremely ill endowed for their work. Recent observations tend,
however, to prove that _Sphecodes_ are to a large extent parasitic at the
expense of bees of the genera _Halictus_ and _Andrena_. Breitenbach has
taken _S. rubicundus_ out of the brood-cells of _Halictus quadricinctus_;
and on one of the few {23}occasions on which this bee has been found in
Britain it was in circumstances that left little doubt as to its being a
parasite of _Andrena nigroaenea_. Marchal[21] has seen _S. subquadratus_
fight with _Halictus malachurus_, and kill it previous to taking possession
of its burrows; and similar observations have been made by Ferton. As the
older observations of Smith, Sichel, and Friese leave little doubt that
_Sphecodes_ are sometimes industrial bees, it is highly probable that we
have in this genus the interesting condition of bees that are sometimes
parasitic, at other times not; but so much obscurity still prevails as to
the habits of _Sphecodes_ that we should do well to delay accepting the
theories that have been already based on this strange state of matters.[22]
Friese states that in _Sphecodes_ the first traces of collecting apparatus
exist; and, accepting the condition of affairs as being that mentioned
above, it is by no means clear whether we have in _Sphecodes_ bees that are
abandoning the parasitic habit or commencing it; or, indeed, whether the
condition of uncertainty may not be a permanent one. It is difficult to
decide as to what forms are species in _Sphecodes_ owing to the great
variation. The Hymenopterist Forster considered that 600 specimens
submitted to him by Sichel represented no less than 140 species, though
Sichel was convinced that nearly the whole of them were one species, _S.
gibbus_. It has recently been found that the male sexual organs afford a
satisfactory criterion. The position of _Sphecodes_ in classification is
doubtful.
[Illustration: Fig. 11.—_Sphecodes gibbus_ ♀. Britain.]
The great majority of the species of short-tongued bees found in Britain
belong to the genera _Andrena_ and _Halictus_, and with some others
constitute the Andrenides of many writers. _Halictus_ includes our smallest
British bees. Their economy escaped the earlier observers, but has recently
been to some extent unravelled by Smith, Fabre, Nicolas, Verhoeff, and
others, and proves to be {24}of great interest and variety. Fabre observed
_H. lineolatus_ and _H. sexcinctus_[23] under circumstances that enabled
him to give them continuous attention, whenever requisite, throughout a
whole year. These bees are to a certain extent social; they are gregarious;
each bee works for its own progeny, but there is collaboration between
members of a colony, inasmuch as a piece of general work is undertaken from
which more families than one derive benefit. This common work is a gallery,
that, ramifying in the earth, gives access to various groups of cells, each
group the production of a single _Halictus_; in this way one entrance and
one corridor serve for several distinct dwellings. The work of excavation
is carried on at night. The cells are oval, and are covered on the interior
with a delicate waterproof varnish; Fabre considers this to be a product of
the salivary glands, like the membrane we noticed when speaking of
_Colletes_. In the south of France both sexes of these species are produced
from the nests in September, and then the males are much more numerous than
the females; when the cold weather sets in the males die, but the females
continue to live on in the cells underground. In the following spring the
females come out and recommence working at the burrows, and also provision
the cells for the young; the new generation, consisting entirely of
females, appears in July, and from these there proceeds a parthenogenetic
generation, which assumes the perfect form in September, and consists, as
we have above remarked, in greater part of males. Pérez,[24] however,
considers that Fabre's observations as to the parthenogenetic generation
were incomplete, and that males might have been found a little earlier, and
he consequently rejects altogether the occurrence of parthenogenesis in
_Halictus_. Nicolas confirms Fabre's observations, so far as the
interesting point of the work done for common benefit is concerned; and
adds that the common corridor being too narrow to permit of two bees
passing, there is a dilatation or vestibule near the entrance that
facilitates passage, and also that a sentinel is stationed at this point.
Smith's observations on _Halictus morio_ in England lead one to infer that
there is but one generation, the appearance of which extends over a very
long period. He says, "Early in April the females appeared, and continued
in numbers up to the end of {25}June"; then there was an interval, and in
the middle of August males began to appear, followed in ten or twelve days
by females. Hence it is probable that in different countries the times of
appearance and the number of generations of the same species may vary.
Verhoeff has described the burrows of _Halictus quadricinctus_ with some
detail. The cells, instead of being distributed as usual throughout the
length of the burrow one by one, are accumulated into a mass placed in a
vault communicating with the shaft. This shaft is continued downwards to a
depth of 10 cm., and forms a retreat for the bees when engaged in
construction. Several advantages are secured by this method, especially
better ventilation, and protection from any water that may enter the shaft.
The larvae that are present in the brood-chambers at any one moment differ
much in their ages, a fact that throws some doubt on the supposed
parthenogenetic generation. No cocoons are formed by these _Halictus_, the
polished interior of the cell being a sufficiently refined resting place
for metamorphosis. Verhoeff states that many of the larvae are destroyed by
mouldiness; this indeed, he considers to be the most deadly of the enemies
of Aculeate Hymenoptera. The nest of _Halictus maculatus_ has also been
briefly described by Verhoeff, and is a very poor construction in
comparison with that of _H. quadricinctus_.
[Illustration: Fig. 12—Nesting of _Halictus quadricinctus_. _u_, Original
burrow, with entrance _e_ thereto; _n_, retreat or continuation of the
burrow; _w_, the vaults; _s_, the accumulation of cells. (After Verhoeff,
_Verh. Ver. Rheinl._ xlviii. 1891; scale not mentioned.)]
The genus _Andrena_ includes a great number of species, Britain possessing
about fifty. They may be described in a general manner as Insects much
resembling the honey-bee—for which, indeed, they are frequently
mistaken—but usually a little smaller in size. Many of the bees we see in
spring, in March or April, are of this genus. They live in burrows in the
ground, preferring sandy places, but frequently selecting a gravel path as
the locality for their operations; they nearly always live {26}in colonies.
Great difficulties attend their study on account of several points in their
economy, such as, that the sexes are different, and frequently not found
together; also that there may be two generations of a species in one year,
these being more or less different from one another. Another considerable
difficulty arises from the fact that these bees are subject to the attacks
of the parasite _Stylops_, by which their form is more or less altered.
These Insects feed in the body of the bee in such a way as to affect its
nutrition without destroying its life; hence they offer a means of making
experiments that may throw valuable light on obscure physiological
questions. Among the effects they produce in the condition of the imago bee
we may mention the enfeeblement of the sexual distinction, so that a
stylopised male bee becomes less different than it usually is from the
female, and a stylopised female may be ill developed and less different
than usual from the male. The colours and hair are sometimes altered, and
distortion of portions of the abdominal region of the bee are very common.
Further particulars as to these parasites will be found at the end of our
account of Coleoptera (p. 298). We may here remark that these _Stylops_ are
not the only parasitic Insects that live in the bodies of Andrenidae
without killing their hosts, or even interrupting their metamorphoses. Mr.
R. C. L. Perkins recently captured a specimen of _Halictus rubicundus_,
from which he, judging from the appearance of the example, anticipated that
a _Stylops_ would emerge; but instead of this a Dipterous Insect of the
family Chloropidae appeared. Dufour in 1837 called attention to a
remarkable relation existing between _Andrena aterrima_ and a parasitic
Dipterous larva. The larva takes up a position in the interior of the bee's
body so as to be partly included in one of the great tracheal vesicles at
the base of the abdomen; and the bee then maintains the parasite in its
position, and at the same time supplies it with air by causing two tracheae
to grow into its body. Dufour states that he demonstrated the continuity of
the tracheae of the two organisms, but it is by no means clear that the
continuity was initially due to the bee's organisation.
[Illustration: Fig. 13—Parasitic Dipterous larva in connection with
tracheal system of _Andrena aterrima_. (After Dufour.)]
{27}[Illustration: Fig. 14.—_D. hirtipes_ ♀. Britain.]
_Dasypoda hirtipes_ appears to be the most highly endowed of the European
Andrenides. The Insects of the genus _Dasypoda_ are very like _Andrena_,
but have only two in place of three submarginal cells (just beneath the
stigma) on the front wing. The female of _D. hirtipes_ has a very dense and
elongate pubescence on the posterior legs, and carries loads of pollen,
each about half its own weight, to its nest. The habits of this insect have
been described by Hermann Müller.[25] It forms burrows in the ground after
the fashion of _Andrena_; this task is accomplished by excavating with the
mandibles; when it has detached a certain quantity of the earth it brings
this to the surface by moving backwards, and then distributes the loose
soil over a considerable area. It accomplishes this in a most beautiful
manner by means of the combined action of all the legs, each pair of these
limbs performing its share of the function in a different manner; the front
legs acting with great rapidity—making four movements in a second—push the
sand backwards under the body, the bee moving itself at the same time in
this direction by means of the middle pair of legs; simultaneously, but
with a much slower movement, the hind legs are stretched and moved
outwards, in oar-like fashion, from the body, and thus sweep away the earth
and distribute it towards each side. This being done the bee returns
quickly into the hole, excavates some more earth, brings it up and
distributes it. Each operation of excavation takes a minute or two, the
distribution on the surface only about fifteen seconds. The burrow extends
to the length of one or two feet, so that a considerable amount of earth
has to be brought up; and when the Insect has covered one part of the
circumference of the mouth of the hole with loose earth, it makes another
patch, or walk, by the side of the first. The main burrow being completed,
the Insect then commences the formation of brood-chambers in connection
with it. Three to six such chambers are formed in connection with a burrow;
the lower one is first made and is provisioned by the bee: for this
{28}purpose five or six loads of pollen are brought to the cell, each load
being, as we have already remarked, about half the weight of the Insect.
This material is then formed into a ball and made damp with honey; then
another load of pollen is brought, is mixed with honey and added as an
outer layer to the ball, which is now remodelled and provided on one side
with three short feet, after which an egg is placed on the top of the mass;
the bee then sets to work to make a second chamber, and uses the material
resulting from the excavation of this to close completely the first
chamber. The other chambers are subsequently formed in a similar manner,
and then the burrow itself is filled up. While engaged in ascertaining
these facts, Müller also made some observations on the way the bee acts
when disturbed in its operations, and his observations on this point show a
very similar instinct to that displayed by _Chalicodoma_, referred to on a
subsequent page. If interrupted while storing a chamber the Insect will not
attempt to make a fresh one, but will carry its stock of provisions to the
nest of some other individual. The result of this proceeding is a struggle
between the two bees, from which it is satisfactory to learn that the
rightful proprietor always comes out victorious. The egg placed on the
pollen-ball in the chamber hatches in a few days, giving birth to a
delicate white larva of curved form. This creature embraces the pollen-ball
so far as its small size will enable it to do so, and eats the food layer
by layer so as to preserve its circular form. The larva when hatched has no
anal orifice and voids no excrement, so that its food is not polluted; a
proper moulting apparently does not take place, for though a new delicate
skin may be found beneath the old one this latter is not definitely cast
off. When the food, which was at first 100 to 140 times larger than the egg
or young larva, is all consumed the creature then for the first time voids
its refuse. During its growth the larva becomes red and increases in weight
from .0025 grains to .26 or .35 grains, but during the subsequent period of
excretion it diminishes to .09 or .15 grains, and in the course of doing so
becomes a grub without power of movement, and of a white instead of a red
colour. After this the larva reposes motionless for many months—in fact,
until the next summer, when it throws off the larval skin and appears as a
pupa. The larval skin thus cast off contrasts greatly with the previous
delicate {29}condition of the integument, for this last exuvium is thick
and rigid. Although it voids no excrement till much later the union of the
stomach and hind-intestine is accomplished when the larva is half-grown. A
larva, from which Müller took away a portion of its unconsumed food-store,
began directly afterwards to emit excrement. The pupa has greater power of
movement than the resting larva; when it has completed its metamorphosis
and become a perfect Insect, it, if it be a female, commences almost
immediately after its emergence to form burrows by the complex and perfect
series of actions we have described.
PARASITIC BEES (Denudatae).—This group of parasitic bees includes fourteen
European genera, of which six are British. They form a group taxonomically
most unsatisfactory, the members having little in common except the
negative characters of the absence of pollen-carrying apparatus. Although
there is a great dearth of information as to the life-histories of
parasitic bees, yet some highly interesting facts and generalisations about
their relations with their hosts have already been obtained. Verhoeff has
recently given the following account of the relations between the parasitic
bee _Stelis minuta_ and its host _Osmia leucomelana_:—The _Osmia_ forms
cells in blackberry stems, provisions them in the usual manner, and
deposits an egg in each. But the _Stelis_ lays an egg in the store of
provisions before the _Osmia_ does, and thus its egg is placed lower down
in the mass of food than that of the legitimate owner, which is in fact at
the top. The _Stelis_ larva emerges from the egg somewhat earlier than the
_Osmia_ larva does. For a considerable time the two larvae so disclosed
consume together the stock of provisions, the _Osmia_ at the upper, the
_Stelis_ at the lower, end thereof. By the consumption of the provisions
the two larvae are brought into proximity, and by this time the _Stelis_
larva, being about twice the size of the _Osmia_ larva, kills and eats it.
Verhoeff witnessed the struggle between the two larvae, and states further
that the operation of eating the _Osmia_ larva after it has been killed
lasts one or two days. He adds that parasitic larvae are less numerous than
the host larvae, it being well known that parasitic bees produce fewer
offspring than host bees. Verhoeff further states that he has observed
similar relations to obtain between the larvae of other parasitic bees and
their hosts, but warns us against concluding that the facts are analogous
in all cases.
{30}[Illustration: Fig. 15.—_Nomada sex-fasciata_ ♀. Britain.]
Fabre has made us acquainted with some points in the history of another
species of the same genus, viz. _Stelis nasuta_, that show a decided
departure from the habits of _S. minuta_. The first-named Insect
accomplishes the very difficult task of breaking open the cells of the
mason-bee, _Chalicodoma muraria_, after they have been sealed up, and then,
being an Insect of much smaller size than the _Chalicodoma_, places several
eggs in one cell of that bee. Friese informs us that parasitic bees and
their hosts, in a great number of cases, not only have in the perfect state
the tongue similarly formed, but also frequent the same species of flower;
thus _Colletes daviesanus_ and its parasite _Epeolus variegatus_ both
specially affect the flowers of _Tanacetum vulgare_. Some of the parasitic
bees have a great resemblance to their hosts; _Stelis signata_, for
instance, is said to be so like _Anthidium strigatum_ that for many years
it was considered to be a species of the genus _Anthidium_. In other cases
not the least resemblance exists between the parasites and hosts. Thus the
species of _Nomada_ that live at the expense of species of the genus
_Andrena_ have no resemblance thereto. Friese further tells us that the
_Andrena_ and _Nomada_ are on the most friendly terms. _Andrena_, as is
well known, forms populous colonies in banks, paths, etc., and in these
colonies the destroying _Nomada_ flies about unmolested; indeed, according
to Friese, it is treated as a welcome guest. He says he has often seen, and
in several localities, _Nomada lathburiana_ and _Andrena ovina_ flying
peacefully together. The _Nomada_ would enter a burrow, and if it found the
_Andrena_ therein, would come out and try another burrow; if when a
marauding _Nomada_ was in a burrow, and the rightful owner, returning laden
with pollen, found on entering its home that an uninvited guest was
therein, the _Andrena_ would go out in order to permit the exit of the
_Nomada_, and then would again enter and add the pollen to the store.
Strange as this may seem at first sight, it is really not so, for, as we
have before had occasion to observe, there is not the slightest reason for
believing that host Insects have any idea whatever that the parasites or
inquilines are injurious to their {31}race. Why then should they attack the
creatures? Provided the parasites do not interfere in any unmannerly way
with the hosts and their work, there is no reason why the latter should
resent their presence. The wild bee that seals up its cell when it has laid
an egg therein, and then leaves it for ever, has no conception of the form
of its progeny; never in the history of the race of the _Andrena_ has a
larva seen a perfect insect and survived thereafter, never has a perfect
Insect seen a larva. There is no reason whatever for believing that these
Insects have the least conception of their own metamorphosis, and how then
should they have any idea of the metamorphosis of the parasite? If the
_Andrena_ found in the pollen the egg of a parasitic _Nomada_, it could of
course easily remove the egg; but the _Andrena_ has no conception that the
presence of the egg ensures the death of its own offspring and though the
egg be that of an enemy to its race, why should it resent the fact? Is it
not clear that the race has always maintained itself notwithstanding the
enemy? Nature has brought about that both host and parasite should
successfully co-exist; and each individual of each species lives, not for
itself, but for the continuance of the species; that continuance is
provided for by the relative fecundities of host and guest. Why then should
the _Andrena_ feel alarm? If the species of _Nomada_ attack the species of
_Andrena_ too much it brings about the destruction of its own species more
certainly than that of the _Andrena_.
[Illustration: Fig. 16.—_Melecta luctuosa_ ♀. Britain.]
Such extremely friendly relations do not, however, exist between all the
parasitic bees and their hosts. Friese says that, so far as he has been
able to observe, the relations between the two are not in general friendly.
He states that marauders of the genera _Melecta_ and _Coelioxys_ seek to
get out of the way when they see the pollen-laden host coming home. But he
does not appear to have noted any other evidence of mistrust between the
two, and it is somewhat doubtful whether this act can properly be
interpreted as indicating fear, for bees, as well as other animals, when
engaged in work find it annoying to be interfered {32}with; it is the
interest of the parasite to avoid annoyance and to be well-mannered in its
approaches. Shuckard, however, says that battles ensue between the parasite
_Melecta_ and its host _Anthophora_, when the two bees meet in the burrows
of the _Anthophora_.[26]
We shall have occasion to remark on some of the habits of _Dioxys cincta_
when considering the history of the mason-bee (_Chalicodoma_), but one very
curious point in its economy must here be noticed. The _Dioxys_, which is a
much smaller bee than the _Chalicodoma_, lays an egg in a cell of the
latter, and the resulting larva frequently has more food in the cell than
it can consume; there is, however, another bee, _Osmia cyanoxantha_, that
frequently takes advantage of an unoccupied cell in the nest of the
_Chalicodoma_, and establishes its own offspring therein. The _Dioxys_, it
seems, cannot, or at any rate does not, distinguish whether a cell is
occupied by _Chalicodoma_ or by _Osmia_, and sometimes lays its egg in the
nest of the _Osmia_, though this bee is small, and therefore provides very
little food for its young. It might be supposed that under these conditions
the _Dioxys_ larva would be starved to death; but this is not so; it has
the power of accommodating its appetite, or its capacity for metamorphosis,
to the quantity of food it finds at its disposal, and the egg laid in the
_Osmia_ cell actually produces a tiny specimen of _Dioxys_, only about half
the natural size. Both sexes of these dwarf _Dioxys_ are produced, offering
another example of the fact that the quantity of food ingested during the
lifetime of the larva does not influence the sex of the resulting imago.
The highly endowed bees that remain to be considered are by some writers
united in a group called Apidae, in distinction from Andrenidae. For the
purposes of this work we shall adopt three divisions, Scopulipedes,
Dasygastres, Sociales.
The group Scopulipedes includes such long-tongued, solitary bees as are not
parasitic, and do not belong to the Dasygastres. It is not, however, a
natural group, for the carpenter-bees (_Xylocopa_) are very different from
_Anthophora_. It has recently been merged by Friese with Andrenides into a
single group called Podilegidae. Four British genera, _Ceratina_,
_Anthophora_, _Eucera_ and _Saropoda_ (including, however, only seven
{33}species), are referred to the Scopulipedes; in some forms a
considerable resemblance to the Bombi is exhibited, indeed the female of
one of our species of _Anthophora_ is so very like the worker of _Bombus
hortorum_ var. _harrisellus_, that it would puzzle any one to distinguish
them by a superficial inspection, the colour of the hair on the hind legs
being the only obvious difference. _Anthophora_ is one of the most
extensive and widely distributed of the genera of bees. Some of the species
make burrows in cliffs and form large colonies which are continued for many
years in the same locality. Friese has published many details of the
industry and metamorphoses of some of the species of this genus; the most
remarkable point he has discovered being that _A. personata_ at Strasburg
takes two years to accomplish the life-cycle of one generation. Some of the
European species of the genus have been found to be very subject to the
attacks of parasites. An anomalous beetle, _Sitaris_, has been found in the
nests of _A. pilipes_; and this same _Anthophora_ is also parasitised by
another beetle, _Meloe_, as well as by a bee of the genus _Melecta_.
The genus _Xylocopa_[27] contains many of the largest and most powerful of
the bees, and is very widely distributed over the earth. In Europe only
four or five species have been found, and none of them extend far
northwards, _X. violacea_ being the only one that comes so far as Paris.
They are usually black or blue-black in colour, of broad, robust build,
with shining integuments more or less covered with hair. _X. violacea_ is
known as the carpenter-bee from its habit of working in dry wood; it does
not touch living timber, but will form its nest in all sorts of dried wood.
It makes a cylindrical hole, and this gives access to three or four
parallel galleries in which the broad cells are placed; the cells are
always isolated by a partition; the bee forms this by cementing together
with the products of its salivary glands the fragments of wood it cuts out.
Its habits have been described at length by Réaumur, who alludes to it
under the name of "abeille perce-bois." This bee hibernates in the imago
condition, both sexes reappearing in the spring. Possibly there is more
than one generation in the year, as Réaumur states that specimens that were
tiny larvae on the 12th of June had by the 2nd of July consumed all their
stock of provisions; they then fasted for a few days, and on the 7th or 8th
of July became pupae, and in the first {34}days of August were ready to
emerge as perfect Insects. Thus the whole cycle of metamorphoses is passed
through in about eight weeks. This species, though very clever in drilling
holes, does not hesitate to appropriate old burrows should they be at hand.
Fabre observed that it was also quite willing to save itself labour by
forming its cells in hollow reeds of sufficient calibre. We have figured
the larva and pupa of this species in the previous volume (p. 170).
[Illustration: Fig. 17.—_Xylocopa_ (_Koptorthosoma_), sp. near
_flavonigrescens_, ♂. Sarawak.]
_Xylocopa chloroptera_ in E. India selects a hollow bamboo for its nidus;
it cements together the pieces obtained in clearing out the bamboo, and
uses them as horizontal partitions to separate the tube into cells. The
species is much infested with a small Chalcid of the genus _Encyrtus_: 300
specimens of the parasite have been reared from a single larva of the bee;
two-thirds of the larvae of this bee that Horne endeavoured to rear were
destroyed by the little Chalcid.
The most beautiful and remarkable of all the bees are the species of
_Euglossa_. This genus is peculiar to Tropical America, and derives its
name from the great length of the proboscis, which in some species
surpasses that of the body. The colours in _Euglossa_ proper are violet,
purple, golden, and metallic green, and two of these are frequently
combined in the most harmonious manner; the hind tibia is greatly developed
and forms a plate, the outer surface of which is highly polished, while the
margins are furnished with rigid hairs. Very little is known as to the
habits of these bees; they were formerly supposed to be {35}social; but
this is doubtful, Bates having recorded that _E. surinamensis_ forms a
"solitary nest." Lucas concluded that _E. cordata_ is social, on the
authority of a nest containing "a dozen individuals." No workers are known.
The species of _Eulema_ have a shorter tongue than _Euglossa_, and in form
and colour a good deal resemble our species of _Bombus_ and _Apathus_.
The group Dasygastres includes seven European genera, four being British
(_Chelostoma_ being included in _Heriades_). The ventral surface of the
hind body is densely set in the females with regularly arranged hairs, by
means of which the pollen is carried. In many of the Dasygastres
(_Megachile_, _e.g._) the labrum is very large, and in repose is inflected
on to the lower side of the head, and closely applied to the doubled-in
tongue, which it serves to protect; the mandibles then lock together
outside the labrum, which is thus completely concealed. This group includes
some of the most interesting of the solitary bees.
[Illustration: Fig. 18.—_Euglossa cordata_, ♂. Amazons. A, The Insect with
extended proboscis; B, outer face of hind tibia and tarsus.]
The genus _Chalicodoma_ is not found in our own country, but in the South
of France there exist three or four species. Their habits have given rise
to much discussion, having been described by various naturalists, among
whom are included Réaumur and Fabre. These Insects are called mason-bees,
and construct nests of very solid masonry. _C. muraria_ is in appearance
somewhat intermediate between a honey-bee and a _Bombus_; it is densely
hairy, and the sexes are very different in colour. It is solitary in its
habits, and usually chooses a large stone as a solid basis for its
habitation. On this a cell is formed, the material used being a kind of
cement made by the Insect from the mixture of a {36}suitable sort of earth
with the material secreted by its own salivary glands; the amount of cement
used is reduced by the artifice of building small stones into the walls of
the cell; the stones are selected with great care. When a cell about an
inch in depth has been formed in this manner, the bee commences to fill it
with food, consisting of honey and pollen; a little honey is brought and is
discharged into the cell, then some pollen is added. This bee, like other
Dasygastres, carries the pollen by means of hairs on the under surface of
the body; to place this pollen in the cell the Insect therefore enters
backwards, and then with the pair of hind legs brushes and scrapes the
under surface of the body so as to make the pollen fall off into the cell;
it then starts for a fresh cargo; after a few loads have been placed in the
receptacle, the Insect mixes the honey and pollen into a paste with the
mandibles, and again continues its foraging until it has about half filled
the cell; then an egg is laid, and the apartment is at once closed with
cement. This work is all accomplished, if the weather be favourable, in
about two days, after which the Insect commences the formation of a second
cell, joined to the first, and so on till eight or nine of these
receptacles have been constructed; then comes the final operation of adding
an additional protection in the shape of a thick layer of mortar placed
over the whole; the construction, when thus completed, forms a sort of dome
of cement about the size of half an orange. In this receptacle the larvae
pass many months, exposed to the extreme heat of summer as well as to the
cold of winter. The larvae, however, are exposed to numerous other perils;
and we have already related (vol. v. p. 540) how _Leucospis gigas_ succeeds
in perforating the masonry and depositing therein an egg, so that a
_Leucospis_ is reared in the cell instead of a _Chalicodoma_.
[Illustration: Fig. 19—_Chalicodoma muraria_. Greece. A, Male; B, female.]
{37}This Insect has been the object of some of J. H. Fabre's most
instructive studies on instinct.[28] Although it is impossible for us here
to consider in a thorough manner the various points he has discussed, yet
some of them are of such interest and importance as to demand something
more than a passing allusion.
We have mentioned that the nest of _Chalicodoma_ is roofed with a layer of
solid cement in addition to the first covering with which the bee seals up
each cell. When the metamorphoses of the imprisoned larva have been passed
through, and the moment for its emergence as a perfect Insect has arrived,
the prisoner has to make its way through the solid wall by which it is
encompassed. Usually it finds no difficulty in accomplishing the task of
breaking through the roof, so that the powers of its mandibles must be very
great. Réaumur has, however, recorded that a nest of this mason-bee was
placed under a glass funnel, the orifice of which was covered with gauze,
and that the Insects when they emerged from the nest were unable to make
their way through the gauze, and consequently perished under the glass
cover; and he concluded that such insects are only able to accomplish the
tasks that naturally fall to their lot. By some fresh experiments Fabre,
however, has put the facts in a different light. He remarks that when the
Insects have, in the ordinary course of emergence, perforated the walls of
their dark prison, they find themselves in the daylight, and at liberty to
walk away; when they have made their escape from a nest placed under a
glass cover, they, having no knowledge of glass, find themselves in
daylight and imprisoned by the glass, which, to their inexperience, does
not appear to be an obstacle, and they therefore, he thought, might perhaps
exhaust themselves in vain efforts to pass through this invisible obstacle.
He therefore took some cocoons containing pupae from a nest, placed each
one of them in a tube of reed, and stopped the ends of the reeds with
various substances, in one case earth, in another pith, in a third brown
paper; the reeds were then so arranged that the Insects in them were in a
natural position; in due course all the Insects emerged, none of them
apparently having found the novel nature of the obstacle a serious
impediment. Some complete nests were then taken with their inmates, and to
the exterior of one of them a sheet of opaque paper was closely fastened,
while to another the same {38}sort of paper was applied in the form of a
dome, leaving thus a considerable space between the true cover of the nest
and the covering of paper. From the first nest the Insects made their
escape in the usual manner, thus again proving that paper can be easily
pierced by them. From the second nest they also liberated themselves, but
failed to make their way out through the dome of paper, and perished
beneath it; thus showing that paper added to the natural wall caused them
no difficulty, but that paper separated therefrom by a space was an
insuperable obstacle. Professor Pérez has pointed out that this is no doubt
due to the large space offered to the bee, which consequently moves about,
and does not concentrate its efforts on a single spot, as it of course is
compelled to do when confined in its natural cell.
The power of the mason-bee to find its nest again when removed to a
distance from it is another point that was tested by Du Hamel and recounted
by Réaumur. As regards this Fabre has also made some very valuable
observations. He marked some specimens of the bee, and under cover removed
them to a distance of four kilometres, and then liberated them; the result
proved that the bees easily found their way back again, and indeed were so
little discomposed by the removal that they reached their nests laden with
pollen as if they had merely been out on an ordinary journey. On one of
these occasions he observed that a _Chalicodoma_, on returning, found that
another bee had during her absence taken possession of her partially
completed cell, and was unwilling to relinquish it; whereupon a battle
between the two took place. The account of this is specially interesting,
because it would appear that the two combatants did not seek to injure one
another, but were merely engaged in testing, as it were, which was the more
serious in its claims to the proprietorship of the cell in dispute. The
matter ended by the original constructor regaining and retaining
possession. Fabre says that in the case of _Chalicodoma_ it is quite a
common thing for an uncompleted cell to be thus appropriated by a stranger
during the absence of the rightful owner, and that after a scene of the
kind described above, the latter of the two claimants always regains
possession, thus leading one to suppose that some sense of rightful
ownership exists in these bees; the usurper expressing, as it were, by its
actions the idea—Before I {39}resign my claims I must require you to go
through the exertions that will prove you to be really the lawful owner.
Another experiment was made with forty specimens of _Chalicodoma
pyrenaica_, which were removed to a distance of four kilometres and then
liberated. About twenty of the individuals had been somewhat injured by the
processes of capturing, marking, and transferring, and proved unable to
make a proper start. The others went off well when released, and in forty
minutes the arrivals at the nest had already commenced. The next morning he
was able to ascertain that fifteen at least had found their way back, and
that it was probable that most of the uninjured bees had reached home; and
this although, as Fabre believed, they had never before seen the spot where
he liberated them.
These observations on the power of _Chalicodoma_ to regain its nest
attracted the attention of Charles Darwin, who wrote to M. Fabre, and
suggested that further observations should be made with the view of
ascertaining by means of what sense these bees were able to accomplish
their return. For it must be borne in mind that this bee is very different
from the domestic bee, inasmuch as it enjoys but a brief life in the winged
state, and it is therefore to be presumed that an individual has no
knowledge of such comparatively distant localities as those to which Fabre
transported it. Further observations made by the Frenchman have
unfortunately failed to throw any light on this point. Darwin thought it
might possibly be some sensitiveness to magnetic conditions that enabled
the bees to return home, and suggested that they should be tested as to
this. Fabre accordingly made some minute magnets, and fixed one to each bee
previous to letting them loose for a return journey. This had the effect of
completely deranging the bees; and it was therefore at first thought that
the requisite clue was obtained. It occurred to the experimenter, however,
to try the plan of affixing small pieces of straw to the bees instead of
magnets, and on this being done it was found that the little creatures were
just as much deranged by the straws as they were by the magnets: thus it
became evident that no good grounds exist for considering that the bees are
guided by magnetic influences.
One of the species[29] of _Chalicodoma_ observed by Fabre fixes {40}its
nests to the small boulders brought down and left by the Rhone on the waste
places of its banks. This habit afforded Fabre an opportunity of removing
the nests during the process of construction, and of observing the effect
this produced on the architects. While a bee that had a nest partially
constructed was absent, he removed the stone and the nest attached to it
from one situation to another near at hand and visible from the original
site. In a few minutes the bee returned and went straight to the spot where
the nest had been; finding its home absent it hovered for a little while
around the place, and then alighted on the vacated position, and walked
about thereon in search of the nest; being after some time convinced that
this was no longer there, it took wing, but speedily returned again to the
place and went through the same operations. This series of manoeuvres was
several times repeated, the return always being made to the exact spot
where the nest had been originally located; and although the bee in the
course of its journeys would pass over the nest at a distance of perhaps
only a few inches, it did not recognise the object it was in search of. If
the nest were placed very near to the spot it had been removed from—say at
a distance of about a yard—it might happen that the bee would actually come
to the stone to which the nest was fixed, would visit the nest, would even
enter into the cell it had left partially completed, would examine
circumspectly the boulder, but would always leave it, and again return to
the spot where the nest was originally situated, and, on finding that the
nest was not there, would take its departure altogether from the locality.
The home must be, for the bee, in the proper situation, or it is not
recognised as the desired object. Thus we are confronted with the strange
fact that the very bee that is able to return to its nest from a distance
of four kilometres can no longer recognise it when removed only a yard from
the original position. This extraordinary condition of the memory of the
Insect is almost inconceivable by us. That the bee should accurately
recognise the spot, but that it should not recognise the cell it had itself
just formed and half-filled with honey-paste, seems to us almost
incredible; nevertheless, the fact is quite consistent with what we shall
subsequently relate in the case of the solitary wasp _Bembex_. A cross
experiment was made by taking away the stone with the attached nest of the
bee while the latter {41}was absent, and putting in its place the nest of
another individual in about the same stage of construction; this nest was
at once adopted by the bee, which indeed was apparently in no way deranged
by the fact that the edifice was the work of another. A further experiment
was made by transposing the positions of two nests that were very near
together, so that each bee when returning might be supposed to have a free
choice as to which nest it would go to. Unhesitatingly each bee selected
the nest that, though not its own, was in the position where its own had
been. This series of experiments seems to prove that the _Chalcidoma_ has
very little sense as to what is its own property, but, on the other hand,
has a most keen appreciation of locality. As, however, it might be supposed
that the bees were deceived by the similarity between the substituted
nests, Fabre transposed two nests that were extremely different, one
consisting of many cells, the other of a single incomplete cell; it was, of
course, a necessary condition of this experiment that each of the two
nests, however different in other respects, should possess one cell each in
similar stages of construction; and when that was the case each bee
cheerfully adopted the nest that, though very different to its own, was in
the right place. This transposition of nests can be rapidly repeated, and
thus the same bee may be made to go on working at two different nests.
Suppose, however, that another sort of change be made. Let a nest,
consisting of a cell that is in an early stage of construction, be taken
away, and let there be substituted for it a cell built and partially stored
with food. It might be supposed that the bee would gladly welcome this
change, for the adoption of the substituted cell would save it a great deal
of work. Not so, however; the bee in such a case will take to the
substituted cell, but will go on building at it although it is already of
the full height, and will continue building at it until the cell is made as
much as a third more than the regulation height. In fact the bee, being in
the building stage of its operations, goes on building, although in so
doing it is carrying on a useless, if not an injurious, work. A similar
state ensues when the Insect ceases to build and begins to bring provisions
to the nest; although a substituted cell may contain a sufficient store of
food, the bee goes on adding to this, though it is wasting its labours in
so doing. It should be noted that though the bee must go through the
{42}appropriate stages of its labours whether the result of so doing be
beneficial or injurious, yet it is nevertheless to some extent controlled
by the circumstances, for it does not in such cases complete what should
have been the full measure of its own individual work; it does not, for
instance, raise the cell to twice the natural height, but stops building
when the cell is about one-third larger than usual, as if at that stage the
absurdity of the situation became manifest to it.
Fabre's experiments with the _Chalicodoma_ are so extremely instructive as
regards the nature of instinct in some of the highest Insects, that we must
briefly allude to some other of his observations even at the risk of
wearying the reader who feels but little interest in the subject of Insect
intelligence.
Having discovered that a mason-bee that was engaged in the process of
construction would go on building to an useless or even injurious extent,
Fabre tried another experiment to ascertain whether a bee that was engaged
in the process of provisioning the nest, would do so in conditions that
rendered its work futile. Taking away a nest with completely built cell
that a bee was storing with food, he substituted for it one in which the
cell was only commenced, and therefore incapable of containing food; when
the bee with its store of provisions reached this should-be receptacle it
appeared to be very perplexed, tested the imperfect cell with its antennae,
left the spot and returned again; repeating this several times it finally
went to the cell of some stranger to deposit its treasure. In other cases
the bee broke open a completed cell, and having done so went on bringing
provisions to it, although it was already fully provisioned and an egg laid
therein: finally, the little creature having completed the bringing of this
superfluous tale of provisions, deposited a second egg, and again sealed up
the cell. But in no case does the bee go back from the provisioning stage
to the building stage until the cycle for one cell of building,
provisioning, and egg-laying is completed: but when this is the case, the
building of a fresh cell may be again undertaken. This is a good example of
the kind of consecutive necessity that seems to be one of the chief
features of the instinct of these industrious little animals. Another
equally striking illustration of these peculiarities of instinct is offered
by interfering with the act of putting the provisions into the cell. It
will be recollected that {43}when the bee brings provisions to add to the
stock, it carries both honey and pollen; in order to deliver these it
begins by entering head first into the cell and disgorging the honey, then
emerging it turns round, enters backwards and scrapes off the pollen from
its body. If after the honey has been discharged, the bee be interfered
with and gently removed to a slight distance with a straw, it returns to
complete its task, but instead of going on with the actions at the point at
which the interruption took place, it begins the series over again, going
in—at any rate partially—head first, although it has no honey to discharge,
and having performed this useless ceremony it then emerges, turns round and
adds the pollen. This illustration is in some respects the reverse of what
might have been expected, for the Insect here does not continue the act at
the interrupted point, but begins the series of actions afresh.
It would be reasonable to suppose that an Insect that takes the pains to
provide for the safety of its progeny by constructing a complex edifice of
cement, secures thereby the advantage of protection for its young. But this
is far from being the case. Notwithstanding the cement and the thick dome
of mortar, the _Chalicodoma_ is extremely subject to the attacks of
parasites. The work performed by the creature in constructing its mass of
masonry is truly astounding; Fabre calculated from measurements he made
that for the construction and provisioning of a single cell, the goings and
comings of the bee amounted to 15 kilometres, and it makes for each nest
sometimes as many as fifteen cells. Notwithstanding all this labour, it
would appear that no real safety for the larvae is obtained by the work.
Some sixteen—possibly more—other species of Insects get their living off
this industrious creature. Another bee, _Stelis nasuta_, breaks open the
cells after they have been completely closed and places its own eggs in
them, and then again closes the cells with mortar. The larvae of this
_Stelis_ develop more rapidly than do those of the _Chalicodoma_, so that
the result of this shameless proceeding is that the young one of the
legitimate proprietor—as we human beings think it—is starved to death, or
is possibly eaten up as a dessert by the _Stelis_ larvae, after they have
appropriated all the pudding.
Another bee, _Dioxys cincta_, is even more audacious; it flies about in a
careless manner among the _Chalicodoma_ at their {44}work, and they do not
seem to object to its presence unless it interferes with them in too
unmannerly a fashion, when they brush it aside. The _Dioxys_, when the
proprietor leaves the cell, will enter it and taste the contents; after
having taken a few mouthfuls the impudent creature then deposits an egg in
the cell, and, it is pretty certain, places it at or near the bottom of the
mass of pollen, so that it is not conspicuously evident to the
_Chalicodoma_ when the bee again returns to add to or complete the stock of
provisions. Afterwards the constructor deposits its own egg in the cell and
closes it. The final result is much the same as in the case of the
_Stelis_, that is to say, the _Chalicodoma_ has provided food for an
usurper; but it appears probable that the consummation is reached in a
somewhat different manner, namely, by the _Dioxys_ larva eating the egg of
the _Chalicodoma_, instead of slaughtering the larva. Two of the
Hymenoptera Parasitica are very destructive to the _Chalicodoma_, viz.
_Leucospis gigas_ and _Monodontomerus nitidus_; the habits of which we have
already discussed (vol. v. p. 543) under Chalcididae. Lampert has given a
list of the Insects attacking the mason-bee or found in its nests;
altogether it would appear that about sixteen species have been recognised,
most of which destroy the bee larva, though some possibly destroy the bee's
destroyers, and two or three perhaps merely devour dead examples of the
bee, or take the food from cells, the inhabitants of which have been
destroyed by some untoward event. This author thinks that one half of the
bees' progeny are made away with by these destroyers, while Fabre places
the destruction in the South of France at a still higher ratio, telling us
that in one nest of nine cells, the inhabitants of three were destroyed by
the Dipterous Insect, _Anthrax trifasciata_, of two by _Leucospis_, of two
by _Stelis_, and of one by the smaller Chalcid; there being thus only a
single example of the bee that had not succumbed to one or other of the
enemies. He has sometimes examined a large number of nests without finding
a single one that had not been attacked by one or other of the parasites,
and more often than not several of the marauders had attacked the nest.
It is said by Lampert and others that there is a passage in Pliny relating
to one of the mason-bees, that the Roman author had noticed in the act of
carrying off stones to build into its nest; being unacquainted with the
special habits of the bee, he {45}seems to have supposed that the insect
was carrying the stone as ballast to keep itself from being blown away.
[Illustration: Fig. 20—_Anthidium manicatum_, Carder-bee. A, Male; B,
female.]
The bees of the genus _Anthidium_ are known to possess the habit of making
nests of wool or cotton, that they obtain from plants growing at hand. We
have one species of this genus of bees in Britain; it sometimes may be seen
at work in the grounds of our Museum at Cambridge: it is referred to by
Gilbert White, who says of it, in his _History of Selborne_: "There is a
sort of wild bee frequenting the garden-campion for the sake of its
tomentum, which probably it turns to some purpose in the business of
nidification. It is very pleasant to see with what address it strips off
the pubes, running from the top to the bottom of a branch, and shaving it
bare with the dexterity of a hoop-shaver. When it has got a bundle, almost
as large as itself, it flies away, holding it secure between its chin and
its fore legs." The species of this genus are remarkable as forming a
conspicuous exception to the rule that in bees the female is larger than
the male. The species of _Anthidium_ do not form burrows for themselves,
but either take advantage of suitable cavities formed by other Insects in
wood, or take possession of deserted nests of other bees or even empty
snail-shells. The workers in cotton, of which our British species _A.
manicatum_ is one, line the selected receptacle with a beautiful network of
cotton or wool, and inside this place a finer layer of the material, to
which is added some sort of cement that prevents the honied mass stored by
the bees in this receptacle from passing out of it. _A. diadema_, one of
the species that form nests in hollow stems, has been specially observed by
Fabre; it will take the cotton for {46}its work from any suitable plant
growing near its nest, and does not confine itself to any particular
natural order of plants, or even to those that are indigenous to the South
of France. When it has brought a ball of cotton to the nest, the bee
spreads out and arranges the material with its front legs and mandibles,
and presses it down with its forehead on to the cotton previously
deposited; in this way a tube of cotton is constructed inside the reed;
when withdrawn, the tube proved to be composed of about ten distinct cells
arranged in linear fashion, and connected firmly together by means of the
outer layer of cotton; the transverse divisions between the chambers are
also formed of cotton, and each chamber is stored with a mixture of honey
and pollen. The series of chambers does not extend quite to the end of the
reed, and in the unoccupied space the Insect accumulates small stones,
little pieces of earth, fragments of wood or other similar small objects,
so as to form a sort of barricade in the vestibule, and then closes the
tube by a barrier of coarser cotton taken frequently from some other plant,
the mullein by preference. This barricade would appear to be an ingenious
attempt to keep out parasites, but if so, it is a failure, at any rate as
against _Leucospis_, which insinuates its eggs through the sides, and
frequently destroys to the last one the inhabitants of the fortress. Fabre
states that these _Anthidium_, as well as _Megachile_, will continue to
construct cells when they have no eggs to place in them; in such a case it
would appear from his remarks that the cells are made in due form and the
extremity of the reed closed, but no provisions are stored in the chambers.
The larva of the _Anthidium_ forms a most singular cocoon. We have already
noticed the difficulty that arises, in the case of these Hymenopterous
larvae shut up in small chambers, as to the disposal of the matters
resulting from the incomplete assimilation of the aliment ingested. To
allow the once-used food to mingle with that still remaining unconsumed
would be not only disagreeable but possibly fatal to the life of the larva.
Hence some species retain the whole of the excrement until the food is
entirely consumed, it being, according to Adlerz, stored in a special pouch
at the end of the stomach; other Hymenoptera, amongst which we may mention
the species of _Osmia_, place the excreta in a vacant space. The
_Anthidium_ adopts, however, a most remarkable system: about the middle of
its {47}larval life it commences the expulsion of "frass" in the shape of
small pellets, which it fastens together with silk, as they are voided, and
suspends round the walls of the chamber. This curious arrangement not only
results in keeping the embarrassing material from contact with the food and
with the larva itself, but serves, when the growth of the latter is
accomplished, as the outline or foundations of the cocoon in which the
metamorphosis is completed. This cocoon is of a very elaborate character;
it has, so says Fabre, a beautiful appearance, and is provided with a very
peculiar structure in the form of a small conical protuberance at one
extremity pierced by a canal. This canal is formed with great care by the
larva, which from time to time places its head in the orifice in process of
construction, and stretches the calibre by opening the mandibles. The
object of this peculiarity in the fabrication of the elaborate cocoon is
not clear, but Fabre inclines to the opinion that it is for respiratory
purposes.
Other species of this genus use resin in place of cotton as their working
material. Among these are _Anthidium septemdentatum_ and _A. bellicosum_.
The former species chooses an old snail-shell as its nidus, and constructs
in it near the top a barrier of resin, so as to shut off the part where the
whorl is too small; then beneath the shelter of this barrier it accumulates
a store of honey-pollen, deposits an egg, and completes the cell by another
transverse barrier of resin; two such cells are usually constructed in one
snail-shell, and below them is placed a barricade of small miscellaneous
articles, similar to what we have described in speaking of the
cotton-working species of the genus. This bee completes its metamorphosis,
and is ready to leave the cell in early spring. Its congener, _A.
bellicosum_, has the same habits, with the exception that it works later in
the year, and is thus exposed to a great danger, that very frequently
proves fatal to it. This bee does not completely occupy the snail-shell
with its cells, but leaves the lower and larger portion of the shell
vacant. Now, there is another bee, a species of _Osmia_, that is also fond
of snail-shells as a nesting-place, and that affects the same localities as
the _A. septemdentatum_; very often the _Osmia_ selects for its nest the
vacant part of a shell, the other part of which is occupied by the
_Anthidium_; the result of this is that when the metamorphoses are
completed, the latter bee is unable to effect its escape, and {48}thus
perishes in the cell. Fabre further states with regard to these interesting
bees, that no structural differences of the feet or mandibles can be
detected between the workers in cotton and the workers in resin; and he
also says that in the case where two cells are constructed in one
snail-shell, a male individual is produced from the cell of the greater
capacity, and a female from the other.
_Osmia_ is one of the most important of the genera of bees found in Europe,
and is remarkable for the diversity of instinct displayed in the formation
of the nests of the various species. As a rule they avail themselves for
nidification of hollow places already existing; choosing excavations in
wood, in the mortar of walls, and even in sandbanks; in several cases the
same species is found to be able to adapt itself to more than one kind of
these very different substances. This variety of habit will render it
impossible for us to do justice to this interesting genus within the space
at our disposal, and we must content ourselves with a consideration of one
or two of the more instructive of the traits of _Osmia_ life. _O.
tridentata_ forms its nest in the stems of brambles, of which it excavates
the pith; its mode of working and some other details of its life have been
well depicted by Fabre. The Insect having selected a suitable bramble-stalk
with a cut extremity, forms a cylindrical burrow in the pith thereof,
extending the tunnel as far as will be required to allow the construction
of ten or more cells placed one after the other in the axis of the
cylinder; the bee does not at first clear out quite all the pith, but
merely forms a tunnel through it, and then commences the construction of
the first cell, which is placed at the end of the tunnel that is most
remote from the entrance. This cavity is to be of oval form, and the Insect
therefore cuts away more of the pith so as to make an oval space, but
somewhat truncate, as it were, at each end, the plane of truncation at the
proximal extremity being of course an orifice.
[Illustration: Fig. 21.—_Osmia tricornis_, ♀. Algeria.]
{49}The first cell thus made is stored with pollen and honey, and an egg is
deposited. Then a barrier has to be constructed to close this chamber; the
material used for the barrier is the pith of the stem, and the Insect cuts
the material required for the purpose from the walls of the second chamber;
the excavation of the second chamber is, in fact, made to furnish the
material for closing up the first cell. In this way a chain of cells is
constructed, their number being sometimes as many as fifteen. The mode in
which the bees, when the transformations of the larvae and pupae have been
completed, escape from the chain of cells, has been the subject of much
discussion, and errors have arisen from inference being allowed to take the
place of observation. Thus Dufour, who noted this same mode of construction
and arrangement in another Hymenopteron (_Odynerus nidulator_), perceived
that there was only one orifice of exit, and also that the Insect that was
placed at the greatest distance from this was the one that, being the
oldest of the series, might be expected to be the first ready to emerge;
and as the other cocoons would necessarily be in the way of its getting
out, he concluded that the egg that was last laid produced the first Insect
ready for emergence. Fabre tested this by some ingenious experiments, and
found that this was not the case, but that the Insects became ready to
leave their place of imprisonment without any reference to the order in
which the eggs were laid, and he further noticed some very curious facts
with reference to the mode of emergence of _Osmia tridentata_. Each Insect,
when it desires to leave the bramble stem, tears open the cocoon in which
it is enclosed, and also bites through the barrier placed by the mother
between it and the Insect that is next it, and that separates it from the
orifice of exit. Of course, if it happen to be the outside one of the
series it can then escape at once; but if it should be one farther down in
the Indian file it will not touch the cocoon beyond, but waits patiently,
possibly for days; if it then still find itself confined it endeavours to
escape by squeezing past the cocoon that intervenes between it and liberty,
and by biting away the material at the sides so as to enlarge the passage;
it may succeed in doing this, and so get out, but if it fail to make a side
passage it will not touch the cocoons that are in its way. In the ordinary
course of events, supposing all to go well with the family, all the cocoons
produce their inmates in a state for emergence within {50}a week or two,
and so all get out. Frequently, however, the emergence is prevented by
something having gone wrong with one of the outer Insects, in which case
all beyond it perish unless they are strong enough to bite a hole through
the sides of the bramble-stem. Thus it appears that whether a particular
_Osmia_ shall be able to emerge or not depends on two things—(1) whether
all goes well with all the other Insects between it and the orifice, and
(2) whether the Insect can bite a lateral hole or not; this latter point
also largely depends on the thickness of the outer part of the stem of the
bramble. Fabre's experiments on these points have been repeated, and his
results confirmed by Nicolas.
The fact that an _Osmia_ would itself perish rather than attack the cocoon
of its brother or sister is certainly very remarkable, and it induced Fabre
to make some further experiments. He took some cocoons containing dead
specimens of _Osmia_, and placed them in the road of an _Osmia_ ready for
exit, and found that in such case the bee made its way out by demolishing
without any scruple the cocoons and dead larvae that intervened between it
and liberty. He then took some other reeds, and blocked the way of exit
with cocoons containing living larvae, but of another species of
Hymenoptera. _Solenius vagus_ and _Osmia detrita_ were the species
experimented on in this case, and he found that the _Osmia_ destroyed the
cocoon and living larvae of the _Solenius_, and so made its way out. Thus
it appears that _Osmia_ will respect the life of its own species, and die
rather than destroy it, but has no similar respect for the life of another
species.
Some of Fabre's most instructive chapters are devoted to the habits and
instincts of various species of the genus _Osmia_. It is impossible here to
find space even to summarise them, still more impossible to do them
justice; but we have selected the history just recounted, because it is
rare to find in the insect world instances of such self-sacrifice by an
individual for one of the same generation. It would be quite improper to
generalise from this case, however, and conclude that such respect for its
own species is common even amongst the Osmia. Fabre, indeed, relates a case
that offers a sad contrast to the scene of self-sacrifice and respect for
the rights of others that we have roughly portrayed. He was able to induce
a colony of _Osmia tricornis_ (another species of the genus, be it noted)
to establish itself and {51}work in a series of glass tubes that he placed
on a table in his laboratory. He marked various individuals, so that he was
able to recognise them and note the progress of their industrial works.
Quite a large number of specimens thus established themselves and concluded
their work before his very eyes. Some individuals, however, when they had
completed the formation of a series of cells in a glass tube or in a reed,
had still not entirely completed their tale of work. It would be supposed
that in such a case the individual would commence the formation of another
series of cells in an unoccupied tube. This was not, however, the case. The
bee preferred tearing open one or more cells already completed—in some
cases, even by itself—scattering the contents, and devouring the egg; then
again provisioning the cell, it would deposit a fresh egg, and close the
chamber. These brief remarks will perhaps suffice to give some idea of the
variety of instinct and habit that prevails in this very interesting genus.
Friese observes that the variety of habits in this genus is accompanied as
a rule by paucity of individuals of a species, so that in central Europe a
collector must be prepared to give some twenty years or so of attention to
the genus before he can consider he has obtained all the species of _Osmia_
that inhabit his district.
As a prelude to the remarks we are about to make on the leaf-cutting bees
of the genus _Megachile_ it is well to state that the bee, the habits of
which were described by Réaumur under the name of "l'abeille tapissière,"
and that uses portions of the leaves of the scarlet poppy to line its nest,
is now assigned to the genus _Osmia_, although Latreille, in the interval
that has elapsed since the publication of Réaumur's work, founded the genus
_Anthocopa_ for the bee in question. _Megachile_ is one of the most
important of the genera of the Dasygastres, being found in most parts of
the world, even in the Sandwich Islands; it consists of bees averaging
about the size of the honey-bee (though some are considerably larger,
others smaller), and having the labrum largely developed; this organ is
capable of complete inflection to the under side of the head, and when in
the condition of repose it is thus infolded, it underlaps and protects the
larger part of the lower lip; the mandibles close over the infolded labrum,
so that, when the Insect is at rest, this appears to be altogether absent.
These bees are called leaf-cutters, from their habit of forming the cells
for their nest {52}out of pieces of the leaves of plants. We have several
species in Britain; they are very like the common honey-bee in general
appearance, though rather more robustly formed. These Insects, like the
Osmiae, avail themselves of existing hollow places as receptacles in which
to place their nests. _M. albocincta_ frequently takes possession of a
deserted worm-burrow in the ground. The burrow being longer than necessary
the bee commences by cutting off the more distant part by means of a
barricade of foliage; this being done, it proceeds to form a series of
cells, each shaped like a thimble with a lid at the open end (Fig. 22, A).
The body of the thimble is formed of large oval pieces of leaf, the lid of
smaller round pieces; the fragments are cut with great skill from the
leaves of growing plants by the Insect, which seems to have an idea of the
form and size of the piece of foliage necessary for each particular stage
of its work.
[Illustration: Fig. 22—Nidification of leaf-cutting bee, _Megachile
anthracina_. A, one cell separated, with lid open; the larva (_a_) reposing
on the food; B, part of a string of the cells. (After Horne.)]
Horne has given particulars as to the nest of _Megachile anthracina_
(_fasciculata_), an East Indian species.[30] The material employed was
either the leaves of the Indian pulse or of the rose. Long pieces are cut
by the Insect from the leaf, and with these a cell is formed; a circular
piece is next cut, and with this a lid is made for the receptacle. The
cells are about the size and shape of a common thimble; in one specimen
that Horne examined no less than thirty-two pieces of leaf disposed in
seven layers were used for one cell, in addition to three pieces for the
round top. The cells are carefully prepared, and some kind of matter of a
gummy nature is believed to be used to keep in place the pieces forming the
interior layers. The cells are placed end to end, as shown in Fig. 22, B;
five to seven cells form a series, and four or six series are believed to
be constructed by one pair {53}of this bee, the mass being located in a
hollow in masonry or some similar position. Each cell when completed is
half filled with pollen in the usual manner, and an egg is then laid in it.
This bee is much infested by parasites, and is eaten by the Grey Hornbill
(_Meniceros bicornis_).
_Megachile lanata_ is one of the Hymenoptera that in East India enter
houses to build their own habitations. According to Horne both sexes take
part in the work of construction, and the spots chosen are frequently of a
very odd nature. The material used is some kind of clay, and the natural
situation may be considered to be the interior of a hollow tube, such as
the stem of a bamboo; but the barrel of a gun, and the hollow in the back
of a book that has been left lying open, have been occasionally selected by
the Insect as suitable. Smith states that the individuals developed in the
lower part of a tubular series of this species were females, "which sex
takes longer to develop, and thus an exit is not required for them so soon
as for the occupants of the upper cells which are males." _M. proxima_, a
species almost exactly similar in appearance to _M. lanata_, makes its
cells of leaf-cuttings, however, and places them in soft soil.
Fabre states that _M. albocincta_, which commences the formation of its
nest in a worm-burrow by means of a barricade, frequently makes the
barricade, but no nest; sometimes it will indeed make the barricade more
than twice the proper size, and thus completely fill up the worm burrow.
Fabre considers that these eccentric proceedings are due to individuals
that have already formed proper nests elsewhere, and that after completing
these have still some strength remaining, which they use up in this
fruitless manner.
The SOCIAL BEES (Sociales) include, so far as is yet known, only a very
small number of genera, and are so diverse, both in habits and structure,
that the propriety of associating them in one group is more than doubtful;
the genera are _Bombus_ (Fig. 331, vol. v.), with its commensal genus or
section, _Psithyrus_ (Fig. 23); _Melipona_ (Fig. 24), in which _Trigona_
and _Tetragona_ may at present be included, and _Apis_ (Fig. 6); this
latter genus comprising the various honey-bees that are more or less
completely domesticated in different parts of the world.
In the genus _Bombus_ the phenomena connected with the social life are more
similar to what we find among wasps {54}than to what they are in the genus
_Apis_. The societies come to an end at the close of the season, a few
females live through the winter, and each of these starts a new colony in
the following spring. Males, females and workers exist, but the latter are
not distinguished by any good characters from the females, and are, in
fact, nothing but more or less imperfect forms thereof; whereas in _Apis_
the workers are distinguished by structural characters not found in either
of the true sexes.
Hoffer has given a description of the commencement of a society of _Bombus
lapidarius_.[31] A large female, at the end of May, collected together a
small mass of moss, then made an expedition and returned laden with pollen;
under cover of the moss a cell was formed of wax taken from the hind-body
and mixed with the pollen the bee had brought in; this cell was fastened to
a piece of wood; when completed it formed a subspherical receptacle, the
outer wall of which consisted of wax, and whose interior was lined with
honey-saturated pollen; then several eggs were laid in this receptacle, and
it was entirely closed. Hoffer took the completed cell away to use it for
museum purposes, and the following day the poor bee that had formed it
died. From observations made on _Bombus agrorum_ he was able to describe
the subsequent operations; these are somewhat as follows:—The first cell
being constructed, stored, and closed, the industrious architect, clinging
to the cell, takes a few days' rest, and after this interval commences the
formation of a second cell; this is placed by the side of the first, to
which it is connected by a mixture of wax and pollen; the second cell being
completed a third may be formed; but the labours of the constructor about
this time are augmented by the hatching of the eggs deposited a few days
previously; for the young larvae, having soon disposed of the small
quantity of food in the interior of the waxen cell, require feeding. This
operation is carried on by forming a small opening in the upper part of the
cell, through which the bee conveys food to the interior by ejecting it
from her mouth through the hole; whether the food is conveyed directly to
the mouths of the larvae or not, Hoffer was unable to observe; it being
much more difficult to approach this royal founder without disturbing her
than it is the worker-bees that carry on similar occupations at a
subsequent period in the history of the {55}society. The larvae in the
first cell, as they increase in size, apparently distend the cell in an
irregular manner, so that it becomes a knobbed and rugged, truffle-like
mass. The same thing happens with the other cells formed by the queen. Each
of these larval masses contains, it should be noticed, sister-larvae all of
one age; when full grown they pupate in the mass, and it is worthy of
remark that although all the eggs in one larval mass were laid at the same
time, yet the larvae do not all pupate simultaneously, neither do all the
perfect Insects appear at once, even if all are of one sex. The pupation
takes place in a cocoon that each larva forms for itself of excessively
fine silk. The first broods hatched are formed chiefly, if not entirely, of
workers, but small females may be produced before the end of the season.
Huber and Schmiedeknecht state that though the queen provides the
worker-cells with food before the eggs are placed therein, yet no food is
put in the cells in which males and females are produced. The queen, at the
time of pupation of the larvae, scrapes away the wax by which the cocoons
are covered, thus facilitating the escape of the perfect Insect, and, it
may also be, aiding the access of air to the pupa. The colony at first
grows very slowly, as the queen can, unaided, feed only a small number of
larvae. But after she receives the assistance of the first batch of workers
much more rapid progress is made, the queen greatly restricting her
labours, and occupying herself with the laying of eggs; a process that now
proceeds more and more rapidly, the queen in some cases scarcely ever
leaving the nest, and in others even becoming incapable of flight. The
females produced during the intermediate period of the colony are smaller
than the mother, but supplement her in the process of egg-laying, as also
do the workers to a greater or less extent. The conditions that determine
the egg-laying powers of these small females and workers are apparently
unknown, but it is ascertained that these powers vary greatly in different
cases, so that if the true queen die the continuation of the colony is
sometimes effectively carried on by these her former subordinates. In other
cases, however, the reverse happens, and none of the inhabitants may be
capable of producing eggs: in this event two conditions may be present;
either larvae may exist in the nest, or they may be absent. In the former
case the workers provide them with food, and the {56}colony may thus still
be continued; but in the latter case, there being no profitable occupation
for the bees to follow, they spend the greater part of the time sitting at
home in the nest.
Supposing all to go well with the colony it increases very greatly, but its
prosperity is checked in the autumn; at this period large numbers of males
are produced as well as new queens, and thereafter the colony comes to an
end, only a few fertilised females surviving the winter, each one to
commence for herself a new colony in the ensuing spring.
The interior of the nest of a bumble-bee (_Bombus_) frequently presents a
very irregular appearance; this is largely owing to the fact that these
bees do not use the cells as cradles twice, but form others as they may be
required, on the old remains. The cells, moreover, are of different sizes,
those that produce workers being the smallest, those that cradle females
being the largest, while those in which males are reared are intermediate
in size. Although the old cells are not used a second time for rearing
brood they are nevertheless frequently adapted to the purposes of
receptacles for pollen and for honey, and for these objects they may be
increased in size and altered in form.
It may be gathered from various records that the period required to
complete the development of the individual _Bombus_ about midsummer is four
weeks from the deposition of the egg to the emergence of the perfect
Insect, but exact details and information as to whether this period varies
with the sex of the Insect developed are not to be found. The records do
not afford any reason for supposing that such distinction will be found to
exist: the size of the cells appears the only correlation, suggested by the
facts yet known, between the sex of the individual and the circumstances of
development.
The colonies of _Bombus_ vary greatly in prosperity, if we take as the test
of this the number of individuals produced in a colony. They never,
however, attain anything at all approaching to the vast number of
individuals that compose a large colony of wasps, or that exist in the
crowded societies of the more perfectly social bees. A populous colony of a
subterranean _Bombus_ may attain the number of 300 or 400 individuals.
Those that dwell on the surface are as a rule much less populous, as they
are less protected, so that changes of weather are more {57}prejudicial to
them. According to Smith, the average number of a colony of _B. muscorum_
in the autumn in this country is about 120—viz. 25 females, 36 males, 59
workers. No mode of increasing the nests in a systematic manner exists in
this genus; they do not place the cells in stories as the wasps do; and
this is the case notwithstanding the fact that a cell is not twice used for
the rearing of young. When the ground-space available for cell-building is
filled the _Bombus_ begins another series of cells on the ruins of the
first one. From this reason old nests have a very irregular appearance, and
this condition of seeming disorder is greatly increased by the very
different sizes of the cells themselves. We have already alluded to some of
these cells, more particularly to those of different capacities to suit the
sexes of the individuals to be reared in them. In addition to these there
are honey-tubs, pollen-tubs, and the cells of the _Psithyrus_ (Fig. 23),
the parasitic but friendly inmates of the _Bombus_-nests. A nest of
_Bombus_, exhibiting the various pots projecting from the remains of empty
and partially destroyed cells, presents, as may well be imagined, a very
curious appearance. Some of the old cells apparently are partly destroyed
for the sake of the material they are composed of. Others are formed into
honey-tubs, of a make-shift nature. It must be recollected that, as a
colony increases, stores of provisions become absolutely necessary,
otherwise in bad weather the larvae could not be fed. In good weather, and
when flowers abound, these bees collect and store honey in abundance; in
addition to placing it in the empty pupa-cells, they also form for it
special receptacles; these are delicate cells made entirely of wax filled
with honey, and are always left open for the benefit of the community. The
existence of these honey-tubs in bumble-bees' nests has become known to our
country urchins, whose love for honey and for the sport of bee-baiting
leads to wholesale destruction of the nests. According to Hoffer, special
tubs for the storing of pollen are sometimes formed; these are much taller
than the other cells. The _Psithyrus_ that live in the nests with the
_Bombus_ are generally somewhat larger than the latter, and consequently
their cells may be distinguished in the nests by their larger size. A
bumble-bees' nest, composed of all these heterogenous chambers rising out
of the ruins of former layers of cells, presents a scene of such apparent
disorder that {58}many have declared that the bumble-bees do not know how
to build.
Although the species of _Bombus_ are not comparable with the hive-bee in
respect of the perfection and intelligent nature of their work, yet they
are very industrious Insects, and the construction of the dwelling-places
of the subterranean species is said to be carried out in some cases with
considerable skill, a dome of wax being formed as a sort of roof over the
brood cells. Some work even at night. Fea has recorded the capture of a
species in Upper Burmah working by moonlight, and the same industry may be
observed in this country if there be sufficient heat as well as light.
Godart, about 200 years ago, stated that a trumpeter-bee is kept in some
nests to rouse the denizens to work in the morning: this has been treated
as a fable by subsequent writers, but is confirmed in a circumstantial
manner by Hoffer, who observed the performance in a nest of _B. ruderatus_
in his laboratory. On the trumpeter being taken away its office was the
following morning filled by another individual The trumpeting was done as
early as three or four o'clock in the morning, and it is by no means
impossible that the earliness of the hour may have had something to do with
the fact that for 200 years no one confirmed the old naturalist's
observation.
One of the most curious facts in connection with _Bombus_ is the excessive
variation that many of the species display in the colour of the beautiful
hair with which they are so abundantly provided. There is not only usually
a difference between the sexes in this respect, but also extreme variation
within the limits of the same sex, more especially in the case of the males
and workers; there is also an astonishing difference in the size of
individuals. These variations are carried to such an extent that it is
almost impossible to discriminate all the varieties of a species by
inspection of the superficial characters. The structures peculiar to the
male, as well as the sting of the female, enable the species to be
determined with tolerable certainty. Cholodkovsky,[32] on whose authority
this statement as to the sting is made, has not examined it in the workers,
so that we do not know whether it is as invariable in them as he states it
to be in queens of the same species. According to Handlirsch,[33] each
{59}species of _Bombus_ has the capacity of variation, and many of the
varieties are found in one nest, that is, among the offspring of a single
pair of the species, but many of the variations are restricted to certain
localities. Some of the forms can be considered as actual ("fertige")
species, intermediate forms not being found, and even the characters by
which species are recognised being somewhat modified. As examples of this
he mentions _Bombus silvarum_ and _B. arenicola_, _B. pratorum_ and _B.
scrimshiranus_. In other cases, however, the varieties are not so
discontinuous, intermediate forms being numerous; this condition is more
common than the one we have previously described; _B. terrestris_, _B.
hortorum_, _B. lapidarius_ and _B. pomorum_ are examples of these variable
species. The variation runs to a considerable extent in parallel lines in
the different species, there being a dark and a light form of each; also
each species that has a white termination to the body appears in a form
with a red termination, and _vice versa_. In the Caucasus many species that
have everywhere else yellow bands possess them white; and in Corsica there
are species that are entirely black, with a red termination to the body,
though in continental Europe the same species exhibit yellow bands and a
white termination to the body. With so much variation it will be readily
believed that much remains to be done in the study of this fascinating
genus. It is rich in species in the Northern hemisphere, but poor in the
Southern one, and in both the Ethiopian and Australian regions it is
thought to be entirely wanting.
The species of the genus _Psithyrus_ (_Apathus_ of many authors) inhabit
the nests of _Bombus_; although less numerous than the species of the
latter genus, they also are widely distributed. They are so like _Bombus_
in appearance that they were not distinguished from them by the earlier
entomologists; and what is still more remarkable, each species of
_Psithyrus_ resembles the _Bombus_ with which it usually lives. There
appear, however, to be occasional exceptions to this rule, Smith having
seen one of the yellow-banded _Psithyrus_ in the nest of a red-tailed
_Bombus_. _Psithyrus_ is chiefly distinguished from _Bombus_ by the absence
of certain characters that fit the latter Insects for their industrial
life; the hind tibiae have no smooth space for the conveyance of pollen,
and, so far as is known, there are only two sexes, males and perfect
females.
{60}[Illustration: Fig. 23—_Psithyrus vestalis_, Britain. A, Female, x 3/2;
B, outer side of hind leg.]
The _Bombus_ and _Psithyrus_ live together on the best terms, and it
appears probable that the latter do the former no harm beyond appropriating
a portion of their food supplies. Schmiedeknecht says they are commensals,
not parasites; but it must be admitted that singularly few descriptions of
the habits and life-histories of these interesting Insects have been
recorded. Hoffer has, however, made a few direct observations which
confirm, and at the same time make more definite, the vague ideas that have
been generally prevalent among entomologists. He found and took home a nest
of _Bombus variabilis_, which contained also a female of _Psithyrus
campestris_, so that he was able to make observations on the two. The
_Psithyrus_ was much less industrious than the _Bombus_, and only left the
nest somewhat before noon, returning home again towards evening; after
about a month this specimen became still more inactive, and passed entire
days in the nest, occupying itself in consuming the stores of honey of its
hosts, of which very large quantities were absorbed, the _Psithyrus_ being
much larger than the host-bee. The cells in which the young of the
_Psithyrus_ are hatched are very much larger than those of the _Bombus_,
and, it may therefore be presumed, are formed by the _Psithyrus_ itself,
for it can scarcely be supposed that the _Bombus_ carries its complaisance
so far as to construct a cell specially adapted to the superior stature of
its uninvited boarder. When a _Psithyrus_ has been for some time a regular
inhabitant of a nest, the _Bombus_ take its return home from time to time
as a matter of course, displaying no emotion whatever at its entry.
Occasionally Hoffer tried the introduction of a _Psithyrus_ to a nest that
had not previously had one as an inmate. The new arrival caused a great
hubbub among the _Bombus_, which rushed to it as if to attack it, but did
not do so, and the alarm soon subsided, the _Psithyrus_ taking up the
position in the nest usually affected by the individuals of the species. On
{61}introducing a female _Psithyrus_ to a nest of _Bombus_ in which a
_Psithyrus_ was already present as an established guest, the latter
asserted its rights and drove away the new comer. Hoffer also tried the
experiment of placing a _Psithyrus campestris_ in the nest of _Bombus
lapidarius_—a species to which it was a stranger; notwithstanding its haste
to fly away, it was at once attacked by the _Bombus_, who pulled it about
but did not attempt to sting it.
When _Psithyrus_ is present in a nest of _Bombus_ it apparently affects the
inhabitants only by diminishing their stores of food to so great an extent
that the colony remains small instead of largely increasing in numbers.
Although _Bombus variabilis_, when left to itself, increases the number of
individuals in a colony to 200 or more, Hoffer found in a nest in which
_Psithyrus_ was present, that on the 1st of September the assemblage
consisted only of a queen _Bombus_ and fifteen workers, together with
eighteen specimens of the _Psithyrus_, eight of these being females.
The nests of _Bombus_ are destroyed by several animals, probably for the
sake of the honey contained in the pots; various kinds of small mammals,
such as mice, the weasel, and even the fox, are known to destroy them; and
quite a fauna of Insects may be found in them; the relations of these to
their hosts are very little known, but some undoubtedly destroy the bees'
larvae, as in the case of _Meloe_, _Mutilla_ and _Conops_. Birds do not as
a rule attack these bees, though the bee-eater, _Merops apiaster_, has been
known to feed on them very heavily.
The genera of social bees known as _Melipona_, _Trigona_ or _Tetragona_,
may, according to recent authorities, be all included in one genus,
_Melipona_. Some of these Insects are amongst the smallest of bees, so that
one, or more, species go by the name of "Mosquito-bees." The species appear
to be numerous, and occur in most of the tropical parts of the continents
of the world, but unfortunately very little is known as to their
life-histories or economics; they are said to form communities consisting
at times of a countless number of individuals; but it has not been
thoroughly ascertained whether these are the produce of a single queen, as
in the case of the hive-bee, or whether there may be more than one
egg-producer in each community. The late F. Smith thought the former of
these alternatives would prove to be correct. These mosquito-bees are
frequently spoken of as stingless bees, but this is not quite correct, for
although they do not sting, {62}von Ihering[34] says that all the essential
elements of the sting are present, the pointed or penetrating part of the
apparatus being stunted.
It would serve no useful purpose to attempt to construct the social history
of these stingless bees from the numerous brief scattered accounts in
entomological literature, for they refer to different species; it is,
however, positively stated by Smith on the authority of Peckolt[35] that
_Trigona mosquito_ sends off swarms after the manner of the hive-bee in
this country, and that after searching six hives only one royal female
could be found in each.
[Illustration: Fig. 24.—_Melipona_ sp. ♀. Amazons.]
The nests of many of these little bees are rich in honey, and they have a
host of enemies from man and monkeys downwards; and as they do not defend
themselves by stinging, it might be supposed they would have but a poor
time of it. From the accounts that have been published we may, however,
gather that they are rich in devices for the protection of their nests, and
for the exclusion of intruders. Bates has given some particulars as to
_Melipona interrupta_ (_fasciculata_); it is about one-third shorter than
the hive-bee, and its colonies are composed of an immense number of
individuals. The workers are usually occupied in gathering pollen; but they
also collect clay in a similar manner, and convey it to the nest, where it
is used for building a wall to complete the fortification of the nest,
which is placed either in a suitable bank, or in a trunk of a tree; in
either situation it is completely built in with clay. A nest which Bates
saw opened contained about two quarts of pleasantly-tasted liquid honey.
Forty-five species of these little bees were found in different parts of
the Amazons Valley, the largest kind being half an inch in length, the
smallest very minute, not more than one-twelfth of an inch. These little
creatures are thus masons as well as workers in wax and resin, and they are
also gatherers of nectar, pollen, and resin.
{63}According to Gosse, one of these bees is well known in Jamaica, where
they are called "Angelitos," in consequence of their not stinging people.
He observed a nest of this bee in a tree, and found it to be much infested
by black ants anxious to obtain entrance to it; three bees, however, stood
sentinel in the entrance, so as to completely block it and keep out
intruders, but the middle bee moved on one side out of the way directly one
of its fellows wished to come in or out of the nest. The honey accumulated
by this species is kept in clusters of cups about the size of a pigeon's
egg, at the bottom of the hive and away from the brood-cells. The queen or
mother-bee is lighter in colour than the others, and has the hind body
twice the length of theirs.
Hockings[36] has given us some details as to the natural history of two of
these bees that inhabit Australia, where they are called "Karbi" and
"Kootchar," the first being, it is supposed, _Trigona carbonaria_, Smith:
it is usually about three-sixteenths of an inch in length, the queen, when
fully developed, being nearly twice that length. The comb is built in a
most peculiar form, being, it is said, in the shape of a spiral staircase,
and tapering towards the ends: honey-pots and pollen are constructed for
the storage of food. The comb is encased in wax, and outside it a labyrinth
of waxen passages is formed. The entrance to the colony is guarded by a
line of bees who inspect every one that arrives, and it is surprising to
see how soon a stranger is discovered and pounced upon before it has time
even to alight; the intruder, when caught, is held by several bees, who put
it on the rack by holding and stretching out its limbs to their full
extent, retaining it in this position for as long as an hour, by which time
the unfortunate prisoner is usually dead. These bees, as well as many other
allied species, fight desperately with their mandibles, and are apparently
of a very fierce disposition. The other species, called "Kootchar," is said
to produce a very large number of drones, and the habits and dispositions
of the bees differ considerably from those of the "Karbi": the entrance to
their hive is guarded by a pipe of propolis (a sort of resinous wax) about
an inch in length, having an exceedingly sticky outer edge, and it is by
this pipe alone that access to the interior can be gained. At night the
entrance is closed by numerous minute globules of semi-fluid gum placed
against it, thus forming a thin wall full of air-holes. {64}The colonies of
"Kootchar" can be united by taking away a queen and then packing her
brood-nest, bees and all, against that of the colony it is to be joined to.
This cannot be done with the "Karbi." The account given by Mr. Hockings
contains a great many other interesting details, and there can be no doubt
that a full account of the natural history of these Insects would be very
instructive.
Fritz Müller has recorded a singular case bearing on the instinct of these
social Insects: he says that a nest of a small _Trigona_ was built in a
hollow tree, and that as a consequence of the irregularity of the hole the
bees were obliged to give a very irregular shape to their combs of honey.
These bees were captured and put in a spacious box (presumably together
with the irregular comb, but this he unfortunately does not mention): after
a year, "when perhaps not a single bee survived of those which had come
from the canella tree," they still continued to build irregular combs,
though quite regular combs were built by several other communities of the
same species that he had kept. These bees, he also tells us, do not use
pure wax for the construction of their combs, but mix it with resin or gum
that gives it a peculiar odour and appearance. He captured two communities
of a common _Melipona_, one of which had the combs made of dark reddish
brown, the other of pale yellowish brown, wax, and in captivity in a
distant locality each of the two communities continued to form its comb in
the same way, thus showing the continuity that prevails in these cases as
long as circumstances permit. Müller thinks this due to imitation, but it
seems at least as probable that it is due to perception of the properties
of the nest. The nest has a certain colour that the worker-bee matches.
Several species of the _Melipona_ and _Trigona_ were imported from Brazil
to France, and kept there for some time in captivity by M. Drory. Girard
has published[37] some details as to these colonies, and is of opinion that
some of them indicate an intelligence or instinct superior to that of the
honey-bee. The queen-bee of _M. scutellaris_ seems to display more
intelligence than the corresponding sex of _A. mellifica_. The mode of
feeding the larvae apparently differs from that of _A. mellifica_, a
provision of pollen being first placed in the cell, then some honey; when
{65}sufficient food for the whole consumption of a larva is accumulated the
queen deposits an egg in the cell, which is at once completely closed by
the worker. The interior of the abode of these bees is quite dark, only a
very small orifice being left, and in this a sentinel is constantly on the
alert. The same writer states that _Trigona crassipes_ has the very
peculiar habit of always locating its brood-comb in the nest of a species
of _Termes_.
The honey-bee, _Apis mellifica_ (Fig. 6), is considered the highest form
attained by the Anthophilous division of the Hymenoptera. The
differentiation of the three forms, male, female, and worker, is here
carried to a greater degree of perfection than in the other bees. The
drones are the males; the individuals we see gathering honey are always
workers, neither the male nor the female in this species taking any part in
procuring food for themselves or for the colony. In addition to this the
colonies formed may be described as permanent: they do not come to an end
at the close of one season, and provision is made for the formation of a
new colony while the old one still persists, by means of a peculiar process
called swarming. The life-history of _Apis mellifica_ and its anatomy and
physiology have been discussed in a whole library of works, and we need
only notice the chief features. When a swarm of bees leaves a hive it
consists of the queen-bee or female, and a number of workers, these latter
being, in fact, the surplus population that has been produced in the hive.
The swarm is not a nuptial flight, as is often supposed, but an act of
emigration. When this swarm has been housed, the bees commence operations
in their new quarters, by secreting wax; they are enabled to do this by
having consumed much saccharine food; the wax is produced by means of
glands in the hind-body over the inner faces of the ventral plates of the
abdominal rings, and it makes its appearance there, after passing from the
interior of the body through some peculiar membranes on the ventral
segments, in the form of thin projecting plates. These the bee takes off
with an apparatus on the hind pair of legs and applies, after working up
with the mandibles, to form the cells in which young ones are to be reared
and food stored. A large number of bees working in common thus produce the
regular and beautiful structure known as the comb; the queen afterwards
lays an egg in each cell, and as these soon hatch, great labour is thrown
on the workers, which have then to feed the young; this {66}they do by
eating honey and pollen, which, being formed into a sort of pap by a
portion of their digestive organs, is then regurgitated and given to the
young, a quantity of it being placed in the cell, so that the larva is
bathed by it, and possibly may absorb the food by the skin as well as the
mouth. When the colony is in good progress and young bees emerge, these act
as nurses, the older ones cease to prepare food and act as foragers,
bringing in honey and pollen which are each stored in separate cells. The
larva in the cell increases its size and sheds a very delicate skin several
times; when the larva has reached its full size no more food is supplied,
but the worker-bees seal up the cell by means of a cover formed of pollen
and wax, in such a manner as to be pervious to air: sealed up in the cell
the larva spins a cocoon for itself, remains therein for a little time as a
larva, then changes to a pupa, and thereafter bites its way out through the
cover of the cell, and appears for the first time as a new being in the
form of a worker-bee; the whole process of development from the egg-state
to the perfect condition of the worker-bee occupies about three weeks.
When the denizens of a hive are about to produce another queen, one or more
royal cells are formed; these are much larger than the ordinary
worker-cells, and of a quite different form. In this cell is placed an egg,
not differing in any respect from the egg that, if placed in an ordinary
cell, produces a worker; when the egg has produced a larva this is tended
with great care and fed throughout its life with royal jelly. This food
appears to be the same as that supplied to an ordinary worker-larva when it
is first hatched; but there is this difference, that whereas the
worker-larva is weaned, and supplied, after the first period of its
existence, with food consisting largely of honey, pollen and water, the
queen-larva is supplied with the pap or royal jelly until it is full grown.
Some difference of opinion exists as to this royal jelly, some thinking
that it is a different substance from what the workers are fed with; and it
is by no means improbable that there may be some difference in the
secretion of the glands that furnish a part of the material composing the
pap. The queen is produced more rapidly than workers are, about sixteen
days being occupied in the process of her development. Only one queen is
allowed in a hive at a time; so that when several queen-cells are formed,
and {67}queen-larvae nurtured in them, the first one that is developed into
a perfect queen goes round and stings the royal nymphs to death while they
are still in their cells. The production of drones is supposed to depend
chiefly on the nature of the egg laid by the queen; it being considered
that an unfertilised egg is deposited for this purpose. There is still some
doubt on this point, however. Though there is no doubt that drones are
produced in great numbers from unfertilised eggs, yet there is not evidence
that they cannot also be produced from fertilised eggs.[38] The drone-cells
are somewhat larger than the ordinary worker-cells, but this is probably
not of much import, and it is said that the larvae intended to produce
drones receive a greater proportion of pap than worker-larvae do: about
twenty-four days are required to produce a drone from the egg.
From this sketch it will be seen that the production of the worker (or
third sex, as it is improperly called, the workers being really females
atrophied in some points and specially developed in others) is dependent on
the social life, in so far at any rate as the special feeding is concerned.
There is good reason for supposing that _A. mellifica_ has been kept in a
state of domestication or captivity for an enormous period of time; and
this condition has probably led to an increase of its natural
peculiarities, or perhaps we should say to a change in them to suit a life
of confinement. This is certainly the case in regard to swarming, for this
process takes place with comparative irregularity in _Apis mellifica_ in a
wild condition. The killing of superfluous queens is also probably a
phenomenon of captivity, for it varies even now in accordance with the
numbers of the colony. It is interesting to notice that in confinement when
a swarm goes from the hive it is the old queen that accompanies it, and
this swarm as a rule settles down near the old hive, so that the queen-bee
being already fertilised, the new swarm and its subsequent increase are
nothing but a division of the old hive, the total products of the two
having but a single father and mother. When a second swarm goes off from a
hive it is accompanied by a young queen, who frequently, perhaps, in the
majority of cases, is unfertilised; this swarm is apt to fly for long
distances, so that the probability of cross-fertilisation is {68}greatly
increased, as the fertilisation of the young new queen is effected during a
solitary flight she makes after the colony has settled down. But in a state
of nature the colonies do not send off swarms every year or once a year,
but increase to an enormous extent, going for years without swarming, and
then when their home is really filled up send off, it may be presumed, a
number of swarms in one year. Thus the phenomena of bee-life in a wild
condition differ considerably from those we see in artificial confinement.
And this difference is probably greatly accentuated by the action of
parasites, the proportions of which to their guests are in a state of
nature liable to become very great; as we have seen to be the case in
_Bombus_.
Under these circumstances it is not a matter for surprise when we find that
the honey-bee has formed distinct races analogous to those that exist in
the case of the domesticated vertebrate animals. The knowledge of these
races is, however, at present very little advanced, and is complicated by
the fact that only imperfect information exists as to the true species of
the genus _Apis_. There is a bee very like our common honey-bee found in
southern Europe called _A. ligustica_; this is certainly a variety of _A.
mellifica_, and the same remark applies to a bee found in Egypt, and called
_A. fasciata_. This gives the honey-bee a very wide distribution, extending
possibly over the whole of the palaearctic region: besides this, the
species has been introduced into various other parts of the world.
According to Karsch the honey-bee shows in Germany several varieties, all
of which belong to the northern form, which may be spoken of as the _A.
domestica_ of Ray; the _A. ligustica_ and _A. fasciata_ form as we have
said distinct races, and it is a remarkable fact that these races remain
distinct even when imported into other climates; though for how long a
period of time this remains true there is very little evidence to show. The
northern form, _A. domestica_, is now found in very widely separated parts
of the world, in some of which it is wild; Smith mentions it as occurring
in the West India islands, throughout the North American continent as far
south as Mexico, even in Central and Southern Africa, and in Australia and
New Zealand. The var. _ligustica_ has been found also at the Cape of Good
Hope. The other species known of the genus _Apis_ all belong to the Old
World, so that there is very little doubt that _A. mellifica_ is also {69}a
true native of the eastern hemisphere, and its original home may possibly
have been not far from the shores of the eastern portion of the
Mediterranean sea. Seven or eight other species of _Apis_ are known, all
but one of which occur in Asia, extending as far as Timor and Celebes. The
exceptional one, _A. adansonii_, occurs in tropical Africa and in
Madagascar. Gerstaecker thought these species might be reduced to four, but
Smith's statement that the males and even the workers show good distinctive
characters seems to be correct. Very little is known as to the honey-bees
of China and Japan.
The queen-bee greatly resembles the worker, but has the hind body more
elongated; she can, however, always be distinguished from the worker by the
absence of the beautiful transverse, comb-like series of hairs on the inner
side of the first joint of the hind foot, the planta, as it is called by
the bee-keeper: she has also no wax plates and differs in important
anatomical peculiarities. The male bee or drone is very different, being of
much broader, more robust build, and with very large eyes that quite meet
in the middle of the upper part of the head: he also has the hind leg
differently shaped. The form of this limb enables the male of _A.
mellifica_ to be distinguished from the corresponding sex of allied species
of the genus.
[Illustration: Fig. 25.—Portions of hind-feet, 1, of male, 2, of worker, 3,
of queen, of the honey-bee; series on the left, outer faces; on the right,
inner faces. _a_, Tip of tibia: _b_, first joint; _c_, second joint of
tarsus.]
We are indebted to Horne for some particulars as to the habits of _A.
dorsata_, an allied East Indian species. He informs us that these bees
greatly disfigure buildings, such as the Taj Mahal at Agra, by attaching
their pendent combs to the marble arches, and are so pertinacious that it
is almost useless to destroy the nests. This bee is said to be so savage in
its disposition that it cannot be domesticated; it attacks the sparingly
clad Hindoos {70}with great ferocity when they disturb its nest.
Notwithstanding its inclination and power to defend its societies this
Insect appears to be destroyed wholesale. Colonel Ramsay failed to
establish hives of it, because the Insects were eaten up by lizards. The
crested honey-buzzard carries off large portions of the comb, and devours
it on a branch of some tree near by, quite regardless of the stings of the
bees; while the fondness of bears for the honey of the "Dingar," as this
species is called, is well known.
Note to P. 33: It has just been discovered that a most remarkable
symbiosis, with structural modification of the bee, exists between the
females of _Xylocopa_, of the Oriental sub-genus _Koptorthosoma_, and
certain Acarids. A special chamber, with a small orifice for entry,
exists in the abdomen of the bee, and in this the Acari are lodged.—See
Perkins, _Ent. Mag._ xxxv. 1899, p. 37.
Note to P. 80: referring to the habits of social wasps in warm countries.
The anticipation we ventured to indulge in is shown to be correct by the
recent observations of Von Ihering.[39] He states that social wasps in
Brazil may be divided into two great groups by their habits, viz. 1.
Summer communities, lasting for one year, and founded annually by
fertilised females that have hibernated—example, _Polistes_; 2. Perennial
communities, founded by swarms after the fashion of bee
colonies—examples, _Polybia_, _Chartergus_.
Note to Vol. V. Pp. 545, 546: The development of _Encyrtus fuscicollis_
has now been studied by Marchal, who has discovered the existence of
embryonic dissociation. The chain of embryos and the epithelial tube in
which they are placed, are formed as follows: the _Encyrtus_ deposits an
egg in the interior of the egg of the _Hyponomeuta_. This does not kill
the egg of the Lepidopteron, but becomes included in the resulting
caterpillar. The amnion of the Chalcid egg lengthens, and forms the
epithelial tube; while the cells within it become dissociated in such a
way as to give rise to a chain of embryos, instead of a single
embryo.—_C.R. Ac. Paris_, cxxvi. 1898, p. 662, and translation in _Ann.
Nat. Hist._ (7), ii. 1898, p. 28.
{71}CHAPTER II
HYMENOPTERA ACULEATA _CONTINUED_—DIVISION II. DIPLOPTERA OR WASPS—
EUMENIDAE, SOLITARY TRUE WASPS—VESPIDAE, SOCIAL WASPS—MASARIDAE
DIVISION II. DIPLOPTERA—WASPS.
_Anterior wings longitudinally plicate in repose; the pronotum extending
back, so as to form on each side an angle reposing on the tegula; the
basal segments of the hind body not bearing nodes or scales; the hind
tarsi formed for simple walking. The species either solitary or social in
their habits; some existing in three forms, males, females, and workers._
[Illustration: Fig. 26—Upper aspect of pronotum and mesonotum of a wasp,
_Eumenes coarctata_. _a_, Angle of pronotum; _b_, tegula; _c_, base of
wing; _d_, mesonotum.]
This division of Hymenoptera includes the true wasps, but not the fossorial
wasps. The name applied to it has been suggested by the fact that the front
wings become doubled in the long direction when at rest, so as to make them
appear narrower than in most other Aculeata (Fig. 27). This character is
unimportant in function so far as we know,[40] and it is not quite constant
in the division, since some of the Masaridae do not exhibit it. The
character reappears outside the Diploptera in the genus _Leucospis_—a
member of the Chalcididae in the parasitic series of Hymenoptera—the
species of which greatly resemble wasps in coloration. A better character
is that furnished by the well-marked angle, {72}formed by the pronotum on
the dorsal part (Fig. 26). By a glance at this part a Diplopterous Insect
can always be readily distinguished.
Three families are at present distinguished in the Diploptera, viz.
Eumenidae, Vespidae and Masaridae. We anticipate that Eumenidae and
Vespidae will ultimately be found to constitute but one family.
FAM. 1. EUMENIDAE—SOLITARY TRUE WASPS.
_Claws of the feet toothed or bifid; middle tibiae with only one spur at
tip. Social assemblages are not formed, and there is no worker-caste, the
duties of nest-construction, etc., being performed solely by the female._
The Eumenidae, or solitary wasps, are very little noticed by the ordinary
observer, but they are nevertheless more numerous than the social Vespidae,
about 800 species being known. In Britain we have sixteen species of the
solitary, as against seven of the social wasps. The Eumenidae exhibit a
considerable diversity in form and structure; some of them have the pedicel
at the base of the abdomen very elongate, while in others this is so short
as to be imperceptible in the ordinary position of the body. A repetition
of similar differences of form occurs in the social wasps, so that
notwithstanding the difference in habits there seems to be no satisfactory
way of distinguishing the members of the two families except by the
structure of the claws and tibial spurs.
[Illustration: Fig. 27.—_Eumenes flavopicta_ ♀. Burma. The wings on the
left in the position of repose, to show folding.]
Fabre has sketched the habits of a species of _Eumenes_, probably _E.
pomiformis_. This _Eumenes_ constructs with clay a small vase-like
earthenware vessel, in the walls of which small stones are embedded (like
Fig. 28, B). This it fills with food for the young. The food consists of
caterpillars to the number of fourteen or sixteen for each nest. These
caterpillars are believed to be stung by the parent-wasp (as is the case in
the {73}fossorial Hymenoptera), but complete evidence of this does not seem
to be extant, and if it be so, the stinging does not completely deprive the
caterpillars of the capacity of movement, for they possess the power of
using their mandibles and of making strokes, or kicking with the posterior
part of the body. It is clear that if the delicate egg of the _Eumenes_ or
the delicate larva that issues from it were placed in the midst of a mass
of this kind, it would probably suffer destruction; therefore, to prevent
this, the egg is not placed among the caterpillars, but is suspended from
the dome covering the nest by a delicate thread rivalling in fineness the
web of the spider, and being above the mass of food it is safe. When the
young larva leaves the egg it still makes use of the shell as its
habitation, and eats its first meals from the vantage-point of this
suspension; although the mass of the food grows less by consumption, the
little larva is still enabled to reach it by the fact that the egg-shell
splits up to a sort of ribbon, and thus adds to the length of the
suspensory thread, of which it is the terminal portion. Finally the heap of
caterpillars shrinks so much that it cannot be reached by the larva even
with the aid of the augmented length of the suspensory thread; by this
time, however, the little creature has so much increased in size and
strength that it is able to take its place amongst the food without danger
of being crushed by the mass, and it afterwards completes its metamorphosis
in the usual manner.
[Illustration: Fig. 28—Nidification of solitary wasps: section through
nest, A, of _Odynerus reniformis_; B, of _Eumenes arbustorum_. _a_, The
suspended egg of the wasp; _b_, the stored caterpillars. (After André.)]
It is known that other species of _Eumenes_ construct vase-like nests; _E.
unguiculata_, however, according to an imperfect account given by Perris,
makes with earth a closed nest of irregular shape, containing three cells
in one mass. The saliva of these builders has the power of acting as a
cement, and of forming with the clay a very impenetrable material. One
species, _E. coarctata_, L. of this genus occurs in Britain. The clay
{74}nests (Fig. 29) of this Insect are often attached to the twigs of
shrubs, while those of the two species previously mentioned are usually
placed on objects that offer a large surface for fixing the foundations to,
such as walls. According to Goureau the larva of this species forms in one
corner of its little abode, separated by a partition, a sort of dust-heap
in which it accumulates the various débris resulting from the consumption
of its stores.
_Eumenes conica_, according to Horne, constructs in Hindostan clay-nests
with very delicate walls. This species provisions its nest with ten or
twelve green caterpillars; on one occasion this observer took from one cell
eight green caterpillars and one black. It is much attacked by parasites
owing, it is thought, to the delicacy of the walls of the cells, which are
easily pierced; from one group of five cells two specimens only of the
_Eumenes_ were reared.
[Illustration: Fig. 29—Nest of _Eumenes coarctata_: A, the nest attached to
wood; B, detached, showing the larva. _a_, the larva; _b_, the partition of
the cell. (After André.)]
_Odynerus_, with numerous sub-genera, the names of which are often used as
those of distinct genera, includes the larger part of the solitary wasps;
it is very widely distributed over the earth, and is represented by many
peculiar species even in the isolated Archipelago of Hawaii; in Britain we
have about fifteen species of the genus. The _Odynerus_ are less
accomplished architects than the species of _Eumenes_, and usually play the
more humble parts of adapters and repairers; they live either in holes in
walls, or in posts or other woodwork, or in burrows in the earth, or in
stems of plants. Several species of the sub-genus _Hoplopus_ have the
remarkable habit of constructing burrows in sandy ground, and forming at
their entry a curvate, freely projecting tube placed at right angles to the
main burrow, and formed of the grains of sand brought out by the Insect
during excavation and cemented together. The habits of one such species
were described by Réaumur, of another by Dufour; and recently Fabre has
added to the accounts of these naturalists some important information drawn
from his own observations on _O. reniformis_.
{75}[Illustration: Fig. 30.—_Odynerus antilope_ ♀. Britain.]
This Insect provisions its cell with small caterpillars to the number of
twenty or upwards (Fig. 28, A.) The egg is deposited before the nest is
stocked with food; it is suspended in such a manner that the suspensory
thread allows the egg to reach well down towards the bottom of the cell.
The caterpillars placed as food in the nest are all curled up, each forming
a ring approximately adapted to the calibre of the cell. Fabre believes
these caterpillars to be partly stupefied by stinging, but the act has not
been observed either by himself, Réaumur, or Dufour. The first caterpillar
is eaten by the wasp-larva from its point of suspension; after this first
meal has been made the larva is supposed to undergo a change of skin; it
then abandons the assistance of the suspensory thread, taking up a position
in the vacant chamber at the end of the cell and drawing the caterpillars
to itself one by one. This arrangement permits the caterpillars to be
consumed in the order in which they were placed in the cell, so that the
one that is weakest on account of its longer period of starvation is first
devoured. Fabre thinks all the above points are essential to the successful
development of this wasp-larva, the suspension protecting the egg and the
young larva from destruction by pressure or movement of the caterpillars,
while the position of the larva when it leaves the thread and takes its
place on the floor of the cell ensures its consuming the food in the order
of introduction; besides this the caterpillars used are of a proper size
and of a species the {76}individuals of which have the habit of rolling
themselves up in a ring; while, as the calibre of the tube is but small,
they are unable to straighten themselves and move about, so that their
consumption in proper order is assured. Some interesting points in the
habits of an allied species, _O._ (_Pterocheilus_) _spinipes_ have been
observed by Verhoeff; the facts as regards the construction and
provisioning of the cell are almost the same as in _O. reniformis_. The
species of _Odynerus_ are very subject to the attacks of parasites, and
are, it is well known, destroyed to an enormous extent by Chrysididae.
Verhoeff says that the wasp in question supplied food much infested by
entoparasites; further, that a fly, _Argyromoeba sinuata_, takes advantage
of the habit of the _Odynerus_ of leaving its nest open during the process
of provisioning, and deposits also an egg in the nest; the _Odynerus_
seems, however, to have no power of discovering the fact, or more probably
has no knowledge of its meaning, and so concludes the work of closing the
cell in the usual way; the egg of the _Argyromoeba_ hatches, and the maggot
produced feeds on the caterpillars the wasp intended for its own offspring.
Verhoeff observed that the egg of the wasp-larva is destroyed, but he does
not know whether this was done by the mother _Argyromoeba_ or by the larva
hatched from her egg. Fabre's observations on allied species of Diptera
render it, however, highly probable that the destruction is effected by the
young fly-larva and not by the mother-fly.
Mr. R. C. L. Perkins once observed several individuals of our British _O.
callosus_ forming their nests in a clay bank, and provisioning them with
larvae, nearly all of which were parasitised, and that to such an extent as
to be evident both to the eye and the touch. In a few days after the wasps'
eggs were laid, swarms of the minute parasites emerged and left no food for
the _Odynerus_. Curiously, as it would seem, certain of the parasitised and
stored-up larvae attempted (as parasitised larvae not infrequently do), to
pupate. From which, as Mr. Perkins remarks, we may infer that (owing to
distortion) the act of paralysing by the wasp had been ineffectual. Mr.
Perkins has also observed that some of the numerous species of Hawaiian
_Odynerus_ make a single mud-cell, very like the pot of an _Eumenes_, but
cylindrical instead of spherical. This little vessel is often placed in a
leaf that a spider curls up; young molluscs of the genus _Achatinella_ also
{77}avail themselves of this shelter, so that a curious colony is formed,
consisting of the _Odynerus_ in its pot, of masses of the young spiders,
and of the little molluscs.
Horne has recorded that the East Indian _O. punctum_ is fond of availing
itself of holes in door-posts where large screws have been; after the hole
has been filled with provisions, the orifice is covered over level with the
surface of the wood so that it eludes human observation. It is nevertheless
discovered by an Ichneumon-fly which pierces the covering with its
ovipositor and deposits an egg within.
The genus _Abispa_ is peculiar to Australia and includes some very fine
solitary wasps, having somewhat the appearance of very large _Odynerus_:
these Insects construct a beautiful nest with a projecting funnel-shaped
entrance, and of so large a size that it might pass for the habitation of a
colony of social wasps; it appears, however, that this large nest is really
formed by a single female.
The species of the genus _Rhygchium_ are also of insecticide habits, and
appear to prefer the stems of pithy plants as the nidus for the development
of the generation that is to follow them. Lichtenstein says that a female
of the European _R. oculatum_ forms fifteen to twenty cells in such a
situation, and destroys 150 to 200 caterpillars, and he suggests that, as
it is easy to encourage these wasps to nest in a suitable spot, we should
utilise them to free our gardens from caterpillars, as we do cats to clear
the mice from our apartments.
The East Indian _R. carnaticum_ seems to have very similar habits to its
European congener, adapting for its use the hollow stems of bamboos. Horne
has recorded a case in which a female of this species took possession of a
stem in which a bee, _Megachile lanata_, had already constructed two cells;
it first formed a partition of mud over the spot occupied by the bee, this
partition being similar to that which it makes use of for separating the
spaces intended for its own young. This species stores caterpillars for the
benefit of its larvae, and this is also the case with another Eastern
species, _R. nitidulum_. This latter Insect, however, does not nidificate
in the stems of plants, but constructs clay cells similar to those of
_Eumenes_, and fixes them firmly to wood. _Rhygchium brunneum_ is said by
Sir Richard Owen to obliterate hieroglyphic inscriptions in Egypt by its
habit of building mud {78}nests amongst them. An individual of this wasp
was found by Dr. Birch when unrolling a mummy—"There being every reason to
believe that the Insect had remained in the position in which it was found
ever since the last rites were paid to the ancient Egyptian."
FAM. 2. VESPIDAE—SOCIAL WASPS.
_Claws of the feet simple, neither toothed nor bifid, middle tibiae with
two spurs at the tip. Insects living in societies, forming a common
dwelling of a papery or card-like material; each generation consists of
males and females and of workers—imperfect females—that assist the
reproductive female by carrying on the industrial occupations._
The anterior wing possesses four submarginal cells, as in the Eumenidae.
The attention of entomologists has been more directed to the habits and
architecture than to the taxonomy of these Insects, so that the external
structure of the Insects themselves has not been so minutely or extensively
scrutinised as is desirable; de Saussure, the most important authority,
bases his classification of the Insects themselves on the nature of the
nests they form. These habitations consist of an envelope, protecting cells
similar in form to the comb of the honey-bee, but there is this important
difference between the two, that while the bee forms its comb of wax that
it secretes, the wasps make use of paper or card that they form from
fragments of vegetable tissue,—more particularly woody fibre—amalgamated by
means of cement secreted by glands; the vegetable fragments are obtained by
means of the mandibles, the front legs playing a much less important part
in the economy of the Vespidæ than they do in that of the bees and
fossorial Hymenoptera.
In most of the nests of Vespidæ the comb is placed in stages or stories one
above the other, and separated by an intervening space, but in many cases
there is only one mass of comb. It is the rule that, when the cells of the
comb are only partially formed, eggs are deposited in them, and that the
larva resulting from the egg is fed and tended by the mother, or by her
assistants, the workers; as the larvae grow, the cells are increased in
correspondence with the size of the larva; the subsequent metamorphosis to
pupa and imago taking place in the cells after they have been entirely
{79}closed. The food supplied is of a varied nature according to the
species, being either animal or vegetable, or both.
[Illustration: Fig. 31—Section of the subterranean nest of the common wasp,
_Vespa germanica_, in position. (After Janet.) _a_, One of the chambers of
an ant's nest, _Lasius flavus_, placed above the wasps' nest; _b_, root to
which the first attachment of the nest was made; _c_, secondary
attachments; _d_, the first-made attachment; _e_, a flint within the
envelopes of the nest; _f_, the chief suspensory pillar of the second layer
of comb; _g_, lateral galleries; _h_, one of the secondary pillars of
suspension between two layers of comb; _i_, the layers of wasp-paper
forming the envelope of nest; _j_, vacant space round the nest; _k_, flints
that fell to the bottom during the work of excavation; _l_, numerous larvae
of a fly, _Pegomyia inanis_ (?) placed vertically in ground beneath the
nest; _m^1_ to _m^7_, the layers of comb, in _m^2_ the cells are indicated,
in _m^8_ (above the main figure) the arrangement of the three cells forming
the commencement of the new layer of comb, _m^7_, is shown; _n_, gallery of
access from surface; _o_, burrow of a mole; _p_, interval of 90 mm. between
top of nest and surface; _q_, height of the nest, 163 mm.]
Although the nests of the social wasps are very elaborate constructions,
yet they serve the purposes of the Insects for only a single season. This
is certainly the case in our own country. Here each nest is commenced by a
single female or queen; she at first performs unaided all the duties for
the inauguration of the colony; she lays the foundation of the cells,
deposits the eggs in them, feeds the young, and thus rears a brood of
workers that at once assist her, and for the future relieve her of a
considerable portion of her former occupations; the nest is by them added
to and increased, till the cold weather of the autumn is at hand; at this
time many males and females are produced; the cold weather either destroys
the inhabitants of the nest, or reduces their vitality so that it is
impossible for them to pursue successfully the avocations necessary for
their subsistence, and {80}they succumb to adversity. The young females,
however, hibernate, and each one that lives through the winter is the
potential founder of a new nest in the way we have already described. It
might be supposed that in tropical countries where no cold season occurs
the phenomena would be different, that the colonies would be permanent, and
that the nests would be inhabited until they were worn out. De Saussure,
however, informs us that this is not the case, but that in the tropics also
the colonies die off annually. "The nests are abandoned," he says, "without
it being possible to discover the reason, for apparently neither diminution
of temperature nor scarcity of food cause them (the Insects) to suffer. One
is tempted to suppose that the death of the Insects is the result of a
physiological necessity."
NESTS OF SOCIAL WASPS.—In Europe wasps' nests disappear very soon after
they are deserted. As it would appear from de Saussure's conclusions that
in the tropics as well as in the temperate regions the rule is that the
colonies endure only a portion of one year, and that a new nest is
commenced by a single founder once in twelve months, it is a somewhat
remarkable fact that some tropical wasp-nests are much more durable than
the lives of the inhabitants require, so that solidly constructed nests are
often found hanging to the trees long after they have been deserted, and
are sometimes overgrown with moss. Cuming has recorded the fact that he
found in South America an old wasp-nest that had been taken possession of
by swallows. We do not assign, however, much importance to the views of de
Saussure, because we may anticipate that enquiry will reveal much variety
in the habits of tropical and sub-tropical wasps. It is known that species
exist that store up honey, after the fashion of bees, and von Ihering has
recently shown[41] that in Brazil, species of several genera form new
colonies by swarming, after the manner of bees. So that it is possible that
certain colonies may remain for a long period in the same nest.
Much more variety exists in wasps' nests than would be supposed probable;
those formed by some of the tropical species of Vespidae are enveloped in
so solid and beautifully constructed an envelope of papier-maché, that they
resist with complete success the torrential rains of the tropics; while
some of those found in our own country are made of extremely soft and
delicate paper, {81}which is probably chiefly glandular products. Our
British Vespidae number only eight species, all belonging to the one genus
Vespa, and yet they exhibit three different modes of nidification. _Vespa
vulgaris_, _V. germanica_ and _V. rufa_ form subterranean nests, while _V.
arborea_, _V. sylvestris_ and _V. norvegica_ suspend their habitations from
the branches of trees, bushes, or strong annual plants. _Vespa crabro_, the
hornet, usually adopts an intermediate course, forming its nest above
ground, but in a spot where it is protected and concealed. The favourite
habitat of this formidable Insect is the interior of an old tree, but the
hornet will sometimes avail itself of the protection of a thatched roof.
Both it and other arboreal species are said, however, to occasionally make
subterranean nests. It is ascertained that _V. austriaca_, the eighth
species, is an inquiline.
[Illustration: Fig. 32—Nest of (?) _Polybia_ sp. The envelope partly cut
open; _o_, entrance. (After de Saussure.)]
De Saussure,[42] the monographer of the social wasps, classifies them
according to the architecture of their nests. He establishes three groups:
(1) Stelocyttares, in which the layers of comb are not connected with the
envelope, but are supported by pillars made by the wasps (Fig. 31); (2)
Poecilocyttares, an unsatisfactory group of which the chief characteristics
appear to be that the nest is always covered by an envelope, and the comb
is supported by an object such as the branch of a tree, round, or on, which
the envelope is placed (Fig. 32); (3) Phragmocyttares, in which the layers
of comb are supported, in part or entirely, by the envelope of the nest,
communication being effected by a hole in each layer of the comb (Fig. 33).
de Saussure's classification is far from satisfactory. There are many
social wasps that construct nests destitute of any proper envelope; as an
example of this, we may mention the species of {82}the abundant genus
_Polistes_; these Insects make hexagonal cells, of paper-like material,
forming an irregular comb, or mass, attached to bushes by a stalk near its
centre; these nests are placed so that the mouths of the open cells look
downwards. The species of _Ischnogaster_ (Fig. 34) make layers of comb,
connected by a pedicel, but without any envelope; these Insects form a
section of Stelocyttares called Gymnodomes.
Most of the nests of the Poecilocyttares have only a single layer of comb.
The wasps of the genera _Synoeca_ and _Polybia_ have the habit of spreading
a layer of cells on a leaf, or on the bark of a tree, and of covering this
with an envelope that is pierced by a single orifice only, but that does
not rest on the cells, and so allows circulation of the Insects between the
cells and the envelope. This appears to be the arrangement in a nest of
_Synoeca cyanea_ preserved in the British Museum; in this construction a
large layer of cells is moulded on the branch of a tree, whose contour, for
a length of two or three feet, it consequently follows; while outside the
mass there is placed a continuous envelope, leaving a considerable distance
between it and the cells.
It would be impossible in the space at our disposal to give a satisfactory
account of all the forms of wasp-nests, and we must therefore refer the
student to de Saussure's work, confining ourselves to a brief notice of
some specially interesting forms. The habitation of the Brazilian _Polybia_
(_Myrapetra_) _scutellaris_ is a very solid, closed structure, covered
externally with rough knobs or angular projections. Although of very large
size—it may be upwards of two feet in length—it is suspended from a branch,
and has but one orifice; the arrangement of the combs in the interior is
that of the Phragmocyttares, they being firmly attached to the outer
envelope, and so placed as to form a curved surface, the convexity of which
is downwards: the number of wasps in a well-developed nest of this kind
must be very great. This species is said to be a honey-gathering wasp.
One of the best known of the South American wasps' nests is the
construction (Fig. 33) of _Chartergus chartarius_; these nests are so
regularly shaped, and formed of papier-maché so compact and solid, as to
look like stone: this edifice is attached in a very firm manner to the
branch of a tree, and has a single portal of entry beneath; its interior
arrangement is much like that of _Myrapetra scutellaris_.
{83}A very remarkable wasp's nest is preserved in the British Museum of
Natural History; it is considered to be the work of _Montezumia dimidiata_
Sauss. an Eumenid wasp; it is a large mass of cells encircling the branch
of a tree, which therefore projects somewhat after the manner of an axle
through the middle: the cells are very numerous, and are quite as regular
as those of the most perfect of the combs of bees: the mass is covered with
a very thick layer of paper, the nest having somewhat the external
appearance of half a cocoa-nut of twice the usual size.
[Illustration: Fig. 33—Section of nest of _Chartergus chartarius_. South
America, _o_, Entrance. (After de Saussure.)]
_Apoica pallida_, a South American Insect, forms a nest in a somewhat
similar manner to _Polistes_, but it is covered on its outer aspect by a
beautiful paper skin, so that the nest looks somewhat like a toadstool of
large size attached to the branch of a tree.
The nests of the Insects of the genus _Polybia_—which we have already
mentioned as located by de Saussure in his unsatisfactory group
Poecilocyttares—usually have somewhat the form and size of pears or apples
suspended to twigs of trees or bushes; these little habitations consist of
masses of cells, wrapped in wasp-paper, in which there are one or more
orifices for ingress and egress. Smith says that the combs in the nest of
_P. pygmaea_ are of the most exquisite construction, and that it is by no
means an uncommon circumstance to find the outer envelope of the nest
ornamented with patches of delicate hexagonal tracery. This nest is about
the size of an orange.
We have already noticed the variety of nests formed by our British species
of the genus _Vespa_; in other parts of the world the edifices formed by
species of _Vespa_ attain a very large size. _V. crabroniformis_ in China,
and _V. velutina_ in India, make nests several feet or even yards in
length, inhabited by an enormous number of individuals; they are apparently
constructed of a material like brittle paper, and are arranged much like
the nests of our British hornet, _V. crabro_. _Vespa orientalis_ mixes a
considerable quantity of earth with the paper it uses for its
{84}constructive efforts. In the British Museum collection there is a nest
said to be that of the Japanese hornet, _V. japonica_. This is completely
covered by a paper envelope, and has apparently only a single small orifice
for ingress and egress. In the same collection there is a nest from Bahia
(believed to be that of a social wasp, though of what species is unknown),
the outer wall of which is apparently formed entirely of earth, and is a
quarter or half an inch thick: the comb inside appears also to be formed of
clay, the whole forming an elaborate construction in pottery. One is
tempted to believe it may prove to be the production of a social Eumenid.
HABITS OF SOCIAL WASPS.—We have already briefly noticed the way in which a
colony of wasps is founded, but some further particulars as to the mode in
which the society is increased and developed may be mentioned. The
queen-wasp makes at first only a very small group of three or four
incomplete cells; each cell is at first circular, or nearly so, and
moreover is of smaller diameter than it will afterwards be. In each of the
first three or four incomplete cells an egg is laid, and more cells are
commenced; but as the eggs soon hatch and produce larvae that grow rapidly,
the labours of the queen-wasp are chiefly directed to feeding the young. At
first she supplies them with saccharine matter, which she procures from
flowers or fruits, but soon gives them a stronger diet of insect meat. This
is procured by chasing living Insects of various kinds. Some species of
wasps prefer particular kinds of Insects, and the hornet is said to be very
fond of the honey-bee, but as a rule Diptera are the prey selected. When an
Insect has been secured, the hard and innutritious parts are bitten off,
and the succulent parts, more especially the thorax which contains chiefly
muscular tissue, are reduced to a pulp by means of the mandibles; this is
offered to the larvae, which are said to stretch out their heads to the
mother to receive the food, after the manner of nestling birds. When a
larva is full grown it spins a cocoon in the cell and changes to a pupa. It
is said by some entomologists that the queen-wasp closes the cell for the
purpose of the larval metamorphosis; but this is contradicted by others,
and is probably erroneous. In about a month, or a little less, from the
time of deposition of the egg, the perfect Insect is ready for issue, and
almost immediately after leaving its cell it assists in the work that is
going on for the development of the society. The {85}Insects produced at
this early period of the colony are exclusively workers, _i.e._ imperfect
females. They relieve the queen of the task of supplying the larvae with
food, and she henceforth remains within the nest, being, it is said,
herself fed by her workers; the society now rapidly increases in numbers,
and fresh combs are formed, the upper layer being always the oldest. About
the month of August, cells of larger size than those that have previously
been constructed are formed, and in these males and perfect females are
produced; in a few weeks after this the colony languishes and becomes
extinct. When it is no longer possible for the enfeebled wasps to carry out
their tasks of feeding the brood, they drag the larvae out of the cells and
destroy them. An uncertain number of queen-wasps seek protected nooks in
which to pass the winter, and each of these queens may be the founder of a
nest in the ensuing spring. It should be remarked that de Saussure states
that all the intermediate grades between perfect and imperfect females
exist, and Marchal's recent observations confirm this. There is in fact no
line of demarcation between worker and queen in the wasps as there is in
the honey-bee. Von Siebold long since drew attention to the existence of
parthenogenesis in certain species of wasps, and it appears probable that
it is of common occurrence.
Our knowledge of the social life of European wasps has recently been much
increased by the observations of two French naturalists, P. Marchal and C.
Janet. The latter has given an elaborate history of a nest of the hornet,
showing the rate and variations of increase in numbers. His observations on
this and other species indicate that warmth is of the utmost importance to
wasps; the Insects themselves create a considerable amount of heat, so that
the temperature of their abodes is much greater than that of the air. He
considers that in Europe an elevated temperature is essential for the
development of the individual,[43] and that the chief object of the various
wrappers of paper with which the Insects surround their nests is to keep up
this high temperature. These envelopes give a great deal of trouble to the
Insects, for they have to be repeatedly {86}destroyed and reformed, as the
combs they contain increase in size. Marchal's observations[44] relate
chiefly to the production of the sexes and worker-forms, in the
subterranean species, _Vespa germanica_ and _V. vulgaris_. The layers of
comb include cells of two sizes. The upper layers, which are the first
formed, consist of small cells only: the lower combs are constructed (at
Paris) early in August, and consist of larger cells from which males and
large females are reared. The males are, however, reared also in large
numbers in the small cells. If the queen be removed, the workers become
fertile, and produce parthenogenetically many eggs, but all of the male
sex. He entertains no doubt that even when the queen is in full vigour the
workers produce males if there is an abundant food supply.
The social wasps at present known number 500 or 600 species. _Polistes_ is
a very extensive genus, and it has also a very wide geographical
distribution; some of the species—and those found in widely-distant parts
of the world—are remarkable on account of their excessive variation in
colour, and it is worthy of note that the extreme forms have been more than
once taken from the same nest.
Next to _Polistes_, _Vespa_ is the most numerous in species, about 150
being known, and it is to this genus that all our British social wasps
belong. No Insects are better known in our islands than these wasps, owing
to the great numbers of individuals that occur in certain seasons, as well
as to their frequently entering our habitations and partaking of our food,
and to the terror that is occasioned by their supposed ferocity and desire
to sting. This last feature is a complete mistake; wasps never sting unless
they are roused to do so by attacks, or by considerable interference with
their work. The only real danger arises from the fact that a wasp may be
occasionally taken into the mouth with fruit, or may be handled unawares.
When they are flying about they are perfectly harmless unless attacked or
irritated, and even if they settle on the person no danger of their
stinging exists unless movement is made. Sichel correctly states that a
person may station himself close to a wasp's nest and remain there without
any risk at all, provided that he makes no movement; indeed, it is more
than probable that if no movement, or if only gentle {87}movement, be made,
the wasps are unaware of the presence of an intruder. It is, however, well
ascertained that if they are molested at their work, more especially when
they are actually engaged in the duties of the nest, they are then
extremely vindictive, and follow for a considerable distance those who have
irritated them. The East Indian _V. velutina_ is specially fierce when
aroused, and is said by Horne to have followed a party through dense jungle
for miles, and on some occasions to have stung animals, and even human
beings, to death.
[Illustration: Fig. 34—_Ischnogaster mellyi_. Java. A, Female imago (the
line at the side shows its length); B, nest, C, maxilla; D, labium; E,
mandible (tip downwards). The nest is probably upside down, although shown
here as by de Saussure.]
This vindictiveness is, however, only an exceptional mood due to some
interference with the colony. Even the hornet, notwithstanding its
threatening appearance, is harmless unless unduly provoked; its nests and
their inhabitants can be kept in domesticity, exhibited to strangers, even
moved from place to place, yet the hornets will not take offence if due
gentleness be observed. It is said that wasps will rear the progeny of a
neighbour in circumstances where this assistance is necessary. Hess has
related a case in which a queen-hornet had commenced a nest, and was killed
by an accident, leaving young brood in the comb {88}unprovided for: as a
result many of the helpless grubs died, and others were in a state of
starvation, when a strange queen-hornet appeared, associated itself with
the comb, and, adopting the orphan brood, nourished them and brought them
to their full size.
We have already alluded to the fact that, so far as external structure is
concerned, there is no great difference between the social and the solitary
wasps. Both, too, run through analogous series of forms and colours, and
the genus _Ischnogaster_ (Fig. 34) seems to connect the two groups by both
its structure and mode of life. The social habits are in many species only
inferred, and with greater knowledge will probably prove fallacious as a
guide to classification; indeed we have already said that in the genus
_Vespa_—perhaps the most perfectly social of all the wasps—there is one
species that has no worker, and that lives, it is supposed, as a parasite,
in the nests of its congeners. For this species, _V. austriaca_, it has
been proposed to create a separate genus, _Pseudovespa_, on account of this
peculiarity of habit, although no structural character has been detected
that could distinguish it. De Saussure has stated his conviction that
workers do not exist in some of the exotic genera, so that it appears
highly probable that with the progress of knowledge the present division
between social and solitary wasps will prove untenable.
Remains of Insects referred to the genera _Polistes_ and _Vespa_ have been
found in tertiary strata in various parts of Europe and in North America.
[Illustration: Fig. 35—_Masaris vespiformis_. A, male; B, female. Egypt.
(After Schaum.)]
FAM. 3. MASARIDAE.
_Anterior wing with two complete sub-marginal cells. Antennae usually
incrassate or clubbed at the extremity. Claws distinctly or obsoletely
dentate._
This is a group of fifty or sixty species with but few genera, {89}and most
of its components appear to be Insects of the greatest rarity. In their
appearance the Insects of this Family differ considerably from the other
Diploptera, and as the wings are only imperfectly, or not at all, plicate,
it must be admitted that the systematic affinities of the group require
reconsideration. The pronotal structure is, however, completely that of
Diploptera. The typical form of the Family, _Masaris vespiformis_, though
described a hundred years since, is a species of such extreme rarity, and
its sexes are so different, that entomologists have only recently been able
to agree about it. It has been found in Egypt and Algeria. The genera
_Ceramius_, _Jugurthia_, _Quartenia_ and _Coelonites_ are also members of
the Mediterranean fauna, while _Paragia_ is Australian, and _Trimeria_
South American. Several species of the genus _Masaris_ inhabit North
America, and Cresson has recently described another Masarid genus from the
same country, under the name of _Euparagia_.
The little that is known of their natural history is almost limited to an
account given by Giraud of the habits of _Ceramius lusitanicus_, of which
species he found a colony near Briançon. The Insect makes nests in the
earth; they are entered by means of a chimney-like passage analogous to
what is formed by certain _Odynerus_; the gallery when completed is about
six centimetres long, and at its extremity is an earthen cell in which the
larva lives; this is fed by the mother, who brings to it from time to time
a supply of a paste, described as being somewhat like dried honey. The
growth of the larva is believed to be rapid.
[Illustration: Fig. 36—Cells constructed by _Coelonites abbreviatus_.
(After André.)]
Some fragmentary observations made by Lichtenstein on _Coelonites
abbreviatus_ have also been recorded. This species, near Montpellier,
constructs earthen cells; they are not, however, subterranean, but are
placed side by side on the dry stems of plants (Fig. 36); these cells are
stored with a material similar to that supplied by _Ceramius lusitanicus_
to its young.
{90}CHAPTER III
HYMENOPTERA ACULEATA _CONTINUED_—DIVISION III. FOSSORES OR FOSSORIAL
SOLITARY WASPS—FAMILY SCOLIIDAE OR SUBTERRANEAN FOSSORS—FAMILY POMPILIDAE
OR RUNNERS—FAMILY SPHEGIDAE OR PERFECT-STINGERS
DIVISION III. FOSSORES.
_Aculeate Hymenoptera, in which the abdomen, though very diverse in form,
does not bear prominences on the upper aspect of the basal segments;
front wing without longitudinal fold along the middle; hairs of body not
plumose. Only two forms (male and female) of each species._
Fossorial Hymenoptera are distinguished from other Aculeates at present
only by negative characters, _i.e._ they are Aculeates, but are not ants,
bees or wasps. According to their habits they fall into four, by no means
sharply distinguished, groups—(1) those that form no special receptacles
for their young, but are either of parasitic or sub-parasitic habits, or
take advantage of the abodes of other Insects, holes, etc.; (2)
constructors of cells of clay formed into pottery by the saliva of the
Insect, and by drying; (3) excavators of burrows in the ground; (4) makers
of tunnels in wood or stems of plants. Several species make use of both of
the last two methods. The habits are carnivorous; the structures formed are
not for the benefit of the makers, but are constructed and stored with food
for the next generation. Their remarkable habits attracted some attention
even 2000 years or more ago, and were to some extent observed by Aristotle.
The great variety in the habits of the species, the extreme industry,
skill, and self-denial they display in carrying out their voluntary
labours, render them one of the most instructive groups of the animal
kingdom. There are no social or gregarious {91}forms, they are true
individualists, and their lives and instincts offer many subjects for
reflection. Unlike the social Insects they can learn nothing whatever from
either example or precept. The skill of each individual is prompted by no
imitation. The life is short, the later stages of the individual life are
totally different from the earlier: the individuals of one generation only
in rare cases see even the commencement of the life of the next; the
progeny, for the benefit of which they labour with unsurpassable skill and
industry, being unknown to them. Were such a solicitude displayed by
ourselves we should connect it with a high sense of duty, and poets and
moralists would vie in its laudation. But having dubbed ourselves the
higher animals, we ascribe the eagerness of the solitary wasp to impulse or
instinct, and we exterminate their numerous species from the face of the
earth for ever, without even seeking to make a prior acquaintance with
them. Meanwhile our economists and moralists devote their volumes to
admiration of the progress of the civilisation that effects this
destruction and tolerates this negligence.
[Illustration: Fig. 37.—_Sceliphron nigripes_ ♀ (Sub-Fam. Sphegides).
Amazons. × 3/2.]
{92}It should be noted that in the solitary as in the social Insects the
males take no part whatever in these industrial occupations, and apparently
are even unaware of them. It is remarkable that, notwithstanding this, the
sexual differences are in the majority less than is usual in Insects. It is
true that the various forms of Scoliidae exhibit sexual distinctions which,
in the case of Thynnides and Mutillides are carried to an extreme degree,
but these are precisely the forms in which skill and ingenuity are
comparatively absent, the habits being rather of the parasitic than of the
industrial kind, while the structure is what is usually called degraded
(_i.e._ wingless). The great difference between the habits of the sexes,
coupled with the fact that there is little or no difference in their
appearance, has given rise to a curious Chinese tradition with regard to
these Insects, dating back to Confucius at least.[45] The habit of stinging
and storing caterpillars in a cell, from which a fly similar to itself
afterwards proceeds having been noticed, it was supposed to be the male
that performed these operations; and that when burying the caterpillars he
addressed to them a spell, the burden of which is "mimic me." In obedience
the caterpillars produce the wasp, which is called to this day "Jiga," that
is in English "mimic me." The idea was probably to the effect that the
male, not being able to produce eggs, used charmed caterpillars to continue
the species.
SUMMARY OF THE PREY OF FOSSORES.
Group of Fossores. Food or Occurrence.
Fam. Scoliidae.
Sub-Fam. Mutillides As parasites on Hymenoptera Aculeata.
" Thynnides (?) Parasites on Lepidopterous pupae.
" Scoliides Larvae of Coleoptera [(?) spiders in the
case of _Elis 4-notata_].
" Rhopalosomides Unknown.
" Sapygides The provisions stored by bees. Caterpillars
(teste Smith).
Fam. Pompilidae Spiders. Rarely Orthoptera (Gryllidae and
Blattidae, teste Bingham) or Coleoptera.
Fam. Sphegidae.
Sub-Fam. Sphegides Orthoptera (especially Locustidae), larvae
of Lepidoptera, Spiders [(?) same species
(_Sceliphron madraspatanum_ and _Sphex
coeruleus_), both spiders and
caterpillars].
" Ampulicides Orthoptera (Blattidae only). {93}
" Larrides Orthoptera of various divisions. Aculeate
Hymenoptera, in the case of _Palarus_.
[Spiders stolen from nests of _Pelopaeus_
by _Larrada_.]
" Trypoxylonides Spiders, caterpillars, Aphidae.
" Astatides _Astata boops_ uses Pentatomid bugs,
cockroaches, and even Aculeate Hymenoptera
(_Oxybelus_, teste Smith).
" Bembecides Diptera and _Cicada_.
" Nyssonides Diptera, Homoptera (_Gorytes mystaceus_
takes _Aphrophora_ out of its "cuckoo-
spit").
" Philanthides Aculeate Hymenoptera (_Philanthus_). Hard
beetles, viz. Curculionidae, Buprestidae,
Chrysomelidae (_Cerceris_).
" Mimesides Small Homoptera, even Aphidae. Diptera
(Tipulidae) in Hawaii.
" Crabronides Diptera, Aphidae [? the same species of
wasps both of these]. Other small
Homoptera. Ants (in the case of
_Fertonius_). Parasitic Hymenoptera (in
the case of _Lindenius_).
Great diversity of opinion exists as to the classification of the Fossores.
This arises chiefly from the incomplete state of the collections studied,
and from the fact that the larger part of the works published are limited
to local faunae. Opinions as to the families vary; some admitting only
three or four, others upwards of twenty. After consideration of the various
views, the writer thinks it best to admit at present only three families,
which speaking broadly, correspond with habits, viz. (1) Scoliidae,
subterranean stingers; (2) Pompilidae, runners; (3) Sphegidae, stingers
above ground.
1. Scoliidae. Pronotum and tegulae in contact. Abdomen with the plane of
the ventral surface interrupted by a chink between the first and second
segments. Numerous wingless forms.
2. Pompilidae. Pronotum and tegulae in contact. Abdomen with the plane of
the ventral surface not interrupted by a chink. Legs very long. No
wingless forms.
3. Sphegidae. Pronotum and tegulae not in contact. No wingless forms.
We shall treat as sub-families those divisions of Scoliidae and Sphegidae
considered by many as families.
{94}FAM. 1. SCOLIIDAE.
The members of this family, so far as is known, display less perfect
instincts than the Sphegidae and Pompilidae, and do not construct cells or
form burrows. Information as to the habits is almost confined to European
forms. We adopt five sub-families.
SUB-FAM. 1. MUTILLIDES.—_The sides of the pronotum reach the tegulae: the
female is destitute of wings and ocelli, frequently having the parts of
the thorax so closely soldered that the divisions between them are
obliterated: the males are winged, furnished with ocelli, and having the
thoracic divisions distinct; intermediate tibiae with two apical spurs.
Front wing with two or three sub-marginal cells. The larvae live
parasitically at the expense of other Hymenoptera Aculeata._
The Mutillides have some resemblance to ants, though, as they are usually
covered with hair, and there is never any node at the base of the abdomen,
they are readily distinguished from the Formicidae. The great difference
between the sexes is their most striking character. Their system of
coloration is often very remarkable, the velvet-like pubescence clothing
their bodies being variegated with patches of sharply contrasted vivid
colour; in other cases the contrast of colour is due to bare, ivory-like
spaces. They have the faculty of stridulating, the position and nature of
the organ for the purpose being the same as in ants.
Very little exact information exists as to the habits and life-histories of
the species. Christ and Drewsen, forty or fifty years ago, recorded that
_M. europaea_ lives in the nests of bees of the genus _Bombus_, and Hoffer
has since made some observations on the natural history of the same species
in South East Europe, where this _Mutilla_ is found in the nests of ten or
eleven species of _Bombus_, being most abundant in those of _B. agrorum_
and _B. variabilis_; occasionally more individuals of _Mutilla_ than of
bees may be found in a nest. He supposes that the egg of the _Mutilla_ is
placed in the young larva of the _Bombus_, and hatches in about three days;
the larva feeds inside the bee-larva, and when growth is completed a cocoon
is spun in the interior of the pupa-case of the bee. When the perfect
Insects emerge, the males leave the nest very speedily, but the females
remain for some time feeding on the bees' honey. Females are usually
produced in greater numbers than males. This account leaves {95}much to be
desired. From the observations of Radoszkowsky it is clear that other
species of Mutillides are by no means confined to the nests of _Bombus_ but
live at the expense of Aculeate Hymenoptera of various groups. This
naturalist asserts that the basal abdominal segment of the parasite
resembles in form that of the species on which it preys.
The apterous condition of the females of Mutillides and Thynnides is very
anomalous in the Fossors; this sex being in the other families
distinguished for activity and intelligence. The difference between the
sexes is also highly remarkable. The males differ from the females by the
possession of wings and by the structural characters we have mentioned, and
also in a most striking manner in both colour and form; Burmeister, indeed,
says that in South America—the metropolis of Mutillides—there is not a
single species in which the males and females are alike in appearance; this
difference becomes in some cases so extreme that the two sexes of one
species have been described as Insects of different families.
[Illustration: Fig. 38—_Mutilla stridula._ Europe. A, Male; B, female.]
Upwards of one thousand species are assigned to the genus _Mutilla_, which
is distributed over the larger part of the world; there is so much
difference in these species as to the nervuration of the wings in the
males, that several genera would be formed for them were it not that no
corresponding distinctions can be detected in the females. Three or four
species of _Mutilla_ are described as being apterous in the male as well as
in the female sex; they are very rare, and little is known about them. Only
three species of Mutillides occur in Britain, and they are but rarely seen,
except by those who are acquainted with their {96}habits. The African and
East Indian genus, _Apterogyna_, includes some extremely peculiar
Hymenoptera; the males have the wing nervuration very much reduced, and the
females are very ant-like owing to the deep constriction behind the first
abdominal ring.
SUB-FAM. 2. THYNNIDES.—_Males and females very different in form; the
male winged, the front wing with three, or only two, sub-marginal cells;
the female wingless and with the thorax divided into three sub-equal
parts._
[Illustration: Fig. 39—_Methoca ichneumonides._ A, Male; B, female.
Britain.]
The Thynnides are by some entomologists not separated from the Mutillides;
but the distinction in the structure of the thorax of the females is very
striking. In the Thynnides the nervuration of the wing appears always to
extend to the outer margin, and in the Mutillides not to do so. This family
is represented in Britain by a single very rare Insect, _Methoca
ichneumonides_: to the unskilled observer the female would appear to be
without doubt an ant. This Insect is by some considered as the type of a
family distinct from the Thynnides proper. Thynnides are numerous in
Australia. Very little is really known as to their habits, though it has
been stated that they are parasitic on Lepidoptera, Bakewell having
obtained specimens from subterranean cocoons of that Order. Those who are
interested in differences between the sexes of one species should examine
the extraordinary examples of that phenomenon presented by the Thynnides;
the dissimilarity throughout the group—which is now of considerable
extent—being so extreme that no entomologist would from simple inspection
believe the two sexes to have any connection; but the fact that they are so
connected has been demonstrated beyond doubt. In very few {97}cases,
however, have the sexes been matched, so that at present males are no doubt
standing in the lists of Hymenoptera as one species and their females as
other species.
SUB-FAM. 3. SCOLIIDES.—_Pronotum reaching back to the tegulae; legs
stout; intermediate tibiae with one apical spur; both sexes winged; the
nervures not extending to the posterior_ (i.e. _distal_) _margin_.
This group includes some of the largest and most powerful of the Aculeate
Hymenoptera. Its members are usually hairy Insects with thick legs, the
colour being black, more or less variegated with bands or spots of red or
yellow; the hind body is elongate, has only a very short pedicel, and in
the male is usually terminated by three projecting spines. The pronotum is
of variable dimensions, but its front angles are always co-adapted with the
points of insertion of the front wings. The nervuration of the front wings
is confined to the basal part, the extensive apical or outer area
possessing no nervures. There is frequently a great difference in the size
of the two sexes of the same species, the female being very much larger
than the other sex. The larvae, so far as is known, devour those of
Lamellicorn Coleoptera.
[Illustration: Fig. 40.—_Scolia haemorrhoidalis_ ♀. Europe.]
Fabre has investigated the habits of some of the species of Scoliides found
in France, and has informed us that their means of subsistence consists of
larvae of the larger Lamellicorn beetles, _Cetonia_, _Oryctes_, _Anoxia_,
and _Euchlora_; these beetles belong to very different divisions of the
Lamellicornia, but they have in common the fact that their larvae are of
subterranean habits, living in the earth or in accumulations of débris in
which there is a large proportion of vegetable matter or roots. The female
_Scolia_ penetrates into the ground in order to find the Lamellicorn larvae
necessary as food for its progeny. _Scolia bifasciata_ {98}attacks the
larvae of several species of _Cetonia_, and _S._ (_Colpa_) _interrupta_
chooses the larvae of the chafers _Anoxia villosa_ and _A. matutinalis_.
The mother _Scolia_ enters the ground in August or September, and having
found a suitable larva stings it and deposits an egg on the ventral surface
of the prey; the paralysed larva is left where it was found, no attempt
being made to place it in a special receptacle. The egg is placed on the
ventral surface, well behind the feet, under a mass of matter in the
alimentary canal. Shortly after being hatched the young destroyer
penetrates with its head the skin of the victim, and in this position
commences to feed; it is necessary that it should obtain its food without
killing the _Cetonia_ larva, for it cannot prosper on decaying food, so
that if the _Cetonia_ larva die the _Scolia_ larva likewise perishes; the
latter, accordingly, does not withdraw its head from the interior of the
victim, but remains always in the same position, as it grows larger
extending its head forwards into the front part of the interior of its
victim; the internal organs of the latter are consumed in a systematic
order so as to delay bringing about its death till the last moment, and
thus all the interior of the _Cetonia_ larva is appropriated till nothing
remains but an empty skin. By a series of experiments, Fabre showed how
essential it is that this apparently revolting operation should be carried
on with all details strictly _en règle_. If the head of the _Scolia_ larva
be taken out from the victim and applied to another part of the body of the
_Cetonia_, the result is that it cannot eat; even if it be replaced in the
original situation, after being taken away, it frequently happens that the
_Cetonia_ larva dies, its death involving also that of the destroyer. It is
necessary, too, that the victim should be paralysed, for if an intact
_Cetonia_ larva be taken and bound down in such a position that it cannot
move, and if a small orifice in its skin be made in the proper spot and a
young _Scolia_ larva be placed on it, the little parasite will avail itself
of the opportunity and commence to feed on the larva provided for it, but
the latter will speedily die, and the _Scolia_ necessarily perishes with
it. Thus both the paralysis of the victim and the special mode of eating
are essential to the life of the _Scolia_. The operation of stinging the
larva so as to produce the necessary paralysis, or rather insensibility, is
a difficult one, and requires great skill and patience. The _Cetonia_ larva
is of large size, and must be pierced in one particular spot; {99}in order
to reach this the _Scolia_ mounts on its victim, and is frequently
dislodged by its struggles; sooner or later, however, the proper position
is obtained by the wasp, and the larva is then stung in the exact spot
necessary to allow the sting (and the poison introduced by it) to reach the
most important of the nervous ganglia that control the movements of the
body, this spot being, in the case of the _Cetonia_, the line of
demarcation between the pro- and meso-thorax, on the middle line of the
ventral surface of the body. The _Scolia_ gives but one sting to the
victim, and this it will not administer until it can do so exactly in the
proper place. This practice of devouring the victim slowly, without killing
it till all is eaten, is very widely spread in the Hymenoptera, and it is
satisfactory to find that we may infer from Fabre's observations that it is
not so horrible as it would at first appear; for it is probable that the
stinging prevents decomposition of the victim, not by reason, as some have
supposed, of the poison injected by the wasp having an antiseptic effect,
but rather by means of destroying sensibility, so that the creature does
not die from the pain, as it is believed it did in certain cases where
Fabre induced the young _Scolia_ larva to feed on a victim that had not
been stung. We may here remark that very little exact information exists as
to the operation of stinging. Fabre attaches great importance to the sting
being inflicted on a nerve-ganglion. Whether a sting that did not reach
this part might not have a sufficient effect appears, however,
doubtful.[46]
A remarkable form of Scoliides, with wings of smaller size than usual and
deeply divided, has been described by Saunders under the name _Pseudomeria
graeca_. Still more remarkable is _Komarovia victoriosa_ found in Central
Asia; in this Insect the male retains the appearance of a slender, pallid
_Scolia_, but the female differs totally in form, and has the peculiar
wings so reduced in size as to be useless for flight.
SUB-FAM. 4. SAPYGIDES.—_Closely allied to the Scoliides, but possessing
slender legs and antennae; also the first abdominal segment is less
disconnected from the second, so that the outline {100}is less
interrupted; the eyes are deeply emarginate; the hind body is not spinose
at the apex._
[Illustration: Fig. 41.—_Sapyga 5-punctata_ ♀, Britain.]
The economy of _Sapyga_, the only genus, has been the subject of difference
of opinion. The views of Latreille and others that these species are
parasitic upon bees is confirmed by the observations of Fabre, from which
it appears that _S. 5-punctata_ lives in the burrows of species of the
bee-genus _Osmia_, consuming the store of provisions, consisting of
honey-paste, that the bee has laid up for its young. According to the same
distinguished observer, the _Sapyga_ larva exhibits hypermetamorphosis
(_i.e._ two consecutive forms), and in its young state destroys the egg of
the bee; but his observations on this point are incomplete and need
repetition. We have two species of _Sapyga_ in Britain; they differ in
colour, and the sexes of _S. 5-punctata_ also differ in this respect; the
abdomen, spotted with white in both sexes is in the female variegate with
red. Smith found our British _Sapyga 5-punctata_ carrying caterpillars.
SUB-FAM. 5. RHOPALOSOMIDES.—_Antennae elongate, spinigerous; ocelli very
prominent; tarsi of peculiar structure, their claws bifid._
[Illustration: Fig. 42—_Rhopalosoma poeyi._ A, female imago; B, front of
head. Cuba. (After Westwood.)]
This sub-family has recently been proposed by Ashmead[47] for {101}an
extremely rare American Insect that had previously been placed by Cresson
among parasitic Hymenoptera. Westwood classed _Rhopalosoma_ among
Diploptera, saying of it "animal quoad affinitates excrucians." We
reproduce Westwood's figure, but not being acquainted with the Insect we
can express no opinion as to whether it is allied to the Scoliidae or to
the Sphegidae. The habits are, we believe, quite unknown.
FAM. 2. POMPILIDAE.
_Pronotum at the sides reaching the tegulae; hind body never definitely
pedicellate, though the first segment is sometimes elongate and conical;
hind legs long; eyes elliptic in form, not emarginate._
The Pompilidae are perhaps the most extensive and important of the groups
of Fossores, and are distributed over all the lands of the globe, with the
exception of some islands and of the inclement arctic regions. The sting of
the Pompilidae, unlike that of most of the Fossores, inflicts a burning and
painful wound; the creatures sometimes attain a length of two or three
inches, and a sting from one of these giants may have serious results.
Although there is considerable variety in the external form of the members
of the group, the characters given above will enable a Pompilid to be
recognised with approximate certainty. The elongation of the hind legs
includes all the parts, so that while the femur extends nearly as far back
as the extremity of the body—in dried examples at any rate—the tibiae and
the long tarsi extend far beyond it; thus these Insects have great powers
of running; they are indeed remarkable for extreme activity and vivacity.
They may frequently be seen running rapidly on the surface of the ground,
with quivering wings and vibrating antennae, and are probably then employed
in the search for prey, or some other of the operations connected with
providing a store of food for their young. Spiders appear to be their
special, if not their only, prey. Several authors have recorded details as
to the various ways in which the prey is attacked. Fabre has observed the
habits of several species, and we select his account of the _modus
operandi_ of species of the genera _Pompilus_ and _Calicurgus_, in their
attacks on poisonous spiders that inhabit holes in the ground or in walls.
The wasp goes to the mouth of the spider's burrow, and the latter then
dashes to the entry, apparently enraged at the audacity of its persecutor.
{102}[Illustration: Fig. 43.—_Calicurgus hyalinatus_ ♀. Britain.]
The _Calicurgus_ will not actually enter a burrow when there is a spider in
it, because if it did so the spider would speedily dispose of the aggressor
by the aid of its poisonous fangs. The _Calicurgus_, therefore, has
recourse to strategy with the object of getting the spider out of its nest;
the wasp seizes its redoubtable foe by one foot and pulls; probably it
fails to extract the spider, and in that case rapidly passes to another
burrow to repeat its tactics; sooner or later a spider is in some moment of
inattention or incapacity dragged from its stronghold, and, being then
comparatively helpless, feels itself at a disadvantage and offers but a
feeble resistance to the wasp, which now pounces on its body and
immediately inflicts a sting between the fangs of the foe, and thus at once
paralyses these dangerous weapons; thereafter it stings the body of the
spider near to the junction of the abdomen and cephalothorax, and so
produces complete inactivity. Having secured its prey, the wasp then seeks
a suitable hole in which to deposit it; probably an empty burrow of a
spider is selected for the purpose, and it may be at a height of several
feet in a wall; the Hymenopteron, walking backwards, drags its heavy prey
up the wall to bring it to the den. When this is accomplished an egg is
deposited on the spider, and the wasp goes in search of a fragment or two
of mortar, with which the mouth of the burrow is finally blocked. Fabre's
accounts refer to the habits of several species, and give a good insight
into some points of the instincts of both the spider and the wasp. It seems
that a sense of superiority is produced in one or other of the foes,
according as it feels itself in suitable conditions; so that though a
spider out of its burrow and on the ground is speedily vanquished by the
Pompilid, yet if the two be confined together in a vase, both are {103}shy
and inclined to adopt defensive or even evasive tactics, the result
probably being that the wasp will be killed by the spider during the night,
that being the period in which the attacking powers of the spider are more
usually brought into play.
It seems to be the habit of some _Pompilus_ to procure a victim before they
have secured a place for its reception; and Fabre took advantage of this
fact, and made very interesting observations on some points of the instinct
of these wasps. Having found a _Pompilus_ that, after having caught a
spider and paralysed it, was engaged in making a retreat for its reception,
he abstracted the booty, which was deposited at the top of a small tuft of
vegetation near to where the _Pompilus_ was at work. In this case the
burrow in course of preparation was subterranean, and was formed by the
_Pompilus_ itself, which therefore could not, while it was engaged
underground, see what took place near it. It is the habit of the wasp to
leave its work of excavation from time to time, and to visit the prey as if
to assure itself of the safety of this object, and to enjoy the
satisfaction of touching it with the mouth and palping it. Desirous of
testing the wasp's memory of locality, Fabre took the opportunity, while
the Insect was working at the formation of its burrow, of removing, as we
have said, the booty from the place where it had been deposited, and
putting it in another spot some half-yard off. In a short time the
_Pompilus_ suspended work and went straight to the spot where it had
deposited its property, and finding this absent, entered on a series of
marches, counter-marches, and circles round the spot where it had left the
prey, as if quite sure that this was really the place where the desired
object ought to be. At last convinced that the paralysed prey was no longer
where it had been placed, the _Pompilus_ made investigations at a greater
distance and soon discovered the spider. Fabre recounts that its movements
then appeared to indicate astonishment at the change of position that it
thus ascertained to have occurred. The wasp, however, soon satisfied itself
that this was really the very object it was seeking, and seizing the spider
by the leg slightly altered its position by placing it on the summit of a
small tuft of vegetation; this latter proceeding being apparently always
carried out by this species of _Pompilus_. Then it returned to its
excavation, and Fabre again removed the spider to a third spot; the wasp
when it next rested from its work made its way {104}immediately to the
second spot, where it had last left the spider, thus showing that it
possessed an accurate memory for locality; the wasp was very much surprised
at the absence of the valued prize and persisted in seeking it in the
immediate vicinity without once returning to the place where it had been
first located. Fabre repeated this manoeuvre five times, and the _Pompilus_
invariably returned at once to the spot where it had last left its prey.
The acute memory for localities displayed by this Insect seems to be more
or less general throughout the Aculeate Hymenoptera, and is of very great
importance to them. The power of finding the object appears to depend on
sight, for when Fabre, after removing the spider to a fresh spot, made a
slight depression in the ground, placed the spider in it and covered it
over with a leaf, the wasp did not find it. At the same time, the Insect's
sight must be a very different sense from our own, for the wasp, when
seeking its lost booty, frequently passed within a couple of inches of it
without perceiving it, though it was not concealed.
Belt gives an example of the habits of the Mexican _Pompilus polistoides_.
He noticed it, when hunting for spiders, make a dart at a web in the centre
of which a spider was stationed; by this movement the creature was
frightened and fell to the ground, where it was seized by the wasp and
stung. The _Pompilus_ then dragged its prisoner up a tree and afterwards
flew off with it, the burden being probably too heavy for conveyance to the
nest without the vantage of an elevation to start from.
Several modifications adopted by Pompilidae in their mode of stinging their
spider-victims have been recorded by Ferton; these we cannot allude to in
detail, but will nevertheless mention that one species stings the body of
its spider-prey at random, and that in other cases it would appear that the
paralysis of the spider is evanescent. In short, there are various degrees
of perfection in the details of the art of stinging.
The most remarkable of the forms of Pompilidae are the numerous species of
_Pepsis_, a genus peculiar to America, whence upwards of 200 species are
already known.[48] Some of them attain a length of two inches or more, and
are able to conquer the largest spiders; even the formidable _Mygale
avicularis_ succumbs to their agility and skill. Some of these _Pepsis_
have beautifully coloured wings; according to Cameron, this may be {105}due
to scales. _P. formosus_, Say, is called in Texas the tarantula-killer;
according to Buckley, its mode of attack on the huge spider is different
from that made use of by its European ally. When it discovers a tarantula
it flies "in circles in the air, around its victim. The spider, as if
knowing its fate, stands up and makes a show of fighting, but the
resistance is very feeble and of no avail. The spider's foe soon discovers
a favourable moment and darts upon the tarantula, whom it wounds with its
sting, and again commences flying in circles." The natural retreat of this
huge spider, _Mygale hentzii_, is in holes in the ground, and this account
does not inform us whether the spider allows itself to be overcome when in
its nest, or is only attacked when out of its retreat.
The genus _Mygnimia_ includes a very large number of species, and has a
wider geographical distribution than _Pepsis_, being found in the tropical
regions of both the Old and New Worlds, some of them rivalling in size and
ferocity the larger specimens of the genus _Pepsis_. In the Insects of this
genus there is usually a more or less distinct small space of more pallid
colour on the middle of each front wing. _Parapompilus_ is a curious genus
consisting of Insects of a great variety of peculiar coloration, and having
the wings short, so as to be of little use for flight. _P. gravesii_ is an
inhabitant of Chili.
_Agenia carbonaria_ and _A. hyalipennis_ are small and feeble Insects
inhabiting the south of Europe. _A. carbonaria_ extends to the south of
England. They construct, as nests for their offspring, small earthenware
vessels, differing in form according to the species, those of _A.
hyalipennis_ being vase-like in shape, while those of _A. carbonaria_ are
contracted near the mouth, something after the fashion of a wide-mouthed
bottle. The Insect is able by some means—Fabre thinks by the use of
saliva—to varnish the interior of the vessel so that it will not absorb
water; the outside of the cells is, however, not so protected, and speedily
crumbles away when exposed to the action of water; hence the vessel is
placed in a protected situation, such as in a tree-stump, or a hole in a
wall, or even in an empty snail-shell under a heap of stones. The cells are
stored with spiders that have been paralysed by stinging and that serve as
food for the larva of the _Agenia_. The larva of _A. carbonaria_ has been
described, and some particulars as to its habits have been given by
Verhoeff. {106}It has been stated that this wasp does not paralyse its prey
by stinging, but substitutes a process of biting to prevent the spider from
hurting the larva that is to feed on it; and Verhoeff's observations seem
to show that the legs of the spider are broken by some proceeding of the
kind. The _Agenia_ larva is of peculiar shape, the head not being inflexed,
while the pleurae of each segment, from the second onwards, are prominent,
so as to give the outline of the body a scalloped appearance. This larva is
much infested by an Ichneumon that devours, it appears, not only the larva
itself, but also the spider that was destined to be food for the larva.
Verhoeff seems to have found some evidence that _Pompilus sericeus_ may
also be a parasite on the _Agenia_.
The construction of earthenware cells, instead of the burrows usual in
Pompilidae, by the species of this genus is one of the cases alluded to in
our introductory remarks as to allied Fossores exhibiting different habits.
Mr. Pride has recently sent us from Brazil similar earthen vessels
constructed by some Pompilid.
The habits of Pompilids of the genus _Ceropales_ are analogous to those of
the parasitic bees. Pérez has recently given us information as to a very
curious form of parasitism in this genus; he says that when a _Pompilus_
has obtained a spider as provision for its young, it is pursued by a
_Ceropales_, which lays an egg on the spider, thus as it were substituting
in advance its own young for that of the _Pompilus_. Information as to the
subsequent course of events in this case is not at present forthcoming. In
another case a _Ceropales_ was observed to oviposit on the spider, not
while this is being carried in, but subsequently by entering the nest for
the purpose; a habit quite similar to that of some parasitic bees. Ferton
has recently made the unexpected discovery that some _Pompilus_ act as
robbers; one individual taking away by force the spider that another has
captured and is carrying off.
Lichtenstein described a Pompilid larva, that he afterwards ascertained to
be _Calicurgus hyalinatus_, as possessing the extraordinary habit of
feeding as an external parasite fixed to the dorsal surface of a spider;
thus repeating, it would appear, the habits of some of the Ichnemonidae,
though the perfect Insect (Fig. 143) does not differ in structure from its
congeners. Emery has given an account of some Pompilids that do not bury
their prey, but after stinging it and depositing an egg, simply leave the
spider on the spot.
{107}Buller has described the habits of a Pompilid in New Zealand; his
account is interesting because it shows a remarkable similarity in the
proceedings of this antipodean wasp to those of its congeners on our own
side of the world. The species is not scientifically named, but it appears
that it is known in New Zealand as "the Mason-bee." It forms a nest of
yellow clay consisting apparently of about eight cells, each of which is
filled with one or more spiders in a paralysed condition. The figure given
of the larva of this Insect by Buller shows it to possess a peculiarly
formed head.
It is pleasing to find that Pompilidae do not make use of cruel methods
when others will serve their purpose. We are informed that a large
Australian Pompilid—_Priocnemis bicolor_—may find a _Cicada_ sucking sap
from a hole it has pierced in a tree. The _Priocnemis_ has not the art of
making the puncture necessary to procure sap, so the wasp seizes the
_Cicada_, and shakes it till it leaves its hold and flies away, when the
_Priocnemis_ takes its place and sips the sap. It is added that the wasp
never hurts the Cicada.
FAM. 3. SPHEGIDAE.
_Pronotum free from the tegulae; when the stigmatic lobes extend as far
back as the wing-insertion, they are placed below it and separated by a
space from it._
This large assemblage of Fossores is the one about which the greatest
difference of opinion prevails. It is based entirely on the prothoracic
characters mentioned above, and cannot be looked on as natural. We shall,
however, follow Kohl[49] in treating for the present as only one family the
divisions considered by many as distinct families. They are ten in number.
SUB-FAM. 1. SPHEGIDES.—_Hind body with a slender pedicel of variable
length; two spurs on the middle tibia. The propodeum usually horizontally
elongate_.[50]
This group includes a great number of species, about 200 of which are
referred to the genus _Sphex_.
{108}The habits of one species of this genus have been fully described by
Fabre; he assigns to the species the name of _S. flavipennis_, but Kohl
considers that it is more probably _S. maxillosus_. This Insect forms its
nests, in the South of France, in the ground, excavating a main shaft with
which are connected cells intended for the reception of the provisions for
the young. The entrance to the burrow is formed by piercing a hole in the
side of a very slight elevation of the soil. Thus the entrance to the
construction consists of a horizontal gallery, playing the part of a
vestibule, and this is used by the _Sphex_ as a place of retreat and
shelter for itself; at the end of the vestibule, which may be two or three
inches long, the excavation takes an abrupt turn downwards, extending in
this manner another two or three inches, and terminating in an oval cell
the larger diameter of which is situate in a horizontal plane. When this
first cell has been completed, stored with food, and an egg laid in it, the
entrance to it is blocked up, and another similar cell is formed on one
side; a third and sometimes a fourth are afterwards made and provisioned,
then the Insect commences anew, and a fresh tunnel is formed; ten such
constructions being the number usually prepared by each wasp. The Insect
works with extreme energy, and as the period of its constructive activity
endures only about a month, it can give but two or three days to the
construction and provisioning of each of its ten subterranean works. The
provisions, according to Fabre, consist of a large species of
field-cricket, of which three or four individuals are placed in each cell.
Kohl states, however, that in Eastern Europe an Insect that he considers to
be the same species as Fabre's _Sphex_, makes use of locusts as provisions,
and he thinks that the habit may vary according to the locality or to the
species of Orthoptera that may be available in the neighbourhood. However
that may be, it is clear from Fabre's account that this part of the
_Sphex's_ duties do not give rise to much difficulty. The cricket, having
been caught, is paralysed so that it may not by its movements destroy the
young larva for whose benefit it is destined. The _Sphex_ then carries it
to the burrow to store it in one of the cells; before entering the cell the
Insect is in the habit of depositing its prey on the ground, then of
turning round, entering the burrow backwards, seizing as it does so the
cricket by the antennae, and so dragging it into the cell, itself going
{109}backwards. The habit of depositing its prey on the ground enabled
Fabre to observe the process of stinging; this he did by himself capturing
a cricket, and when the wasp had momentarily quitted its prey, substituting
the sound cricket for the paralysed one. The _Sphex_, on finding this new
and lively victim, proceeds at once to sting it, and pounces on the
cricket, which, after a brief struggle, is overcome by the wasp; this holds
it supine, and then administers three stings, one in the neck, one in the
joint between the pro- and meso-thorax, and a third at the base of the
abdomen, these three spots corresponding with the situation of the three
chief nervous centres governing the movements of the body. The cricket is
thus completely paralysed, without, however, being killed. Fabre proved
that an Insect so treated would survive for several weeks, though deprived
of all power of movement. Three or four crickets are placed by the wasp in
each cell, 100 individuals or upwards being thus destroyed by a single
wasp. Although the sting has such an immediate and powerful effect on the
cricket, it occasions but a slight and evanescent pain to a human being;
the sting is not barbed, as it is in many bees and true wasps, and appears
to be rarely used by the Insect for any other purpose than that of
paralysing its victims. The egg is laid by the _Sphex_ on the ventral
surface of the victim between the second and third pairs of legs. In three
or four days the young larva makes its appearance in the form of a feeble
little worm, as transparent as crystal; this larva does not change its
place, but there, where it was hatched, pierces the skin of the cricket
with its tiny head, and thus begins the process of feeding; it does not
leave the spot where it first commenced to feed, but gradually enters by
the orifice it has made, into the interior of the cricket. This is
completely emptied in the course of six or seven days, nothing but its
integument remaining; the wasp-larva has by this time attained a length of
about 12 millimetres, and makes its exit through the orifice it entered by,
changing its skin as it does so. Another cricket is then attacked and
rapidly consumed, the whole stock being devoured in ten or twelve days from
the commencement of the feeding operations; the consumption of the
later-eaten crickets is not performed in so delicate a manner as is the
eating of the first victim. When full-grown, the process of forming a
cocoon commences: this is a very elaborate operation, for the encasement
consists of three layers, in {110}addition to the rough silk that serves as
a sort of scaffolding on the exterior: the internal coat is polished and is
of a dark colour, owing to its being coloured with a matter from the
alimentary canal: the other layers of the cocoon are white or pale yellow.
Fabre considers that the outer layers of the cocoon are formed by matter
from the silk-glands, while the interior dark coat is furnished by the
alimentary canal and applied by the mouth of the larva: the object of this
varnish is believed to be the exclusion of moisture from the interior of
the cocoon, the subterranean tunnels being insufficient for keeping their
contents dry throughout the long months of winter. During the whole of the
process of devouring the four crickets, nothing is ejected from the
alimentary canal of the larva, but after the cocoon is formed the larva
ejects in it, once for all, the surplus contents of the intestine. Nine
months are passed by the Insect in the cocoon, the pupal state being
assumed only towards the close of this period. The pupa is at first quite
colourless, but gradually assumes the black and red colour characteristic
of the perfect wasp. Fabre exposed some specimens of the pupa to the light
in glass tubes, and found that they went through the pupal metamorphosis in
just the same manner as the pupae that remained in the darkness natural to
them during this stage of their existence.
_Sphex coeruleus_ is frequently stated to have the habit of provisioning
its nests with both Orthoptera and Spiders; but Kohl considers with reason
that this record is, as regards spiders, a mistake, arising probably from a
confusion with some other Insect of similar appearance, such as _Pelopaeus_
(_Sceliphron_) _coeruleus_. _S. coeruleus_ is no doubt the same as _S._
(_Chlorion_) _lobatus_, which Rothney observed in East India, provisioning
its nests with Orthoptera. He discovered a nest in process of construction,
and during the absence of the mother-wasp abstracted from the burrow a
large field-cricket that she had placed in it; he then deposited the
Orthopteron near the cell; the parent _Sphex_ on returning to work entered
the tunnel and found the provision placed therein had disappeared; she came
out in a state of excitement, looked for the missing cricket, soon
discovered it, submitted it to the process of malaxation or kneading, and
again placed it in the nest, after having cleared it from some ants that
had commenced to infest it. She then disappeared, and Rothney repeated the
experiment; in due course the same series {111}of operations was performed,
and were repeated many times, the _Sphex_ evidently acting in each case as
if either the cricket had disappeared owing to its being incompletely
stunned, or to its having been stolen by ants. Finally, the observer placed
the cricket at a greater distance from the nest, when it recovered from the
ill-treatment it had received sufficiently to make its escape. The points
of interest in this account are the fact that the cricket was only
temporarily paralysed, and that the wasp was quite able to cope with the
two special difficulties that must frequently occur to the species in its
usual round of occupations.
The genus _Ammophila_ is of wide distribution, and its species make
vertical tunnels in the ground. The habits of some of the species found in
France have been described by Fabre. The Insect does not inhabit the burrow
while it is in process of formation, but quits it; and some of the species
temporarily close the entry to the incomplete nest with a stone. The tunnel
is a simple shaft with a single cell at its termination; this is stored
with caterpillars, the different species of _Ammophila_ selecting different
grubs for the purpose. _A. hirsuta_ hibernates in the perfect state, and
carries on its work in the spring; it chooses a single larva of
considerable size belonging to one of the nocturnal Lepidoptera, and this
it paralyses by a series of about nine stings, of which one is implanted in
each segment from the first thoracic ring backwards; it forms the burrow
only after the food to be placed therein has been obtained. The caterpillar
used is subterranean in habit, and the _Ammophila_ detects the larva by
some sense, the nature of which appears at present quite uncertain. _A.
holosericea_ chooses smaller larvae of the family Geometridae, and uses
only one or two stingings to paralyse each larva; several caterpillars are
used to provision a single cell, and they are often selected of different
colours.
Marchal has also published an important account of the proceedings of _A.
affinis_; he confirms Fabre's observations, and even adds to their interest
by suggesting that the _Ammophila_ administers special stings for the
purpose of paralysing the mandibles of the caterpillar and depriving it of
any power of afterwards injuring the larva that will feed on it. He thinks
the mother-_Ammophila_ herself profits by appropriating an exudation from
the victim.
Some species of Sphegides have the curious habit of choosing {112}the
interiors of human habitations as the spots most suitable for the formation
of their own domestic establishments. Fabre has given a charming account of
the habits of _Pelopaeus_ (_Sceliphron_) _spirifex_, a species that
inhabits the South of Europe, and that forms its nests in the cottages of
the peasants. The spot usually selected is a nook in the broad, open
fireplace, out of reach of the flames, though not of the smoke; here the
_Pelopaeus_ forms a nest of earth, consisting of ten to fifty cells, the
material being mud or clay brought in little balls by the aid of the
Insect's mandibles; about twenty visits are required in order to complete
one cell, so that for the construction of a large nest of fifty cells,
about one thousand visits must be made by the Insect. It flies in and out
of the house apparently not at all incommoded by the human habitants, or by
the fact that the peasant's potage may be simmering on the fire quite close
to where the fearless little creature is carrying on its architectural
operations. The cells are stored with spiders, of which the wasp has to
bring a plentiful supply, so that its operations extend over a considerable
period. The prey is captured by the _Pelopaeus_ whilst on the wing, and
carried off at once, being probably stung by the wasp during the process of
transit; apparently it is killed by the operation, not merely paralysed.
Only small spiders are taken by this species, and the larva of the
_Pelopaeus_ consumes them in a short time, one by one, before the process
of decomposition sets in; the egg, too, is laid on the first spider
introduced, and this is of course at the bottom of the cell, so that the
spiders are eaten by the wasp's larva in the order in which they were
brought to the cell. The cell is sealed up when full, the number of spiders
placed in it being on the average about eight. The larva completes its task
of consuming the store in about ten days, and then forms a cocoon for its
metamorphosis. Two or three generations are produced in a single year, the
autumnal one passing eight or nine months in the clay cells, which are
lodged in a nook of the peasant's hearth, and exposed to the smoke of his
fire during all the months of winter. _Pelopaeus_ (_Sceliphron_) is a genus
including many species;[51] several of them are known {113}to be specially
attached to the habitations of human beings. Roth has given an account of
the habits of _P._ (_Sceliphron_) _laetus_ in Australia; he says that in
some parts it is very difficult to keep these wasps out of the houses; the
nest is formed of mud, and constructed on the furniture or in any part of a
room that suits the fancy of the Insect. This it must be admitted is,
according to human ideas, liable to the charge of being very capricious.
Roth timed a wasp building its nest, and found that it brought a fresh load
of mud every two or three minutes. If the wasp be allowed to complete the
nest undisturbed, she does so by adding to the exterior diagonal streaks of
mud, so giving to the nest the look of a small piece of the bark of a
common acacia. The construction consists of from ten to twenty cells, and
when completed is provisioned with spiders for the use of the young. This
wasp is much pestered by parasites, some of which prevent the development
of the larvae by consuming the spiders intended by the mother-wasp for its
young. A fly, of the Order Diptera, is said to follow the wasp when
carrying a spider, and to deposit also an egg on the food; as the Dipterous
larvae have more rapid powers of assimilation, the _Pelopaeus_ larvae are
starved to death; and their mildewed remains may be found in the cell,
after their enemies have become fully developed and have flown away.
Another parasite is said to eat the wasp-larva, and attains this end by
introducing an egg through the mud wall and the cocoon of the wasp—a habit
that seems to indicate a _Leucospid_ parasite. _Tachytes australis_, a wasp
of the sub-family Larrides also dispossesses this _Pelopaeus_ in a manner
we shall subsequently describe. This fragment of natural history from
Australia has a special interest, for we find repeated there similar
complex biological relations to those existing in the case of the European
congeners.
_P._ (_Sceliphron_) _madraspatanus_ is common in the north-west provinces
of Hindostan, and is called the "mud-dauber" by the European residents.
According to Horne it constructs its cells in the oddest places, but
chiefly about the inhabited apartments in houses. It is perfectly fearless
when engaged in building: the cells are four to six in number, and are
usually provisioned with spiders to the number of about twenty. On one
occasion it was observed that green caterpillars were stored instead of
{114}spiders. The species is said to be protected by a peculiar odour as
well as by its sting; it is also stated that it disguises its edifice when
completed by making it look like a dab of mud, and on one occasion "rays of
mud were observed round the nest, even more exactly imitating a lump of mud
thrown with some force." _P._ (_Sceliphron_) _bilineatus_, formerly thought
to be a variety of _P. madraspatanus_, builds its nests in hedges and
trees.
SUB-FAM. 2. AMPULICIDES.—_Prothorax long and narrow, forming a neck in
front; clypeus beak-like; four submarginal cells, the outer one being
complete; metathorax elongate, the posterior part of the metasternum
deeply divided to allow a perfect inflection of the abdomen._
[Illustration: Fig. 44—_Ampulex compressa_. Male. East India.]
This is one of the smallest of the divisions of the Sphegidae, but has a
very wide distribution, being represented in both the Eastern and Western
Hemispheres. It is allied to the Sphegides, but differs by the prolongation
of the neck and of the head, and by the articulation between the petiole
and thorax being placed on the under surface of the body; the wing-nervures
are said to be of inferior importance owing to their frequently differing
in individuals of the same species. These Insects appear to be rare in
individuals, as well as few in species, and but little has been recorded as
to their habits; but it is known that they live on cockroaches. Perkins has
given a brief sketch of the habits of _Ampulex sibirica_ that is of great
interest, but requires confirmation. He says that this Insect, in West
Africa, enters apartments where cockroaches abound, and attacking one, that
may probably be four times its own size, succeeds, after a struggle, in
stinging it; the cockroach instantly becomes quiet and submissive, and
suffers itself to be led away and placed in confinement in some {115}spot
such as a keyhole, and in one case was apparently prevented from afterwards
escaping, by the wasp carrying some heavy nails into the keyhole. The larva
of the _Ampulex_ may be presumed to live on the Blattid, as it is added
that dead bodies of the cockroaches are frequently found with the empty
cocoon protruding from them. This account, if correct, points to some
features in the habits of this Insect that are unique. A remark made by
Rothney in reference to the habits of _A._ (_Rhinopsis_) _ruficornis_ seems
to indicate some similar instinct on the part of that species; he says, "I
also saw two or three of these wasps collar a peculiar cockroach by the
antennae and lead it off into a crack in the bark, but as the cockroach
reappeared smiling each time, I don't know what was up." The same observer
records that this species associates with _Sima rufonigra_, an ant it
greatly resembles in appearance, as well as with a spider that is also of
similar appearance (Fig. 72). Schurr has given a brief account of the
proceedings of _Ampulex compressa_, and his statements also tend to confirm
the correctness of Perkins' report. The habits of a species of _Ampulex_
were partially known to Réaumur, who described them on the authority of M.
Cossigni. The species is believed to be _A. compressa_, which occurs not
only in East India, but also in the island of Bourbon, the locality where
M. Cossigni made his observation: his account is, like the others, a mere
sketch of certain points observed, the most important of which is that when
_Ampulex_ cannot introduce the cockroach into a hole that it has selected
as suitable, it bites off some portions of the body in order to reduce the
poor Insect to the necessary extent.
From these fragmentary observations it would appear that the sting of the
_Ampulex_ has not so powerful a paralysing effect as that of most other
Fossores; and that the _Ampulex_ does not form any nest, but takes
advantage of suitable holes and crevices to store the victim in; also that
it displays considerable ingenuity in the selection of materials with which
to block up the cavity in which it has placed the partially incapacitated
creature.
The genus _Dolichurus_ is by some entomologists considered the type of a
sub-family allied to the Ampulicides; it long consisted of a small and rare
European Insect, but some exotic species have recently been added to it. It
will probably prove not {116}sufficiently distinct from Ampulicides,
although the pronotum is much shorter, but Handlirsch has recently observed
that the European species attacks Blattidae as do the normal Ampulicides;
and Ferton has recorded that _D. haemorrhous_ lives at the expense of
_Loboptera decipiens_, the wasp depositing its egg on the left intermediate
femur of the prey. This is placed in a solitary cell, and is entirely
consumed by the larva, life being preserved till within a few hours of the
end of the repast, which occupies altogether eight days.
SUB-FAM. 3. LARRIDES.—_Hind body not pedicellate, or with only a short
pedicel; one spur on the middle tibia; labrum inconspicuous. Marginal
cell of the front wings appendiculate,[52] or mandibles excised
externally, or both._
This group is by some writers called Tachytides instead of Larrides, as
owing to a change of nomenclature _Tachytes_ may now be considered its
principal genus. It is in connection with this and the neighbouring
sub-families of Sphegidae that some of the greatest taxonomical
difficulties exist. We include in Larrides the "_Miscophus_ group" of Kohl.
The species of the genus _Tachytes_ seem to have habits very similar to
those of the genus _Sphex_; they form shafts in the earth and provision
them with Orthoptera; like the _Sphex_ and other Fossores, they have the
habit, when they fly to their tunnel with a victim, of depositing it for a
short time on the ground close to the mouth of the burrow while they turn
round and enter backwards; and, after doing this they again seize their
prey and drag it into the burrow. Fabre availed himself of an opportunity
to remove the prey while the Hymenopteron was entering the hole alone; as a
result it had to come out again to seek the object; this it soon found, and
carried to the hole, relinquishing it again as usual while it turned round;
Fabre repeated the operation several times, and always with the same
result; the wasp, though it might have kept hold of the victim while it
turned, and thus have saved itself from losing the precious object, never
did so.
{117}One species of _Tachytes_ in the south of France selects as its prey
Orthoptera of the family Mantidae, Insects of a highly ferocious
disposition, and provided with most powerful front legs, capable of cutting
in two by a single act the body of an aggressor like the _Tachytes_; the
latter is, however, by no means dismayed by the arms of its future victim,
but hovering above the latter for some time, as if to confuse it, and
causing it repeatedly to turn its very mobile head, the _Tachytes_ at last
pounces down and instantaneously stings the _Mantis_ in the nerve centre
between the formidable arms, which at once are reduced to incapacity;
subsequently the _Tachytes_ paralyses each of the other pairs of legs, and
then carries off its victim.
[Illustration: Fig. 45.—_Tachytes pectinipes_ ♀. Britain.]
_Larra anathema_ chooses mole-crickets as the viand for its young, and
_Tachysphex panzeri_ selects grasshoppers of the family Acridiidae. _Larra
pompiliformis_ (= _Tachytes niger_, Fabre) sometimes associates itself with
_Sphex flavipennis_ (_? S. maxillosus_, according to Kohl), forming its
burrow amidst the works of a colony of that species, and making use, like
the _Sphex_, of crickets for provender. This led Fabre to believe that the
_Larra_ stole its prey from the _Sphex_, but he has since withdrawn this
indictment, and declares that the _Larra_ obtains its crickets by the more
honourable, if not more humane, process of catching and stinging them
itself. Smith has informed us, on the faith of his own observation, that
_L. pompiliformis_ uses both Lepidopterous larvae and grasshoppers for its
stores.
_T._ (_Larrada_) _australis_, according to Whittell, plays the part of a
burglar, breaking open the cells of _Pelopaeus_ (_Sceliphron_) _laetus_
after they have been completed and stored with spiders; it then takes
possession of the cell, and curiously enough the _Pelopaeus_ permits this,
although the cell contains its egg and the store of food that is intended
for the use of its own young. To us this seems very strange, but it is
probable that the _Pelopaeus_ has no idea of the consequences of the
intruder's operations; {118}it being one of the strange facts of nature
that these highly endowed creatures never even see the offspring for whose
welfare they labour with such extraordinary ingenuity and perseverance.
Neither can we suppose that they have a conception of it derived from a
knowledge of their own individual history; for their very complete
metamorphosis is scarcely reconcilable with any such recollection on their
part. It may possibly therefore be the case that, having no idea whatever
of the offspring, they are equally destitute of any conception that it will
be destroyed by the operations of the _Larrada_. However this may be,
Whittell informs us that both wasps skirmish about for a little as if each
were mistrustful and somewhat afraid of the other; this ends by the
_Pelopaeus_ withdrawing its opposition and by the _Larrada_ taking
possession of the cell, which it then proceeds to divide into two, using
for the purpose of the partition portions of the material of the nest
itself; possibly it is only a contraction of the size of the cell, not a
true division, that is effected; however this may be, after it is
accomplished the _Larrada_ deposits its own egg in the cell, having, it is
believed by Whittell, previously destroyed that of the _Pelopaeus_. Judging
from what occurs in other species it is, however, more probable that the
destruction of the egg or young of the _Pelopaeus_ is carried out by the
larva of the _Larrada_ and not by the parent-wasp. From a remark made by
Maindron as to the proceedings of _Larrada modesta_, in Ternate, it seems
probable that its habits may prove to be similar to those of _L.
australis_, for it frequents the nests of _Pelopaeus_ after they have been
completed.
SUB-FAM. 4. TRYPOXYLONIDES.—_Differ from Larrides by the inner margin of
the eyes being concave, and the marginal cell not appendiculate. (In_
Trypoxylon _there is only one distinct submarginal and one distinct
discoidal cell, a second of each being indicated faintly.)_
The nervuration of _Trypoxylon_ is very peculiar, and differs from that of
the widely-distributed genus _Pison_, though according to Kohl's views the
two may be correctly associated to form this sub-family. The species of
_Trypoxylon_ are apparently rather fond of human propinquity, and build
clay- or mud-nests in or near houses. _T. albitarse_ has this habit, and is
well known in Southern Brazil under the name of "_Marimbouda da casa_";
{119}this Insect, like _Pelopaeus_, stores its nest with spiders, and
Peckholt has remarked that however great may be the number of spiders
placed by the mother-wasp in a cell, they are all consumed by the larva,
none ever being found in the cell after the perfect Insect escapes
therefrom. The European _T. figulus_ forms a nest either in bramble-stems
or in sandy soil or walls; it makes use of spiders as provisions.
SUB-FAM. 5. ASTATIDES.—_Eyes very large in the male, meeting broadly on
the vertex; two spurs on the middle tibia._
[Illustration: Fig. 46—_Astata boops_, male. Britain.]
We have two species of the genus _Astata_ in Britain: one of them—_A.
boops_—is known to form burrows in the ground, each of which contains only
a single cell; this, it appears, is usually provisioned with bugs of the
genus _Pentatoma_, Insects remarkable for their strong and offensive odour.
St. Fargeau records that this species also makes use of a small cockroach
for forming the food-store: thus exhibiting an unique catholicity in the
toleration of the disagreeable; almost the only point of connection between
bugs and cockroaches being their disagreeable character. According to
Smith, _Oxybelus_, another genus of Fossores, is also used. Authorities are
far from agreement as to the validity and relations of the sub-family
Astatides. It consists only of the widely-distributed genus _Astata_, with
which the North American _Diploplectron_ (with one species) is doubtfully
associated.
SUB-FAM. 6. BEMBECIDES.—_Labrum frequently elongate; wing-nervures
extending very near to the outer margin; marginal cell of front wing not
appendiculate; mandibles not emarginate externally; hind body stout, not
pedicellate._
The elongation of the labrum, though one of the most trustworthy of the
characters of the Bembecides, cannot be altogether {120}relied on owing to
the variation it presents both in this and the allied sub-families. The
Bembecides carry their prey to their young tucked underneath their own
bodies and hugged to the breast; they affect loose, sandy soils for
nidification; make use, in the great majority of the cases where the habits
are known, of Diptera for provisions, and give these dead to the young;
making repeated visits to supply fresh food to the progeny, which
notwithstanding this fact, are distributed in isolated burrows.
[Illustration: Fig. 47.—_Bembex rostrata_ ♂. Europe.]
One of the most interesting of Fabre's studies of the instincts of
Hymenoptera is devoted to _Bembex rostrata_. The Bembecides have the habit
of forming their nests in the ground in wide expanses of sand, and of
covering them up, they leave them so that there appears to be absolutely
nothing by which the exact position of the nest can be traced; nevertheless
the _Bembex_ flies direct to it without any hesitation. How necessary it is
to these Insects to possess this faculty of finding their nests will be
understood when we recall that the _Bembex_ does not provision its nest
once and for all, but supplies the young at first with only insufficient
food, and has therefore to return at daily, or other intervals, with a
fresh store of provisions. The burrow is made in the sand by means of the
fore-legs; these work with such rapidity and skill that a constant stream
of sand flows out behind the Insect while it is engaged in the act of
excavation. The nest or cell in which the larva is to live, is formed by
this process of digging; but no fastening together of the material occurs,
nor does any expedient seem to be resorted to, other than that of making a
way through the sand by clearing out all the pieces of stick or stone that
might diminish facility of access. The cell being formed, the _Bembex_
leaves the spot in search of prey, and when it has secured a victim in the
shape of a two-winged fly, it returns therewith to the burrow, and the
booty is placed therein, an egg being deposited on it. The wasp then leaves
the burrow, disguising, however, the spot where it is situate, and flies
away; to proceed possibly with the formation {121}of other burrows.[53] In
the course of twenty-four hours the egg hatches, and the larva in two or
three days completely devours the stock provided for it. The mother-wasp
then returns with another fly—this time probably a larger one—penetrates
rapidly to the bottom of the burrow, and again retreats, leaving the second
stock of provisions for the benefit of the greedy larva. These visits of
supply are repeated with increased frequency, as the appetite of the larva
for the benefit of which they are made increases with its growth. During
the fourteen or fifteen days that form this portion of the life-cycle, the
single larva is supplied with no less than fifty to eighty flies for food.
To furnish this quantum, numerous visits are made to each burrow, and as
the mother _Bembex_ has several burrows—though how many does not appear to
be known—her industry at this time must be very great. All the while, too,
a great danger has to be avoided, for there is an enemy that sees in the
booty brought by the _Bembex_ to its young, a rich store for its own
progeny. This enemy is a feeble, two-winged fly of the family Tachinidae
and the genus _Miltogramma_; it hangs about the neighbourhood of the nests,
and sooner or later finds its opportunity of descending on the prey the
_Bembex_ is carrying, choosing for its purpose a moment when the _Bembex_
makes a brief delay just at the mouth of the burrow; then down comes the
_Miltogramma_ and lays one, two, or three eggs on some portion of the booty
that may be projecting from beneath the body of the wasp. This latter
carries in the food for its own young, but thus introduces to the latter
the source of its destruction, for the _Miltogramma_ larvae eat up the
supply of food intended for the _Bembex_ larvae, and if there be not enough
of this provender they satisfy their voracity by eating the _Bembex_ larva
itself. It is a remarkable fact that notwithstanding the presence of these
strange larvae in the nest the mother _Bembex_ continues to bring food at
proper intervals, and, what is stranger still, makes no effort to rid the
nest of the intruders: returning to the burrow with a supply of food she
finds therein not only her legitimate offspring, a single tenant, but
several others, strangers, it may be to the number of twelve; although she
would have no difficulty in freeing the nest from this band of little
brigands, she makes no attempt to do so, but continues to bring the
{122}supplies. In doing so she is fulfilling her duty; what matters it that
she is nourishing the enemies of her race? Both race and enemies have
existed for long, perhaps for untold periods of time, why then should she
disturb herself, or deviate from her accustomed range of duties? Some of us
will see in such proceedings only gross stupidity, while others may look on
them as sublime toleration.
The peculiar habits of _Bembex rostrata_ are evidently closely connected
with the fact that it actually kills, instead of merely paralysing, its
prey; hence the frequent visits of supply are necessary that the larvae may
have fresh, not putrefying, food; it may also be because of this that the
burrow is made in a place of loose sand, so that rapid ingress may be
possible to the _Bembex_ itself, while the contents of the burrow are at
the same time protected from the inroads of other creatures by the burrow
being filled up with the light sand. Fabre informs us that the _Bembex_
larva constructs a very remarkable cocoon in connection with the peculiar
nature of the soil. The unprotected creature has to pass a long period in
its cocoon, and the sandy, shifting soil renders it necessary that the
protecting case shall be solid and capable of keeping its contents dry and
sound. The larva, however, appears to have but a scanty supply of silk
available for the purpose of constructing the cocoon, and therefore adopts
the device of selecting grains of sand, and using the silk as a sort of
cement to connect them together. For a full account of the ingenious way in
which this difficult task is accomplished the reader should refer to the
pages of Fabre himself. Bembecides appear to be specially fond of members
of the Tabanidae (or Gad-fly family) as provender for their young. These
flies infest mammals for the purpose of feasting on the blood they can draw
by their bites, and the Bembecides do not hesitate to capture them while
engaged in gratifying their blood-thirsty propensities. In North America a
large species of Bembecid sometimes accompanies horsemen, and catches the
flies that come to attack the horses; and Bates relates that on the Amazons
a Bembecid as large as a hornet swooped down and captured one of the large
blood-sucking Motuca flies that had settled on his neck. This naturalist
has given an account of some of the Bembecides of the Amazons Valley,
showing that the habits there are similar to those of their European
congeners.
{123}_Sphecius speciosus_ is a member of the Stizinae, a group recognised
by some as a distinct sub-family. It makes use, in North America, of
Insects of the genus _Cicada_ as food for its young. Burrows in the ground
are made by the parent Insect; the egg is deposited on the _Cicada_, and
the duration of the feeding-time of the larva is believed to be not more
than a week; the pupa is contained in a silken cocoon, with which much
earth is incorporated. Riley states that dry earth is essential to the
well-being of this Insect, as the _Cicada_ become mouldy if the earth is at
all damp. As the _Cicada_ is about twice as heavy as the _Sphecius_ itself,
this latter, when about to take the captured burden to the nest, adopts the
plan of climbing with it to the top of a tree, or some similar point of
vantage, so that during its flight it has to descend with its heavy burden
instead of having to rise with it, as would be necessary if the start were
made from the ground.
SUB-FAM. 7. NYSSONIDES.—_Labrum short; mandibles entire on the outer
edge; hind body usually not pedicellate; wing with the marginal cell not
appendiculate._
This group has been but little studied, and there is not much knowledge as
to the habits of the species. It is admitted to be impossible to define it
accurately. It is by some entomologists considered to include _Mellinus_,
in which the abdomen is pedicellate (Fig. 48), while others treat that
genus as forming a distinct sub-family, Mellinides. Kohl leaves _Mellinus_
unclassified. Gerstaecker has called attention to the fact that many of the
Insects in this group have the trochanters of the hind and middle legs
divided: the division is, as a rule, not so complete as it usually is in
Hymenoptera Parasitica; but it is even more marked in some of these
Nyssonides than it is in certain of the parasitic groups.
_Mellinus arvensis_ is one of our commonest British Fossores, and we are
indebted to the late F. Smith for the following account of its habits: "It
preys upon flies, and may be commonly observed resorting to the droppings
of cows in search of its prey; it is one of the most wary and talented of
all its fraternity; were it at once to attempt, by a sudden leap, to dart
upon its victim, ten to one it would fail to secure it; no, it does no such
thing, it wanders about in a sort of innocent, unconcerned way, amongst
{124}the deluded flies, until a safe opportunity presents itself, when its
prey is taken without any chance of failure; such is its ordinary mode of
proceeding. At Bournemouth the flies are more active, more difficult to
capture, or have they unmasked the treacherous _Mellinus?_ and is it found
necessary to adopt some fresh contrivance in order to accomplish its ends?
if so, it is not deficient in devices. I noticed once or twice, what I took
to be a dead specimen of _Mellinus_, lying on patches of cow-dung; but on
attempting to pick them up off they flew; I at once suspected the creature,
and had not long to wait before my suspicions were confirmed. Another,
apparently dead fellow, was observed; and there, neither moving head or
foot, the treacherous creature lay, until a fine specimen of a Bluebottle
ventured within its grasp, when, active as any puss, the _Mellinus_ started
into life, and pounced upon its victim."
[Illustration: Fig. 48.—_Mellinus arvensis_ ♀. Britain.]
Lucas states that in the north of France _Mellinus sabulosus_ provisions
its nest with Diptera, which it searches for on the flowers of
Umbelliferae, and then carries to its nest. This is a burrow in the earth,
and when it is reached the Hymenopteron deposits its Insect burden for a
moment on the ground while it turns round in order to enter the burrow
backwards. The same writer states that two varieties of this Insect live
together—or rather in the same colonies—and make use of different species
of Diptera, even of different genera, as food for their young. These
Diptera are stung before being placed in the nest. The stinging does not
kill the Insect, however, for Lucas was able to keep one specimen alive for
six weeks after it had passed this trying ordeal.
SUB-FAM. 8. PHILANTHIDES.—_Labrum small; anterior wings with three
complete submarginal cells; hind body constricted at the base but not so
as to form a slender pedicel._
This sub-family contains Insects resembling wasps or Crabronides in
appearance, and is, as regards the pronotal structure, {125}intermediate
between the two great divisions of the Fossores, for the pronotal lobe
extends nearly or quite as far back as the tegulae, and in _Philanthus_ the
two come into almost actual contiguity.
The species of the genus _Cerceris_ are numerous in Europe, and several of
them are known to make burrows in the ground, and store them with beetles
for the benefit of the future larvae. The beetles chosen differ in family
according to the species of _Cerceris_; but it appears from the
observations of Fabre and Dufour that one kind of _Cerceris_ never in its
selection goes out of the limits of a particular family of beetles, but,
curiously enough, will take Insects most dissimilar in form and colour
provided they belong to the proper family. This choice, so wide in one
direction and so limited in another, seems to point to the existence of
some sense, of the nature of which we are unaware, that determines the
selection made by the Insect. In the case of our British species of
_Cerceris_, Smith observed _C. arenaria_ carrying to its nest Curculionidae
of very diverse forms; while _C. labiata_ used a beetle—_Haltica tabida_—of
the family Chrysomelidae.
[Illustration: Fig. 49.—_Philanthus triangulum_ ♂. Britain.]
The beetles, after being caught, are stung in the chief articulation of the
body, that, namely, between the pro- and mesothorax. _Cerceris
bupresticida_ confines itself exclusively to beetles of the family
Buprestidae. It was by observations on this Insect that Dufour first
discovered the fact that the Insects stored up do not decay: he thought,
however, that this was due to the liquid injected by the wasp exercising
some antiseptic power; but the observations of Fabre have shown that the
preservation in a fresh state is due to life not being extinguished; the
stillness, almost as if of death, being due to the destruction of the
functional activity of the nerve centres that govern the movements of the
limbs.
{126}It has long been known that some species of _Cerceris_ prey on bees of
the genus _Halictus_, and Marchal has recently described in detail the
proceedings of _C. ornata_. This Insect catches a _Halictus_ on the wing,
and, holding its neck with the mandibles, bends her body beneath it, and
paralyses it by a sting administered at the front articulation of the neck.
The _Halictus_ is subsequently more completely stunned or bruised by a
process of kneading by means of the mandibles of the _Cerceris_. Marchal
attaches great importance to this "malaxation"; indeed, he is of opinion
that it takes as great a part in producing or prolonging the paralysis as
the stinging does. Whether the malaxation would be sufficient of itself to
produce the paralysis he could not decide, for it appears to be impossible
to induce the _Cerceris_ to undertake the kneading until after it has
reduced the _Halictus_ to quietude by stinging.
Fabre made some very interesting observations on _Cerceris tuberculata_,
their object being to obtain some definite facts as to the power of these
Insects to find their way home when removed to a distance. He captured
twelve examples of the female, marked each individual on the thorax with a
spot of white paint, placed it in a paper roll, and then put all the rolls,
with their prisoners, in a box; in this they were removed to a distance of
two kilometres from the home and then released. He visited the home five
hours afterwards, and was speedily able to assure himself that at any rate
four out of the twelve had returned to the spot from whence they had been
transported, and he entertained no doubt that others he did not wait to
capture had been equally successful in home-finding. He then commenced a
second experiment by capturing nine examples, marking each with two spots
on the thorax, and confining them in a dark box. They were then transported
to the town of Carpentras, a distance of three kilometres, and released in
the public street, "in the centre of a populous quarter," from their dark
prison. Each _Cerceris_ on being released rose vertically between the
houses to a sufficient height, and then at once passed over the roofs in a
southerly direction—the direction of home. After some hours he went back to
the homes of the little wasps, but could not find that any of them had then
returned; the next day he went again, and found that at any rate five of
the _Cerceris_ liberated the previous day were then at home. This record is
of considerable {127}interest owing to two facts, viz. that it is not
considered that the _Cerceris_ as a rule extends its range far from home,
and that the specimens were liberated in a public street, and took the
direction of home at once.
_Philanthus apivorus_ is one of the best known of the members of this
sub-family owing to its habit of using the domestic honey-bee as the food
for its offspring. In many respects its habits resemble those of _Cerceris
ornata_, except that the _Philanthus_ apparently kills the bee at once,
while in the case of the _Cerceris_, the _Halictus_ it entombs does not
perish for several days. The honey-bee, when attacked by the _Philanthus_,
seems to be almost incapable of defending itself, for it appears to have no
power of finding with its sting the weak places in the armour of its
assailant. According to Fabre, it has no idea of the _Philanthus_ being the
enemy of its race, and associates with its destroyer on amicable terms
previous to the attack being made on it. The _Philanthus_ stings the bee on
the under-surface of the mentum; afterwards the poor bee is subjected to a
violent process of kneading, by which the honey is forced from it, and this
the destroyer greedily imbibes. The bee is then carried to the nest of the
_Philanthus_. This is a burrow in the ground; it is of unusual depth—about
a yard according to Fabre—and at its termination are placed the cells for
the reception of the young; in one of these cells the bee is placed, and an
egg laid on it: as the food in this case is really dead, not merely in a
state of anæsthesia, the _Philanthus_ does not complete the store of food
for its larvae all at once, but waits until the latter has consumed its
first stock, and then the mother-wasp supplies a fresh store of food. In
this case, therefore, as in _Bembex_, the mother really tends the
offspring.
SUB-FAM. 9. MIMESIDES.—_Small Insects with pedicellate hind body, the
pedicel not cylindric; mandibles not excised externally; inner margin of
eyes not concave; middle tibia with one spur; wings with two, or three,
submarginal cells._
Mimesides is here considered to include the Pemphredonides of some authors.
Mimesides proper comprises but few forms, and those known are small
Insects. _Psen concolor_ and _P. atratus_ form their nests in hollow stems,
and the former provisions its nest with Homopterous Insects of the family
Psyllidae. Little {128}information exists as to their habits; but Verhoeff
states that the species of _Psen_—like members of the Pemphredoninae—do not
form cocoons.
The Pemphredonine subdivision includes numerous small and obscure Insects
found chiefly in Europe and North America (Fig. 51, _P. lugubris_); they
resemble the smaller black species of Crabronides, and are distinguished
from them chiefly by the existence of at least two complete, submarginal
cells on the anterior wing instead of one.
[Illustration: Fig. 50.—_Mimesa bicolor_ ♂. Britain.]
The species of _Passaloecus_ live in the burrows that they form in the
stems of plants; _Pemphredon lugubris_ frequents the decayed wood of the
beech. The larva and pupa of the latter have been described by Verhoeff; no
cocoon is formed for the metamorphosis. Both these genera provision their
nests with Aphidae. This is also the case with _Stigmus pendulus_, but the
burrows of this species form a complex system of diverticula proceeding
from an irregular main channel formed in the pithy stems of bushes.
_Cemonus unicolor_, according to Giraud, forms its burrows in
bramble-stems, but it also takes advantage, for the purposes of
nidification, of the abandoned galls of _Cynips_, and also of a peculiar
swelling formed by a fly—_Lipara lucens_—on the common reed, _Arundo
phragmites_. This species also makes use of Aphidae, and Verhoeff states
that it has only an imperfect instinct as to the amount of food it stores.
[Illustration: Fig. 51.—_Pemphredon lugubris_ ♀. Britain.]
SUB-FAM. 10. CRABRONIDES.—_Pronotum short, front wing with one complete
submarginal and two discoidal cells: hind body {129}variable in form,
pedicellate in some abnormal forms, but more usually not stalked._
The Crabronides (_Vespa crabro_, the hornet, is not of this sub-family) are
wasp-like little Insects, with unusually robust and quadrangular head. They
frequently have the hind tibiae more or less thickened, and the clypeus
covered with metallic hair. It appears at present that they are specially
attached to the temperate regions of the northern hemisphere, but this may
possibly be in part due to their having escaped attention elsewhere. In
Britain they form the most important part of the fossorial Hymenoptera, the
genus _Crabro_ (with numerous sub-genera) itself comprising thirty species.
The males of some of the forms have the front tibiae and tarsi of most
extraordinary shapes. They form burrows in dead wood, or in pithy stems,
(occasionally in the earth of cliffs), and usually store them with Diptera
as food for the larvae: the wings and dried portions of the bodies of the
flies consumed by Crabronides are often exposed to view when portions of
old wood are broken from trees.
[Illustration: Fig. 52.—_Crabro cephalotes_ ♀. Britain.]
The genus _Oxybelus_ is included by some systematists, but with doubt, in
this sub-family; if not placed here, it must form a distinct sub-family. It
has the metathorax spinose, and the sub-marginal and first discoidal cells
are not, or are scarcely, separated.
_Crabro leucostomus_ has been observed by Fletcher to form cells for its
larvae in the soft wood of broken willows: the food stored therein consists
of two-winged flies of the family Dolichopodidae. This _Crabro_ is
parasitised by an Ichneumonid of the genus _Tryphon_, and by a two-winged
fly of uncertain genus, but belonging to the family Tachinidae. The
metamorphoses of _Crabro chrysostomus_ have been briefly described by
Verhoeff: the food stored consists of Diptera, usually of the family
{130}Syrphidae; the larva spins an orange-red cocoon, passes the winter
therein, and assumes the pupal form in the spring; there is, he says, a
segment more in the female pupa than there is in the male.
The species of the sub-genus _Crossocerus_ provision their nests with
Aphididae, but _C. wesmaeli_ makes use, for the purpose, according to
Ferton, of an elegant little fly of the family Tipulidae; according to
Pissot this same wasp also makes use of a species of _Typhlocyba_, a genus
of the Homopterous division of Rhynchota. Supposing there to be no mistake
as to this latter observation, the choice of Diptera and of Homoptera by
the same species indicates a very peculiar habit.
_Fertonius_ (_Crossocerus_) _luteicollis_ in Algeria forms cells at a
slight depth in sandy soil, and provisions them with ants. The ant selected
is _Tapinoma erraticum_, and the individuals captured are the wingless
workers. The mode of hunting has been described by Ferton; the wasp hovers
over one of the ant-paths at a distance of a few millimetres only above the
surface, and when an ant that is considered suitable passes, the
_Fertonius_ pounces on it, stings it, and carries it off to the burrow;
forty or fifty ants are accumulated in a cell, the egg is laid in the heap
of victims about one-third of the depth from the bottom; the resulting
larva sucks the ants one by one, by attaching itself to the thorax behind
the first pair of legs. There is a very interesting point in connection
with the habits of this species, viz. that the ants are not only alive, but
lively; they have, however, lost the power of co-ordinating the movements
of the limbs, and are thus unable to direct any attack against the feeble
larva. Ferton thinks there are three generations of this species in a
single year.
* * * * *
Note.—In a note on p. 99 we have mentioned the new publication of Mr. and
Mrs. Peckham on the habits of Fossores. We may here add that it contains
much fresh information on these Insects, together with criticisms of the
views of Fabre and others. One of the points most noteworthy is that they
have observed _Crabro stirpicola_ working night and day for a period of
forty-two consecutive hours. They made experiments on _Bembex spinolae_
with a view of ascertaining whether the female provisions two nests
simultaneously; as the result they think this improbable. If the female
Bembecid make nests only consecutively, it is clear it must have but a
small fecundity. The larval life extends over about fifteen days; and if
we allow three months as the duration of life of a female, it is evident
that only about six young can be produced in a season.
{131}CHAPTER IV
HYMENOPTERA ACULEATA _CONTINUED_—DIVISION IV. FORMICIDAE OR ANTS
DIVISION IV. HETEROGYNA OR FORMICIDAE—ANTS.
_The segment, or the two segments, behind the propodeum, either small or
of irregular form, so that if not throughout of small diameter, the
articulation with the segment behind is slender, and there is great
mobility. The trochanters undivided. The individuals of each species are
usually of three kinds, males, females and workers; the latter have no
wings, but the males and females are usually winged, though the females
soon lose the flying organs. They live in communities of various numbers,
the majority being workers. The larvae are helpless maggots fed and
tended by the workers or by the female._
[Illustration: Fig. 53—Abdomens of ants. A, Of _Camponotus rubripes_
(Formicides); B, of _Ectatomma auratum_ (Ponerides); C, of _Aphaenogaster
barbara_ (Myrmicides). _a_, Propodeum; _b_, first abdominal segment forming
a scale or node; _c_, second; _d_, third abdominal segment.]
In ants the distinction between the three great regions of the body is very
marked. The abdomen is connected with the propodeum in a peculiar manner,
one or two segments being detached from the main mass to form a very mobile
articulation. This is the most distinctive of the characters of ants. The
structure and form of these parts varies {132}greatly in the family: and
the Amblyoponides do not differ in a marked manner from the Scoliidae in
fossorial Hymenoptera.
[Illustration: Fig. 54—Front of head of _Dinoponera grandis_. A, Mouth
closed; B, open.]
The arrangement of the parts of the mouth is remarkable, and results in
leaving the mandibles quite free and unconnected with the other trophi; the
mouth itself is, except during feeding, closed completely by the lower lip
and maxilla assuming an ascending vertical direction, while the upper lip
hangs down and overlaps the lower lip, being closely applied to it; so that
in Ponerides the palpi, except the apices of the maxillary pair, are
enclosed between the upper and lower lips (Fig. 54, A). In Cryptocerini the
palpi are not covered by the closed lips, but are protected by being placed
in chinks at the outsides of the parts closing the mouth. The mandibles of
ants can thus be used in the freest manner without the other parts of the
mouth being opened or even moved. The mandibles close transversely over the
rest of the mouth, and when shut are very firmly locked. There are,
however, some ants in which the lips remain in the position usual in
mandibulate Insects.
The antennae, except in the males of some species, have a long basal joint
and are abruptly elbowed at its extremity. The eyes and ocelli vary
excessively, and may be totally absent or very highly developed in the same
species. The winged forms are, however, never blind. The size of the head
varies extremely in the same species; it is frequently very small in the
males, and largest in the workers. In some ants the worker-caste consists
of large-headed and small-headed individuals; the former are called
soldiers, and it has been supposed that some of them may act the part of
superior officers to the others. It should be clearly understood that there
is no definite distinction between soldiers and workers; so that in this
respect they are widely different from Termites.
{133}[Illustration: Fig. 55—_Oecodoma cephalotes._ South America. A, Worker
major; B, female after casting the wings.]
[Illustration: Fig. 56.—Stridulating organ of an ant, _Myrmica rubra_, var.
_laevinodis_. Sagittal section of part of the 6th and 7th post-cephalic
segments. (After Janet.) _a_, _a^1_, muscles; _b_, connecting membrane
(corrugated) between 6th and 7th segments: _c_, 6th segment; _d_, its edge
or scraper; _e_, striate area, or file on 7th segment; _f_, posterior part
of 7th segment; _g_, cells, inside body; _h_, trachea.]
The complex mass forming the thorax is subject to great change of structure
in the same species, according as the individuals are winged or wingless.
The sutures between the dorsal (notal) pieces are frequently obliterated in
the workers, while they are distinct in the males and females, and the
pieces themselves are also much larger in size in these sexed individuals.
The pro-mesothoracic stigma is apparently always distinct; the
meso-metathoracic one is distinct in the male _Dorylus_, but can scarcely
be detected in the winged forms of other ants, owing to its being enclosed
within, and covered by, the suture between the two segments: in the
workers, however, it is usually quite conspicuous. The posterior part of
the thoracic mass, the propodeum or median segment, is of considerable
size; no transverse suture between the component pieces of this part can be
seen, but its stigma is always very distinct. The peduncle, or pedicel,
formed by the extremely mobile segment or segments at the base of the
abdomen (already noticed as forming the most conspicuous character of the
family), exhibits much variety. Sometimes the first segment bears a plate
or shield called a scale (Fig. 53, A, _b_); at other times there are two
{134}small segments (Fig. 53, B, C, _b_, _c_) forming nodes or knots, of
almost any shape. The articulations between these segments are of the most
perfect description. In many ants these parts bear highly developed
stridulating organs, and the delicacy and perfection of the articulations
allow the parts to be moved either with or without producing stridulation.
In the male sex the peduncle and its nodes are much less perfect, and
possess comparatively little capacity for movement; in the male of
_Dorylus_ (Figs. 79, A, and 80, _f_) the single node is only imperfectly
formed. The eyes and ocelli of the males are usually more largely developed
than they are in the female, though the head is much smaller.
The legs of ants are elongate, except in a few forms; the Cryptocerini and
the males of Dorylides being the most conspicuous exceptions. The tarsi are
five-jointed, the basal joint being disproportionately elongate, so that in
use it acts in many species as if it were a portion of the tibia, the other
four joints forming the functional foot. The front tibiae are furnished
with a beautiful combing apparatus (Fig. 57).
[Illustration: Fig. 57.—Combs and brushes on front leg of an ant,
_Dinoponera grandis_ (tip of tibia, bearing the comb-like spur, and the
base of the first joint of the tarsus; cf. fig. 75). A, Inner, B, outer
aspect.]
FEATURES OF ANT-LIFE.—In order that the reader may realise the nature of
ant-life we may briefly recount its more usual and general features.
Numerous eggs are produced in a nest by one or more queens, and are taken
care of by workers. These eggs hatch and produce helpless maggots, of which
great care is taken by the workers. These nurses feed their charges from
their own mouths, and keep the helpless creatures in a fitting state by
transporting them to various chambers in conformity with changes of
temperature, humidity, and so on. When full grown the maggots change to
pupae. In some species the maggots form cocoons for themselves, but in
others this is not the case, and the pupae are naked.[54] After a brief
period of {135}pupal life a metamorphosis into the perfect Insect occurs.
The creatures then disclosed may be either winged or wingless; the wingless
are the workers and soldiers—imperfect females—the winged are males or
females fully developed. The workers remain in or near the nest they were
produced in, but the winged individuals rise into the air for a nuptial
flight, often in great numbers, and couple. When this is accomplished the
male speedily dies, but the females cast their wings and are ready to enter
on a long life devoted to the production of eggs. From this account it will
be gathered that males are only found in the nests for a very short time;
the great communities consisting at other periods entirely of the two kinds
of females and of young. The imperfect females are themselves in some
species of various kinds; each kind being restricted, more or less
completely, to a distinct kind of duty.
No Insects are more familiar to us than ants; in warm countries some of
them even invade the habitations of man, or establish their communities in
immediate proximity to his dwellings. Their industry and pertinacity have,
even in remote ages, attracted the attention and admiration of serious men;
some of whom—we need scarcely mention Solomon as amongst them—have not
hesitated to point out these little creatures as worthy of imitation by
that most self-complacent of all the species of animals, _Homo sapiens_.
Observation has revealed most remarkable phenomena in the lives of these
Insects. Indeed, we can scarcely avoid the conclusion that they have
acquired in many respects the art of living together in societies more
perfectly than our own species has, and that they have anticipated us in
the acquisition of some of the industries and arts that greatly facilitate
social life. The lives of individual ants extend over a considerable number
of years—in the case of certain species at any rate—so that the competence
of the individual may be developed to a considerable extent by exercise;
and one generation may communicate to a younger one by example the arts of
living by which it has itself profited. The prolonged life of ants, their
existence in the perfect state at all seasons, and the highly social life
they lead are facts of the greatest biological importance, and are those
that we should expect to be accompanied by greater and wider competence
than is usually exhibited {136}by Insects. There can indeed be little doubt
that ants are really not only the "highest" structurally or mechanically of
all Insects, but also the most efficient. There is an American saying to
the effect that the ant is the ruler of Brazil. We must add a word of
qualification; the competence of the ant is not like that of man. It is
devoted to the welfare of the species rather than to that of the
individual, which is, as it were, sacrificed or specialised for the benefit
of the community. The distinctions between the sexes in their powers or
capacities are astonishing, and those between the various forms of one sex
are also great. The difference between different species is extreme; we
have, in fact, the most imperfect forms of social evolution coexisting,
even locally, with the most evolute.
These facts render it extremely difficult for us to appreciate the ant; the
limitations of efficiency displayed by the individual being in some cases
extreme, while observation seems to elicit contradictory facts. About two
thousand species are already known, and it is pretty certain that the
number will reach at least five thousand. Before passing to the
consideration of a selection from what has been ascertained as to the
varieties of form and of habits of ants we will deal briefly with their
habitations and polymorphism, reserving some remarks as to their
associations with other Insects to the conclusion of this chapter.
NESTS.—Ants differ greatly from the other Social Hymenoptera in the nature
of their habitations. The social bees construct cells of wax crowded
together in large numbers, and the wasps do the like with paper; the eggs
and young being placed, each one in a separate cell, the combinations of
which form a comb. Ants have, however, a totally different system; no comb
is constructed, and the larvae are not placed in cells, but are kept in
masses and are moved about from place to place as the necessities of
temperature, air, humidity and other requirements prompt. The habitations
of ants are in all cases irregular chambers, of which there is often a
multiplicity connected by galleries, and they sometimes form a large system
extending over a considerable area. Thus the habitations of ants are more
like those of the Termites than those of their own allies among the
Hymenoptera. They are chiefly remarkable for their great variety, and for
the skilful manner in which they are adapted by their little artificers to
particular conditions. The most usual form in Europe, is a {137}number of
subterranean chambers, often under the shelter of a stone, and connected by
galleries. It is of course very difficult to trace exactly the details of
such a work, because when excavations are made for the purposes of
examination, the construction becomes destroyed; it is known, however, that
some of these systems extend to a considerable depth in the earth, it is
said to as much as nine feet, and it is thought the object of this is to
have access to sufficiently moist earth, for ants are most sensitive to
variations in the amount of moisture; a quite dry atmosphere is in the case
of many species very speedily fatal. This system of underground labyrinths
is sometimes accompanied by above-ground buildings consisting of earth more
or less firmly cemented together by the ants; this sort of dwelling is most
frequently adopted when the soil in which the nests are placed is sandy; it
is probable that the earth is in such cases fastened together by means of a
cement produced by the salivary glands of the ants, but this has not been
determined with certainty; vaulted galleries or tunnels of this kind are
constructed by many species of ants in order to enable them to approach
desired objects.
[Illustration: Fig. 58—Portion of combined nest of _Formica fusca_ and
_Solenopsis fugax_. (After Forel.) × ⅔. _f_, _f′_, Chambers of _Formica_,
recognisable by the coarser shading; _s_, _s′_, chambers of the
_Solenopsis_ (with finer shading); _s″_, opening in one of the chambers,
the entrance to one of the galleries that connects the chambers of the
Solenopsis; _w_, walls forming the foundations of the nest and the limits
of the chambers.]
In South America _Camponotus rufipes_ and other species that habitually
dwell in stumps, in certain districts where they are liable to inundations,
build also nests of a different nature on trees for refuge during the
floods. In Europe, a little robber-ant, _Solenopsis fugax_, constructs its
dwelling in combination with that of _Formica fusca_ (Fig. 58), in such a
manner that its chambers cannot, on account of the small size of the
orifices, be entered by the much larger _Formica_. Hence the robber obtains
an easy living at the expense of the larger species. The Sauba or Sauva
ants of South America (the genus _Atta_ of some, _Oecodoma_ of other
authors) appear to be most proficient in the art of {138}subterranean
mining. Their systems of tunnels and nests are known to extend through many
square yards of earth, and it is said on the authority of Hamlet Clark that
one species tunnelled under the bed of the river Parahyba at a spot where
it was as broad as the Thames at London Bridge.
A considerable number of ants, instead of mining in the ground, form
chambers in wood; these are usually very close to one another, because, the
space being limited, galleries cannot be indulged in. _Camponotus
ligniperdus_ in Europe, and _C. pennsylvanicus_ in North America, work in
this way.
Our British _Lasius fuliginosus_ lives in decayed wood. Its chambers are
said by Forel to consist of a paper-like substance made from small
fragments of wood. _Cryptocerus_ burrows in branches. _Colobopsis_ lives in
a similar manner, and Forel informs us that a worker with a large head is
kept stationed within the entrance, its great head acting as a stopper;
when it sees a nest-fellow desirous of entering the nest, this animated and
intelligent front-door then retreats a little so as to make room for
ingress of the friend. Forel has observed that in the tropics of America a
large number of species of ants live in the stems of grass. There is also
quite a fauna of ants dwelling in hollow thorns, in spines, on trees or
bushes, or in dried parts of pithy plants; and the tropics also furnish a
number of species that make nests of delicate paper, or that spin together
by means of silk the leaves of trees. One eastern species—_Polyrhachis
spinigera_—fabricates a gauze-like web of silk, with which it lines a
subterranean chamber after the manner of a trap-door spider.
[Illustration: Fig. 59—Ant-plant, _Hydnophytum montanum_. Java. (After
Forel.)]
Some species of ants appear to find both food and shelter {139}entirely on
the tree they inhabit, the food being usually sweet stuff secreted by
glands of the plant. It is thought that the ants in return are of
considerable benefit to the plant by defending it from various small
enemies, and this kind of symbiosis has received much attention from
naturalists. A very curious condition exists in the epiphytic plants of the
genera _Myrmecodia_ and _Hydnophytum_; these plants form large bulb-like
(Fig. 59) excrescences which, when cut into, are found to be divided into
chambers quite similar to those frequently made by ants. Though these
structures are usually actually inhabited by ants, it appears that they are
really produced by the plant independent of the Insects.
VARIABILITY AND POLYMORPHISM OF ANTS.—Throughout the Hymenoptera there are
scattered cases in which one of the sexes appears in dimorphic form. In the
social kinds of bees and wasps the female sex exists in two conditions, a
reproductive one called queen, and an infertile one called worker, the
limits between the two forms seeming in some cases (honey-bee) to be
absolute as regards certain structures. This sharp distinction in structure
is rare; while as regards fertility intermediate conditions are numerous,
and may indeed be induced by changing the social state of a community.[55]
In ants the phenomena of the kind we are alluding to are very much more
complex. There are no solitary ants; associations are the rule (we shall
see there are one or two cases in which the association is with individuals
of other species). In correlation with great proclivity to socialism we
find an extraordinary increase in the variety of the forms of which species
are made up. In addition to the male and female individuals of which the
species of Insects usually consist, there are in ants workers of various
kinds, and soldiers, all of which are modified infertile females. But in
addition to the existence of these castes of infertile females, we find
also numerous cases of variability or of dimorphism of the sexual
individuals; and this in both sexes, though more usually in the female.
Thus there exists in ants an extraordinary variety in the polymorphism of
forms, as shown by the table on p. 141, where several very peculiar
conditions are recorded.
The complex nature of these phenomena has only recently {140}become known,
and as yet has been but little inquired into. The difference between the
thoracic structure in the case of the winged and wingless females of
certain species (Fig. 55, and in vol. v. fig. 339) is enormous, but in
other species this difference appears to be much less. The ordinary
distinctions between the queen-female and worker-females appear to be of
two kinds; firstly, that the former is winged, the latter wingless;[56] and
secondly, that the former possesses a _receptaculum seminis_, the latter
does not. In a few cases it would seem that the dimorphism of winged and
wingless forms is not complete, but that variability exists. Intermediate
conditions between the winged and wingless forms are necessarily rare;
nevertheless a certain number have already been detected, and specimens of
_Lasius alienus_ have been found with short wings. In rather numerous
species some or all of the fertile females depart from the usual state and
have no wings; (a similar condition is seen, it will be recollected, in
Mutillides and Thynnides of the neighbouring family Scoliidae). A
dimorphism as regards wings also exists in the male sex, though it is only
extremely rarely in ants that the males are wingless. Neverless a few
species exist of which only wingless males have been found, and a few
others in which both winged and wingless individuals of this sex are known
to occur. The wingless males of course approach the ordinary workers (=
infertile wingless females) in appearance, but there is not at present any
reason for supposing that they show any diminution in their male sexual
characters. The distinction between workers and females as based on the
existence or non-existence of a _receptaculum seminis_ has only recently
become known, and its importance cannot yet be estimated. The adult,
sexually capable, though wingless forms, are called ergatoid, because they
are similar to workers (Ἐργατης, a worker).[57]
{141}TABLE OF THE CHIEF FORMS OF POLYMORPHISM IN ANTS.
OW♂ = Ordinary Winged Male.
E♂ = Ergatoid Male.
OW♀ = Ordinary Winged Female.
EF♀ = Ergatoid Fertile Female.
I♀W = Intermediate between Female and Worker.
Sol = Soldier.
WMj = Worker Major.
WMi = One or more kinds of Worker Minor.
+———————————————————————————+———+———+———+———————+———————+———+—————+—————+
| Name of Ants. |OW♂|E♂ |OW♀| EF♀ | I♀W |Sol| WMj | WMi |
+———————————————————————————+———+———+———+———————+———————+———+—————+—————+
| _Myrmica_, _Polyrhachis_, | + | | + | | | | + | |
| etc. | | | | | | | | |
| | | | | | | | | |
| _Camponotus_, _Atta_, | + | | + | | | | + | + |
| Pheidologeton_, etc. | | | | | | | | |
| | | | | | | | | |
| _Pheidole_, subg. | + | | + | | | + | | + |
| Colobopsis_ | | | | | | | | |
| | | | | | | | | |
| _Eciton hamatum_, | | | | | | | | |
| E. quadriglume_, | + | | | + | | + | + | + |
| E. foreli_, etc. | | | | | | | | |
| | | | | | | | | |
| _Cryptocerus_ | + | | + | | | + | + | + |
| discocephalus_, etc. | | | | | | | | |
| | | | | | | | | |
| _Strongylognathus_ | + | | + | | | + | | |
| | | | | | | | | |
| _Carebara_ and | | | | | | | | |
| Solenopsis_ (except | + | | + | | | | | + |
| S. germinata_) | | | | | | | | |
| | | | | | | | | |
| _Solenopsis geminata_ | + | | + | | | | + | + |
| | | | | | | | | |
| _Formica rufa_ | + | | + | | + | | | |
| | | | | |except-| | | |
| | | | | |ionally| | | |
| | | | | | | | | |
| _Ponera punctatissima_ | + | + | + | | | | + | |
| | | | | | | | | |
| _Ponera ergatandria_ | ? | + | + | | | | + | |
| | | | | | | | | |
| _Cardiocondyla emeryi_ | + | | + | + | | | + | |
| | | | | | | | | |
| _C. wroughtonii_ and | | + | + | | | | + | |
| C. stambuloffi_ | | | | | | | | |
| | | | | | | | | |
| _Formicoxenus nitidulus_ | | + | + | | | | + | |
| | | | | | | | | |
| _Tomognathus_ | + | | | + | | | | |
| | | | | | | | | |
| _Odontomachus haematodes_ | + | | + | + | | | + | |
| | | | |except-| | | | |
| | | | |ionally| | | | |
| | | | | | | | | |
| _Polyergus_ | + | | + | + | | | | |
| | | | | | | | | |
| _Dorylus_, _Anomma_, | + | | | + | | | + | + |
| Eciton_ part. | | | | | | | | |
| | | | | | | | | |
| _Aenictus_ | + | | | | | | | + |
| | | | | | | | | |
| _Leptogenys_, _Diacamma_ | + | | | + | + | | + | |
| | | | | | | | | |
| _Myrmecocystus melliger_, | + | | + | | | | + | |
| M. mexicanus_ | | | | | | | and | + |
| | | | | | | |honey| |
| | | | | | | |-pots| |
| | | | | | | | | |
| | | | | | | | + | + |
| _Ponera eduardi_ | + | | + | | | |eyes |eyes |
| | | | | | | |large|obso-|
| | | | | | | | |lete |
| | | | | | | | | |
| _Anergates_ | | + | + | | | | | |
+———————————————————————————+———+———+———+———————+———————+———+—————+—————+
In addition to the above there are apparently cases of females with
post-metamorphic growth in Dorylides, but these have not yet been the
subject of investigation.
{142}Much has been written about the mode in which the variety of forms of
a single species of ant is produced. As to this there exists but little
actual observation or experiment, and the subject has been much complicated
by the anxiety of the writers to display the facts in a manner that will
support some general theory. Dewitz was of opinion that workers and queens
of ants were produced from different kinds of eggs. This view finds but
little support among recent writers. Hart in recording the results of his
observations on the parasol ant (of the genus _Atta_)—one of the species in
which polymorphism is greatest—says[58] that these observations prove that
"ants can manufacture at will, male, female, soldier, worker or nurse," but
he has not determined the method of production, and he doubts it being "the
character of the food." There is, however, a considerable body of evidence
suggesting that the quality or quantity of the food, or both combined, are
important factors in the treatment by which the differences are produced.
The fact that the social Insects in which the phenomena of caste or
polymorphism occur, though belonging to very diverse groups, all feed their
young, is of itself very suggestive. When we add to this the fact that in
ants, where the phenomena of polymorphism reach their highest complexity,
the food is elaborated in their own organs by the feeders that administer
it, it appears probable that the means of producing the diversity may be
found herein. Wasmann has pointed out that the ants'-nest beetle,
_Lomechusa_, takes much food from the ants, and itself destroys their
young, and that in nests where _Lomechusa_ is abundant a large percentage
of ergatogynous forms of the ants are produced. He attributes this to the
fact that the destruction of the larvae of the ant by the beetle brings
into play the instinct of the ants, which seek to atone for the destruction
by endeavouring to produce an increased number of fertile forms; many
ergatogynous individuals being the result. This may or may not be the case,
but it is clear that the ants' instinct cannot operate without some
material means, and his observation adds to the probability that this means
is the food supply, modified either qualitatively or quantitatively.
The existence of these polymorphic forms led Herbert Spencer to argue that
the form of an animal is not absolutely {143}determined by those "Anlagen"
or rudiments that Weismann and his school consider to be all important in
determining the nature or form of the individual, for if this were the
case, how can it be, he asked, that one egg may produce either a worker,
nurse, soldier or female ant? To this Wasmann (who continued the
discussion) replied by postulating the existence of double, triple or
numerous rudiments in each egg, the treatment the egg receives merely
determining which of these rudiments shall undergo development.[59] Forel
seems to have adopted this explanation as being the most simple. The
probability of Weismann's hypothesis being correct is much diminished by
the fact that the limit between the castes is by no means absolute. In many
species intermediate forms are common, and even in those in which the
castes are believed to be quite distinct, intermediate forms occur as very
rare exceptions.[60] Emery accounts[61] for the polymorphism, without the
assistance of the Weismannian hypothetical compound rudiments, by another
set of assumptions; viz. that the phenomenon has been gradually acquired by
numerous species, and that we see it in various stages of development; also
that variation in nutrition does not affect all the parts of the body
equally, but may be such as to carry on the development of certain portions
of the organisation while that of other parts is arrested. Speaking broadly
we may accept this view as consistent with what we know to be the case in
other Insects, and with the phenomena of post-embryonic development in the
class. But it must be admitted that our knowledge is at present quite
inadequate to justify the formulation of any final conclusions.
The geological record of Formicidae is not quite what we should have
expected. They are amongst the earliest Hymenoptera; remains referred to
the family have been found in the Lias of Switzerland and in the English
Purbecks. In Tertiary times Formicidae appear to have been about the most
abundant of all Insects. At Florissant they occur in thousands and form in
individuals about one-fourth of all the Insects found there. They have also
been met with numerously in the European Tertiaries, and Mayr studied no
less than 1500 specimens found {144}in amber. Formicides and Myrmicides are
more abundant than Ponerides, but this latter group has the larger
proportion of extinct genera; conditions but little dissimilar to those
existing at present.
CLASSIFICATION OF ANTS.—Ants are considered by many entomologists to form a
series called Heterogyna. They can, however, be scarcely considered as more
than a single family, Formicidae, so that the serial name is superfluous.
Their nearest approach to other Aculeates is apparently made, by
_Amblyopone_, to certain Mutillides (_e.g._ _Apterogyna_) and to the
Thynnides, two divisions of Scoliidae. Emery considers Dorylides rather
than Amblyoponides to be the most primitive form of ants, but we are
disposed to consider Forel's view to the effect we have above mentioned as
more probably correct. The point is, however, very doubtful. The condition
of the peduncle is in both the sub-families we have mentioned very
imperfect compared with that of other ants. Both these sub-families are of
very small extent and very imperfectly known. We shall also follow Forel in
adopting six sub-families, Camponotides, Dolichoderides, Myrmicides,
Ponerides, Dorylides, and Amblyoponides. Emery rejects the Amblyoponides as
being merely a division of the Ponerides. This latter group displays the
widest relations of all the sub-families, and may be looked on as a sort of
central form. The Camponotides and Dolichoderides are closely allied, and
represent the highest differentiation of the families in one direction. The
Myrmicides are also highly differentiated, but are not allied to the
Camponotides and Dolichoderides.[62]
SUB-FAM. 1. CAMPONOTIDES.—_Hind body furnished with but one constriction,
so that only a single scale or node exists on the pedicel. Poison-sac
forming a cushion of convolutions, on which is situate the modified
sting, which forms merely an ejaculatory orifice for the poison._
The members of this very extensive division of ants can be readily
distinguished from all others, except the Dolichoderides, by the absence of
a true sting, and by the peculiar form of the hind body; this possesses
only a single scale at the base, and has no {145}constriction at all on the
oval, convex and compact mass of the abdomen behind this. The cloacal
orifice is circular, not, as in other ants, transverse. These characters
are accompanied by a difference in habits. The Camponotides, though they do
not sting, produce poison in large quantity, and eject it to some distance.
Hence, if two specimens are confined in a tube they are apt to kill one
another by the random discharges they make. Janet suggests that in order to
neutralise the effect of this very acid poison, they may have some means of
using, when they are in their natural abodes, the alkaline contents of a
second gland with which they are provided. We shall mention the characters
by which the Camponotides are distinguished from the small sub-family
Dolichoderides when we deal with the latter.
The sub-family includes 800 or more species. _Camponotus_ itself is one of
the most numerous in species of all the genera of Formicidae, and is
distributed over most parts of the earth. We have no species of it in
Britain, but in the south of Europe the _Camponotus_ become very
conspicuous, and may be seen almost everywhere stalking about, after the
fashion of our British wood-ant, _Formica rufa_, which in general
appearance _Camponotus_ much resembles.
Until recently, the manner in which fresh nests of ants were founded was
unknown. In established nests the queen-ant is fed and tended by the
workers, and the care of the helpless larvae and pupae also devolves
entirely on the workers, so that the queens are relieved of all functions
except that of producing eggs. It seemed therefore impossible that a fresh
nest could be established by a single female ant unless she were assisted
by workers. The mode in which nests are founded has, however, been recently
demonstrated by the observations of Lubbock, M‘Cook, Adlerz, and more
particularly by those of Blochmann, who was successful in observing the
formation of new nests by _Camponotus ligniperdus_ at Heidelberg. He found
under stones in the spring many examples of females, either solitary or
accompanied only by a few eggs, larvae or pupae. Further, he was successful
in getting isolated females to commence nesting in confinement, and
observed that the ant that afterwards becomes the queen, at first carries
out by herself all the duties of the nest: beginning by making a small
burrow, she lays some eggs, and when these hatch, feeds and tends the
larvae and pupae; the first specimens of these {146}latter that become
perfect Insects are workers of all sizes, and at once undertake the duties
of tending the young and feeding the mother, who, being thus freed from the
duties of nursing and of providing food while she is herself tended and
fed, becomes a true queen-ant. Thus it seems established that in the case
of this species the division of labour found in the complex community, does
not at first exist, but is correlative with increasing numbers of the
society. Further observations as to the growth of one of these nascent
communities, and the times and conditions under which the various forms of
individuals composing a complete society first appear, would be of
considerable interest.
An American species of the same genus, _C. pennsylvanicus_, the
carpenter-ant, establishes its nests in the stumps of trees. Leidy observed
that solitary females constructed for themselves cells in the wood and
closed the entrances, and that each one in its solitary confinement reared
a small brood of larvae. The first young produced in this case are said to
be of the dwarf caste, and it was thought by the observer that the ant
remained not only without assistance but also without food during a period
of some weeks, and this although she was herself giving food to the larvae
she was rearing.
Adlerz states that the females or young queens take no food while engaged
in doing their early work, and that the large quantity of fat-body they
possess enables them to undergo several months of hunger. In order to feed
the young larvae they use their own eggs or even the younger larvae. It is
to the small quantity of food rather than to its nature that he attributes
the small size of the first brood of perfect workers. M. Janet[63] has
recently designed an ingenious and simple apparatus for keeping ants in
captivity. In one of these he placed a solitary female of _Lasius alienus_,
unaccompanied by any workers or other assistants, and he found at the end
of 98 days that she was taking care of a progeny consisting of 50 eggs, 2
larvae, 5 pupae in cocoons, 5 without cocoons. On the 102nd day workers
began to emerge from the cocoons.[64] From these observations it is evident
that the queen-ant, when she begins her nest, lives under conditions
extremely different from those of the royal state she afterwards reaches.
{147}In many kinds of ants the full-grown individuals are known to feed not
only the larvae by disgorging food from their own mouths into those of the
little grubs, but also to feed one another. This has been repeatedly
observed, and Forel made the fact the subject of experiment in the case of
_Camponotus ligniperdus_. He took some specimens and shut them up without
food for several days, and thereafter supplied some of them with honey,
stained with Prussian blue; being very hungry, they fed so greedily on this
that in a few hours their hind bodies were distended to three times their
previous size. He then took one of these gorged individuals and placed it
amongst those that had not been fed. The replete ant was at once explored
by the touches of the other ants and surrounded, and food was begged from
it. It responded to the demands by feeding copiously a small specimen from
its mouth: when this little one had received a good supply, it in turn
communicated some thereof to other specimens, while the original well-fed
one also supplied others, and thus the food was speedily distributed. This
habit of receiving and giving food is of the greatest importance in the
life-history of ants, and appears to be the basis of some of the
associations that, as we shall subsequently see, are formed with ants by
numerous other Insects.
[Illustration: Fig. 60—_Oecophylla smaragdina._ Worker using a larva for
spinning.]
_Oecophylla smaragdina_, a common ant in Eastern Asia, forms shelters on
the leaves of trees by curling the edges of leaves and joining them
together. In doing this it makes use of an expedient that would not be
believed had it not been testified by several competent and independent
witnesses. The perfect ant has no material with which to fasten together
the edges it curls; its larva, however, possesses glands that secrete a
supply of material for it to form a cocoon with, and the ants utilise the
larvae to effect their purpose. Several of them combine to hold the foliage
in the desired position, and while they do so, other ants come up, each one
of which carries a larva in its jaws, applies the mouth of the larva to the
parts where the cement is required, and makes it disgorge the sticky
{148}material. Our figure is taken from a specimen (for which we are
indebted to Mr. E. E. Green) that was captured in the act of bearing a
larva.
_Formica rufa_, the Red-ant, Wood-ant, or Hill-ant, is in this country one
of the best-known members of the Formicidae. It frequents woods, especially
such as are composed, in whole or part, of conifers, where it forms large
mounds of small sticks, straws, portions of leaves, and similar material.
Although at first sight such a nest may appear to be a chaotic
agglomeration, yet examination reveals that it is arranged so as to leave
many spaces, and is penetrated by galleries ramifying throughout its
structure. These mound-nests attain a considerable size when the operations
of the industrious creatures are not interfered with, or their work
destroyed, as it too often is, by ignorant or mischievous persons. They may
reach a height of three feet or near it, and a diameter of twice that
extent. The galleries by which the heaps are penetrated lead down to the
earth below. From the mounds extend in various directions paths constantly
traversed by the indefatigable ants. M‘Cook observed such paths in the
Trossachs; they proceed towards the objects aimed at in lines so straight
that he considers they must be the result of some sense of direction
possessed by the ants; as it is impossible to suppose they could perceive
by the sense of sight the distant objects towards which the paths were
directed: these objects in the case M‘Cook describes were oak-trees up
which the ants ascended in search of Aphides.
M‘Cook further observed that one of the oak-trees was reached by
individuals from another nest, and that each of the two parties was limited
to its own side of the tree, sentinels being placed on the limits to
prevent the trespassing of an intruder; he also noticed that the ants saw
an object when the distance became reduced to about an inch and a half from
them. This species is considered to be wanting in individual courage; but
when acting in combination of vast numbers it does so with intelligence and
success. It does not make slaves, but it has been observed by Bignell and
others that it sometimes recruits its numbers by kidnapping individuals
from other colonies of its own species. Its nests are inhabited by forty or
fifty species of guests of various kinds, but chiefly Insects. Another ant,
_Myrmica laevinodis_, sometimes lives with it in perfect harmony, and
_Formicoxenus {149}nitidulus_ lives only with _F. rufa_. Amongst the most
peculiar of its dependants we may mention large beetles of the genera
_Cetonia_ and _Clythra_, which in their larval state live in the hills of
the wood-ant. It is probable that they subsist on some of the vegetable
matter of which the mounds are formed. Adlerz has given some attention to
the division of labour amongst the different forms of the workers of ants,
and says that in _F. rufa_ it is only the bigger workers that carry
building and other materials, the smaller individuals being specially
occupied in the discovery of honey-dew and other Aphid products. In
_Camponotus_ it would appear, on the other hand, that the big individuals
leave the heavy work to be performed by their smaller fellows.
The wood-ant and its near allies have been, and indeed still are, a source
of great difficulty to systematists on account of the variation that occurs
in the same species, and because this differs according to locality. Our
European _F. rufa_ has been supposed to inhabit North America, and the
interesting accounts published by M‘Cook of the mound-making ant of the
Alleghanies were considered to refer to it. This Insect, however, is not
_F. rufa_, as was supposed by M‘Cook, but _F. exsectoides_, Forel. It forms
colonies of enormous extent, and including an almost incredible number of
individuals. In one district of about fifty acres there was an Ant City
containing no less than 1700 of these large ant-hills, each one teeming
with life. It was found by transferring ants from one hill to another that
no hostility whatever existed between the denizens of different hills; the
specimens placed on a strange hill entered it without the least hesitation.
Its habits differ in some particulars from those of its European congener;
the North American Insect does not close the formicary at night, and the
inquilines found in its nest are very different from those that live with
_F. rufa_ in Europe. Whether the typical wood-ant occurs in North America
is doubtful, but there are races there that doubtless belong to the
species.
_F. sanguinea_ is very similar in appearance to its commoner congener _F.
rufa_, and is the only slave-making ant we possess in Britain. This species
constructs its galleries in banks, and is of very courageous character,
carrying out its military operations with much tactical ability. It is
perfectly able to live without the assistance of slaves, and very
frequently does so; indeed it {150}has been asserted that it is in our own
islands (where, however, it is comparatively rare) less of a slave-owner
than it is in Southern Europe, but this conclusion is very doubtful. It
appears when fighting to be rather desirous of conquering its opponents by
inspiring terror and making them aware of its superiority than by killing
them; having gained a victory it will carry off the pupae from the nest it
has conquered to its own abode, and the ants of the stranger-species that
develop from these pupae serve the conquerors faithfully, and relieve them
of much of their domestic duties. The species that _F. sanguinea_ utilises
in this way in England are _F. fusca_, _F. cunicularia_, and possibly
_Lasius flavus_. Huber and Forel have given graphic accounts of the
expeditions of this soldier-ant. In the mixed colonies of _F. sanguinea_
and _F. fusca_ the slaves do most of the house-work, and are more skilful
at it than their masters. Adlerz says that one of the slaves will
accomplish twice as much work of excavation in the same time as the
slave-owner; these latter being lazy and fond of enjoyment, while the
slaves are very industrious.
[Illustration: Fig. 61—Head of _Polyergus rufescens_. (After André.)]
_Polyergus rufescens_, an European ant allied to _Formica_, is renowned
since the time of Huber (1810) as the slave-making or Amazon ant. This
creature is absolutely dependent on its auxiliaries for its existence, and
will starve, it is said, in the midst of food unless its servitors are
there to feed it. Wasmann, however, states that _Polyergus_ does possess
the power of feeding itself to a certain extent. Be this as it may, the
qualities of this ant as warrior are superb. When an individual is fighting
alone its audacity is splendid, and it will yield to no superiority of
numbers; when the creatures are acting as part of an army the individual
boldness gives place to courage of a more suitable sort, the ants then
exhibiting the act of retreating or making flank movements when necessary.
If a _Polyergus_ that is acting as a member of a troop finds itself
isolated, and in danger of being overpowered, it has then no hesitation in
seeking safety even by flight. This species is provided with mandibles of a
peculiar nature; they are not armed with teeth, {151}but are pointed and
curved; they are therefore used after the manner of poignards, and when the
ant attacks a foe it seizes the head between the points of these curved
mandibles, and driving them with great force into the brain instantly
paralyses the victim.
Mandibles of this shape are evidently unfitted for the purposes of general
work, they can neither cut, crush, nor saw, and it is not impossible that
in their peculiar shape is to be found the origin of the peculiar life of
_Polyergus_: we find similar mandibles reappearing amongst the aberrant
Dorylides, and attaining a maximum of development in the ferocious
_Eciton_; they also occur, or something like them, in a few aberrant
Myrmicides; and in the male sex of many other ants, which sex exercises no
industrial arts, this sort of mandible is present.
The ants that _Polyergus_ usually attacks in order to procure slaves are
_Formica fusca_ and _F. fusca_, race _auricularia_; after it has routed a
colony of one of these species, _P. rufescens_ pillages the nest and
carries off pupae and some of the larger larvae to its own abode. When the
captives thus deported assume the imago state, they are said to commence
working just as if they were in their own houses among their brothers and
sisters, and they tend their captors as faithfully as if these were their
own relatives: possibly they do not recognise that they are in unnatural
conditions, and may be quite as happy as if they had never been enslaved.
The servitors are by no means deficient in courage, and if the place of
their enforced abode should be attacked by other ant-enemies they defend it
bravely. The fact that _P. rufescens_ does not feed its larvae has been
considered evidence of moral degeneration, but it is quite possible that
the Insect may be unable to do so on account of some deficiency in the
mouth-parts, or other similar cause. The larvae of ants are fed by
nutriment regurgitated from the crop of a worker (or female), and applied
to the excessively minute mouth of the helpless grub: for so delicate a
process to be successfully accomplished, it is evident that a highly
elaborated and specialised arrangement of the mouth-parts must exist, and
it is by no means improbable that the capacity of feeding its young in true
ant-fashion is absent in _Polyergus_ for purely mechanical reasons.
M‘Cook states that the North American ant, _Polyergus lucidus_, which some
entomologists consider to be merely a variety of {152}the European species,
makes slaves of _Formica schaufussi_, itself does no work, and partakes of
food only when fed by its servitors. He did not, however, actually witness
the process of feeding. When a migration takes place the servitors deport
both the males and females of _P. lucidus_. M‘Cook adds that the servitors
appear to be really mistresses of the situation, though they avail
themselves of their power only by working for the advantage of the other
species.
[Illustration: Fig. 62—_Myrmecocystus mexicanus._ Honey-pot ant, dorsal
view.]
[Illustration: Fig. 63—_Myrmecocystus mexicanus._ Lateral view.]
The honey-ant of the United States and Mexico has been investigated by
M‘Cook and others; the chief peculiarity of the species is that certain
individuals are charged with a sort of honey till they become enormously
distended, and in fact serve as leather bottles for the storage of the
fluid. The species _Myrmecocystus hortideorum_ and _M. melliger_, are
moderate-sized Insects of subterranean habits, the entrance to the nest of
_M. hortideorum_ being placed in a small raised mound. The honey is the
product of a small gall found on oak leaves, and is obtained by the
worker-ants during nocturnal expeditions, from which they return much
distended; they feed such workers left at home as may be hungry, and then
apparently communicate the remainder of the sweet stuff they have brought
back to already partly charged "honey-bearers" left in the nest. The
details of the process have not been observed, but the result is that the
abdomens of the bearers become distended to an enormous extent (Figs. 62,
63), and the creatures move but little, and remain suspended to the roof of
a special chamber. It is considered by M‘Cook that these living honey-tubs
preserve the food till a time when it is required for the purposes of
feeding the community. The distension is produced entirely by the
overcharging of the honey-crop, the other contents of the abdomen being
{153}forced by the distention to the posterior part of the body. Lubbock
has since described an Australian ant, _Melophorus inflatus_, having a
similar peculiar habit, but belonging to the allied tribe Plagiolepisii.
Quite recently a South African honey-tub ant belonging to the distinct
genus _Plagiolepis_ (_Ptrimeni_ For.) has been discovered, affording a
proof that an extremely specialised habit may arise independently of
relation between the Insects, and in very different parts of the world.
Species of the genus _Lasius_ are amongst the most abundant of the
ant-tribe in Britain. They are remarkable for their constructive powers.
_L. niger_, the common little black garden-ant, forms extensive
subterranean galleries, and is extremely successful in the cultivation of
various forms of Aphidae, from the products of which the species derives a
large part of its subsistence. The ants even transport the Aphidae to
suitable situations, and thus increase their stock of this sugary kind of
cattle, and are said to take the eggs into their own dwellings in the
autumn so that these minute and fragile objects may be kept safe from the
storms and rigours of winter. These little creatures are brave, but when
attacked by other ants they defend themselves chiefly by staying in their
extensive subterranean galleries, and blocking up and securing these
against their assailants.
_L. fuliginosus_, another of our British species, has very different
habits, preferring old trees and stumps for its habitation; in the hollows
of these it forms dwellings of a sort of card; this it makes from the
mixture of the secretions of its salivary glands with comminuted fragments
of wood, after the fashion of wasps. It is a moderate-sized ant, much
larger than the little _L. niger_, and is of a black colour and remarkably
shining; it gives off a very strong but by no means disagreeable odour, and
may be seen on the hollow trees it frequents, stalking about in large
numbers in a slow and aimless manner that contrasts strikingly with the
active, bustling movements of so many of its congeners. When this species
finds suitable trees near one another, a colony is established in each; the
number of individuals thus associated becomes very large, and as the
different colonies keep up intercommunication, this habit is very useful
for purposes of defence. Forel relates that he once brought a very large
number of _Formica pratensis_ and liberated them at the base of a tree in
which was a nest of _L. fuliginosus_; these latter, finding {154}themselves
thus assaulted and besieged, communicated in some way, information of the
fact to the neighbouring colonies, and Forel soon saw large columns of the
black creatures issuing from the trees near by and coming with their
measured paces to the assistance of their _confrères_, so that the invaders
were soon discomfited and destroyed. Although the European and North
American representatives of the sub-family Camponotides live together in
assemblies comprising as a rule a great number of individuals, and although
the separate nests or formicaries which have their origin from the natural
increase of a single original nest keep up by some means a connection
between the members, and so form a colony of nests whose inhabitants live
together on amicable terms, yet there is no definite information as to how
long such association lasts, as to what is the nature of the ties that
connect the members of the different nests, nor as to the means by which
the colonies become dissociated. It is known that individual nests last a
long time. Charles Darwin has mentioned in a letter to Forel that an old
man of eighty told him he had noticed one very large nest of _Formica rufa_
in the same place ever since he was a boy. But what period they usually
endure is not known, and all these points probably vary greatly according
to the species concerned. It has been well ascertained that when some ants
find their nests, for some unknown reason, to be unsuitable the inhabitants
leave their abodes, carrying with them their young and immature forms, and
being accompanied or followed by the various parasites or commensals that
are living with them. Wasmann and other entomologists have observed that
the ants carry bodily some of their favourite beetle-companions, as well as
members of their own species. Forel observed that after a nest of _Formica
pratensis_ had been separated into two nests placed at a considerable
distance from one another so as to have no intercommunication, the members
yet recognised one another as parts of the same family after the lapse of
more than a month; but another observation showed that after some years of
separation they were no longer so recognised.
Although it is now well ascertained that ants are able to distinguish the
individuals belonging to their own nests and colonies from those that,
though of their own species, are not so related to them, yet it is not
known by what means the recognition is effected; there is, however, some
reason to suppose that it {155}is by something of the nature of odour. One
observer has noticed that if an ant fall into water it is on emerging at
first treated as if it were a stranger by its own friends; but other
naturalists have found this not to be the case in other species. Contact
with corrosive sublimate deprives ants for a time of this power of
recognising friends, and under its influence they attack one another in the
most ferocious mariner.
The nests and colonies of the species of Camponotides we have considered
are all constructed by societies comprising a great number of individuals;
there are, however, in the tropics numerous species that form their nests
on foliage, and some of these contain only a few individuals. The
leaf-nests (Fig. 64) of certain species of _Polyrhachis_ are said to be
formed of a paper-like material, and to contain each a female and about 8
or 10 worker ants. Forel[65] has examined nests of several Indian species,
and finds they differ from those of other ants in consisting of a single
cavity, lined with silk like that of a spider. These nests are further said
to be constructed so as to render them either inconspicuous or like other
objects on the leaves; _P. argentea_ covers its small dwelling with little
bits of vegetable matter, and a nest of _P. rastella_ was placed between
two leaves in such a manner as to be entirely hidden. All the species of
the genus do not, however, share these habits, _P. mayri_ making a
card-nest, like _Dolichoderus_ and some other ants. The species of the
genus _Polyrhachis_ are numerous in the tropics of the Old World.
[Illustration: Fig. 64—Nest of _Polyrhachis_ sp. (After Smith.)]
Forbes noticed that a species of this genus, that makes its paper-like nest
on the underside of bamboo-leaves produces a noise {156}by striking the
leaf with its head in a series of spasmodic taps. The same observer has
recorded a still more interesting fact in the case of another species of
this genus—a large brown ant—found in Sumatra. The individuals were "spread
over a space, perhaps a couple of yards in diameter, on the stem, leaves,
and branches of a great tree which had fallen, and not within sight of each
other; yet the tapping was set up at the same moment, continued exactly the
same space of time, and stopped at the same instant; after the lapse of a
few seconds all recommenced at the same instant. The interval was always of
about the same duration, though I did not time it; each ant did not,
however, beat synchronously with every other in the congeries nearest to
me; there were independent tappings, so that a sort of tune was played,
each congeries dotting out its own music, yet the beginnings and endings of
the musical parties were strictly synchronous."
[Illustration: Fig. 65—_Polyrhachis pandurus_, worker. Singapore.]
Mr. Peal has also recorded that an ant—the name is not mentioned, but it
may be presumed to be an Assamese species—makes a concerted noise loud
enough to be heard by a human being at twenty or thirty feet distance, the
sound being produced by each ant scraping the horny apex of the abdomen
three times in rapid succession on the dry, crisp leaves of which the nest
is usually composed. These records suggest that these foliage-ants keep up
a connection between the members of different nests somewhat after the same
fashion as do so many of the terrestrial Camponotides. Although the species
of Camponotides have no special organ for the production of sound in the
position in which one is found in Myrmicides and Ponerides, yet it is
probable that they are able to produce a sound by rubbing together other
parts of the abdomen.
{157}SUB-FAM. 2. DOLICHODERIDES.—_Hind body furnished with but one
constriction so that only a single scale or node is formed; Sting
rudimentary; the poison-sac without cushion._
[Illustration: Fig. 66—_Tapinoma erraticum_, worker. Britain. Upper side
and profile.]
The Dolichoderides are similar to Camponotides in appearance, and are
distinguished chiefly by the structure of the sting and the poison
apparatus. To this we may add that Forel also considers the gizzard to be
different in the two sub-families, there being no visible calyx in the
Dolichoderides, while this part is largely developed in the Camponotides.
This is one of the least extensive of the sub-families of ants, not more
than 150 species being yet discovered. Comparatively little is known of the
natural history of its members, only a very small number of species of
Dolichoderides being found in Europe. The best known of these (and the only
British Dolichoderid) is _Tapinoma erraticum_, a little ant of about the
size of _Lasius niger_, and somewhat similar in appearance, but very
different in its habits. _T. erraticum_ does not cultivate or appreciate
Aphides, but is chiefly carnivorous in its tastes. Our knowledge of it is
due to Forel, who has noticed that it is very fond of attending the fights
between other ants. Here it plays the part of an interested spectator, and
watching its opportunity drags off the dead body of one of the combatants
in order to use it as food. Although destitute of all power of stinging,
this Insect has a very useful means of defence in the anal glands with
which it is provided; these secrete a fluid having a strong characteristic
odour, and possessing apparently very noxious qualities when applied to
other ants. The _Tapinoma_ has no power of ejecting the fluid to a
distance, but is very skilful in placing this odorous matter on the body of
an opponent by touching the latter with the tip of the abdomen; on this
being done its adversary is usually discomfited. This {158}Insect is
subterranean in its habits, and is said to change its abode very
frequently. _T. erraticum_ occurs somewhat rarely in Britain. Forel has
also noted the habits of _Liometopum microcephalum_, another small European
species of Dolichoderides. It is a tree-ant, and by preference adopts, and
adapts for its use, the burrows made by wood-boring beetles. It forms
extremely populous colonies which may extend over several large trees, the
inhabitants keeping up intercommunication by means of numerous workers. No
less than twelve mighty oaks were found to be thus united into a colony of
this ant in one of the Bulgarian forests. The species is very warlike, and
compensates for the extreme minuteness of its individuals by the skilful
and rapid rushes made by combined numbers on their ant-foes of larger size.
Fritz Müller has given a brief account, under the name of the Imbauba ant,
of a Brazilian arboreal ant, that forms small nests in the interior of
plants. The species referred to is no doubt an _Azteca_, and either _A.
instabilis_, or _A. mulleri_. The nests are founded by fertilised females
which may frequently be found in the cells on young _Cecropia_ plants. Each
internode, he says, has on the outside, near its upper part, a small pit
where the wall is much thinner, and in this the female makes a hole by
which she enters. Soon afterwards the hole is completely closed by a
luxuriant excrescence from its margins, and it remains thus closed until
about a dozen workers have developed from the eggs of the female, when the
hole is opened anew from within by the workers. It is said that many of the
larvae of these ants are devoured by the grubs of a parasite of the family
Chalcididae. This Insect is thought to protect the plant from the attacks
of leaf-cutting ants of the genus _Atta_.
We may here briefly remark that much has been written about the benefits
conferred on plants by the protection given to them in various ways by
ants: but there is reason to suppose that a critical view of the subject
will not support the idea of the association being of supreme importance to
the trees.[66]
SUB-FAM. 3. MYRMICIDES.—_Pedicel of abdomen formed of two well-marked
nodes (knot-like segments). Sting present (absent in the Cryptocerini and
Attini). (It should be noted that the {159}workers of the genera Eciton
and Aenictus of the subfamily Dorylides have, like the Myrmicides, two
nodes in the pedicel.)_
This sub-family consists of about 1000 species, and includes a great
variety of forms, but, as they are most of them of small size, they are
less known than the Camponotides, and much less attention has been paid to
their habits and intelligence. Forel, until recently, adopted four groups:
Myrmicini, Attini, Pseudomyrmini and Cryptocerini; but he is now disposed
to increase this number to eight.[67] They are distinguished by differences
in the clypeus, and in the form of the head; but it must be noted that the
characters by which the groups are defined are not in all cases fully
applicable to the males. The Cryptocerini are in external structure the
most highly modified of Hymenoptera, if not of all the tribes of Insecta.
[Illustration: Fig. 67—_Pheidologeton laboriosus_, large and small workers.
East India.]
i. The Myrmicini proper are defined by Forel as having the antennae
inserted near the middle, a little behind the front, of the head, which has
carinae on the inner sides, but none on the outer sides, of the insertions
of the antennae; the clypeus extends between the antennae.
[Illustration: Fig. 68—_Formicoxenus nitidulus_, male. (After Adlerz.)]
Certain genera of small European ants of the group Myrmicini display some
most anomalous phenomena. This is especially the case in _Formicoxenus_,
_Anergates_ and _Tomognathus_. The facts known have, however, been most of
them only recently discovered, and some obscurity still exists as to many
of even the more important points in these extraordinary life-histories.
{160}[Illustration: Fig. 69.—_Anergates atratulus_. Europe. A, male, with
part of hind leg broken off; B, female, with wings: C, female, after
casting the wings and becoming a queen.]
It has long been known that the little _Formicoxenus nitidulus_ lives as a
guest in the nests of _Formica rufa_, the wood-ant; and another similar
ant, _Stenamma westwoodi_, which shares the same life, was declared by
Nylander and Smith to be its male; it was however shown some years ago by
André that this is a mistake, and that _S. westwoodi_ is really the male of
another ant that had till then been called _Asemorhoptrum lippulum_. This
correction left the workers and females of _Formicoxenus nitidulus_
destitute of a male, but Adlerz has recently discovered that the male of
this species is wingless and similar to the worker, the female being a
winged Insect as usual. It is very curious that the characters by which the
male is distinguished from the worker should vary in this species; but
according to Adlerz this is the case, individuals intermediate in several
points between the males and workers having been discovered. This
phenomenon of quite wingless males in species where the female is winged is
most exceptional, and is extremely rare in Insects; but it occurs, as we
shall see, in one or two other Myrmicides. Charles Darwin made the very
reasonable suggestion that winged males may be developed occasionally as an
exceptional phenomenon, and it is very probable that this may be the case,
though it has not yet been demonstrated. _Formicoxenus nitidulus_ occurs in
England in the nests of _Formica rufa_ and of _F. congerens_, but we are
not aware that the male has ever been found in this country. The genus
_Anergates_ is allied to _Formicoxenus_, and occurs in Central Europe, but
has not been found in Britain; the female, as in _Formicoxenus_, is winged
and the male wingless, but there is no worker-caste; the male is a rather
helpless creature, and incapable of leaving the nest. The species lives in
company with _Tetramorium caespitum_ a little ant very like _Myrmica_, and
not uncommon in South-East England. The female _Anergates_ is at {161}first
an active little creature with wings, but after these are lost the body of
the Insect becomes extremely distended as shown in Fig. 69, C; the creature
is in this state entirely helpless, and as there are no workers, the
_Anergates_ is completely dependent, for the existence of itself and its
larvae, on the friendly offices of the _Tetramorium_ that lives with it.
The mode of the association of these two Insects is at present both
unparalleled and inexplicable, for only workers of the _Tetramorium_ are
found in company with the ♂ and ♀ _Anergates_; the community, in fact,
consisting of males and females of one species and workers of another. The
nests of _Anergates_ are so rare that only a few naturalists have been able
to observe them (Schenk, von Hagens, and Forel may be specially mentioned),
but in the spots where they occur, nests of the _Tetramorium_, containing
all the forms of that species, are numerous, and it therefore seems
probable that a young fertile female of the _Anergates_ may leave a nest in
which it was born, enter a nest of the _Tetramorium_, and, destroying the
queen thereof, substitute herself in the place of the victim; but if this
be really the case, the larvae and pupae of the _Tetramorium_ must also be
destroyed, for no young of the _Tetramorium_ are ever found in these
strange associations. It is very difficult to believe that the
_Tetramorium_ workers should be willing to accept as their queen a creature
that commenced her acquaintance with them by destroying their own queen or
queens and a number of their young sisters; especially as the _Tetramorium_
is a more powerful ant than the _Anergates_, and could readily dispose of
the murderous intruder if it were disposed to do so. It is known, however,
that colonies of _Tetramorium_ completely destitute of queens sometimes
occur, and Wasmann has suggested that the female _Anergates_ may seek out
one of these, and installing herself therein as a substitute, may be
accepted by the orphaned colony. This plausible hypothesis has still to be
verified.
The genus _Cardiocondyla_ also exhibits the phenomenon of apterous,
worker-like males, while in one species, _C. emeryi_, a winged male is also
known to exist.
_Tomognathus sublaevis_ is a little Myrmicid ant, found rarely in Denmark
and Sweden, where its habits have recently been studied by Adlerz. A band
of the _Tomognathus_ attack the nest of another little Myrmicid,
_Leptothorax acervorum_, and succeed by their own pertinacity and the fears
of the _Leptothorax_ in {162}obtaining possession of it; the legitimate
owners disappear, leaving the _Tomognathus_ in possession of their larvae
and pupae; these complete their development only to find themselves the
slaves of _Tomognathus_. The subsequent relations of the two ants are
friendly, the slaves even preventing their masters from wandering from the
nest when they wish to do so. If an established mixed community of this
nature is in want of additional servitors, the _Tomognathus_ secure a
supply by raids after the fashion of the Amazon-ant, bringing back to their
abode larvae and pupae of _Leptothorax_ to be developed as slaves. It was
formerly supposed that the _Tomognathus_ continued its species by perpetual
parthenogenesis of the workers, for neither males nor females could be
found. Adlerz[68] has, however, now discovered the sexual individuals. The
male is an ordinary winged ant, and is so like that sex of the
_Leptothorax_, that Adlerz had failed to distinguish the two before he
reared them. The females are apterous, and in fact like the workers. It
would perhaps be more correct to say that the workers of this species vary
greatly but never become winged; some of them have ocelli and a structure
of the thorax more or less similar to that of winged females, though none
have been found with wings. Certain of these females possess a receptaculum
seminis, and Adlerz treats this as the true distinction between female and
worker. In accordance with this view the female of _Tomognathus_ may be
described as a worker-like individual possessing a receptaculum seminis,
and having more or less of the external structures of winged females,
though never being actually winged. It is probable that other workers
reproduce parthenogenetically. The males of this species will not unite
with females from the same nest, thus differing from many other ants, in
which union between individuals of the same nest is the rule. Finally, to
complete this curious history, we should remark that the larvae of the
_Tomognathus_ are so similar to those of the _Leptothorax_ that Adlerz is
quite unable to distinguish the two.
_Strongylognathus testaceus_ and _S. huberi_ live in association with
_Tetramorium caespitum_, and are cared for by these latter ants; it is
notable that as in the case of the slave-making _Polyergus rufescens_ the
mandibles of the _Strongylognathus_ are cylindrical and pointed, and
therefore unsuitable for industrial occupations. {163}_S. testaceus_ is a
weak little ant, and lives in small numbers in the nests with _T.
caespitum_, which it is said to greatly resemble in appearance. The
proportions of the forms of the two species usually associated is peculiar,
there being a great many workers of _T. caespitum_ both in the perfect and
pupal states, and also all the sexes of the _Strongylognathus_, of which,
however, only a few are workers. This would seem to suggest that _S.
testaceus_ attacks and pillages the nests of _T. caespitum_ in order to
carry off worker pupae, just as _Polyergus rufescens_ does. But the facts
that _S. testaceus_ is a weaker Insect than the _Tetramorium_, and that
only a few of its worker-caste are present in a community where there are
many workers of the _Tetramorium_, seem to negative the view that the
latter were captured by the former; and the mode in which the associated
communities of these two species are started and kept up is still therefore
in need of explanation.
_Strongylognathus huberi_ is a much stronger Insect than its congener, _S.
testaceus_, and Forel has witnessed its attack on _Tetramorium caespitum_.
Here the raid is made in a similar manner to that of _Polyergus rufescens_
on _Formica_; the _Tetramorium_ is attacked, and its pupae carried off to
the abode of the _Strongylognathus_ to serve in due time as its slaves. The
mandibles of _S. huberi_, being similar in form to those of _Polyergus
rufescens_ are used in a similar manner.
Although _T. caespitum_ is common enough in South-East England, it is to be
regretted that none of the guests or associates we have mentioned in
connection with it occur in this country. It is a most variable species,
and is distributed over a large part of the globe.
Our British species of Myrmicides, about ten in number, all belong to the
group Myrmicini; none of them are generally common except _Myrmica rubra_,
which is a most abundant Insect, and forms numerous races that have been
considered by some entomologists to be distinct species; the two most
abundant of these races are _M. ruginodis_ and _M. scabrinodis_, which
sometimes, at the time of the appearance of the winged individuals, form
vast swarms.
The tiny _Monomorium pharaonis_ is a species that has been introduced into
Britain, but now occurs in houses in certain towns; it sometimes
accumulates on provisions in such numbers as to be a serious nuisance.
Seventeen thousand {164}individuals weigh 1 gramme, and it is probable that
a nest may include millions of specimens.
The genus _Aphaenogaster_[69] and its immediate allies include the
harvesting ants of Europe and North America: they form subterranean nests
consisting of isolated chambers connected by galleries; some of the
chambers are used as store-houses or granaries, considerable quantities of
corn, grass, and other seeds being placed in them. _A. structor_ and _A.
barbarus_ have been observed to do this in Southern Europe, by Lespès,
Moggridge, and others.
[Illustration: Fig. 70—_Aphaenogaster (Messor) barbarus._ Algeria. A, male;
B, winged female; C, large worker or soldier; D, small worker. × 3/2.]
In the deserts about Algeria and Tunis a harvesting ant, _Aphaenogaster
(Messor) arenarius_, is an important creature: its subterranean dwellings
are very extensive, and are placed at a depth of several feet from the
surface. Entrance to these dwellings is obtained by small holes, which are
the orifices of galleries many feet in length: the holes are surrounded by
pellets of sand projecting somewhat above the general surface, and
consequently making the places conspicuous. The subterranean works occupy
an area of fifty or a hundred square yards excavated at a depth of three to
six feet. In these immense nests there exists a form of worker, of very
small size, that never comes to the surface.[70]
_Pogonomyrmex barbatus_ and other species have been observed to do
harvesting in North America. After the workers of _P. barbatus_ have taken
the seeds into the nest they separate the husks and carry them out,
depositing them on a heap or {165}kitchen-midden, formed near by. M‘Cook
has witnessed and described the process of stripping the seeds.
Certain genera—e.g. _Aphaenogaster_, _Pheidole_—exhibit great disparity in
the forms of the workers, some of which are of size much superior to the
others, and possess disproportionately large heads; these large individuals
are found in the same nest as the smaller forms. All the intermediate forms
may frequently be found, and at the same time, in the genus
_Aphaenogaster_; but in _Pheidole_ intermediates are of the utmost rarity.
The genus _Cremastogaster_ is remarkable on account of the shape of the
hind body and its articulation, which give the abdomen the appearance of
being put on upside down. This mode of articulation may allow the Insect to
threaten its enemies when they are in front of it; but it is doubtful
whether the _Cremastogaster_ possesses an effective sting.
[Illustration: Fig. 71—_Cremastogaster tricolor_, worker. A, with abdomen
extended; B, uplifted.]
ii. The group Attini is distinguished by the presence of a carina near the
eye, by the antennae being inserted at a moderate distance from one
another, by the clypeus being prolonged backwards between them; and by the
absence of a sting. The group is not represented in Europe, but in Tropical
America the ants belonging to it are amongst the most important of natural
objects. The species of the genus _Atta_ (usually styled _Oecodoma_) are
the formidable leaf-cutting ants of America. They occur in enormous
colonies in certain places, and will in a short time completely strip a
tree of its leaves. As they appear to prefer trees of a useful kind,
especially those planted by man, their ravages are often of the most
serious nature. The natives, feeling it hopeless to contend with these
Insect hordes, only too frequently abandon all attempts to cultivate the
trees and vegetables the Insects are fond of. Both Bates and Belt have
{166}given accounts of some points in the economy of these ants. They are
amongst the largest of the Formicidae, the females in some cases measuring
about two and a half inches across their expanded wings; the males are much
smaller, but are less dissimilar to their partners than is usual among
ants. The workers, on the other hand, are so extremely different, that no
one would suppose them to be at all related to the males and females (see
vol. v. Fig. 339).
The mode of operation of these ants is to form paths from their formicary
extending for a considerable distance in various directions, so that they
have a ready access to any spot in a district of considerable extent; when
a tree or bush is found bearing leaves suitable for their purposes, the
worker ants ascend it in large numbers and cut up the leaves by biting out
of them pieces similar in size and shape to a small coin; these pieces are
then carried back in the jaws of the ants to their nests; the ant-paths are
therefore constantly traversed by bands of little creatures carrying
burdens homewards, or hurrying outwards in search of suitable trees.
The formicaries are of considerable size, and are described as consisting
of low mounds of bare earth of considerable extent. Bates speaks of as
great a circumference as forty yards; these accumulations of earth have
frequently an appearance different from the adjoining soil, owing to their
being formed of subsoil brought up from below; they are kept bare by the
ants constantly bringing to and depositing on the surface fresh material
resulting from their subterranean excavations. The true abodes, beneath the
earth, are of greater extent than the mounds themselves, and extend to a
considerable depth; they consist of chambers connected by galleries.
The leaf-cutting ants extend their range to North America, and M‘Cook has
recently called attention to a case there in which _A. fervens_ made an
underground route at an average depth of 18 inches, and at an occasional
depth of 6 feet, extending 448 feet entirely beneath the earth, after which
it was continued for 185 feet to reach a tree which the ants were engaged
in defoliating. This route, extending altogether to a length of more than
600 feet, presented only a very slight deviation from a straight line drawn
between the point of departure and the object to be attained. By what sense
this ant was enabled {167}to make a subterranean tunnel in a straight line
to a desired object situated at so great a distance, we know not.
The use the leaf-cutting ants make of the enormous amount of material they
gather was for long a subject of debate, and has only recently been
ascertained by the observations of Möller. After being carried to the nest
the pieces of leaves are cut into small fragments by another set of workers
and formed into balls, which are packed in various parts of the nest, and
amongst which the mycelium of a fungus—_Rozites gongylophora_—ramifies.
This fungus the ants cultivate in the most skilful manner: they manage to
keep it clear from mouldiness and bacterial agents, and to make it produce
a modified form of growth in the shape of little white masses, each one
formed by an agglomeration of swellings of the mycelium. These form the
chief food of the colony. Möller ascertained by experiment that the results
were due to a true cultivation on the part of the ants: when they were
taken away from the nests, the mycelium produced two kinds of conidia
instead of the ant-food.
Many details of the economy of these leaf-cutting ants are still very
imperfectly known. The large-headed forms, called soldiers, have been the
subject of contradictory statements; Bates having concluded from his own
observations that they are harmless, while Mr. J. H. Hart assures us that
they are very fierce and vindictive, and inflict very serious wounds by
biting (the Attini do not sting). We anticipate that the observations of
both these naturalists will prove to be substantially correct, and that the
differences in habits will be found to be owing to distinctions in the
conditions of the community. In connection with this point we may remark
that the function of the excessively large heads of certain kinds of
soldier-ants is still obscure. In the East Indian _Pheidologeton diversus_
the big soldiers are quite one hundred times as large as the smaller
workers. As these latter bite viciously it would naturally be supposed that
their gigantic _confrères_ with enormous heads would be warriors of a most
formidable nature; but, as a matter of fact, the giants are unable to bite
even when they try to do so. Aitken has somewhere suggested that these
enormous individuals play the part of state elephants; and we have been
informed by Colonel Bingham that the small ants may frequently be seen
riding in numbers on their unwieldy fellows. We anticipate {168}however,
that some other function will be found to exist for these forms with
enormous heads. An examination of their organs of sense and of voice is
very desirable.
Details of the modes in which the great communities of the leaf-cutting
Attidae are maintained, are still wanting. The females do not, we have been
informed by Mr. Hart, possess any considerable powers of aftergrowth, so
that there is no reason to suppose them to be unusually prolific. At
certain seasons great swarms of winged individuals are produced, and after
leaving the nests pair in the manner of our European _Myrmica_. Possibly
the females may, after losing their wings, again enter the large
communities. Von Ihering states that the workers of _Atta lundi_ are
fertile.
iii. The group Pseudomyrmini includes the genera _Pseudomyrma_ and _Sima_,
which are by some entomologists treated as but a single genus. The antennae
are inserted near together on the front of the head; there is no carina on
the head external to their insertion, and the clypeus does not extend
forwards between them. The Insects are usually of elongate form, possess a
sting, and have a naked pupa. The group occurs in both hemispheres, but is
exclusively exotic, and but little is known of the habits of its members.
Forel has recently observed that numerous species live inside dried stems
of grass or in hollow twigs, and are beautifully adapted for this mode of
life by their elongate form, some of them being as slender as needles. Some
interesting observations have been made in Nicaragua by Belt on
_Pseudomyrma bicolor_ and its relations with an acacia-tree, in the thorns
of which it lives. The acacia in question is called the bull's-horn thorn,
because the branches and trunk are armed with strong curved spines, set in
pairs, and much resembling the horns of the quadruped whose name they bear.
The ant takes possession of a thorn by boring a small hole near the distal
extremity, and forms its nest inside. The leaves of this plant are provided
with glands that secrete a honey-like fluid, which it appears forms the
chief, if not the sole, subsistence of the ant. Belt considers that the
presence of the ant is beneficial to the acacia; he supposes that the ants
assume the rights of proprietors, and will not allow caterpillars or
leaf-cutting ants to meddle with their property; the leaves are, he thinks,
so preserved to the benefit of the tree.
{169}[Illustration: Fig. 72—_Sima rufo-nigra_ and its associates. A, winged
female; B, worker, of the ant; C, _Rhinopsis ruficornis_; a fossorial wasp
of the sub-family _Ampulicides_; D, a spider, _Salticus_ sp. The coloration
is extremely similar in all these creatures.]
Rothney has given some particulars of the habits of _Sima rufo-nigra_, an
ant of this group that appears to be not uncommon near Calcutta, where it
lives on the trunks of trees in company with a spider and a wasp that
greatly resemble it in form and in colour. The three creatures seem to
associate together on amicable terms; indeed the wasp and the ant
occasionally indulge in wrestling matches without doing one another any
serious harm. In connection with this fact we may observe that other
species of ants have been observed to indulge in sports and feats of
agility.
_S. leviceps_, an Australian species of this genus, is furnished with a
stridulating file that has the appearance of being constructed so as to
produce two very different kinds of sounds.
[Illustration: Fig. 73—Stridulating file of _Sima leviceps_.]
iv. The Cryptocerini are distinguished from other ants by their antennae
being inserted at the sides of the head, where they are placed between
ridges or in a groove into which they can be withdrawn; when in some cases
they are entirely concealed. These ants assume a great variety of shapes
and forms, some of which look almost as if they were the results of an
extravagant imagination. The skeleton is usually much harder than it is in
other {170}ants; the abdomen consists almost entirely of one very large
segment, there being, however, three others visible at its extremity; these
segments can be only slightly protruded, and the ants have no power of
stinging. They are probably most of them arboreal in their habits. Nearly
all of the known forms are exotic. According to the observations of Bates
the species of the genus _Cryptocerus_ in the Amazons Valley may frequently
be observed in dry open places on low trees and bushes, or running on
branches of newly felled trees; they also visit flowers abundantly. The
species generally are wood-borers, usually perforating the dead branches of
trees. _C. atratus_ has been observed to construct its nests in the dead,
suspended branches of woody climbers; a number of neatly drilled holes are
all that can be seen externally; but, inside, the wood is freely perforated
with intercommunicating galleries. Each community appears to consist of a
single female and two kinds of workers; the latter in some species are
quite unlike each other, differing in the form of the head, and in the
armature of the thorax and nodes of the peduncle. The species of
_Cryptocerus_ appear to be omnivorous, and are frequently attracted by the
excrement of birds. The pupae are not enclosed in a cocoon. In the South of
Europe two very minute ants, of the genera _Strumigenys_ and _Epitritus_,
belonging to this family, are met with under very large stones partly
embedded in the earth. They are of the greatest rarity.
[Illustration: Fig. 74—_Cyrptocerus atratus_, worker. Amazons. The
compressed first joint of the hind foot is shown at _a_ and _b_ in
different positions.]
SUB-FAM. 4. PONERIDES.—_Hind body elongate, furnished with one node at
the base, and having also great capacity of movement between the first
and second segments, between which there is usually a slight
constriction. Sting well developed._
This sub-family includes numerous genera and about 400 species. The
Ponerides have an elongate hind-body; the second segment behind the node is
capable of great movement in and out of the preceding segment, and for this
purpose is furnished with a basal portion slightly more slender than the
apical part; this {171}basal part is usually concealed within the more
anterior segment, the hind margin of which embraces it very closely. On the
middle of the dorsal aspect of this articulation there is usually placed a
stridulating organ, consisting of an elongate band or patch of very fine
lines; this gives out a sound when the second segment is moved in and out
of the first at a time when the posterior edge of the latter is slightly
depressed.
We follow Forel in including the Australian bull-dog ants—_Myrmecia_—in
Ponerides, as well as the Odontomachi. The former have, however, a definite
pedicel, consisting of two nodes (Fig. 76). In the Odontomachi the
mandibles are approximate at their bases, being inserted on the middle of
the front of the head (Fig. 77).
This sub-family includes a considerable number of species, and is found in
all parts of the world. Extremely little is known as to the habits, but the
true Ponerides do not, so far as is known, occur in large communities, and
it seems probable that they are destitute of the powers of combined action
that are so remarkable in the Camponotides, and in some of the Myrmicides
and Dorylides. Most of the species that have been described are known by
only one sex, so that very little knowledge exists as to the sexual
distinctions; but from the little that is known it would appear that the
three sexual forms are not so differentiated as they are in most of the
Camponotides and Myrmicides.
[Illustration: Fig. 75—_Dinoponera grandis_, worker. Amazons.]
The species of the genus _Leptogenys_ are believed by Emery and Forel to
possess an apterous female. Mr. Perkins has observed that the Hawaiian _L.
falcigera_ has workers with different kinds of sting, but no true female.
Males of this species are, however, abundant. Wroughton has recently
discovered that one member of this genus is of Termitophagous habits, but
this is not the case with _L. falcigera_. _Dinoponera grandis_ (Fig. 75) is
the largest of the Ponerides, its {172}workers attaining an inch and a
quarter in length. This Insect, according to Bates, marches in single file
in the thickets at Pará; its colonies consist of a small number of
individuals, and are established at the roots of slender trees. The effects
of its powerful sting are not so serious as is the case with some of the
smaller ants.
In Britain we have only two representatives of the sub-family, viz. _Ponera
contracta_, a small ant of dirty-yellow colour, found rarely in the
Southern counties, living in moss or under stones. Its colonies consist of
only a few individuals; Forel giving fifty as the highest number he has
observed. The second species, _P. punctatissima_, presents the almost
unique peculiarity of possessing two forms of the male sex, one of them
resembling the worker in most of its peculiarities, and in being destitute
of wings, while the other is winged, as is usual in male ants. In the
island of St. Vincent another species of _Ponera_ has been discovered
having an apterous and worker-like male, and was named by Forel _P.
ergatandria_.[71] The discovery of this form has led him to express some
doubt as to whether _Ponera punctatissima_ has two forms of males; but it
seems probable that it really is so, the ergatoid males being produced
under somewhat different circumstances from the normal males. We shall
subsequently see that _Cardiocondyla_ and a few other Myrmicides exhibit an
analogous peculiarity.
The genus _Myrmecia_ is confined to the Australian continent and Tasmania,
and includes a considerable number of species of large and moderate-sized
ants, the classification of which has been a subject of difference of
opinion. This has arisen from the fact that the nodes of the abdominal
pedicel are more similar to those existing in the Myrmicides than to those
of the typical Ponerides. There are, however, some American members of the
latter sub-family (_Paraponera clavata_, _e.g._) that differ but little in
this point from _Myrmecia_, and, moreover, the pupae of _Myrmecia_ are
enclosed in a cocoon, while in the Myrmicides they are usually naked. On
the other hand the nests are, it appears, very large and populous, more
like what exists in the Myrmicides; there is no true stridulating organ on
the first abdominal segment. The genus is therefore one of those
interesting anomalies that form so large a proportion of the Australian
{173}fauna, and will probably be ultimately treated as a distinct
sub-family. There are about thirty species.
The ants of this genus are well known to the residents in Australia, where
they are called "bull-dog ants." They form large mounds of earth for their
nests. The workers, and females (Fig. 76) are much alike except during the
period when the latter are still carrying their wings. The males, however,
differ considerably, being of more slender form, and possessing only
insignificant mandibles, and straight antennae with a quite short basal
joint.
[Illustration: Fig. 76—_Myrmecia pyriformis._ Australia. Female after
casting wings.]
Forel considers _Myrmecia_ to be the most formidable of all the ants; the
hills are said to be sometimes five feet high, and the colonies are immense
in numbers, while the Insect is an inch or more in length, and armed with a
very powerful sting, the use of which on the human body is said to give
rise in some cases to serious symptoms. On the other hand, we have seen
statements to the effect that the sting of _Myrmecia_ has only very
evanescent sequelae; it is also said that the ant-hills have only a slight
elevation, so that probably both these points differ according to the
species. It appears from a communication of Miss Shepherd's that the
formidable _Myrmecia forficata_ has its larvae destroyed by a parasitic
Hymenopteron (_Eucharis myrmeciae_) of brilliant colour and considerable
size, so that we have the curious fact of the hordes of this most
formidably armed ant, which possesses also large eyes, falling a victim to
a brilliant and very conspicuous Insect. Particulars of this case of
parasitic attack are still wanting. There are other cases known of the
larvae of ants being destroyed by parasitic Diptera and Hymenoptera, but in
none of them have any sufficient observations been made as to the mode in
which the attack is made. Lowne says that _M. gulosa_ itself attacks large
beetles of the genus _Anoplognathus_ and buries them; and he also adds the
very curious statement that _M. nigrocincta_, when running, is able to take
leaps of a foot in length.
The Odontomachi were formerly considered a distinct sub-family,
distinguished by the peculiar mandibles (Fig. 77). {174}Many of the
Ponerides have elongate mandibles, but they are inserted at the sides of
the front of the head, not in the middle of the front. These organs in some
species of Odontomachi serve as levers, by aid of which the Insect can
execute considerable leaps. In only a few species are the males known; Mayr
and Forel state that they are destitute of the peculiar mandibles
characteristic of the worker.
[Illustration: Fig. 77—_Anochetus ghiliani_, worker. Tangier.]
The unique European representative of the Odontomachi, _Anochetus
ghiliani_, occurs in Andalusia. Near Tangier Mr. George Lewis found it to
be not uncommon; but the sexes are not known, and it even appears doubtful
whether there exists any well-marked division between workers and female.
Lewis observed, among the ordinary forms, individuals with longer bodies,
usually one in a nest, and he supposed these to be females; Saunders, on
examining these examples, found them to possess distinct ocelli, and
therefore agreed with Lewis as to their being the female sex. Dr. Emery
subsequently examined these same specimens, and took what is scarcely a
different view, viz. that they are not females but an intermediate form;
and he also expressed the opinion that "the true female may not exist." The
male of _Anochetus_ is not known. The female of _A. mayri_, a Neotropical
species, has rudimentary wings.
SUB-FAM. 5. DORYLIDES.—_Clypeus extremely small, the antennae inserted
very near the front margin of the head. Hind body usually elongate and
subcylindrical, with an imperfect pedicel formed by the constriction of
the back of the first segment, but occasionally there are two nodes in
the workers. Distinctions between the two sexes, and between the workers
and sexed forms, enormous, the queens truly wingless. The females and
workers usually blind, or at any rate destitute of facetted eyes. (In
Ecitonini the antennae are not inserted quite at the front of the head,
and there are two nodes in the pedicel.)_
{175}We have reserved to the end of the ants the consideration of the two
groups Dorylides and Amblyoponides, recent investigations having rendered
it somewhat doubtful whether they can be maintained as distinct from
Ponerides. The chief character of the Dorylides is that the males are much
less ant-like in form than they are in the other groups, and that the
distinction between the females and workers are enormous. The little that
is known as to the males and females of this group suggests the view that
these sexes may offer sufficient reason for keeping the Dorylides as a
group distinct from the other ants; but it must be admitted that it is very
difficult to find satisfactory characters to distinguish the workers of the
Dorylides in some cases from the Ponerides, in others (_Eciton_) from the
Myrmicides.[72]
[Illustration: Fig. 78—Various forms of worker of _Eciton hamatum_.
Guatemala.]
The Dorylides are of great interest, for they exhibit the remarkable
phenomenon of a nomadic social life, accompanied by imperfect sight in the
wanderers. The sub-family includes two apparently distinct groups: (1) the
Ecitonini, peculiar to the New World, and having a close relationship with
the Myrmicides; and (2) the Dorylini existing chiefly in the eastern
hemisphere, and related closely by its workers to the Ponerides and
Amblyoponides. (i.) The Ecitonini consist of the species of the genus
_Eciton_, the wandering ants of America, and of _Labidus_, which there is
now good reason for believing to consist of the males of _Eciton_. The
female is still uncertain. The _Eciton_ are nomad ants having no fixed
abode, but wandering from place to place in search of prey, and forming
temporary resting-places. The {176}species are rather numerous, and the
habits of several have been described by Bates, who, however, was not
acquainted with some of the most peculiar features in their biology, these
having been since revealed by Belt and W. Müller.
These ants are predaceous in their habits, and some of the species travel
in vast hordes; they occasionally enter houses and clear them of much of
the vermin with which they may be infested. They have no facetted eyes,
some of the forms being quite blind, while others have a pair of peculiar
lenses in the position normally occupied by the compound eyes. Usually
there are two castes of the workers, and in some species these are very
different from one another, the mandibles being in the larger form very
elongate, cylindrical and unfit for industrial purposes, while the
individuals of the smaller caste have the outer jaws shorter, with their
edges apposed and coadapted: in other species individuals with mandibles
differentiated from the normal form do not exist. The nomad habits of these
ants were described by Bates, but the detection of their temporary
resting-places was reserved for Belt, who found that, after their
plundering raids, they retired to a place of concealment, and there
clustered together in a compact mass like a swarm of bees. Belt says: "They
make their temporary habitations in hollow trees and sometimes underneath
large fallen trunks that offer suitable hollows. A nest that I came across
in the latter situation was open at one side. The ants were clustered
together in a dense mass, like a great swarm of bees, hanging from the
roof, but reaching to the ground below. Their innumerable long legs looked
like brown threads binding together the mass, which must have been at least
a cubic yard in bulk, and contained hundreds of thousands of individuals,
although many columns were outside, some bringing in the pupae of ants,
others the legs and dissected bodies of various Insects. I was surprised to
see in this living nest tubular passages leading down to the centre of the
mass, kept open, just as if it had been formed of inorganic materials. Down
these holes the ants who were bringing in booty passed with their prey. I
thrust a long stick down to the centre of the cluster and brought out
clinging to it many ants holding larvae and pupae."
Turning now to the _Labidus_ question: many American species of this genus
have long been known, though all of them {177}by the male sex only. The
discoveries (to be subsequently alluded to) made in the Old World as to the
relations between the driver ants and _Dorylus_ raised a suspicion that
_Labidus_ might be the male of _Eciton_, the distinctions in the two cases
being very analogous: this conjecture has been almost proved to be correct
by the recent observations of Hetschko and W. Müller. The latter, who
observed the temporary nests of _Eciton hamatum_, confirms Belt's
statements as to the ants hanging together in clumps, like swarms of bees;
he also states that the change from one temporary abode to another takes
place at night, though, as is well known, the hunting forays of this ant
are carried on in the daytime. The periods of migration appear to be
determined by the time at which all the larvae have assumed the pupal
state, this at any rate being the time chosen in the case observed by
Müller. This naturalist bagged a part of one of the nests by the aid of
ether, and found the larger portion to consist of pupae; there were also
some larvae and eggs; a specimen of _Labidus_ (_L. burchelli_) was also
found on friendly terms with the _Eciton_-workers; and myrmecophilous
Coleoptera were discovered. The pupae are enclosed in cocoons. Persistent
search failed to reveal any female, but the examination was made under
great difficulties. Müller also states that the earliest pupated larvae
yield soldiers, the latest the smallest forms of workers. From observations
made by Forel on a pupa, it seems probable that a wingless form of male may
be found to exist. If therefore, as appears practically certain, _Labidus_
is the winged male of _Eciton_, it is probable also that males of more or
less worker-like form exist, as is now known to be the case in some other
Formicidae.
We may here notice a peculiar apterous female ant recently described by
André under the name of _Pseudodicthadia incerta_. He thought this might
prove to be the female of _Eciton-Labidus_; but his description and figure
are imperfect, and do not greatly support his idea of a connection between
_Eciton_ and _Pseudodicthadia_.
ii. The group Dorylini includes the genus _Dorylus_, which was founded many
years ago for Insects very like _Labidus_. As in the case of the American
Insect named, males only were known; two or three allied genera, consisting
exclusively of individuals of the sex mentioned, were subsequently
described. In the {178}regions inhabited by these males numerous species of
blind ants are known, but only in the worker form, and were, or still are,
referred to genera called _Typhlopone_ and _Anomma_. Nothing that could be
considered to be a female pertaining to any of these Insects was discovered
until Gerstaecker described under the generic name _Dicthadia_ an
extraordinary apterous female ant found in Java, and it was suspected that
it might be the long-expected female of the male _Dorylus_ and of the
worker _Typhlopone_ or _Anomma_. This remained for many years without
confirmation, but in 1880 Trimen announced the discovery in South Africa of
an enormous apterous female ant, allied to _Dicthadia_; it had been
disinterred from a nest of small red ants believed (wrongly) to be
_Anomma_. As _Dorylus_ had been previously found in connection with allied
worker ants it has since then been clear that notwithstanding the enormous
differences existing between these three forms they may all pertain to one
(or to closely allied) species. From this summary the student should
understand that he will find in myrmecological literature many references
to two or three genera that really belong to one species.
[Illustration: Fig. 79—_Dorylus helvolus._ Africa. A, male; B, female
(_Dicthadia_); C, worker major (_Typhlopone_); D, worker minor. (After
Emery.)]
The workers of the Dorylini at present known are without exception quite
blind, and are believed to be all of predaceous habits; it is thought by
some that they have no fixed abodes, but, like the Ecitonini, frequently
change their residence, and it has been suggested that in doing so they
make use of the nests of other ants as temporary abodes; all these points
are, however, still unsettled, and as there are several genera it is not
unlikely that considerable variety will be found to prevail. The driver
ants of Africa, belonging to the genus _Anomma_, are in some {179}respects
similar to _Eciton_ in habits, as they enter human habitations and cause
nearly everything else to quit; it is probable that they are also
exclusively carnivorous. Savage detected the nests of _A. arcens_, but the
account he has given of them is too vague to permit one to decide whether
the assemblages he saw were of a nomad kind. The workers of this species
vary greatly in size, and Emery has recently stated that he believes all
the supposed species of the genus to be merely varieties of _A.
burmeisteri_. The female of the driver ants is still quite unknown. A
_Dorylus_ has been ascertained to be the male of _Typhlopone_. The male
_Dorylus_ (Figs. 79, A, and 80) is of great interest, for the propodeum is
in a more primitive form than it is in any other petiolate Hymenopteron
known to us, while at the same time the pronotum and mesonotum are very
highly developed. The genus _Typhlatta_ Sm. has been recently identified by
Wroughton and Forel as the worker-condition of which _Aenictus_ is the
winged male. The genus _Alaopone_ will probably be found to have some
species of _Dorylus_ as its male.
[Illustration: Fig. 80—Body of male of _Dorylus_ sp. Delagoa Bay. _a_,
pronotum; _b_, _c_, divisions of mesonotum; _d_, metanotum; _e_, propodeum;
_f_, first abdominal segment; _g_, _h_, points of insertion of anterior and
posterior wings.]
The females of the Dorylides are amongst the rarest of Insects, and are
also amongst the greatest of natural curiosities. Although worker ants and
female ants are merely forms of one sex—the female—yet in this sub-family
of ants they have become so totally different from one another in size,
form, structure, and habits that it is difficult to persuade oneself they
can possibly issue from similar eggs. In the Insect world there are but few
cases in which males differ from females so greatly as the workers of
Dorylides do from the females, the phenomena finding their only parallel in
the soldiers and females of Termites; the mode in which this difference is
introduced into the life of the individuals of one sex is unknown. The
largest of all the Dorylides are the African Insects of the genus
_Rhogmus_. Only the male is known.
{180}The specimens of female Dorylides that have been detected may, after
fifty or sixty years of research, be still counted on the fingers. As the
greatest confusion exists in entomological literature owing to the forms of
a single species having been described as two or three genera, the
following summary of the principal names of genera of Dorylides may be
useful:—
_Eciton_ = the workers, _Labidus_ = male: ♀ unknown.
_Pseudodicthadia_: female only known, possibly that of _Eciton_.
_Cheliomyrmex_: workers and soldiers only known.
_Aenictus_ = the male, _Typhlatta_ = worker: ♀ unknown.
_Rhogmus_: male; female unknown. (According to Emery the worker is very
small and like _Alaopone_.)
_Anomma_: only worker known; male probably a _Dorylus_.
_Dorylus_ = male; _Dicthadia_ = ♀: _Alaopone_ and _Typhlopone_ = workers.
SUB-FAM. 6. AMBLYOPONIDES.—_Abdomen destitute of distinct pedicel; the
articulation between the first and second segments behind the true
petiole being broad._
[Illustration: Fig. 81—_Amblyopone_, worker. Tasmania.]
We follow Forel in separating _Amblyopone_ and a few allies from the
Ponerides, because the abdominal pedicel is more imperfect than in any
other ants. It is, indeed, very difficult to frame a definition that will
include the Amblyoponides among ants, and at the same time separate
Formicidae and Scoliidae. Forel considers the Amblyoponides to approach
closely to certain divisions of the Scoliidae (Thynnides, _e.g._). Little
is known of these Insects, though they are widely distributed. _Amblyopone_
is found in Australia and New Zealand; the allied genus _Stigmatomma_ has a
wide distribution, occurring even in Europe. The social life is believed to
be imperfect, and the habits subterranean and sedentary. The males and
females are winged; the latter much resemble the workers, which are nearly
blind, and have a considerable general resemblance to _Anomma_ in
Dorylides.
ASSOCIATION OF ANTS WITH OTHER KINDS OF INSECTS.—We have already alluded to
the fact that a few species of ants are {181}used by other species as
attendants, and that the two kinds then live together quite amicably; and
we have also seen that a few ants live in association with other species on
terms that are not yet understood. One little ant, _Formicoxenus
nitidulus_, lives only in the large nests of _Formica rufa_; these ants
tolerate the little _Formicoxenus_, which so far as is known does them
neither good nor harm. There are also a considerable number of species of
small ants that are in the habit of choosing the neighbourhood of larger
species for their dwelling-places; in some cases the nests are constructed
actually within a portion of the edifice of the more powerful species, and
the rule then appears to be that these neighbours do not molest one
another. Notwithstanding the militant lives that many of them lead, ants
cannot be considered as of generally ferocious disposition.
But the most remarkable point in connection with their toleration consists
in the fact that the nests of many species are inhabited by quite a colony
of foreign Insects of various Orders; many of these, being found nowhere
else, are spoken of as ants'-nest or Myrmecophilous Insects.[73] The
relations of ants with other Insects are of the most varied and complex
character; some of their guests live with them on terms of the most
intimate association, being indeed absolutely dependent for their existence
on the good offices of their hosts; others of the ants'-nest Insects are
enemies, while others are neutral or indifferent to the ants. We have
already mentioned that the guests migrate in company with their hosts.
Many species of ants derive a considerable portion of their sustenance from
the sweet substances excreted by Aphidae. Ants may constantly be seen
occupied with clusters of Aphidae, and it is said that the ingenious little
creatures defend from enemies the manufacturers of the sweet-stuff they are
so fond of, even going so far as to form barricades and covered places for
the isolation and protection of this peculiar kind of cattle; a few ants
keep some of the root-feeding Aphidae in their nests. Coccidae and other
Homoptera, which also excrete much matter of a sugary nature, are likewise
consorted with by ants; as are also the larvae of some butterflies of the
family Lycaenidae; these latter being believed to furnish to the ants some
substance of a nutritious kind.
{182}[Illustration: Fig. 82—The beetle, _Atemeles_, soliciting food from an
ant. (After Wasmann.)]
The Insects we have spoken of are, however, rather of the nature of
ant-cattle, and the fondness of the ants for them is not very remarkable.
The relations of the ants to the peculiar species of Insects that live only
in or around their nests are much more extraordinary. The greater number of
these guests belong to the Order Coleoptera, and of these there are many
hundreds—probably many thousands—of species that depend on ants for their
existence. The family Pselaphidae furnishes a large number of ants'-nest
beetles, and it appears probable that most of them excrete some sugary
substance of which the ants are fond. Many of these Pselaphidae are of the
most fantastic shapes, more especially the members of the sub-family
Clavigerides. But the most curious of all the ant's-nest beetles are the
Paussidae, a family exclusively dependent on ants, and having the curious
faculty, when disturbed, of bombarding—that is, of discharging a small
quantity of vapour or liquid in a state of minute subdivision accompanied
by a detonation. Many species of _Staphylinidae_ are peculiar to
ant's-nests, and most of them are indifferent or inimical to their hosts,
but some of them, such as _Atemeles_ (Fig. 82) and _Lomechusa_, are
doubtless producers of sweet stuff that is liked by the ants. The ants feed
some of their special favourites amongst these guests in the same manner as
they feed one another, viz. by opening the mouth, causing a drop of liquid
to appear on the lip, and remaining passive while the guest partakes of the
proffered _bonne bouche_. This way of giving food to other individuals is a
most remarkable feature in the character of ants; it is not the same system
that they adopt in feeding the larvae, for they then make a series of
actual movements, and force the nutriment into the mouths of the grubs.
Besides the Insects we have mentioned there are also Orthoptera, Hemiptera,
Poduridae and Thysanura, Acari, and small Isopod crustaceans that live
exclusively in company with ants. We have mentioned that a few
Hymenopterous and Dipterous parasites have been detected living at the
expense of ants; it is probable that closer observation of the ant larvae
and pupae in their nests {183}will disclose a greater number of the
parasites of this latter class.
Much attention has been given to the relations between ants and their
guests by Wasmann.[74] He arranges them in four categories; 1, "Symphily"
for the true guests, which are fed and tended by the ants, the guests often
affording some substance the ants delight in; 2, "Metochy," the class of
tolerated guests, being so far as is known not disagreeable to the hosts;
3, "Synecthry," including those Insects, etc., to which the ants are
hostile, but which nevertheless maintain themselves in the midst of their
foes; 4, Parasites, dwelling in the bodies of the adult, or of the young
ants. Many of these ants'-nest Insects present a more or less perfect
resemblance to the ants in one or more points, such as sculpture, colour,
size, or form. To these resemblances Wasmann attaches great importance. We
should, too, notice that some of the inquilines[75] have become acquainted
with the movements and habits of the ants, and stroke them (as the ants do
one another) to induce them to disgorge food in the manner we have alluded
to. According to Janet, ants of the genus _Lasius_ are infested by Acari of
the genus _Antennophorus_. The ants carry the mites, which assume positions
so as not to cause greater inconvenience than is inevitable. Moreover, the
ants give food to the mites when requested, and behave in a most obliging
way to them, though there is not any reason for supposing that in this case
the ants derive any benefit from the Symphily.
The relations between ants and plants have been of late years much
discussed. We have already briefly alluded to the subject when speaking of
the Pseudomyrmini. We will here only remark that ants frequent plants not
only for the purpose of securing the sweet stuff excreted by the Aphidae
that live on them, but also for the sake of getting the sweet products the
plants themselves afford. Mr. Aitken, speaking of ants in India, says: "I
have come to the conclusion that one of the most important sources of
food-supply which ants have is the sacchariferous glands to be found at the
bases of so many leaves." It is supposed that the ants are on the whole
beneficial to the plants that thus afford them supply; and this fact is
considered by many to afford an adequate explanation of the existence of
these interesting relations.
{184}CHAPTER V
COLEOPTERA—OR BEETLES
ORDER V. COLEOPTERA.
_Apparently wingless Insects when at rest, but really with four wings;
the elytra, or anterior pair, shell-like, reposing on the back of the
body and fitted together accurately along the middle by a straight
suture; the posterior pair membranous, folded together under the elytra.
Mouth with mandibles; lower lip not divided along the middle.
Metamorphosis great and very abrupt; the larva being a grub or maggot,
which changes to a pupa (usually soft) in which the external structure of
the perfect Insect is conspicuous._
Coleoptera—or Beetles—are chiefly distinguished from other Insects by the
solidity of their external integument, and by the peculiar nature of the
first pair of their alar organs, which do not serve as instruments of
flight, but as shells for protecting the upper face of the after-body,
which, unlike the other parts, remains as a rule soft and membranous. These
modifications of structure, though apparently slight, must be really
extremely advantageous, for beetles are the predominant Order of Insects in
the existing epoch. They depart from most other Insects in being less
aerial in their habits; therefore, notwithstanding their enormous numbers,
they do not meet the eye so frequently as flies, bees, or butterflies. The
parts of the hard outer skeleton are beautifully fitted together, and as
their modifications are easily appreciated they offer as fascinating a
subject for study as do the skeletons of Vertebrata. The habits of beetles
are so extremely varied that it is but little exaggeration to say that
Coleoptera are to be found everywhere, when looked for. The number of
species at present known is probably about 150,000. Of these somewhere
about 3300 have been found in Britain.
{185}[Illustration: Fig. 83—Under-surface of a beetle, _Harpalus
caliginosus_; legs and antenna of one side, and some parts of the mouth
removed. A, antenna; B, mandible; C, labrum; D, ligula; E, paraglossa; F,
labial palp; G, inner lobe of maxilla; H, outer lobe (palpiform) of
maxilla; I, maxillary palp; K, mentum; L, gena; M, gula; N, buccal fissure;
V, plates of ventral segments. 1, Prosternum; 2, prosternal episternum; 3,
prosternal epimeron; 4, anterior and middle coxal cavities; 5, inflexed
side of pronotum; 6, mesosternum; 7, mesosternal episternum; 8, mesosternal
epimeron; 9, metasternum; 10, posterior division of metasternum or
ante-coxal piece; 11, metasternal episternum; 12, metasternal epimeron; 13,
epipleuron or inflexed margin of elytron; 14, ventral or ambulatory setae;
15, trochanter; 16, posterior coxa; 17, femur; 18, tibia; 19, tarsus.
(Modified from Leconte and Horn.)]
The structure of the hard parts of the skeleton is of importance, as the
classification of this enormous number of species is entirely based
thereon; it will be readily understood from the accompanying diagram (Fig.
83). The general proportions of the chief parts of the body call for a few
remarks. The prothorax is remarkably free, and is therefore capable of a
much greater amount of movement independent of the after-body than it is in
other Insects. The mesothorax is, on the other hand, much reduced; its
chief function in the higher forms is to support the elytra, and to help to
keep them together by means of its scutellum. The metathorax, on the
contrary, is largely developed, except in the rather numerous forms that
are entirely deprived of powers of flight. The composition of the abdomen
has been a subject of great difference of opinion. Its upper surface is
usually entirely covered by the elytra; the parts visible on the lower
surface are called ventral segments, and are usually five in number.
Although these five plates may constitute all that is superficially visible
of the abdomen, yet if the elytra are taken off it is found that a larger
number of segments—usually seven or eight—are visible on the dorsum. This
seeming discrepancy of number between the {186}dorsal and ventral plates is
due to two facts; 1, that the hind coxae have a great and complex
development, so that they conceal the true base of the venter, which,
moreover, remains membranous to a greater or less extent, and thus allows
much mobility, and at the same time a very accurate coadaptation between
the hard parts of the venter and the metasternum[76]; 2, that the terminal
segments are withdrawn into the interior of the body, and are
correspondingly much modified, the modification being greater in the case
of the ventral than in that of the dorsal plates. The anatomy of the parts
of the abdomen that are not externally visible has not been adequately
studied by coleopterists, but Verhoeff has inaugurated a careful study of
the comparative anatomy of the terminal segments[77]; unfortunately,
however, he has not so thoroughly studied the modifications at the base,
and as it is not clear that these are so uniform as he has taken for
granted, it is possible that his numbering of the segments may have to be
in some cases modified. The retracted plates or segments are so intimately
connected with the internal copulatory organs that it is no easy matter to
interpret them. For the nomenclature of these parts we must refer the
student to Verhoeff's later works. He considers the abdomen as composed of
ten segments, the dorsal plates being demonstrable, while the tenth ventral
plate is usually absent. The anal orifice is placed immediately beneath the
tenth dorsal plate, and above the genital orifice, which lies behind and
above the ninth ventral plate. Peytoureau admits a diversity in both the
number of segments and the position of the orifice. These studies in
comparative anatomy are surrounded with difficulties, and no morphological
conclusions based on them can be considered as final until they have been
confirmed by observation of the development of the parts.
The elytra—or wing-cases—frequently have a remarkable sculpture, the use of
which is unknown. According to Hofbauer there are between the outer and
inner layers, glands secreting a {187}fluid that reaches the surface
through small pores. Hicks supposed that he detected nerve cells. Meinert
is of opinion that the elytra correspond to the tegulæ of Hymenoptera
rather than to the wings of other Insects, but the little evidence that
exists is not favourable to this view. The two elytra are usually, in
repose, very perfectly fitted together by a complete coadaptation along the
middle of the body, so that it is difficult to separate them; this line of
junction is called the suture. There are forms in which the coadaptation is
quite imperfect (Malacodermidae) and some in which it does not exist at all
(_Meloë_). The wings proper of beetles correspond to the posterior pair in
other Insects, and are much more irregular in nervuration than those of
most other Insects, correlative, it is supposed, with the folding they are
subjected to in order to get them beneath the wing-cases. There are large
numbers of species, genera, and groups of genera, all the members of which
have the wings so much reduced in size as to be quite useless for purposes
of flight. These forms are called apterous, though they are not really so,
for the elytra (which are really the anterior wings) are present, and even
the posterior wings are not truly absent in these cases, though they are
sometimes so extremely rudimentary as to elude all but the most careful
observation. The number of forms in which the elytra are absent is
extremely small; this condition occurs only in the female sex; it is
usually confined to cases in which the female is larva-like in form; but in
the extraordinary Mediterranean Lamellicorn genus, _Pachypus_, the females
are destitute of wings and elytra, though the anterior parts of the body
are normally formed: these individuals live underground and rarely or never
emerge. When the wings are absent the elytra are frequently soldered; that
is to say, united together along the suture by some sort of secondary
exudation; this union occurs in every degree of firmness, and appears to be
variable in the individuals of one species; probably in accordance with the
age of the individual. In most beetles the elytra are not only themselves
closely connected, but are also very accurately coadapted with the sides of
the body, except at the tip. Sometimes a coadaptation occurs between the
tips of the elytra and the body, but not at the tip of the latter. In such
cases one or more dorsal plates are left exposed: the last of such exposed
dorsal plates is termed pygidium; a similar plate anterior to the pygidium
is called propygidium.
{188}LARVAE.—Owing to the difficulty of rearing Coleoptera, less is perhaps
known of their life-histories than of those of other Insects. They exhibit,
however, extreme diversity correlative with the great specialisation of so
many beetles to particular kinds of life. Most beetles must have exactly
the right conditions to live in. The larvae of many forms are known. They
are composed of a head, three thoracic segments (usually very distinct),
and a number of abdominal segments varying from eight to ten. Coleopterous
larvae are usually described as having nine abdominal segments; and it is
but rarely that ten can be readily detected; they are, however, visible in
various forms, as is the case in the form figured (Fig. 84). A great many
of them possess a peculiar pseudopod at the underside of the body near or
at the extremity; it can in many cases be entirely retracted into the body,
and is generally described as being the protruded termination of the
alimentary canal. Inspection of a series of larvae shows that it represents
a body segment: it is sometimes armed with hooks. Three pairs of small
thoracic legs are often present, but are very often completely absent.
These thoracic legs may be present in the young larva, but not in the older
(_Bruchus_). The usual number of spiracles is nine pairs, one prothoracic,
eight abdominal; but this is subject to many exceptions, and mesothoracic
and metathoracic stigmata are occasionally found. The figures we give in
the following pages will enable the student to form some idea of the
variety of form exhibited by beetle larvae.
[Illustration: Fig. 84—Larva of a beetle, Family Cerambycidae (? _Aromia
moschata_). The first spiracle is placed just at the hind margin of the
large prothoracic segment. (From La Massane.)]
Pupation usually takes place in a cavity in the earth, or near the
feeding-place, but a great many species form a cocoon, composed either of
fragments of earth or of wood, and slightly cemented together. A few
suspend themselves by the tail after the manner of butterfly caterpillars
(Cassididae, Coccinellidae). The pupae are usually extremely soft, their
appendages not being fastened to the body. But some pupae (Staphylinides)
are truly obtected, having a hard shell and the rudimentary appendages
fastened by exudation to the body, like Lepidopterous pupae, and others
(Coccinellidae) are intermediate {189}between this state and the normal
soft pupa. The pupal state lasts but a short time, from one to three weeks
being the usual period. The perfect Insect is at first soft and almost
colourless, and it is often some days before it attains its complete
coloration and hardness.
CLASSIFICATION.—Owing to the hardness of the skeleton, beetles shrivel but
little after death, so that the form and relations of the various sclerites
can usually be detected with ease. These sclerites seem to be remarkably
constant (except in the case of sexual distinctions) within the limits of
each species, and are very useful for the formation of genera and groups of
genera; but they vary so much outside the limits mentioned that it is very
difficult to make use of them for defining the larger groups. Hence it is
not easy to frame accurate definitions of the families, and still less so
to arrange these families in more comprehensive series. The natural
difficulty has been much increased by the habit coleopterists have of
framing their definitions on what is visible without the aid of dissection.
Nevertheless considerable progress has been made. We are obliged at present
to adopt upwards of eighty families; and we are able to distinguish on
positive characters five series; this leaves a large number of forms still
unclassified, and these we have here associated as a sixth series, which we
have called Coleoptera Polymorpha. This series corresponds with the two
series called in books Clavicornia and Serricornia. As it is admitted to be
impossible to define these two series, we think it much better to act
accordingly, and to establish for the present a great group that can only
be characterised by the fact that its members do not belong to any of the
other five series. No doubt a larger knowledge of development, coupled with
the advance of comparative anatomy, will ultimately bring about a better
state of affairs. The Strepsiptera, with one family Stylopidae, are only
provisionally included among the Coleoptera. These six series are fairly
equal as regards extent. Though the Polymorpha includes the larger number
of forms, yet a large part of them belong to four great families
(Staphylinidae, Buprestidae, Elateridae, Malacodermidae), which are easily
recognisable, so that the number of unmanageable forms is not really great.
Indeed, an acquaintance with the external anatomy of two or three dozen
species, selected as typical, would enable a student to classify {190}with
tolerable certainty the vast majority of species that he would subsequently
meet with.
Series 1. _Lamellicornia._—Antennae with the terminal joints leaf-like
(or broader than the others, if not actually leaf-like), and capable of
separation and of accurate apposition. Tarsi five-jointed.
Series 2. _Adephaga_—(_Caraboidea_ of some authors).—Antennae never
lamelliform, thin at the end; all the tarsi five-jointed, with the fourth
joint quite distinct. Maxillae highly developed, with the outer lobe
slender and divided into two segments so as to be palpiform. Abdomen with
six (or more) ventral segments visible.
Series 3. _Polymorpha._—Antennae frequently with either a club, _i.e._
the distal joints broader [Clavicorn series of authors], or the joints
from the third onwards more or less saw-like, the serrations being on the
inner face [Serricorn series of authors]; but these and all the other
characters, including the number of joints in the feet, very variable.
Series 4. _Heteromera._—Front and middle tarsi five-jointed, hind tarsi
four-jointed. Other characters very variable.
Series 5. _Phytophaga._—Tarsi four-jointed [apparently], but with a small
additional joint at the base of the fourth joint: sole usually densely
pubescent [sometimes the feet are bare beneath or bristly, and
occasionally the small joint at the base of the fourth joint is more
distinct].
Series 6. _Rhynchophora._—Head prolonged in front to form a beak; gula
indistinguishable. [Palpi usually not evident.] Tarsi four-jointed
[apparently], but with a very minute additional joint at the extreme base
of the fourth joint.
_Strepsiptera_ (see p. 298).
The first and second series, with much of the third, form the Pentamera,
the fifth and sixth the Tetramera [or Pseudotetramera[78]]. The term
Isomera was applied by Leconte and Horn to a combination of series 1, 2, 3,
and 5.
SERIES 1. LAMELLICORNIA.
_Tarsi five-jointed; antennae with the terminal joints (usually three,
sometimes more), broader on one side, so as to form a peculiar club, the
leaves of which are movable, and in repose are more or less perfectly
coadapted so as to have the appearance of being but one piece._
This series includes three families, Passalidae, Lucanidae, and
Scarabaeidae; the latter includes an enormous majority of the species, and
in them the structure of the antennae characteristic of the series is well
developed; but in the other two families {191}the form of the antennae is
not so widely different from that of other Coleoptera. The larvae live on
decaying vegetable matter, roots or dung. They have three pairs of legs,
and are thick clumsy grubs with curved bodies, the last two segments being
of larger size than usual. Many of them possess organs of stridulation, and
the structure of their spiracles is very peculiar, each one being more or
less completely surrounded by a chitinous plate. The spiracles usually form
a system entirely closed, except at the moment when the skin is shed and
the tracheal exuviae are detached. Meinert[79] considers these spiracles to
be organs of hearing. The life of the larvae is passed underground or in
the decaying wood on which the Insect feeds.
[Illustration: Fig. 85.—Antennae of Lamellicorns. 1, _Neleus interruptus_;
2, _Lucanus cervus_ ♂; 3, _Phanaeus splendidulus_ ♀; 4, _Phileurus didymus_
♀; 5, _Polyphylla fullo_ ♂.]
Most of the members of this series are remarkable on account of the great
concentration of the nerve-centres. This is extreme in _Rhizotrogus_, where
there are only two great ganglia, viz. the supra-oesophageal and a great
ganglion situate in the thorax, and consisting of the conjoined
infra-oesophageal, thoracic, and abdominal ganglia. According to Brandt[80]
there are several distinct forms of concentration in the series; the
Lucanidae only participate in it to the extent that the perfect Insects
exhibit fewer ganglia than the larvae; the latter possess two cephalic,
three thoracic, and eight abdominal ganglia, while the perfect Insect has
the abdominal ganglia reduced in number to six, and {192}they are placed
partially in the thorax. The diminution in number takes place in this case
by the amalgamation of the first two abdominal with the last thoracic
ganglia.
[Illustration: Fig. 86—View of one side of meso- and metathorax of a
Passalid larva from Borneo showing the stridulating organs. _a_, _b_,
Portions of the metathorax; _c_, coxa of 2nd leg; _d_, striate or
stridulating area thereon; _e_, basal part of femur of middle leg; _f_,
hairs with chitinous process at base of each; _g_, the diminutive 3rd leg
modified for scratching the striated area. × 20.]
FAM. 1. PASSALIDAE.—_Labrum large, mobile; mentum deeply cut out in the
middle for the accommodation of the ligula; the lamellae of the antenna
brought together by the curling up of the antenna. The elytra entirely
cover the dorsal surface of the abdomen._ There are four or five hundred
species of this family known; they are usually shining-black, unattractive
beetles, of large size, and are abundant in the decaying wood of tropical
forests. They are quite absent from Europe, and there is only one species
in the United States of North America. The larvae are very interesting,
from the fact that they appear to have only four legs. This arises from the
posterior pair being present only as very short processes, the function of
which is to scrape striated areas on the preceding pair of legs and so
produce sound. In the species figured (Fig. 86) this short leg is a
paw-like structure, bearing several hard digits; but in other species it is
more simple, and without the digits. The perfect Insect has no
sound-producing organs, and it is very remarkable therefore to find the
larvae {193}provided with highly-developed stridulatory structures. No
auditory organ is known, unless the peculiar spiracles be such.
[Illustration: Fig. 87—Head and prothorax of forms of the male of a
stag-beetle; _Homocoderus mellyi_ (Africa). A, Large, B, intermediate, C,
small forms. (From a photograph by R. Oberthür.)]
FAM. 2. LUCANIDAE (_Stag-beetles_).—_Labrum indistinct, fixed; mentum not
excised; antennae not curled in repose, with but little coadaptation of the
terminal joints; the elytra entirely cover the dorsal surface of the
abdomen._ The Stag-beetles are well known on account of the extraordinary
development of the mandibles in the male sex, these organs being in some
cases nearly as long as the whole of the rest of the Insect, and armed with
projections or teeth that give the Insects a most formidable appearance. So
far as we have been able to discover, these structures are put to very
little use, and in many cases are not capable of being of service even as
weapons of offence. The males are usually very much larger than the
females, and are remarkable on account of the great variation in the
stature of different individuals of the same species; correlative with
these distinctions of individual size we find extreme differences in the
development of the head and mandibles. Moreover, the small male specimens
exhibit not merely reductions in the size of the mandibles, but also show
considerable differences in the form of these parts, due, in some cases,
apparently to the fact that only when a certain length of the mandible is
attained is there any development of certain of the minor projections: in
other cases it is not possible to adopt this view, as the small mandibles
bear as many projections as the large forms do, or even more. In each
species these variations fall, in the majority of cases, into distinct
states, so that entomologists describe them as "forms," the largest
developments being called teleodont, the smallest priodont; the terms
mesodont and amphiodont being applied to intermediate states. Leuthner, who
has examined many specimens, states that in _Odontolabis sinensis_, no
intermediates between the teleodont and mesodont forms occur, and as the
{194}two forms are very different they are liable to be mistaken for
distinct species.
There are at present between 500 and 600 species of stag-beetles known; the
Indo-Malayan and Austro-Malayan regions being richest in them. Australia
possesses many remarkable and aberrant forms. In the Ceratognathini—a group
well represented in New Zealand as well as in Australia—the structure of
the antennae is like that of the Scarabaeidae, rather than of the
Lucanidae. The most aberrant form known is, however, our common
_Sinodendron cylindricum_; this departs in numerous features from other
Lucanidae, and instead of the mandibles of the male being more largely
developed, there is a horn on the head; it is very doubtful whether this
Insect should be allowed to remain in the family. Little is known of the
habits and development of Lucanidæ, except in the case of three or four
species that are common in Europe.
[Illustration: Fig. 88—_Sinodendron cylindricum._ A, Larva; B, pupa. New
Forest.]
The common stag-beetle, _Lucanus cervus_, is our largest British beetle.
The larva much resembles that of _Melolontha vulgaris_, but attains a
larger size, and the anal aperture is placed longitudinally instead of
transversely; it lives in decaying wood, or eats the roots of trees without
being injurious; its life in this state lasts about four years; the pupal
period is passed through rapidly, and the perfect Insect may remain for
months underground before it becomes active; this occurs in June and July.
This larva stridulates by scraping certain hard tubercular ridges on the
third pair of legs, over a specially adapted rough area at the base of the
second pair.
The Passalidae and Lucanidae are united by some authorities as a group
called Pectinicornia; the term Lamellicornia being then confined to the
Scarabaeidae. The Passalidae appear, however, to be really more nearly
allied to the Scarabaeidae than to the Lucanidae.
FAM. 3. SCARABAEIDAE (_Chafers_).—_The leaflets of the antennae are well
coadapted, and are susceptible of separation. The elytra {195}usually leave
the pygidium uncovered. The number of visible ventral segments is usually
six, or at the sides seven, not five, as in Lucanidae and Passalidae._ This
is one of the most important families of Insects. About 13,000 species are
already known; as some of them are highly remarkable creatures on account
of the males being armed with horns, they are figured in many works on
natural history. There is great variety of form, and the following five
sub-families may be adopted, though authorities are by no means agreed as
to the classification of this extensive family, which, moreover, be it
remarked, is increasing by the discovery of about 300 new species every
year.
Abdominal spiracles placed in a line on the connecting membranes, and
entirely covered by the wing-cases (Laparosticti).
Sub-fam. 1. COPRIDES.[81]
Abdominal spiracles placed almost in a line, but only the basal three on
the connecting membranes; the terminal one usually not covered by the
wing-cases. Sub-fam. 2. MELOLONTHIDES.
Abdominal spiracles placed in two lines, the basal three on the
connecting membranes, the others on the ventral segments (Pleurosticti).
The claws of the tarsi unequal. Sub-fam. 3. RUTELIDES.
The claws of the tarsi equal; the front coxae transverse, but little
prominent in the descending axis. Sub-fam. 4. DYNASTIDES.
The claws of the tarsi equal; the front coxae more prominent, shorter
transversely. Sub-fam. 5. CETONIIDES.
i. The Coprides form an immense group of about 5000 species; they differ
somewhat in habits from other Lamellicorns, inasmuch as most of them live
on dung, or decaying animal matter; the sub-family connects with the
Lucanidae, so far as superficial characters go, by means of two of its
groups, Trogini and Nicagini, the latter being very near to the
Ceratognathini in Lucanidae. So little is known as to the morphology and
development of these groups that it is not possible to pronounce an opinion
as to the validity of this apparent alliance. _Trox_ stridulates by rubbing
two raised lines on the penultimate dorsal segment across two striate ribs
on the inner face of the elytra; _Geotrupes_, on the other hand, produces
an audible sound by rubbing together a file on the posterior coxa and a
fine ridge on the contiguous ventral segment. The larva in this genus has a
different organ {196}for stridulation from the imago; it is placed on the
second and third pairs of legs, the latter pair being much reduced in size.
The most interesting division of the Coprides is the group Scarabaeini. No
member of this group inhabits the British islands, but in Southern Europe,
and in still warmer lands, these Insects are well known from the curious
habit many of the species have of rolling about balls of dung and earth.
The long hind legs are chiefly used for this purpose, and it is on the
peculiar structure of these limbs that the group has been established. Many
of the stone Scarabaei found in Egyptian tombs represent some kind of
Scarabaeini, and it has been said that the ancient Egyptians looked on
these Insects as sacred because of their movements. These must certainly
appear very strange to those who see them and are unacquainted with their
object. It is stated that the dwellers in the valley of the Nile thought
the actions of these Insects, when rolling their balls, were typical of the
planetary and lunar revolutions; and that the sudden appearance of the
beetles after a period of complete absence was emblematic of a future life.
Many accounts have been given of the habits of members of this group, but
according to Fabre all are more or less erroneous; and he has described the
habits and life-history of _Scarabaeus sacer_ (Fig. 89), as observed by him
in Southern France. These Insects act the part of scavengers by breaking up
and burying the droppings of cattle and other animals. The female
_Scarabaeus_ detaches a portion of the dung and forms it into a ball,
sometimes as large as the fist; this it rolls along by means of its hind
legs, by pushing when necessary with its broad head, or by walking
backwards and dragging the ball with its front legs. The strength and
patience displayed by the creature in the execution of this task are
admirable. Frequently the owner of this small spherical property is joined,
so Fabre informs us, by a friend, who is usually of the same sex and
assists her in pushing along the ball till a suitable place is reached.
When this is attained, the owner commences to excavate a chamber for the
reception of the ball; sometimes the false friend takes advantage of the
opportunity thus offered and carries off the ball for her own use. Should
no disappointment of this sort occur, the _Scarabaeus_ accomplishes the
burying of the ball in its subterranean chamber, and accompanies it for the
purpose of devouring it; the feast is continued without intermission till
the food is entirely {197}exhausted, when the _Scarabaeus_ seeks a fresh
store of provender to be treated in a similar manner. According to M.
Fabre's account these events occur in the spring of the year, and when the
hot weather sets in the _Scarabaeus_ passes through a period of quiescence,
emerging again in the autumn to recommence its labours, which are now,
however, directed immediately to the continuance of the species; a larger
subterranean chamber is formed, and to this retreat the beetle carries dung
till it has accumulated a mass of the size of a moderate apple; this
material is carefully arranged, previous to the laying of the egg, in such
a manner that the grub to be hatched from the egg shall find the softest
and most nutritive portions close to it, while the coarser and more
innutritious parts are arranged so as to be reached by the grub only after
it has acquired some strength; lastly, a still more delicate and nutritive
paste is prepared by the mother beetle for a first meal for the
newly-hatched grub, by some of the food being submitted to a partial
digestion in her organs; finally, the egg is deposited in the selected
spot, and the chamber closed. Certain of the Coprides exhibit, according to
Fabre, some extremely exceptional features in their life-histories. The
mother, instead of dying after oviposition, survives, and sees the growth
of her young to the perfect state, and then produces another generation. No
similar case can be pointed out in Insects, except in the Social kinds; but
from these the Coprides observed by Fabre differ profoundly, inasmuch as
the number of eggs produced by the mother is extremely small; _Copris
hispanus_, for instance, producing in each of its acts of oviposition only
one, two, or three eggs.
[Illustration: Fig. 89—_Scarabaeus sacer._ Portugal.]
{198}ii. The Melolonthides are probably almost as numerous as the Coprides,
some 4000 species being already known. The larvae are believed to feed
chiefly on roots. _Melolontha vulgaris_, the common cockchafer, is very
abundant in some parts of Europe, and owing to this and to the great damage
it causes, has attracted much attention. The memoir by Straus-Durckheim[82]
on its anatomy is one of the classical works of Entomology. This Insect is
so injurious in some parts of France that money is paid by the local
authorities for its destruction. M. Reiset informs us that under this
arrangement 867,173,000 perfect cockchafers, and 647,000,000 larvae were
destroyed in the Seine-inférieure in the four years from the middle of 1866
to 1870. Unlike the Coprides, the larval life in Melolonthides is
prolonged, and that of the imago is of brief duration. In Central Europe
the life-cycle of the individual in _M. vulgaris_ occupies three years,
though in dry periods it may be extended to four years. In Scandinavia the
time occupied by the development appears to be usually five years. The
fertile female enters the ground and deposits its eggs in two or three
successive batches of about fifteen each. The eggs swell as the development
of the embryo progresses; the larva emerges about five weeks after the eggs
have been deposited, and is of relatively large size. When young the larvae
can straighten themselves out and crawl, but when older they lose this
power, and when above ground rest helplessly on their sides. In the winter
they descend deeply into the earth to protect themselves from frost. The
pupa state lasts only a few days, but after the final transformation the
perfect Insect may remain motionless for as much as eight months
underground before commencing its active life in the air.[83] In the
perfect state the Insect is sometimes injurious from the large quantity of
foliage it destroys. Schiödte[84] considered that these larvae (and those
of numerous other Scarabaeidae) stridulate by rubbing certain projections
on the stipes of the maxilla against the under-surface of the mandible.
These surfaces appear, however, but little adapted for the purpose of
producing sound.
iii. The Rutelides number about 1500 species; there are many {199}Insects
of brilliant metallic colours amongst them, but very little is known as to
their life-histories. The larvae are very much like those of Melolonthides.
iv. The Dynastides are the smallest division in number of species, there
being scarcely 1000 known; but amongst them we find in the genera
_Dynastes_ and _Megasoma_ some of the largest of existing Insects. The
horns and projections on the heads and prothoraces of some of the males of
these Insects are truly extraordinary, and it does not appear possible to
explain their existence by any use they are to their possessors. These
structures are but little used for fighting. Baron von Hügel informs the
writer that in Java he has observed large numbers of _Xylotrupes gideon_;
he noticed that the males sometimes carry the females by the aid of their
horns; but this must be an exceptional case, for the shape of these
instruments, in the majority of Dynastides, would not allow of their being
put to this use. The development of these horns varies greatly in most of
the species, but he did not find that the females exhibited any preference
for the highly armed males. The fact that the males are very much larger
than the females, and that the armature is usually confined to them,
suggests, however, that some sexual reason exists for these remarkable
projections. Many Dynastides possess organs of stridulation, consisting of
lines of sculpture placed so as to form one or two bands on the middle of
the propygidium, and brought into play by being rubbed by the extremities
of the wing-cases. This apparatus is of a less perfect nature than the
structures for the same purpose found in numerous other beetles. We have no
member of this sub-family in Britain, and there are scarcely a dozen in all
Europe. Decaying vegetable matter is believed to be the nutriment of
Dynastides. The European _Oryctes nasicornis_ is sometimes found in numbers
in spent tan. The growth and development of the individual is believed to
be but slow.
v. The Cetoniides are renowned for the beauty of their colours and the
elegance of their forms; hence they are a favourite group, and about 1600
species have been catalogued. They are specially fond of warm regions, but
it is a peculiarity of the sub-family that a large majority of the species
are found in the Old World; South America is inexplicably poor in these
Insects, notwithstanding its extensive forests. In this sub-family the mode
of flight is peculiar; the elytra do not extend down the {200}sides of the
body, so that, if they are elevated a little, the wings can be protruded.
This is the mode of flight adopted by most Cetoniides, but the members of
the group Trichiini fly in the usual manner. In Britain we have only four
kinds of Cetoniides; they are called Rose-chafers. The larvae of _C.
floricola_ and some other species live in ants' nests made of vegetable
refuse, and it is said that they eat the ants' progeny. Two North American
species of _Euphoria_ have similar habits. The group Cremastochilini
includes numerous peculiar Insects that apparently have still closer
relations with ants. Most of them are very aberrant as well as rare forms,
and it has been several times observed in North America that species of
_Cremastochilus_ not only live in the nests of the ants, but are forcibly
detained therein by the owners, who clearly derive some kind of
satisfaction from the companionship of the beetles. The species of the
genus _Lomaptera_ stridulate in a peculiar manner, by rubbing the edges of
the hind femora over a striate area on the ventral segments.
SERIES II. ADEPHAGA OR CARABOIDEA.
_All the tarsi five-jointed; antennae filiform, or nearly so; mouth-parts
highly developed, the outer lobe of the maxilla nearly always divided
into a two-jointed palpus; supports of the labial palpi developed as
joints of the palpi, and in some cases approximate at their bases.
Abdomen with the exposed segments one more in number at the sides than
along the middle, the number being usually five along the middle, six at
each side._
This extensive series includes the tiger-beetles, ground-beetles, and true
water-beetles; it consists of six families, and forms a natural assemblage.
It is sometimes called Carnivora or Filicornia. The exceptions to the
characters we have mentioned are but few. The supports of the labial palpi
are frequently covered by the mentum, and then the palpi appear
three-jointed; but when the joint-like palpiger is not covered these palps
appear four-jointed. As a rule, approximation of these supports is
indicative of high development. In some of the lower forms the trophi
remain at a lower stage of development than is usual. This is especially
the case with the genus _Amphizoa_, which forms of {201}itself the family
Amphizoidae. The Bombardier-beetles make an exception as regards the
abdominal structure, for in some of them no less than eight segments are
visible, either along the middle line or at the sides of the venter. In
Hydroporides (one of the divisions of Dytiscidae) the front and middle feet
have each only four joints. Many naturalists unite the Gyrinidae with the
Adephaga, and a few also associate with them the Paussidae and Rhysodidae;
but we think it better at present to exclude all these, though we believe
that both Paussidae and Rhysodidae will ultimately be assigned to the
series. The larvae are usually very active, and have a higher development
of the legs than is usual in this Order. Their tarsi possess two claws.
FAM. 4. CICINDELIDAE (_Tiger-beetles_).—_Clypeus extending laterally in
front of the insertion of the antennae. Lower lip with the palpi usually
greatly developed, but with the ligula and paraglossae very much reduced,
often scarcely to be detected. Maxillae with the outer lobe forming a
two-jointed palp,[85] the inner lobe elongate, furnished at the tip with a
hook-like process, which is usually articulated by a joint with the lobe
itself._ The tiger-beetles are very active Insects, running with extreme
speed, and sometimes flying in a similar manner; they are all predaceous,
and amongst the most voracious and fierce of the carnivorous beetles, so
that they well deserve their name. Bates, speaking of the Amazonian
_Megacephala_, says "their powers of running exceed anything I have ever
observed in this style of Insect locomotion; they run in a serpentine
course over the smooth sand, and when closely pursued by the hand they are
apt to turn suddenly back and thus baffle the most practised hand and eye."
He further says that the species he observed (being of diverse colours)
agreed in colour with the general colours of the "locale they inhabit." The
larvae of Cicindelidae live in deep burrows, sinking more or less
vertically into the ground, and in these they take up a peculiar position,
for which their shape is specially adapted; the head and prothorax are
broad, the rest of the body slender, the fifth segment of the abdomen is
furnished on the back with a pair of strong hooks; the ocelli on the sides
of the head are very perfect. Supporting itself at the top of the burrow by
means of these hooks and of its terminal tube, the larva blocks the mouth
of the burrow with its large head and prothorax, and {202}in this position
waits for its prey. This consists of Insects that may alight on the spot or
run over it. When an Insect ventures within reach, the head of the larva is
thrown back with a rapid jerk, the prey is seized by the long sharp
mandibles, dragged to the bottom of the burrow and devoured. The burrows
are often more than a foot deep, and are said to be excavated by the larva
itself, which carries up the earth on the shovel-like upper surface of its
head. The female tiger-beetle is endowed with powerful and elongate
excavating instruments at the termination of the body, and it is probable
that when placing the egg in the earth she facilitates the future
operations of the larva by forming the outlines of the burrow. Extremely
few larvae of Cicindelidae are known, but they all exhibit the type of
structure mentioned above, and apparently have similar habits. Our little
British _Cicindela_, most of which are so active on the wing, agree in
these respects with the African species of _Manticora_, which are entirely
apterous, and are the largest of the Cicindelidae. Péringuey found a
breeding-ground of _M. tuberculata_ near Kimberley; the larvae were living
in the usual Cicindelid manner; but the ground was so hard that he was not
able to investigate the burrows, and there were but few Insects that could
serve as food in the neighbourhood.
[Illustration: Fig. 90—_Cicindela hybrida._ Britain. A, larva (after
Schiödte); B, imago, male.]
The Cicindelidae, although one of the smaller families of Coleoptera, now
number about 1400 species; of these about one-half belong to the great
genus _Cicindela_, to which our four British representatives of the
Cicindelidae are all assigned. There is no general work of much consequence
on this important family, and its classification is not thoroughly
established.[86]
{203}[Illustration: Fig. 91—Mouth-parts of tiger-beetles. A, Profile of
_Pogonostoma_ sp. (Madagascar): _a_, antenna; _b_, labial palp; _c_,
maxillary palp; _d_, palpiform lobe of maxilla; _e_, mandible; _f_, labrum.
B, Section of head of _Manticora maxillosa_ (South Africa): _a_, front of
upper part of head-capsule; _b_, gula; _c_, tentorium; _d_, eye; _e_,
labrum; _f_, left mandible; _g_, maxilla; _h_, maxillary palp; _i_, labial
palp; _k_, support of this palp; _l_, labium.]
Tiger-beetles display considerable variety of structure, especially as
regards the mouth, which exhibits very remarkable developments of the palpi
and labrum (Fig. 91). The tiger-beetles, like most other Insects that
capture living prey, do not consume their victims entire, but subsist
chiefly on the juices they squeeze out of them; the hard and innutritious
parts are rejected after the victim has been thoroughly lacerated and
squeezed; the mouth forms both trap and press; the palpi spread out in
order to facilitate the rapid engulfing of a victim, then close up under it
and help to support it in the mouth; while the labrum above closes the
cavity in the other direction. The mouth itself is a large cavity
communicating very freely with the exterior, but so completely shut off
from the following parts of the alimentary canal that it is difficult to
find the orifice of communication; the labium being much modified to form
the posterior wall. For the capture of the prey, always living but of
various kinds, a mechanism with great holding power and capable of rapid
action is required. The mouth of the terrestrial _Manticora_ (Fig. 91, B),
exhibits great strength; some of the chitinous parts are extremely thick,
the mandibles are enormous, the palpi, however, are comparatively low in
development. In the arboreal genus _Pogonostoma_ the palpary structures
(Fig. 91, A) attain a development scarcely equalled elsewhere in the Insect
world. The great majority of the Cicindelidae are inhabitants of the
warmer, or of the tropical regions of the world, and very little is known
as to their life-histories; they show great diversity in their modes of
hunting their prey. Some are wingless; others are active on the wing; and
of both of these divisions there are forms that are found only on trees or
bushes. Some, it is believed, frequent only the mounds of Termites. The
characteristic feature common {204}to all is great activity and excessive
wariness. The genus _Pogonostoma_, to which we have already alluded, is
confined to Madagascar, where the species are numerous, but are rare in
collections on account of the difficulty of securing them. Raffray informs
us that certain species frequent the trunks of trees, up which they run in
a spiral manner on the least alarm. The only way he could obtain specimens
was by the aid of an assistant; the two approached a tree very quietly from
opposite sides, and when near it, made a rush, and joined hands as high up
the trunk as they could, so as to embrace the tree, when the _Pogonostoma_
fell to the ground and was captured.
[Illustration: Fig. 92—_Leistus spinibarbis._ A, Larva (after Schiödte); B,
imago. Britain.]
FAM. 5. CARABIDAE (_Ground-beetles_).—_Clypeus not extending laterally in
front of the antennae. Maxillae with the outer lobe destitute of an
articulated hook at the tip. Antennae covered (except the basal joints)
with a minute pubescence. Hind legs not very different from the middle
pair, formed for running, as usual in beetles._ This is one of the largest
and most important of the families of Coleoptera, including as it does
12,000 or 13,000 described species. In this country Carabidae are nearly
entirely terrestrial in habits, and are scarcely ever seen on the wing;
many of the species indeed have merely rudimentary wings; in the tropics
there are, however, many arboreal forms that take wing with more or less
alertness. The larvae (Fig. 92, A) are usually elongate in form and run
freely; they may be known by their tarsi ending in two claws, by the
exserted, sharp, calliper-like mandibles, by the body ending in two
processes (sometimes jointed) and a tube of varying length projecting
backwards. The pupae usually have the hind pair of legs so arranged that
the tips of the tarsi project behind, beyond the extremity of the
{205}body. The Carabidae are carnivorous and predaceous both as larvae and
perfect Insects; they attack living Insects, worms, or other small, soft
creatures, but do not disdain dead specimens. Some species of _Carabus_,
found in North Africa where snails abound, are specially formed for
attacking these molluscs, having the head long and slender so that it can
be thrust into the shell of the snail. A few species have been detected
eating growing corn, and even the young seeds of some Umbelliferae; these
belong chiefly to the genera _Harpalus_, _Zabrus_, and _Amara_. Some
species of the abundant genera _Pterostichus_ and _Harpalus_, are said to
be fond of ripe strawberries. The most anomalous forms of Carabidae are the
Pseudomorphides, a sub-family almost peculiar to Australia, the members of
which live under bark, and have but little resemblance to other Carabids
owing to their compact forms and continuous outlines. The genus _Mormolyce_
is one of the wonders of the Insect world on account of the extraordinary
shape of its members; the sides of the elytra form large crinkled
expansions, and the head is unusually elongate. These Insects live on the
underside of fallen trees in the Malay Archipelago and Peninsula; no reason
whatever can be at present assigned for their remarkable shape.
There are a considerable number of blind members of this family: some of
them live in caverns; these belong chiefly to the genus _Anophthalmus_,
species of which have been detected in the caves of the Pyrenees, of
Austria, and of North America. It has been shown that the optic nerves and
lobes, as well as the external organs of vision, are entirely wanting in
some of these cave Carabidae; the tactile setae have, however, a larger
development than usual, and the Insects are as skilful in running as if
they possessed eyes. _Anophthalmus_ is closely related to our British genus
_Trechus_, the species of which are very much given to living in deep
crevices in the earth, or under large stones, and have some of them very
small eyes. In addition to these cavernicolous _Anophthalmus_, other blind
Carabidae have been discovered during recent years in various parts of the
world, where they live under great stones deeply embedded in the earth;
these blind lapidicolous Carabidae are of extremely minute size and of most
sluggish habits; the situations in which they are found suggest that many
successive generations are probably passed under the same stone. Not a
single specimen has ever been found above ground. The minute {206}Carabids
of the genus _Aëpus_, that pass a large part of their lives under stones
below high-water mark (emerging only when the tide uncovers them), on the
borders of the English Channel and elsewhere, are very closely allied to
these blind Insects, and have themselves only very small eyes, which,
moreover, according to Hammond and Miall, are covered in larger part by a
peculiar shield.[87] A few Carabidae, of the genera _Glyptus_ and
_Orthogonius_, are believed to live in the nests of Termites. Savage found
the larva of _G. sculptilis_ in the nests of _Termes bellicosus_; it has
been described by Horn, and is said to bear so great a resemblance to young
queens of the Termites as to have been mistaken for them.[88] Mr. Haviland
found _Rhopalomelus angusticollis_ in Termites' nests in South Africa.
Péringuey states that it emits a very strong and disagreeable odour. It is
probable that it preys on the Termites, and this also is believed to be the
habit of the Ceylonese _Helluodes taprobanae_. Some species of the
Mediterranean genus _Siagona_ stridulate by means of a file on the under
surface of the prothorax, rubbed by a striate area, adapted in form, on the
anterior femora.
A valuable memoir on the classification of this important family is due to
the late Dr. G. H. Horn;[89] he arranges Carabidae in three sub-families;
we think it necessary to add a fourth for _Mormolyce_:
1. Middle coxal cavities enclosed externally by the junction of the meso-
and meta-sternum; neither epimeron nor episternum attaining the
cavity.
Head beneath, with a deep groove on each side near the eye for the
reception of the antennae or a part thereof.
Sub-fam. 3. Pseudomorphides.
Head without antennal grooves. Sub-fam. 2. Harpalides.
2. Middle coxal cavities attained on the outside by the tips of the
episterna and epimera. Sub-fam. 4. Mormolycides.
3. Middle coxal cavities attained on the outside by the tips of the
epimera, but not by those of the episterna.
Sub-fam. 1. Carabides.
These four sub-families are of extremely different extent and nature. The
Harpalides are the dominant forms, and include upwards of 10,000 known
species; while the various tribes into which the sub-family is divided
include, as a rule, each many {207}genera; the Carabides are next in
importance, with upwards of 2000 species, but are divided into a
comparatively large number of tribes, each of which averages a much smaller
number of genera than do the tribes of Harpalides; Pseudomorphides includes
only about 100 species; and Mormolycides consists of the single genus
_Mormolyce_ with three species.
FAM. 6. AMPHIZOIDAE.—_Antennae destitute of pubescence: outer lobe of
maxilla not jointed; metasternum with a short transverse impressed line on
the middle behind. Hind legs slender, not formed for swimming._ This family
is limited to the genus _Amphizoa_; the species of which may be briefly
described as lowly organised Carabidae that lead an aquatic life. The
geographical distribution is highly remarkable, there being but three
species, two of which live in Western North America, the third in Eastern
Tibet. The habits of American _Amphizoa_ are known; they pass a life of
little activity in very cold, rapid streams; they do not swim, but cling to
stones and timber. The larva was recently discovered in Utah by Messrs.
Hubbard and Schwarz:[90] it has the same habits as the perfect Insect, and
in general form resembles the larvae of the genus _Carabus_; but it has no
terminal tube to the body, the abdomen consisting of eight segments and a
pair of short terminal appendages; the spiracles are obsolete, with the
exception of a pair placed near to one another at the termination of the
eighth abdominal segment. As regards the mouth this larva is Carabid, as
regards the abdomen and stigmata Dytiscid of a primitive type.
[Illustration: Fig. 93—_Amphizoa lecontei._ North America. A, Larva; B,
imago.]
{208}[Illustration: Fig. 94—_Pelobius tardus._ Britain. A, Young larva; B,
adult larva; C, imago. (A and B after Schiödte.)]
FAM. 7. PELOBIIDAE.—_Antennae destitute of pubescence: outer lobe of
maxilla jointed, metasternum with a short transverse impressed line on the
middle behind. Hind legs rather slender, formed for swimming, the tarsi
longer than the tibiae._ This family is limited to the one genus _Pelobius_
(_Hygrobia_ of some authors). Like _Amphizoa_, to which it is in several
respects analogous, it has a singular geographical distribution; there are
only four known species, one lives in Britain and the Mediterranean region,
one in Chinese Tibet, two in Australia. _Pelobius_ may be briefly described
as a Carabid adapted to a considerable extent for living in and swimming
about in water; differing thus from _Amphizoa_, which has no special
adaptation for swimming. The larva of _Pelobius_ is remarkable; it breathes
by means of branchial filaments on the under surface of the body, the
spiracles being present, though those of the abdomen are very minute and
the others small. The head is very large, the mandibles are not tube-like,
the food being taken after the manner of the Carabidae; the 8th abdominal
segment ends in three long processes; the small 9th segment is retracted
beneath them. The adult _Pelobius tardus_ is remarkable for its loud
stridulation. The sound is produced by an apparatus described correctly by
Charles Darwin;[91] {209}there is a file on the inside of the wing-cases,
and the Insect turns up the tip of the abdomen and scrapes the file
therewith. The Insects are called squeakers in the Covent Garden market,
where they are sold.
[Illustration: Fig. 95—_Cnemidotus caesus._ England. A, Imago; B, larva,
highly magnified. (After Schiödte.)]
FAM. 8. HALIPLIDAE.—_Antennae bare, ten-jointed; metasternum marked by a
transverse line; posterior coxae prolonged as plates, covering a large part
of the lower surface of the abdomen; the slender, but clubbed, hind femora
move between these plates and the abdomen._ The Haliplidae are aquatic, and
are all small, not exceeding four or five millimetres in length. The
ventral plates are peculiar to the Insects of this family, but their
function is not known. The larvae are remarkable on account of the fleshy
processes disposed on their bodies; but they exhibit considerable variety
in this respect; their mandibles are grooved so that they suck their prey.
In the larva of _Haliplus_, according to Schiödte, there are eight pairs of
abdominal spiracles, but in _Cnemidotus_ (Fig. 95, B), there are no
spiracles, and air is obtained by means of a trachea traversing each of the
long filaments. The Insects of these two genera are so similar in the
imaginal instar that it is well worthy of note that their larvae should be
distinguished by such important characters. Haliplidae is a small family
consisting of three genera, having about 100 species; {210}it is very
widely distributed. We have 13 species in Britain, all the genera being
represented.
[Illustration: Fig. 96.—_Cybister roeseli_ (= _laterimarginalis_ De G.)
Europe. A, Larva (after Schiödte); B, ♂ imago.]
FAM. 9. DYTISCIDAE (_Water-beetles_).—_Antennae bare; hind legs formed for
swimming, not capable of ordinary walking: metasternum without a transverse
line across it; behind closely united with the extremely large coxae. Outer
lobe of maxilla forming a two-jointed palpus._ The Dytiscidae, or true
water-beetles, are of interest because—unlike the aquatic Neuroptera—they
exist in water in both the larval and imaginal instars; nevertheless there
is reason for supposing that they are modified terrestrial Insects: these
reasons are (1) that in their general organisation they are similar to the
Carabidae, and they drown more quickly than the majority of land beetles
do; (2) though the larvae are very different from the larvae of terrestrial
beetles, yet the imaginal instars are much less profoundly changed, and are
capable of existing perfectly well on land, and of taking prolonged flights
through the air; (3) the pupa is, so far as known, always terrestrial. The
larvae and imagos are perfectly at home in the water, except that they must
come to the surface to get air. Some of them are capable, however, when
quiescent, of living for hours together beneath the water, but there
appears to be great diversity in this respect.[92] The hind pair of legs is
the chief means of locomotion. These swimming-legs (Fig. 97) are deserving
of admiration on account of their mechanical perfection; this, however, is
exhibited in various {211}degrees, the legs in the genera _Dytiscus_ and
_Hydroporus_ being but slender, while those of _Cybister_ are so broad and
powerful, that a single stroke propels the Insect for a considerable
distance.
[Illustration: Fig. 97—Hind- or swimming-leg of _Cybister tripunctatus_. A,
The whole leg detached; B, the movable parts in the striking position. _a_,
Coxa; _b_, trochanter; _c_, femur; _d_, tibia; _e_, last joint of tarsus.]
The wing-cases fit perfectly to the body, except at the tip, so as to form
an air-tight space between themselves and the back of the Insect; this
space is utilised as a reservoir for air. When the _Dytiscus_ feels the
necessity for air it rises to the surface and exposes the tip of the body
exactly at the level of the water, separating at the same time the abdomen
from the wing-cases so as to open a broad chink at the spot where the parts
were, during the Insect's submersion, so well held together as to be air-
and water-tight. The terminal two pairs of spiracles are much enlarged, and
by curving the abdomen the beetle brings them into contact with the
atmosphere; respiration is effected by this means as well as by the store
of air carried about under the wing cases. The air that enters the space
between the elytra and body is shut in there when the Insect closes the
chink and again dives beneath the water. The enlargement of the terminal
stigmata in _Dytiscus_ is exceptional, and in forms more highly organised
in other respects, such as _Cybister_, these spiracles remain minute; the
presumption being that in this case respiration is carried on almost
entirely by means of the supply the Insect carries in the space between the
elytra and the base of the abdomen.[93] The structure of the front foot of
the male _Dytiscus_, and of many other water-beetles, is highly remarkable,
the foot being dilated to form a palette or saucer, covered beneath by
sucker-like structures of great delicacy and beauty; by the aid of these
the male is enabled to retain a position on the female for many hours, or
even days, together. Lowne has shown that the {212}suckers communicate with
a sac in the interior of the foot containing fluid, which exudes under
pressure. As the portions of the skeleton of the female on which these
suckers are brought to bear is frequently covered with pores, or minute
pits, it is probable that some correlation between the two organisms is
brought about by these structures. The females in many groups of Dytiscidae
bear on the upper surface of the body a peculiar sculpture of various
kinds, the exact use of which is unknown; in many species there are two
forms of the female, one possessing this peculiar sculpture, the other
nearly, or quite, without it. The larvae of Dytiscidae differ from those of
Carabidae chiefly by the structure of the mouth and of the abdomen. They
are excessively rapacious, and are indeed almost constantly engaged in
sucking the juices of soft and small aquatic animals, by no means excluding
their own kind. The mode of suction is not thoroughly known, but so far as
the details have been ascertained they are correctly described, in the work
on aquatic Insects, by Professor Miall, we have previously referred to; the
mandibles are hollow, with a hole near the tip and another at the base, and
being sharp at the tips are thrust into the body of a victim, and then by
their closure the other parts of the mouth, which are very beautifully
constructed for the purpose, are brought into fitting mechanical positions
for completing the work of emptying the victim. Nagel states that the larva
of _Dytiscus_ injects a digestive fluid into the body of its victim, and
that this fluid rapidly dissolves all the more solid parts of the prey, so
that the rapacious larva can easily absorb all its victim except the
insoluble outer skin. The abdomen consists of only eight segments, and a
pair of terminal processes; the stigmata are all more or less completely
obsolete—according to species—with the exception of the pair on the eighth
segment at the tip of the body; the terminal segments are frequently
fringed with hairs, that serve not only as means of locomotion, but also to
float the pair of active stigmata at the surface when the creature rises to
get air. Although the larvae of Dytiscidae are but little known, yet
considerable diversity has already been found. Those of _Hyphydrus_ and
some species of _Hydroporus_ have the front of the head produced into a
horn, which is touched by the tips of the mandibles.
Dytiscidae are peculiar inasmuch as they appear to flourish {213}best in
the cooler waters of the earth. Lapland is one of the parts of Europe
richest in Dytiscidae, and the profusion of species in the tropics compared
with those of Europe is not nearly so great as it is in the case of most of
the other families of Coleoptera. About 1800 species are at present known,
and we have rather more than 100 species in Britain.[94]
SERIES III. POLYMORPHA.
_Antennae frequently either thicker at the tip (clavicorn) or serrate
along their inner edge (serricorn); but these characters, as well as the
number of joints in the feet and other points, are very variable._
Upwards of fifty families are placed in this series; many of these families
are of very small extent, consisting of only a few species; other families
of the series are much larger, so that altogether about 40,000
species—speaking broadly, about one-fourth of the Coleoptera—are included
in the series. We have already (p. 189) alluded to the fact that it is
formed by certain conventional series, Clavicornia, Serricornia, etc.
united, because it has hitherto proved impossible to define them.
FAM. 10. PAUSSIDAE.—_Antennae of extraordinary form, usually two-jointed,
sometimes six- or ten-jointed. Elytra elongate, but truncate behind,
leaving the pygidium exposed. Tarsi five-jointed._ The Paussidae have
always been recognised as amongst the most remarkable of beetles, although
they are of small size, the largest attaining scarcely half an inch in
length. They are found only in two ways; either in ants' nests, or on the
wing at night. They apparently live exclusively in ants' nests, but migrate
much. Paussidae usually live in the nests of terrestrial ants, but they
have been found in nests of _Cremastogaster_ in the spines of _Acacia
fistulosa_. They have the power of discharging, in an explosive manner, a
volatile caustic fluid from the anus, which is said by Loman to contain
free iodine. Their relations to the ants are at present unexplained, though
much attention has been given to the subject. When observed in the nests
they frequently appear as if asleep, and the ants do not take much notice
of them.
{214}[Illustration: Fig. 98.—_Paussus cephalotes_ ♂. El Hedjaz. (After
Raffray.)]
On other occasions the ants endeavour to drag them into the interior of the
nest, as if desirous of retaining their company: the _Paussus_ then makes
no resistance to its hosts; if, however, it be touched, even very slightly,
by an observer, it immediately bombards: the ants, as may be imagined, do
not approve of this, and run away. Nothing has ever been observed that
would lead to the belief that the ants derive any benefit from the presence
of the Paussi, except that these guests bear on some part of the
body—frequently the great impressions on the pronotum—patches of the
peculiar kind of pubescence that exists in many other kinds of ants'-nest
beetles, and is known in some of them to secrete a substance the ants are
fond of, and that the ants have been seen to lick the beetles. On the other
hand, the Paussi have been observed to eat the eggs and larvae of the ants.
The larva of _Paussus_ is not known,[95] and Raffray doubts whether it
lives in the ants' nests. There are about 200 species of Paussidae known,
Africa, Asia and Australia being their chief countries; one species, _P.
favieri_, is not uncommon in the Iberian peninsula and South France, and a
single species was formerly found in Brazil. The position the family should
occupy has been much discussed; the only forms to which they make any real
approximation are Carabidae, of the group Ozaenides, a group of ground
beetles that also crepitate. Burmeister and others have therefore placed
the Paussidae in the series Adephaga, but we follow Raffray's view (he
being the most recent authority on the family),[96] who concludes that this
is an anomalous group not intimately connected with any other family of
Coleoptera, though having more affinity to Carabidae than to anything else.
The recently discovered genus _Protopaussus_ has eleven joints to the
antennae, and is said to come nearer to Carabidae than the previously known
forms did, and we may anticipate that a more extensive knowledge will show
that the family may find a natural place in the Adephaga. The description
of the abdomen given by Raffray is erroneous; in a specimen of the genus
_Arthropterus_ the writer has dissected, he finds that there {215}are five
ventral segments visible along the middle, six at the sides, as in the
families of Adephaga generally. There is said to be a great difference in
the nervous systems of Carabidae and Paussidae, but so little is known on
this point that we cannot judge whether it is really of importance.
[Illustration: Fig. 99.—A, Larva of _Gyrinus_ (after Schiödte); B, under
side of _Gyrinus_ sp. (after Ganglbauer). 1, Prosternum; 2, anterior coxal
cavity; 3. mesothoracic episternum; 4, mesoepimeron; 5, mesosternum; 6,
metathoracic episternum; 7, middle coxal cavity; 8, metasternum; 9, hind
coxa; 10, ventral segments. [N.B.—The first ventral segment really
consists, at each side, of two segments united; this may be distinctly seen
in many Gyrinidae.]]
FAM. 11. GYRINIDAE (_Whirligig beetles_).—_Antennae very short; four eyes;
middle and hind legs forming short broad paddles; abdomen with six segments
visible along the middle, seven along each side._ These Insects are known
to all from their habit of floating lightly on the surface of water, and
performing graceful complex curves round one another without colliding;
sometimes they may be met with in great congregations. They are admirably
constructed for this mode of life, which is comparatively rare in the
Insect world; the Hydrometridae amongst the bugs, and a small number of
different kinds of Diptera, being the only other Insects that are devoted
to a life on the surface of the waters. Of all these, Gyrinidae are in
their construction the most adapted for such a career. They are able to
dive to escape danger, and they then carry with them a small supply of air,
but do not stay long beneath the surface. Their two hind pairs of legs are
beautifully constructed as paddles, expanding mechanically when moved in
the backward direction, and collapsing into an extremely small space
directly the resistance they meet with is in the other direction. The front
legs of these Insects are articulated to the thorax in a peculiar direction
so that their soles do not look {216}downwards but towards one another;
hence the sensitive adhesive surface used during coupling is placed on the
side of the foot, forming thus a false sole: a remarkable modification
otherwise unknown in Insects. They breathe chiefly by means of the very
large metathoracic spiracles.
The larvae (Fig. 99, A) are purely aquatic, and are highly modified for
this life, being elongate creatures, with sharp, mandibles and nine
abdominal segments, each segment bearing on each side a trachea branchia;
these gills assist to some extent in locomotion. The stigmata are quite
obsolete, but the terminal segment bears four processes, one pair of which
may be looked on as cerci, the other as a pair of gills corresponding with
the pair on each of the preceding segments. The mandibles are not
suctorial, but, according to Meinert, possess an orifice for the discharge
of the secretion of a mandibular gland. Gyrinidae are chiefly carnivorous
in both the larval and imaginal instars. Fully 300 species are known; they
are generally distributed, though wanting in most of the islands of the
world except those of large size. The finest forms are the Brazilian
_Enhydrus_ and the _Porrorhynchus_ of tropical Asia.[97] In Britain we have
nine species, eight of _Gyrinus_, one of _Orectochilus_; the latter form is
rarely seen, as it hides during the day, and performs its rapid gyrations
at night.
The Gyrinidae are one of the most distinct of all the families of
Coleoptera: by some they are associated in the Adephagous series; but they
have little or no affinity with the other members thereof. Without them the
Adephaga form a natural series of evidently allied families, and we
consider it a mistake to force the Gyrinidae therein because an objection
is felt by many taxonomists to the maintenance of isolated families. Surely
if there are in nature some families allied and others isolated, it is
better for us to recognise the fact, though it makes our classifications
look less neat and precise, and increases the difficulty of constructing
"tables."
FAM. 12. HYDROPHILIDAE.—_Tarsi five-jointed, the first joint in many cases
so small as to be scarcely evident: antennae short, of less than eleven
joints, not filiform, but consisting of {217}three parts, a basal part of
one or two elongate joints, an intermediate part of two or more small
joints, and an apical part of larger (or at any rate broader) joints, which
are pubescent, the others being bare. Outer lobe of maxillae usually
complex, but not at all palpiform, maxillary palpi often very long; the
parts of the labium much concealed behind the mentum, the labial palpi very
widely separated. Hind coxae extending the width of the body, short, the
lamina interior small in comparison with the lamina exterior. Abdomen of
five visible segments._ The Hydrophilidae are an extensive family of
beetles, unattractive in colours and appearance, and much neglected by
collectors. A large part of the family live in water, though most of them
have only feeble powers of aquatic locomotion, and the beetles appear
chiefly to devote their attention to economising the stock of air each
individual carries about. The best known forms of the family are the
species of _Hydrophilus_. They are, however, very exceptional in many
respects, and are far more active and predaceous than most of the other
forms. Much has been written about _Hydrophilus piceus_, one of the largest
of British beetles. This Insect breathes in a most peculiar manner: the
spiracles are placed near bands of delicate pubescence, forming tracts that
extend the whole length of the body, and in this particular species cover
most of the under surface of the body; these velvety tracts retain a
coating of air even when the Insect is submerged and moves quickly through
the water. It would appear rather difficult to invent a mechanism to supply
these tracts with fresh air without the Insect leaving the water; but
nevertheless such a mechanism is provided by the antennae of the beetle,
the terminal joints of which form a pubescent scoop, made by some longer
hairs into a funnel sufficiently large to convey a bubble of air. The
Insect therefore rises to the surface, and by means of the antennae, which
it exposes to the air, obtains a supply with which it surrounds a large
part of its body; for, according to Miall, it carries a supply on its back,
under the elytra, as well as on its ventral surface. From the writer's own
observations, made many years ago, he inclines to the opinion that the way
in which the _Hydrophilus_ uses the antennae to obtain air varies somewhat
according to circumstances.
Many of the members of the sub-family Hydrophilides construct egg-cocoons.
In the case of _Hydrophilus piceus_, the {218}boat-like structure is
provided with a little mast, which is supposed by some to be for the
purpose of securing air for the eggs. _Helochares_ and _Spercheus_ (Fig.
100) carry the cocoon of eggs attached to their own bodies. _Philydrus_
constructs, one after the other, a number of these egg-bags, each
containing about fifteen eggs, and fixes each bag to the leaf of some
aquatic plant; the larvae as a rule hatch speedily, so that the advantage
of the bag is somewhat problematic.
[Illustration: Fig. 100.—_Spercheus emarginatus_ ♀. Britain. A, Upper
surface of beetle; B, under surface of abdomen, with the egg-sac ruptured
and some of the eggs escaping.]
The larvae of the aquatic division of the family have been to a certain
extent studied by Schiödte and others; those of the Sphaeridiides—the
terrestrial group of the family—are but little known. All the larvae seem
to be predaceous and carnivorous, even when the imago is of
vegetable-feeding habits; and Duméril states that in _Hydrous caraboides_
the alimentary canal undergoes a great change at the period of
metamorphosis, becoming very elongate in the adult, though in the larva it
was short. The legs are never so well developed as they are in the
Adephaga, the tarsi being merely claw-like or altogether wanting; the
mandibles are never suctorial. The respiratory arrangements show much
diversity. In most of the Hydrophilides the process is carried on by a pair
of terminal spiracles on the eighth abdominal segment, as in Dytiscidae,
and these are either exposed or placed in a respiratory chamber. In
_Berosus_ the terminal stigmata are obsolete, and the sides of the body
bear long branchial filaments. Cussac says that in _Spercheus_ (Fig. 101)
there are seven pairs of abdominal spiracles, and that the larva breathes
by presenting these to the air;[98] but Schiödte states that in this form
there are neither thoracic nor abdominal spiracles, except a pair placed in
a respiratory chamber on the eighth segment of the abdomen, after the
manner described by Miall as existing in _Hydrobius_. No doubt Cussac was
wrong in supposing the peculiar lateral abdominal processes to be
{219}stigmatiferous. In _Berosus_ there are patches of aëriferous, minute
pubescence on the body. The pupae of Hydrophilides repose on the dorsal
surface, which is protected by spinous processes on the pronotum, and on
the sides of the abdomen.
We have already remarked that this is one of the most neglected of the
families of Coleoptera, and its classification is not satisfactory. It is
usually divided into Hydrophilides and Sphaeridiides. The Sphaeridiides are
in large part terrestrial, but their separation from the purely aquatic
Hydrophilides cannot be maintained on any grounds yet pointed out.
Altogether about 1000 species of Hydrophilidae are known, but this probably
is not a tenth part of those existing. In Britain we have nearly ninety
species. Some taxonomists treat the family as a series with the name
Palpicornia. The series Philhydrida of older authors included these Insects
and the Parnidae and Heteroceridae.
[Illustration: Fig. 101—Larva of _Spercheus emarginatus_. (After
Schiödte).]
FAM. 13. PLATYPSYLLIDAE.—This consists of a single species. It will be
readily recognised from Fig. 102, attention being given to the peculiar
antennae, and to the fact that the mentum is trilobed behind. This curious
species has been found only on the beaver. It was first found by Ritsema on
American beavers (_Castor canadensis_) in the Zoological Gardens at
Amsterdam, but it has since been found on wild beavers in the Rhone in
France; in America it appears to be commonly distributed on these animals
from Alaska to Texas. It is very remarkable that a wingless parasite of
this kind should be found in both hemispheres. The Insect was considered by
Westwood to be a separate Order called Achreioptera, but there can be no
doubt that it is a beetle. It is also admitted that it shows some points of
resemblance with Mallophaga, the habits of which are similar. Its
Coleopterous nature is confirmed by the larva, which has been described by
both Horn and Riley.[99] Little is known as to the food and life-history.
Horn states that the eggs are placed on {220}the skin of the beaver amongst
the densest hair; the larvae move with a sinuous motion, like those of
Staphylinidae. It has been suggested that the Insect feeds on an Acarid,
_Schizocarpus mingaudi_; others have supposed that it eats scales of
epithelium or hairs of the beaver.
[Illustration: Fig. 102—_Platypsyllus castoris._ A, Upper side; B, lower
side, with legs of one side removed; C, antenna. (After Westwood.)]
[Illustration: Fig. 103—_Leptinus testaceus._ Britain.]
FAM. 14. LEPTINIDAE.—_Antennae rather long, eleven-jointed, without club,
but a little thicker at the extremity. Eyes absent or imperfect. Tarsi
five-jointed. Elytra quite covering abdomen. Mentum with the posterior
angles spinously prolonged._ A family of only two genera and two species.
Their natural history is obscure, but is apparently of an anomalous nature;
the inference that may be drawn from the little that is known being that
they are parasitic on mammals. There is little or nothing in their
structure to indicate this, except the condition of blindness; and until
recently the Insects were classified amongst Silphidae. _Leptinus
testaceus_ (Fig. 103) is a British Insect, and besides occurring in Europe
is well known in North America. In Europe it has been found {221}in curious
places, including the nests of mice and bumble-bees. In America it has been
found on the mice themselves by Dr. Ryder, and by Riley in the nests of a
common field-mouse, together with its larva, which, however, has not been
described. The allied genus _Leptinillus_ is said by Riley to live on the
beaver, in company with _Platypsyllus_.[100] It has been suggested that the
natural home of the _Leptinus_ is the bee's nest, and that perhaps the
beetle merely makes use of the mouse as a means of getting from one nest of
a bumble-bee to another.
FAM. 15. SILPHIDAE.—_The mentum is usually a transverse plate, having in
front a membranous hypoglottis, which bears the exposed labial palpi, and
immediately behind them the so-called bilobed ligula. The anterior coxae
are conical and contiguous: prothoracic epimera and episterna not distinct.
Visible abdominal segments usually five, but sometimes only four, or as
many as seven. Tarsi frequently five-jointed, but often with one joint
less. Elytra usually covering the body and free at the tips, but
occasionally shorter than the body, and even truncate behind so as to
expose from one to four of the dorsal plates; but there are at least three
dorsal plates in a membranous condition at the base of the abdomen._ These
beetles are extremely diverse in size and form, some being very minute,
others upwards of an inch long, and there is also considerable range of
structure. In this family are included the burying-beetles (_Necrophorus_),
so well known from their habit of making excavations under the corpses of
small Vertebrates, so as to bury them. Besides these and _Silpha_, the
roving carrion-beetles, the family includes many other very different
forms, amongst them being the larger part of the cave-beetles of Europe and
North America. These belong mostly to the genera _Bathyscia_ in Europe, and
_Adelops_ in North America; but of late years quite a crowd of these
eyeless cave-beetles of the group Leptoderini have been discovered, so that
the European catalogue now includes about 20 genera and 150 species. The
species of the genus _Catopomorphus_ are found in the nests of ants of the
genus _Aphaenogaster_ in the Mediterranean region. Scarcely anything is
known as to the lives of either the cave-Silphidae or the myrmecophilous
forms.
The larvae of several of the larger forms of Silphidae are well known, but
very little has been ascertained as to the smaller forms. {222}Those of the
burying-beetles have spiny plates on the back of the body, and do not
resemble the other known forms of the family. The rule is that the three
thoracic segments are well developed, and that ten abdominal segments are
also distinct; the ninth abdominal segment bears a pair of cerci, which are
sometimes elongate. Often the dorsal plates are harder and better developed
than is usual in Coleopterous larvae. This is especially the case with some
that are endowed with great powers of locomotion, such as _S. obscura_
(Fig. 104). The food of the larvae is as a rule decomposing animal or
vegetable matter, but some are predaceous, and attack living objects. The
larger _Silpha_ larvae live, like the _Necrophorus_, on decomposing animal
matter, but run about to seek it; hence many specimens of some of these
large larvae may sometimes be found amongst the bones of a very small dead
bird. We have found the larva and imago of _S. thoracica_ in birds' nests
containing dead nestlings. _S. atrata_ and _S. laevigata_ make war on
snails. _S. lapponica_ enters the houses in Lapland and ravages the stores
of animal provisions. _S. opaca_ departs in a very decided manner from the
habits of its congeners, as it attacks beetroot and other similar crops in
the growing state; it is sometimes the cause of serious loss to the growers
of beet. The larvae of the group Anisotomides are believed to be chiefly
subterranean in habits; that of _A. cinnamomea_ feeds on the truffle, and
the beetle is known as the truffle-beetle.
[Illustration: Fig. 104—A, Larva of _Silpha obscura_. Europe. (After
Schiödte). B, _Ptomaphila lacrymosa_, Australia.]
The number of species of Silphidae known must be at present nearer 900 than
800. Of these an unusually large proportion belong to the European and
North American regions; Silphidae being apparently far from numerous in the
tropics. Rather more than 100 species are natives of Britain. The family
reappears in considerable force in New Zealand, and is probably well
represented {223}in South Australia and Tasmania. The most remarkable form
known is perhaps the Australian genus _Ptomaphila_ (Fig. 104, B). The
classification of the family is due to Dr. Horn.[101] The only change of
importance that has since been suggested is the removal of _Sphaerites_
from this family to Synteliidae. Anisotomidae and Clambidae have been
considered distinct families, but are now included in Silphidae.
FAM. 16. SCYDMAENIDAE.—_Minute Insects allied to Silphidae, but with the
hind coxae separated, and the facets of the eyes coarser; the tarsi are
five-jointed; the number of visible abdominal segments is six._ These small
beetles are widely spread over the earth's surface, and about 700 species
are now known, of which we have about a score in Britain; many live in
ants' nests, but probably usually rather as intruders than as guests that
have friendly relations with their hosts. Nothing is known as to their
life-histories, but the food of the imago, so far as is known, consists of
Acari. _Mastigus_ is a very aberrant form, found in moss and dead leaves in
Southern Europe. By means of _Brathinus_ the family is brought very near to
Silphidae; Casey, however, considers _Brathinus_ to belong to Staphylinidae
rather than to Scydmaenidae. The South European _Leptomastax_ is remarkable
on account of the slender, long, sickle-shaped mandibles. The Oriental
genus _Clidicus_ is the largest and most remarkable form of the family; it
has a very slender neck to its broad head, and is more than a quarter of an
inch long.
FAM. 17. GNOSTIDAE.—_Minute Insects with three-jointed antennae,
five-jointed tarsi, and three apparent ventral segments, the first of
which, however, is elongate, and consists of three united plates. Elytra
entirely covering the after-body._ The family consists of two species which
have been found in the nests of ants, of the genus _Cremastogaster_, in
Brazil.[102]
FAM. 18. PSELAPHIDAE.—_Very small Insects; the elytra much abbreviated,
usually leaving as much as half the abdomen uncovered; the maxillary palpi
usually greatly developed, and of a variety of remarkable forms; the
segments of the abdomen not more than seven in number, with little or no
power of movement. Tarsi with not more than three joints._ These small
Coleoptera mostly live in the nests of ants, and present a great diversity
of extraordinary {224}shapes, and very peculiar structures of the antennae
and maxillary palpi. Owing to the consolidation of some of its segments,
the abdomen frequently appears to have less than the usual number. In the
curious sub-family Clavigerides, the antennae may have the joints reduced
to two or even, to all appearance, to one; the tarsi suffer a similar
reduction. There are about 2500 species of Pselaphidae known; many of them
have never been found outside the ants' nests; very little, however, is
known as to their natural history. It is certain that some of them excrete,
from little tufts of peculiar pubescence, a substance that the ants are
fond of. The secretory patches are found on very different parts of the
body and appendages. _Claviger testaceus_ is fed by the ants in the same
way as these social Insects feed one another; the _Claviger_ has also been
seen to eat the larvae of the ants. They ride about on the backs of the
ants when so inclined. The family is allied to Staphylinidae, but is easily
distinguished by the rigid abdomen. Only one larva—that of _Chennium
bituberculatum_—is known. It appears to be very similar to the larvae of
Staphylinidae. The best account of classification and structure is that
given by M. Achille Raffray,[103] who has himself discovered and described
a large part of the known species.
FAM. 19. STAPHYLINIDAE.—_Elytra very short, leaving always some of the
abdominal segments exposed, and covering usually only two of the segments.
Abdomen usually elongate, with ten dorsal, and seven or eight ventral
segments; of the latter six or seven are usually exposed; the dorsal plates
as hard as the ventral, except sometimes in the case of the first two
segments; the segments very mobile, so that the abdomen can be curled
upwards. The number of tarsal joints very variable, often five, but
frequently as few as three, and not always the same on all the feet._
Staphylinidae (formerly called Brachelytra or Microptera) is one of the
most extensive of even the great families of Coleoptera; notwithstanding
their diversity, they may in nearly all cases be recognised by the more
than usually mobile and uncovered abdomen, combined with the fact that the
parts of the mouth are of the kind we have mentioned in Silphidae. The
present state of the classification of this family has been recently
discussed by Ganglbauer.[104]
{225}[Illustration: Fig. 105—Staphylinidae. A, Larva of _Philonthus
nitidus_. Britain. (After Schiödte.) B, _Ocypus olens_, Britain; C, tip of
abdomen, of _O. olens_ with stink-vessels.]
At present about 9000 species are known, some of which are minute, while
scarcely any attain a size of more than an inch in length, our common
British black cock-tail, or "devil's coach-horse beetle," _Ocypus olens_,
being amongst the largest. Though the elytra are short, the wings in many
forms are as large as those of the majority of beetles; indeed many
Staphylinidae are more apt at taking flight than is usual with Coleoptera;
the wings when not in use are packed away under the short elytra, being
transversely folded, and otherwise crumpled, in a complicated but orderly
manner. It is thought that the power of curling up the abdomen is connected
with the packing away of the wings after flight; but this is not the case:
for though the Insect sometimes experiences a difficulty in folding the
wings under the elytra after they have been expanded, yet it overcomes this
difficulty by slight movements of the base of the abdomen, rather than by
touching the wings with the tip. What the value of this exceptional
condition of short elytra and corneous dorsal abdominal segments to the
Insect may be is at present quite mysterious. The habits of the members of
the family are very varied; many run with great activity; the food is very
often small Insects, living or dead; a great many are found in fungi of
various kinds, and perhaps eat them. It is in this family that we meet with
some of the most remarkable cases of symbiosis, i.e. lives of two kinds of
creatures mutually accommodated with good will. The relations between the
Staphylinidae of the genera _Atemeles_ and _Lomechusa_, and certain ants,
in the habitations of which they dwell, are very interesting. The beetles
are never found out of the ants' nests, or at any rate not very far from
them. The most friendly relations exist between them and the ants: they
have patches of yellow hairs, and these {226}apparently secrete some
substance with a flavour agreeable to the ants, which lick the beetles from
time to time. On the other hand, the ants feed the beetles; this they do by
regurgitating food, at the request of the beetle, on to their lower lip,
from which it is then taken by the beetle (Fig. 82). The beetles in many of
their movements exactly resemble the ants, and their mode of requesting
food, by stroking the ants in certain ways, is quite ant-like. So
reciprocal is the friendship that if an ant is in want of food, the
_Lomechusa_ will in its turn disgorge for the benefit of its host. The
young of the beetles are reared in the nests by the ants, who attend to
them as carefully as they do to their own young. The beetles have a great
fondness for the ants, and prefer to sit amongst a crowd thereof; they are
fond of the ants' larvae as food, and indeed eat them to a very large
extent, even when their own young are receiving food from the ants. The
larva of _Lomechusa_, as described by Wasmann (to whom we are indebted for
most of our knowledge of this subject),[105] when not fully grown, is very
similar to the larvae of the ants; although it possesses legs it scarcely
uses them: its development takes place with extraordinary rapidity, two
days, at most, being occupied in the egg, and the larva completing its
growth in fourteen days. Wasmann seems to be of opinion that the ants
scarcely distinguish between the beetle-larvae and their own young; one
unfortunate result for the beetle follows from this, viz. that in the pupal
state the treatment that is suitable for the ant-larvae does not agree with
the beetle-larvae: the ants are in the habit of digging up their own kind
and lifting them out and cleaning them during their metamorphosis; they
also do this with the beetle-larvae, with fatal results; so that only those
that have the good fortune to be forgotten by the ants complete their
development. Thus from thirty _Lomechusa_ larvae Wasmann obtained a single
imago, and from fifty _Atemeles_ larvae not even one.
Many other Staphylinidae are exclusively attached to ants' nests, but most
of them are either robbers, at warfare with the ants—as is the case with
many species of _Myrmedonia_ that lurk about the outskirts of the nests—or
are merely tolerated by the ants, not receiving any direct support from
them. The most {227}remarkable Staphylinidae yet discovered are some
viviparous species, forming the genera _Corotoca_ and _Spirachtha_, that
have very swollen abdomens, and live in the nests of Termites in
Brazil:[106] very little is, however, known about them. A very large and
powerful Staphylinid, _Velleius dilatatus_, lives only in the nests of
hornets and wasps. It has been supposed to be a defender of the
Hymenoptera, but the recent observations of Janet and Wasmann make it clear
that this is not the case: the _Velleius_ has the power of making itself
disagreeable to the hornets by some odour, and they do not seriously attack
it. The _Velleius_ finds its nutriment in larvae or pupae of the wasps that
have fallen from their cells, or in other organic refuse.
The larvae of Staphylinidae are very similar to those of Carabidae, but
their legs are less perfect, and are terminated only by a single claw;
there is no distinct labrum. The pupae of some are obtected, _i.e._ covered
by a secondary exudation that glues all the appendages together, and forms
a hard coat, as in Lepidoptera. We have about 800 species of Staphylinidae
in Britain, and it is probable that the family will prove one of the most
extensive of the Order. It is probable that one hundred thousand species or
even more are at present in existence.
FAM. 20. SPHAERIIDAE.—_Very minute. Antennae eleven-jointed, clubbed. Tarsi
three-jointed. Abdomen with only three visible ventral segments_. This
family includes only three or four species of Insects about 1/50 of an inch
long. They are very convex, and be found walking on mud. _S. acaroides_
occurs in our fens. Mr. Matthews considers that they are most nearly allied
to Hydrophilidae.[107]
[Illustration: Fig. 106—_Trichopteryx fascicularis_. Britain. A, Outline of
perfect Insect; B, part of upper surface; C, larva from side; D, from
above; E, pupa; F, wing; G, natural size of imago.]
FAM. 21. TRICHOPTERYGIDAE.—_Extremely minute: antennae {228}clavicorn
(basal and apical joints thicker than middle joints); tarsi three-jointed;
elytra sometimes covering abdomen, in other cases leaving a variable number
of segments exposed; wings fringed._ This family comprises the smallest
Insects; _Nanosella fungi_ being only 1/100 of an inch long, while the
largest Trichopterygid is only 1/12 of an inch. The small size is not
accompanied by any degeneration of structure, the minute, almost invisible
forms, having as much anatomical complexity as the largest Insects. Very
little is known as to the natural history. Probably these Insects exist in
all parts of the world, for we have about eighty species in England, and
Trichopterygidae are apparently numerous in the tropics.[108]
FAM. 22. HYDROSCAPHIDAE.—_Extremely minute aquatic Insects, with elongate
abdomen. Antennae eight-jointed._ The other characters are much the same as
those we have mentioned for Trichopterygidae. The family is not likely to
come before the student, as only three or four species from Southern Europe
and North America are known.[109]
[Illustration: Fig. 107—A, Larva of _Orthoperus brunnipes_ (after Perris);
B, _O. atomarius_, perfect Insect. Britain.]
FAM. 23. CORYLOPHIDAE.—_Minute beetles. Tarsi four-jointed, but appearing
only three-jointed, owing to the hind joint being concealed by the
emarginate (or notched) second joint. Six free ventral segments. Maxillae
with only one lobe. Antennae of peculiar form._ There are about 200 species
of these little Insects, but the family is apparently represented all over
the world, and will probably prove to be much more extensive. The peculiar
larva of _Orthoperus brunnipes_ was found abundantly by Perris in thatch in
France. Mr. Matthews proposes to separate the genus _Aphanocephalus_ as a
distinct family, Pseudocorylophidae.[110] In Corylophidae the wings are
fringed with long hairs, as is the case in so many small Insects: the
species of _Aphanocephalus_ are rather larger Insects, and the wings are
not fringed; the tarsi are only three-jointed.
{229}FAM. 24. SCAPHIDIIDAE.—_Front coxae small, conical; prothorax very
closely applied to the after-body; hind coxae transverse, widely separated:
abdomen with six or seven visible ventral plates; antennae at the extremity
with about five joints that become gradually broader. Tarsi five-jointed._
This family consists of a few beetles that live in fungi, and run with
extreme rapidity; they are all small, and usually rare in collections. Some
of the exotic forms are remarkable for the extreme tenuity and fragility of
the long antennae, which bear fine hairs. The number of described species
does not at present reach 200, but the family is very widely distributed.
We have three or four species in Britain. All we know of the larvae is a
description of that of _Scaphisoma agaricinum_ by Perris;[111] it is like
the larva of Staphylinidae, there are nine abdominal segments in addition
to a very short, broad pseudopod, and very short cerci. This larva feeds on
agarics; it goes through its development in about three weeks; unlike the
adult it is not very active.
[Illustration: Fig. 108—_Scaphisoma agaricinum._ Britain. A Larva (after
Perris); B perfect Insect.]
FAM. 25. SYNTELIIDAE.—_Antennae clavicorn, with very large club: labium,
with hypoglottis and the parts beyond it, exposed. Front coxae transverse.
Abdomen with five visible ventral segments, and eight or nine dorsal, the
basal four of which are semi-corneous._ This family includes only five
species; its classification has given rise to much difference of opinion.
We have, after consideration of all its characters, established it as a
distinct family[112] allied to Silphidae. The perfect Insects live on the
sap running from trees: but nothing else is known of their natural history.
Like so many others of the very small families of aberrant Coleoptera, it
has a very wide distribution; _Syntelia_ being found in Eastern Asia and
Mexico, while the sub-family Sphaeritides occurs, as a single species, in
Europe and North America. The earlier instars are unknown.
[Illustration: Fig. 109—_Syntelia westwoodi._ Mexico. (From _Biol. Centr.
Amer._)]
{230}[Illustration: Fig. 110—_Platysoma depressum._ Europe. A, Larva (after
Schiödte); B, perfect Insect.]
FAM. 26. HISTERIDAE.—_Very compact beetles, with very hard integument,
short, bent antennae, with a very compact club: no hypoglottis. Elytra
closely applied to body, but straight behind, leaving two segments exposed.
Abdomen with five visible ventral segments; with seven dorsal segments, all
hard. Front coxae strongly transverse, hind coxae widely separated._ The
extremely compact form, and hard integument, combined with the peculiar
antennae—consisting of a long basal joint, six or seven small joints, and
then a very solid club of three joints covered with minute
pubescence—render these Insects unmistakable. The colour is usually shining
black, but there are numerous departures from this. The way in which these
Insects are put together so as to leave no chink in their hard exterior
armour when in repose, is very remarkable. The mouth-parts are rather
highly developed, and the family is entitled to a high rank; it consists at
present of about 2000 species;[113] in Britain we have about 40. The larvae
are without ocelli or labrum, but have well-developed mandibles, the second
and third thoracic segments being short, the ninth segment of the abdomen
terminal, with two distinctly jointed cerci.[114] Histeridae are common in
dung, in carcases, decaying fungi, etc., and some live under bark—these
being, in the case of the genus _Hololepta_, very flat. Some are small
cylinders, elaborately constructed, for entering the burrows of Insects in
wood (_Trypanaeus_); a certain number are peculiar to ants' nests. Formerly
it was supposed that the Insects were nourished on the decaying substances,
but it is now believed, with good reason, that they are eminently
predaceous, in both larval and imaginal {231}instars, and devour the larvae
of Diptera, etc. The relations of the ants'-nest forms to the ants is not
made out, but it is highly probable that they eat the ants' larvae, and
furnish the ants with some dainty relish. A few species live in company
with Termites.
FAM. 27. PHALACRIDAE.—_Body very compact; elytra entirely covering it;
apical joints of antennae rather broader, usually long; front coxae
globular; posterior coxae contiguous; abdomen with five visible ventral
segments; tarsi five-jointed, fourth joint usually small and obscure._ This
family consists entirely of small Insects: the tarsal structure is very
aberrant, and is also diverse, so that the student may without careful
observation pass the Insects over as having only four-jointed tarsi; their
structure, so far as the front two pairs are concerned, being very nearly
that of many Phytophaga. The larvae live in the heads of flowers,
especially of the flowers of Compositae. Having bored their way down the
stems, they pupate in earthen cocoons. Heeger[115] says that he has
observed in favourable seasons six generations; but the larvae die readily
in unfavourable seasons, and are destroyed in vast numbers when the meadows
are mowed. Seven years ago very little was known as to the family, and the
list of their species scarcely amounted to 100, but now probably 300 are
described. They occur in all parts of the world; we have fourteen in
Britain.
[Illustration: Fig. 111—_Olibrus bicolor._ Europe. A, Larva (after Heeger);
B, perfect Insect.]
FAM. 28. NITIDULIDAE.—_Antennae with a three-jointed club; all the coxae
separated, and each with an external prolongation; tarsi five-jointed, the
fourth joint smaller than any of the others; abdomen with five visible
plates._ These Insects are numerous, about 1600 species being at present
known; in many of them the elytra nearly or quite cover the hind body, but
in many others they are more or less abbreviated; in this case the Insects
may be distinguished from Staphylinidae by the form of their antennae, and
the smaller number of visible ventral segments. The habits are very varied,
a great many are found on flowers, others are attracted by the sap of
trees; some live in carcases. We have about 90 species in Britain; several
forms of {232}the genera _Meligethes_ and _Epuraea_ are among the most
abundant of our beetles. Most of what is known as to the larvae is due to
Perris; several have been found living in flowers; that of _Pria_ haunts
the flower of _Solanum dulcamara_ at the junction of the stamens with the
corolla; the larva of _Meligethes aeneus_ sometimes occasions much loss by
preventing the formation of seed in cultivated Cruciferae, such as Rape.
These floricolous larvae grow with great rapidity, and then leave the
flowers to pupate in the ground. The larva of _Nitidula_ lives in carcases,
though it is not very different from that of _Pria_. The larva of _Soronia_
lives in fermenting sap, and has four hooks curving upwards at the
extremity of the body. The curious genus _Cybocephalus_ consists of some
very small, extremely convex Insects that live in flowers in Southern
Europe; they have only four joints to the tarsi. The perfect Insects of the
group Ipides are remarkable from having a stridulating organ on the front
of the head. The classification of the well-known genus _Rhizophagus_ has
given rise to much discussion; although now usually placed in Nitidulidae,
we think it undoubtedly belongs to Cucujidae.
[Illustration: Fig. 112—_Pria dulcamarae._ Britain. A, Larva (after
Perris); B, perfect Insect.]
[Illustration: Fig. 113—_Temnochila coerulea._ Europe. A, Larva (after
Perris); B, perfect Insect.]
FAM. 29. TROGOSITIDAE.—_Differs from Nitidulidae in the structure of the
tarsi; these appear to be four-jointed, with the third joint similar in
size and form to the preceding; they are, however, really five-jointed, an
extremely short basal joint being present. Hind coxae contiguous. The club
of each antenna is bilaterally asymmetric, and the sensitive surface is
confined to certain parts of the joints._ There are some 400 or 500 species
of Trogositidae, but nearly all of them are exotic. The larvae (Fig. 113,
A), are predaceous, destroying other larvae in large numbers, and it is
probable that the imagos do the same. The larva of _Tenebroides_ (better
known as _Trogosita_) _mauritanica_ is found in corn and flour, and is said
to have sometimes been very {233}injurious by eating the embryo of the
corn, but it is ascertained that it also devours certain other larvae that
live on the corn. This beetle has been carried about by commerce, and is
now nearly cosmopolitan. Our three British species of Trogositidae
represent the three chief divisions of the family, viz. Nemosomides,
Temnochilides, Peltides; they are very dissimilar in form, the Peltides
being oval, with retracted head. It is doubtful whether the members of the
latter group are carnivorous in any of their stages; it is more probable
that they live on the fungi they frequent. Peltidae stand as a distinct
family in many works.[116]
[Illustration: Fig. 114—_Bitoma crenata._ Britain. A, Larva (after Perris);
B, perfect Insect.]
FAM. 30. COLYDIIDAE.—_Antennae with a terminal club, tarsi four-jointed,
none of the joints broad; front and middle coxae small, globose, embedded;
hind coxae transverse, either contiguous or separated; five visible ventral
segments, several of which have no movement._ This is a family of interest,
owing to the great diversity of form, to the extraordinary sculpture and
clothing exhibited by many of its members, and to the fact that most of its
members are attached to the primitive forests, and disappear entirely when
these are destroyed. We have fifteen species in Britain, but about half of
them are of the greatest rarity. There are about 600 species known at
present; New Zealand has produced the greatest variety of forms; the
forests of Teneriffe are rich in the genus _Tarphius_. The sedentary lives
of many of these beetles are very remarkable; the creatures concealing
themselves in the crannies of fungus-covered wood, and scarcely ever
leaving their retreats, so that it is the rarest circumstance to find them
at any distance from their homes. _Langelandia anophthalma_ lives entirely
underground and is quite blind, the optic lobes being absent. Some
Colydiidae are more active, and enter the burrows of wood-boring Insects to
destroy the larvae (_Colydium_). Few of the larvae are known; but all
appear to have the body terminated by peculiar hard corneous processes, as
is the case with a great variety of Coleopterous larvae that live in
wood.[117]
{234}FAM. 31. RHYSODIDAE.—_Tarsi four-jointed; mouth-parts covered by the
large mentum; front tibiae notched on the inner edge._ This family consists
only of a few species, but is found nearly all over the world in the warm
and temperate regions. In many of their characters they resemble the
Adephaga, but are very different in appearance and in the mouth. The larvae
are not known. Some authorities think these Insects should be placed in the
series Adephaga,[118] but it is more probable that they will prove to be
amongst the numerous aberrant forms of Coleoptera that approach the various
large natural series, without really belonging to them. The three families,
Colydiidae, Cucujidae, and Rhysodidae, exhibit relations not only with
other families of the Coleoptera Polymorpha, but also with most of the
great series; Adephaga, Rhynchophora, Phytophaga, and Heteromera, being
each closely approached.
FAM. 32. CUCUJIDAE.—_Tarsi five- or four-jointed, the first joint often
short: antennae sometimes clubbed, but more often quite thin at the tip;
front and middle coxae deeply embedded, globular, but with an angular
prolongation externally; abdomen with five visible ventral segments, all
movable._ This family and the Cryptophagidae are amongst the most difficult
families to define; indeed it is in this portion of the Clavicorns that an
extended and thorough study is most urgently required. The Cucujidae
include a great diversity of forms; they are mostly found under the bark of
trees, and many of them are very flat. Many of the larvae are also very
flat, but Ferris says there is great diversity in their structure: they are
probably chiefly carnivorous. There are about 400 species described; we
have nearly a score in Britain.
[Illustration: Fig. 115—_Brontes planatus._ Britain. A, Larva; B, pupa; C,
perfect Insect. (A and B after Perris.)]
The family Cupesidae of certain taxonomists must be at present associated
with Cucujidae, though the first joint of the tarsus is elongate.
{235}FAM. 33. CRYPTOPHAGIDAE.—_Front and middle coxae very small and deeply
embedded; antennae with enlarged terminal joints; tarsi five-jointed, the
posterior sometimes in the male only four-jointed; abdomen with five
visible ventral segments, capable of movement, the first much longer than
any of the others._ A small family composed of obscure forms of minute
size, which apparently have mould-eating habits, though very little is
known on this point and several of the genera (_Antherophagus_,
_Telmatophilus_) are found chiefly on growing plants, especially in
flowers. Although the imago of _Antherophagus_ lives in flowers, yet the
larva has only been found in the nests of bumble-bees; there is reason for
believing that the imago makes use of the bee to transport it from the
flowers it haunts to the nests in which it is to breed;[119] this it does
by catching hold of the bee with its mandibles when the bee visits the
flower in which the beetle is concealed. It is strange the beetle should
adopt such a mode of getting to its future home, for it has ample wings. We
must presume that its senses and instinct permit it to recognise the bee,
but do not suffice to enable it to find the bee's nest. Some of the larvae
of the genus _Cryptophagus_ are found abundantly in the nests of various
wasps, where they are probably useful as scavengers, others occur in the
nests of social caterpillars, and they are sometimes common in loose straw;
this being the habitat in which Perris found the one we figure.
[Illustration: Fig. 116—_Cryptophagus dentatus._ Britain. A, Larva (after
Perris); B, perfect Insect.]
FAM. 34. HELOTIDAE.—_Front and middle coxal cavities round, with scarcely
any angular prolongation externally; all the coxae widely separated; five
visible ventral segments, all mobile._ The Insects of this family are
closely allied to Trogositidae and Nitidulidae, and have the tarsal
structure of the former family; but the Helotidae are different in
appearance from any members of either of these two families, and are
readily distinguished by the coxal character. They are frequently
classified with the Erotylidae, from which they differ by the differently
shaped feet, especially by the diminished basal joint. {236}There is but
one genus, and for a long time only two or three species were known, and
were great rarities in collections; in the last few years the number has
been raised to nearly forty.[120] They are remarkable beetles with oblong
form, and a somewhat metallic upper surface, which is much sculptured, and
possesses four yellow, smooth spots on the elytra. According to Mr. George
Lewis they are found feeding at the running sap of trees, but the larvae
are not known. Helotidae are peculiar to the Indo-Malayan region (including
Japan) with one species in Eastern Africa.
FAM. 35. THORICTIDAE.—_Tarsi five-jointed, none of the joints broad; front
coxae small, rather prominent, but not at all transverse; five visible
ventral plates, all mobile; metasternum very short; antennae short, with a
solid club._ This little family, consisting of the genus _Thorictus_,
appears to be a distinct one, though the structure has only been very
imperfectly studied. It is peculiar to the Mediterranean region, where the
species live in ants' nests. They appear to be on terms of great intimacy
with the ants; a favourite position of the beetle is on the scape of the
antenna of an ant; here it hooks itself on firmly, and is carried about by
the ant. Like so many other ants'-nest beetles, Thorictidae possess tufts
of golden hair, which secrete some substance, the flavour of which is
appreciated by the ants; these tufts in Thorictidae are situated either at
the hind angles of the pronotum, or on the under surface of the body on
each side of the breast; Wasmann thinks that when the beetles are riding
about, as above described, the ants have then an opportunity of getting at
the patches on the under surface.
[Illustration: Fig. 117—_Tritoma bipustulata._ Erotylidae. Britain. A,
Larva (after Perris); B, perfect Insect.]
FAM. 36. EROTYLIDAE.—_Tarsi five-jointed, but with the fourth usually very
small, the first three more or less broad and pubescent beneath. Antennae
strongly clubbed. Front and middle coxal acetabula round, without angular
prolongation externally; five visible ventral segments._ This is now a
large and important family of about 1800 species, but it is chiefly exotic
and tropical, its members haunting the fungoid growths {237}in forests. We
have only six species in Britain, and the whole of Europe has only about
two dozen, most of them insignificant (and in the case of the Dacnides
aberrant, approaching the Cryptophagidae very closely). The sub-family
Languriides (quite wanting in Europe) consists of more elongate Insects,
with front acetabula open behind; they have different habits from
Erotylides proper; some are known to live as larvae in the stems of
herbaceous plants. They possess a highly developed stridulating organ on
the front of the head. The Clavicorn Polymorpha are very closely connected
with the Phytophaga by Languriides.
FAM. 37. MYCETOPHAGIDAE.—_Tarsi four-jointed, slender, the front feet of
the male only three-jointed; coxae oval, not deeply embedded; abdomen with
five ventral segments, all movable._ A small family, of interest chiefly
because of the anomaly in the feet of the two sexes, for which it is
impossible to assign any reason. The species are small, uninteresting
Insects that live chiefly on Cryptogams of various kinds, especially in
connection with timber; the larvae being also found there. There are about
a dozen species in Britain, and scarcely 100 are described from all the
world. The Diphyllides, placed by Leconte and Horn in this family, seem to
go better in Cryptophagidae.
[Illustration: Fig. 118—_Litargus bifasciatus._ Mycetophagidae. Britain. A,
Larva (after Perris); B, perfect Insect.]
FAM. 38. COCCINELLIDAE (_Lady-birds_).—_Tarsi apparently three-jointed; the
first two joints pubescent beneath; the third joint consisting really of
two joints, the small true third joint being inserted near the base of the
second joint, the upper surface of which is grooved to receive it. Head
much concealed by the thorax. Antennae feebly clubbed._ The lady-birds
number fully 2000 species. The structure of their feet distinguishes them
from nearly all other Coleoptera except Endomychidae, which are much less
rotund in form, and have larger antennae. One genus of
Endomychids—_Panomoea_—bears, however, a singular resemblance to
lady-birds, both in form and style of coloration. Several species of
Coccinellidae are remarkable on account of the numerous variations in
colour they present. Coccinellidae frequently multiply to an enormous
extent, and are of great value, as they destroy wholesale the plant-lice,
scale-Insects, {238}and Acari that are so injurious to cultivated plants.
They also eat various other soft-bodied Insects that attack plants. As they
are excessively voracious, and are themselves singularly free from enemies
and multiply with great rapidity, all these features of their economy
render them of inestimable value to the agriculturist and horticulturist.
The species of the sub-family Epilachnides feed on plants, and one or two
are occasionally injurious. The body-fluid of Coccinellidae has an
unpleasant odour and taste. Many lady-birds have the power of exuding, when
disturbed, small quantities of a yellow fluid. Lutz has shown that this is
not a special secretion, but an exudation of the fluid of the body that
takes place through a small orifice at the tip of the tibia, from pressure
caused by contraction of the body and limb.[121]
The larvae are much more active than beetle-larvae usually are, and many of
them are very conspicuous when running about on plants to hunt their prey.
They usually cast their skins three times, and sometimes concomitantly
change a good deal in colour and form; the larval life does not usually
exceed four or five weeks; at the end of which time the larva suspends
itself by the posterior extremity, which is glued by a secretion to some
object; the larval skin is pushed back to the anal extremity, disclosing
the pupa; this differs in several respects from the usual pupa of beetles;
it is harder, and is coloured, frequently conspicuously spotted, and
dehisces to allow the escape of the beetle, so that the metamorphosis is
altogether more like that of Lepidoptera than that of Coleoptera. There is
much variety in the larvae; some of them bear large, complexly-spined,
projections; those of the group Scymnites have small depressions on the
surface, from which it has been ascertained that waxy secretions exude; but
in _Scymnus minimus_ no such excretions are formed. Certain species, when
pupating, do not shuffle the skin to the extremity of the body, but retain
it as a covering for the pupa. The larvae that feed on plants are much less
active than the predaceous forms. We are well supplied with Coccinellidae
in Britain, forty species being known here.
The systematic position of Coccinellidae amongst the Coleoptera has been
for long a moot point. Formerly they were associated with various other
beetles having three-jointed, or apparently three-jointed, feet, as a
series with the name Trimera, or {239}Pseudotrimera. But they are generally
placed in the Clavicorn series, near Endomychidae. Verhoeff has recently
made considerable morphological studies on the male genital organs of
Coleoptera, and as the result, he concludes that Coccinellidae differ
radically from all other Coleoptera as regards these structures, and he
therefore treats them as a distinct series or sub-order, termed
Siphonophora. The genus _Lithophilus_ has been considered doubtfully a
member of Coccinellidae, as the tarsi possess only in a slight degree the
shape characteristic of the family: Verhoeff finds that they are truly
Coccinellidae, forming a distinct division, Lithophilini; and our little
species of _Coccidula_, which have somewhat the same appearance as
Lithophilini, he treats as another separate group, Coccidulini.
FAM. 39. ENDOMYCHIDAE.[122]—_Tarsi apparently three-jointed, the first two
joints broad, the terminal joint elongate; at the base of the terminal
joint there is, however, a very small joint, so that the tarsi are
pseudotetramerous; antennae rather large, with a large club; labium not at
all retracted behind the mentum; front and middle coxae globose; abdomen
with five movable ventral segments, and a sixth more or less visible at the
tip._ This family includes a considerable diversity of elegant Insects that
frequent fungoid growths on wood. It comprises at present fully 500
species, but nearly the whole of them are exotic, and inhabit the tropical
forests. We have only two British species, both of which are now rarities,
but apparently were much commoner at the beginning of the century. The
larvae are broader than is usual in Coleoptera; very few, however, are
known.
[Illustration: Fig. 119—_Mycetaea hirta._ Britain. A, Larva (after
Blisson); B, perfect Insect.]
FAM. 40. MYCETAEIDAE.—_Tarsi four-jointed, the first two joints not very
different from the third, usually slender; abdomen with five visible
ventral segments, which are movable; front and middle coxae globular._ The
little Insects composing this family are by many placed as a division of
Endomychidae, and Verhoeff is of opinion that the group is an altogether
artificial one; but we think, with Duval, it makes matters simpler to
separate them. There are only {240}some forty or fifty species, found
chiefly in Europe and North America. We have three in Britain; one of
these, _Mycetaca hirta_ is very common, and may be found in abundance in
cellars in the heart of London, as well as elsewhere; it is said to have
injured the corks of wine-bottles, and to have caused leakage of the wine,
but we think that it perhaps only increases some previous deficiency in the
corkage, for its natural food is fungoid matters. The larva is remarkable
on account of the clubbed hairs at the sides of the body.
FAM. 41. LATRIDIIDAE.—_Tarsi three-jointed; anterior coxal cavities round,
not prolonged externally; abdomen with five visible and mobile ventral
segments._ Very small Insects, species of which are numerous in most parts
of the world, the individuals being sometimes very abundant. The larvae
(Fig. 120, A) are said by Perris to have the mandibles replaced by fleshy
appendages. The pupa of _Latridius_ is remarkable, on account of the
numerous long hairs with heads instead of points; the larva of _Corticaria_
is very like that of _Latridius_, but some of the hairs are replaced by
obconical projections. The sub-family Monotomides is by many treated as a
distinct family; they have the elytra truncate behind, exposing the
pygidium, and the coxae are very small and very deeply embedded. Most of
the Latridiidae are believed to live on fungoid matters; species of
_Monotoma_ live in ants' nests, but probably have no relations with the
ants. A few species of Latridiides proper also maintain a similar life;
_Coluocera formicaria_ is said to be fond of the stores laid up by
_Aphaenogaster structor_ in its nests. About 700 species are now known;
scarcely any of the individuals are more than one-tenth of an inch long. We
have about 40 species in Britain. The North American genus _Stephostethus_
has the prosternum constructed behind the coxae, somewhat in the same
manner as it is in the Rhynchophorous series of Coleoptera.
[Illustration: Fig. 120—_Latridius minutus._ Britain. A, Larva (after
Perris); B, perfect Insect.]
FAM. 42. ADIMERIDAE.—_Tarsi appearing only two-jointed, a broad basal joint
and an elongate claw-bearing joint, but between the two there are two very
small joints._ This family consists only of the American genus _Adimerus_;
nothing is known of {241}the life-history of these small Insects. They are
of some interest, as this structure of the foot is not found in any other
beetles.
[Illustration: Fig. 121—_Adimerus setosus._ Adimeridae. A, the Insect; B,
one foot more enlarged. Mexico. From _Biol. Centr. Amer. Col._ ii. pt. i.]
[Illustration: Fig. 122—_Tiresias serra._ Larva. New Forest.]
FAM. 43. DERMESTIDAE.—_Tarsi five-jointed; antennae usually short, with the
club frequently very large in proportion, and with the under side of the
thorax bearing a hollow for its reception. Front coxae rather long,
oblique: hind coxa formed to receive the femur when in repose._ A family of
300 or 400 species of small or moderate-sized beetles; the surface, usually
covered with fine hair, forming a pattern, or with scales. _Byturus_, the
position of which has long been disputed, has now been placed in this
family; it has a more imperfectly formed prosternum, and the third and
fourth joints of the tarsi are prolonged as membranous lobes beneath; the
hind coxae leave the femora quite free. Dermestidae in the larval state
nearly all live on dried animal matter, and are sometimes very destructive;
some of them totally destroy zoological collections. They are very
remarkable on account of the complex clothing of hairs they bear; they have
good powers of locomotion, and many of them have a peculiar gait, running
for a short distance, then stopping and vibrating some of their hairs with
extreme rapidity. They exhibit great variety of form. Many of them are
capable of supporting life for long periods on little or no food, and in
such cases moult an increased number of times: pupation takes place in the
larval skin. _Anthrenus fasciatus_ has been reared in large numbers on a
diet of dried horse-hair in furniture. The young larva of this species
observed by the writer did not possess the remarkable, complex arrangement
of hairs that appeared when it was further grown. The most curious of
Dermestid larvae is that of _Tiresias serra_, which lives amongst cobwebs
in {242}old wood, and probably feeds on the remains of Insects therein,
perhaps not disdaining the cobwebs themselves. Attention has been
frequently called to the hairs of the larvae of these Insects, but they
have never been adequately discussed, and their function is quite unknown.
FAM. 44. BYRRHIDAE (_Pill-beetles_).—_Oval or round, convex beetles; tarsi
five-jointed, front coxae not exserted, transverse; hind coxa shielding the
retracted femur. The whole of the appendages capable of a complete
apposition to the body._ Although a small family of only 200 or 300
species, Byrrhidae are so heterogeneous that no characteristic definition
that will apply to all the sub-families can be framed. Very little is known
as to their life-histories. _Byrrhus pilula_ is one of our commonest
beetles, and may be found crawling on paths in early spring even in towns;
it moves very slowly, and when disturbed, at once contracts the limbs so
completely that it looks like an inanimate object. The larva is
cylindrical, soft; the prothoracic and last two abdominal segments are
larger than the others, the last bearing two pseudopods; its habits are
unknown, and no good figure exists of it.
The chief groups of Byrrhidae are Nosodendrides, Byrrhides (including
Amphicyrtides), Limnichides, and Chelonariides. The first consists of
species frequenting the exuding sap of trees; they have an unusually large
mentum, abruptly clubbed antennae, and the head cannot be retracted and
concealed. The genus _Nosodendron_ seems to be distributed over a large
part of the world. The Byrrhides have the antennae gradually thicker
towards the tip, the mentum small, and the head and thorax so formed that
the former can be perfectly retracted. The species are rather numerous, and
are found in the northern and antipodeal regions, being nearly completely
absent from the tropics. The Limnichides are minute Insects living in very
moist places; they have small delicate antennae, which are imperfectly
clubbed. The group is very widely distributed.
The Chelonariides are a very peculiar form of Coleoptera: oval Insects of
small size with the prothorax so formed that the head can be withdrawn
under (rather than into) it, and then abruptly inflexed, so that the face
then forms part of the under surface: the antennae have the basal three
joints thicker than the others; these being not in the least clubbed, but
having the {243}joints so delicately connected that the organs are rarely
unmutilated. The modifications of the head and prothorax are quite unlike
those of other Byrrhidae, and if the Chelonariides do not form a distinct
family, they should be associated with Dascillidae. Nothing is known as to
the earlier stages. They are chiefly tropical Insects, though one species
is found in North America.
FAM. 45. CYATHOCERIDAE.—_Minute Insects of broad form; parts of the mouth
concealed; antennae four-jointed; tarsi not divided into joints; prosternum
small._ The only species of this aberrant family, _Cyathocerus horni_, has
been found in Central America. Nothing is known as to its life-history.
FAM. 46. GEORYSSIDAE.—_Antennae short, clubbed; tarsi four-jointed;
prosternum very small; front coxae exserted, but not contiguous._ There are
about two dozen species of these small beetles known. Our British
_Georyssus pygmaeus_ lives in extremely wet places, and covers itself with
a coating of mud or fine sand so that it can only be detected when in
movement. Nothing further is known as to its life-history or habits.
Members of the genus have been detected in widely-separated parts of the
globe.
FAM. 47. HETEROCERIDAE.—_Labrum and mandibles projecting forwards; antennae
short, the terminal seven joints broad and short, forming a sort of broad
serrate club; legs armed with stout spines; tarsi four-jointed._ The
Heteroceridae are small beetles covered with very dense but minute
pubescence; they live in burrows among mud or sand in wet places, and are
found in many parts of the world. They possess a stridulating organ in the
form of a slightly elevated curved line on each side of the base of the
abdomen, rubbed by the posterior femur. The larvae live in the same places
as the beetles; they have well-developed thoracic legs, the mandibles are
porrect, the three thoracic segments rather large, and the body behind
these becomes gradually narrower; they are believed to eat the mud amongst
which they burrow. We have seven British species of Heteroceridae.
FAM. 48. PARNIDAE.—_Prosternum distinct in front of the coxae, usually
elongate, behind forming a process received into a definite cavity on the
mesosternum; head retractile, the mouth protected by the prosternum. Tarsi
five-jointed, terminal joint long._ {244}Although the characters of these
Insects are not very different from those of Byrrhidae, of Dascillidae, and
even of certain Elateridae, there is practically but little difficulty in
distinguishing Parnidae. They are of aquatic habits, though many, in the
perfect state, frequently desert the waters. There are about 300 or 400
species known, but the family is doubtless more extensive, as these small
beetles attract but little notice. There are two groups:—1. Parnides, in
which the front coxae have a considerable transverse extension, the
antennae are frequently short and of peculiar structure, and the body is
usually clothed with a peculiar, dense pubescence. 2. Elmides, with round
front coxae, a bare, or feebly pubescent body, and simple antennae.
_Parnus_ is a genus commonly met with in Europe, and is less aquatic in
habits than its congeners; it is said to enter the water carrying with it a
coating of air attached to its pubescence. Its larvae are not well known;
they live in damp earth near streams, and are said to much resemble the
larvae of Elateridae. _Potamophilus acuminatus_ has a very interesting
larva, described by Dufour; it lives on decaying wood in the Adour. It is
remarkable from the ocelli being arranged so as to form an almost true eye
on each side of the head; there are eight pairs of abdominal spiracles, and
also a pair on the mesothorax, though there are none on the pro- or
meta-thorax; each of the stigmata has four elongate sacs between it and the
main tracheal tube; the body is terminated by a process from which there
can be protruded bunches of filamentous branchiae. The larvae of
_Macronychus quadrituberculatus_ is somewhat similar, though the features
of its external structure are less remarkable. The Elmides live attached to
stones in streams; the larva is rather broad, fringed at the sides of the
body, and bears behind three elegant sets of fine filamentous branchiae.
The North American genus _Psephenus_ is placed in Parnidae, though instead
of five, the male has seven, the female six, visible ventral segments; the
larva is elliptical, with dilated margins to the body. Friederich, has
given,[123] without mentioning any names, a detailed account of Brazilian
Parnid larvae, that may perhaps be allied to _Psephenus_.
FAM. 49. DERODONTIDAE.—_Tarsi five-jointed, slender, fourth joint rather
small; front coxae prominent and transversely {245}prolonged; middle coxae
small; abdomen with five visible segments, all mobile, the first not
elongated._ One of the smallest and least known of the families of
Coleoptera; it consists of four or five species of small Insects of the
genera _Derodontus_ and _Peltasticta_, found in North America, Europe, and
Japan. The distinction of the family from Cleridae is by no means certain;
our European _Laricobius_ apparently possessing characters but little
different. Nothing is known as to the life-histories.
FAM. 50. CIOIDAE.—_Small or minute beetles; antennae short, terminal joints
thicker; tarsi short, four-jointed; anterior and middle coxae small, oval,
deeply embedded; abdomen with five ventral segments, all mobile._ The
position of these obscure little Insects seems to be near Colydiidae and
Cryptophagidae, though they are usually placed near Bostrichidae. So far as
known, they all live in fungi, or in wood penetrated by fungoid growths.
The cylindrical larvae live also in similar matter; they usually have the
body terminated behind by one or two hooks curved upwards; that of _Cis
melliei_ (Fig. 124) has, instead of these hooks, a curious chitinous tube.
About 300 species of the family are now known; a score, or so, occurring in
Britain. The Hawaiian Islands have a remarkably rich and varied fauna of
Cioidae.
[Illustration: Fig. 123—_Derodontus maculatus._ North America.]
[Illustration: Fig. 124—_Cis melliei._ Martinique. A, Perfect Insect; B,
pupa; C, larva; D, terminal portion of body of larva. (After Coquerel.)]
FAM. 51. SPHINDIDAE.—This family of half a dozen species of rare and small
Insects, differs from Cioidae by the tarsi being five-jointed at any rate
on the front and middle feet, opinions differing as to whether the number
of joints of the hind tarsi is four or five. These Insects live in fungi
growing in wood, _e.g._ _Reticularia hortensis_, that are at first pulpy
and {246}afterwards become powder. The larvae of both of our British
genera, _Sphindus_ and _Aspidiphorus_, have been described by Perris, who
considers them allied to the fungivorous Silphidae and Latridiidae. The
systematic position of these Insects has been the subject of doubt since
the days of Latreille.
FAM. 52. BOSTRICHIDAE (APATIDAE of some authors).—_Tarsi five-jointed, but
the first joint very short and imperfectly separated from the second; front
coxae prominent, contiguous, very little extended transversely; five
visible ventral segments._ The Bostrichidae attack dry wood, and sometimes
in such large numbers that timber is entirely destroyed by them; most of
them make cylindrical burrows into the wood. The larvae have the posterior
part of the body incurved, and resemble the wood-boring larvae of Anobiidae
rather than the predaceous larvae of Cleridae. We follow Leconte and Horn
in placing Lyctides as a division of Bostrichidae; although differing very
much in appearance, they have similar habits and larvae. The typical
Bostrichides are remarkable for their variety of sculpture and for the
shapes of the posterior part of the body; this part is more or less
conspicuously truncate, and furnished with small prominences. _Dinapate
wrightii_, found in the stems of a species of _Yucca_ in the Mojave desert
of California, attains a length of nearly two inches; its larva is
extremely similar to that of _A. capucina_. Some of the forms (_Phonapate_)
stridulate in a manner peculiar to themselves, by rubbing the front leg
against some projections at the hind angle of the prothorax. Upwards of 200
species of the family are known. In Britain we have only four small and
aberrant forms.
[Illustration: Fig. 125—_Apate capucina._ Europe. A, Larva (after Perris);
B, perfect Insect.]
FAM. 53. PTINIDAE.—_Tarsi five-jointed, first joint not reduced in size,
often longer than second; front and middle coxae small, not transversely
extended, the former slightly prominent; five visible ventral segments;
prosternum very short._ Here are included two sub-families, Ptinides and
Anobiides; they are considered as distinct families by many authors, but in
the present imperfect state of knowledge[124] it is not necessary to treat
them separately.
{247}[Illustration: Fig. 126—"Biscuit-weevil." _Anobium paniceum._]
[Illustration: Fig. 127.—Early stages of _Anobium paniceum_. A, Eggs,
variable in form; B, larva; C, pupa; D, asymmetrical processes terminating
body of pupa. [This larva is probably the "book-worm" of librarians].]
Ptinidae are sometimes very destructive to dried animal matter, and attack
specimens in museums; Anobiides bore into wood, and apparently emerge as
perfect Insects only for a very brief period; _Anobium_ (_Sitodrepa_)
_paniceum_ is, however, by no means restricted in its tastes; it must
possess extraordinary powers of digestion, as we have known it to pass
several consecutive generations on a diet of opium; it has also been
reported to thrive on tablets of dried compressed meat; in India it is said
to disintegrate books; a more usual food of the Insect is, however, hard
biscuits; weevilly biscuits are known to every sailor, and the so-called
"weevil" is usually the larva of _A. paniceum_ (Fig. 127, B). In the case
of this Insect we have not detected more than one spiracle (situate on the
first thoracic segment); the other known larvae of Anobiides are said to
possess eight abdominal spiracles. The skeleton in some of this sub-family
is extremely modified, so as to allow the Insects to pack themselves up in
repose; the head is folded in over the chest, and a cavity existing on the
breast is thus closed by the head; in this cavity the antennae and the
prominent mouth-parts are received and protected; the legs shut together
{248}in an equally perfect manner, so that no roughness or chink remains,
and the creature looks like a little hard seed. _Anobium striatum_ is a
common Insect in houses, and makes little round holes in furniture, which
is then said to be "worm-eaten." _A._ (_Xestobium_) _tessellatum_, a much
larger Insect, has proved very destructive to beams in churches, libraries,
etc. These species are the "death-watches" or "greater death-watches" that
have been associated with the most ridiculous superstitions (as we have
mentioned in Volume V., when speaking of the lesser death-watches, or
Psocidae). The ticking of these Insects is really connected with sex, and
is made by striking the head rapidly against the wood on which the Insect
is standing.
The very anomalous genus _Ectrephes_ (Fig. 128) is found in ants' nests in
Australia. Westwood placed it in Ptinidae. Wasmann has recently treated it
as a distinct family, Ectrephidae, associating it with _Polyplocotes_ and
_Diplocotes_, and treating them as allied to Scydmaenidae.
[Illustration: Fig. 128—_Ectrephes kingi._ West Australia. (After
Westwood.)]
FAM. 54. MALACODERMIDAE.—_Seven (or even eight) visible ventral segments,
the basal one not co-adapted in form with the coxae; tarsi five-jointed.
Integument softer than usual, the parts of the body not accurately
co-adapted._ This important family includes a variety of forms: viz.
Lycides, Drilides, Lampyrides, Telephorides; though they are very different
in appearance, classifiers have not yet agreed on separating them as
families. Of these the Lampyrides, or glow-worms, are of special interest,
as most of their members give off a phosphorescent light when alive; in
many of them the female is apterous and like a larva, and then the light it
gives is usually conspicuous, frequently much more so than that of its
mate; in other cases the males are the most brilliant. The exact importance
of these characters in the creatures' lives is not yet clear, but it
appears probable that in the first class of cases the light of the female
serves as an attraction to the male, while in the second class the very
brilliant lights of the male serve as an amusement, or as an incitement to
rivalry amongst the individuals of this sex.
{249}[Illustration: Fig. 129—_Phengodes hieronymi._ Cordoba, South America.
(After Haase.) A, Male; B, female. _l_, _l_, Positions of luminous spots;
_ls_, spiracles. About × 3.]
The well-known fire-flies (_Luciola_) of Southern Europe are an example of
the latter condition. They are gregarious, and on calm, warm nights crowds
of them may be seen moving and sparkling in a charming manner. These
individuals are all, or nearly all, males; so rare indeed is the female
that few entomologists have even noticed it. The writer once assisted in a
large gathering of _Luciola italica_ in the Val Anzasca, which consisted of
many hundreds of specimens; all of those he caught, either on the wing or
displaying their lights on the bushes, were males, but he found a solitary
female on the ground. This sex possesses ordinary, small eyes instead of
the large, convex organs of the male, and its antennae and legs are much
more feeble, so that though provided with elytra and wings it is altogether
a more imperfect creature. Emery has given an account of his observations
and experiments on this Insect, but they do not give any clear idea as to
the exact function of the light.[125] In our British glow-worm the female
is entirely apterous—hence the name glow-worm—but the male has elytra and
ample wings, and frequently flies at night into lighted apartments.
Although so little has been ascertained as to the light of Lampyridae,
there are two facts that justify us in supposing that it is in some way of
importance to the species. These are: (1) that in a great many species the
eyes have a magnificent and unusual development; (2) that the habits of the
creatures are in nearly all cases nocturnal. It is true that the little
_Phosphaenus hemipterus_ is said to be diurnal in habits, but it is
altogether an exceptional form, being destitute of wings in both sexes, and
possessed of only very feeble light-giving powers, and we have, moreover,
very little real knowledge as to its natural history; it is said {250}that
the female is of the utmost rarity, though the male is not uncommon.
The nature of the luminosity of _Lampyris_ has given rise to many
contradictory statements; the light looks somewhat like that given off by
phosphorus, and is frequently spoken of as phosphorescence; but
luminescence is a better term. The egg, larva, pupa, and male are luminous
as well as the female (at any rate in _L. noctiluca_); the luminescence is,
however, most marked in the female imago, in which it is concentrated near
the extremity of the abdomen; here there are two strata of cells, and many
fine capillary tracheae are scattered through the luminous substance.
Wielowiejski concludes that the light-producing power is inherent in the
cells of the luminous organ, and is produced by the slow oxidation of a
substance formed under the influence of the nervous system. The cells are
considered to be essentially similar to those of the fat-body.[126] The
luminescence of Lampyridae is very intermittent, that is to say, it is
subject to rapid diminutions and increases of its brilliancy; various
reasons have been assigned for this, but all are guesses, and all that can
be said is that the changes are possibly due to diminution or increase of
the air-supply in the luminous organ, but of the way in which this is
controlled there seems to be no evidence. Considerable difference of
opinion has existed as to the luminescence of the eggs of _Lampyris_. If it
exist in the matter contained in the egg, it is evident that it is
independent of the existence of tracheae or of a nervous system. Newport
and others believed that the light given by the egg depended merely on
matter on its exterior. The observations of Dubois[127] show, however, that
it exists in the matter in the egg; he has even found it in the interior of
eggs that had been deposited unfertilised.
From time to time, since the commencement of the nineteenth century, there
have appeared imperfect accounts of extraordinary light-giving larvae found
in South America, of various sizes, but attaining in some cases a length,
it is said, of three inches; they are reported as giving a strong red light
from the two extremities of the body, and a green light from numerous
points along the {251}sides of the body, and hence are called, it is said,
in Paraguay the railway-beetle. We may refer the reader to Haase's
paper[128] on the subject of these "larvae," as we can here only say that
it appears probable that most of these creatures may prove to be adult
females of the extraordinary group Phengodini, in which it would appear
that the imago of the female sex is in a more larva-like state than it is
in any other Insects. The males, however, are well-developed beetles;
unlike the males of Lampyrides, in general they have not peculiar eyes, but
on the other hand they possess antennae which are amongst the most highly
developed known, the joints being furnished on each side with a long
appendage densely covered with pubescence of a remarkable character. There
is no reason to doubt that Haase was correct in treating the Insect we
figure (Fig. 129, B) as a perfect Insect; he is, indeed, corroborated by
Riley.[129] The distinctions between the larva and female imago are that
the latter has two claws on the feet instead of one, a greater number of
joints in the antennae, and less imperfect eyes; the female is in fact a
larva, making a slightly greater change at the last ecdysis, than at those
previous. It is much to be regretted that we have so very small a knowledge
of these most interesting Insects. Malacodermidae are probably the most
imperfect or primitive of all beetles, and it is a point of some interest
to find that in one of them the phenomena of metamorphosis are reduced in
one sex to a minimum, while in the other they are—presumably at
least—normal in character.
Numerous larvae of most extraordinary, though diverse, shapes, bearing long
processes at the sides of the body, and having a head capable of complete
withdrawal into a slender cavity of the thorax, have long been known in
several parts of the world, and Dr. Willey recently found in New Britain a
species having these body-processes articulated. Though they are doubtless
larvae of Lampyrides, none of them have ever been reared or exactly
identified.
A very remarkable Ceylonese Insect, _Dioptoma adamsi_ Pascoe, is placed in
Lampyrides, but can scarcely belong there, as apparently it has but five or
six visible ventral segments; this Insect has two pairs of eyes, a large
pair, with coarse facets on {252}the under side of the head, and a
moderate-sized pair with fine facets on the upper side. Nothing is known as
to the habits of this curiosity, not even whether it is luminous in one or
both sexes.
It is believed that the perfect instar of Lampyrides takes no food at all.
The larvae were formerly supposed to be vegetarian, but it appears probable
that nearly all are carnivorous, the chief food being Mollusca either
living or dead. The larvae are active, and in many species look almost as
much like perfect Insects as do the imagos.
The other divisions of Malacodermidae—Lycides, Drilides, Telephorides—also
have predaceous, carnivorous larvae. All these groups are extensive. Though
much neglected by collectors and naturalists, some 1500 species of the
family Malacodermidae have been detected. We have about 50 in Britain, and
many of them are amongst the most widely distributed and abundant of our
native Insects. Thus, however near they may be to the primitive condition
of Coleoptera, it is highly probable that they will continue to exist
alongside of the primitive Cockroaches and Aptera, long after the more
highly endowed forms of Insect-life have been extinguished wholesale by the
operations of mankind on the face of the earth.
[Illustration: Fig. 130—_Malachius aeneus._ Britain. A, Larva (after
Perris); B, female imago.]
FAM. 55. MELYRIDAE (or MALACHIIDAE).—_Six visible and moveable ventral
abdominal segments; the basal part more or less distinctly co-adapted with
the coxae._ These Insects are extremely numerous, but have been very little
studied. In many works they are classified with Malacodermidae, but were
correctly separated by Leconte and Horn, and this view is also taken by Dr.
Verhoeff, the latest investigator. The smaller number of visible ventral
segments appears to be due to a change at the base correlative with an
adaptation between the base of the abdomen and the hind coxae. The
characters are singularly parallel with those of Silphidae; but in
Melyridae the antennae are filiform or serrate, {253}not clavate. The
habits in the two families are different, as the Melyridae are frequenters
of flowers. Many of the Melyridae have the integument soft, but in the
forms placed at the end of the family—_e.g._ _Zygia_—they are much firmer.
Thus these Insects establish a transition from the Malacodermidae to
ordinary Coleoptera. Although the imagos are believed to consume some
products of the flowers they frequent, yet very little is really known, and
it is not improbable that they are to some extent carnivorous. This is the
case with the larvae that are known (Fig. 130, larva of _Malachius
aeneus_). These are said by Perris to bear a great resemblance to those of
the genus _Telephorus_, belonging to the Malacodermidae.
FAM. 56. CLERIDAE.—_Tarsi five-jointed; but the basal joint of the
posterior very indistinct, usually very small above, and closely united
with the second by an oblique splice; the apices of joints two to four
usually prolonged as membranous flaps; anterior coxae prominent, usually
contiguous, rather large, but their cavities not prolonged externally;
labial palpi usually with large hatchet-shaped terminal joint; ventral
segments five or six, very mobile._ The Cleridae are very varied in form
and colours; the antennae are usually more or less clubbed at the tip, and
not at all serrate, but in _Cylidrus_ and a few others they are not
clubbed, and in _Cylidrus_ have seven flattened joints. The student should
be very cautious in deciding as to the number of joints in the feet in this
family, as the small basal joint is often scarcely distinguishable, owing
to the obliteration of its suture with the second joint. The little Alpine
_Laricobius_ has the anterior coxal cavities prolonged externally, and the
coxae receive the femora to some extent, so that it connects Cleridae and
Derodontidae. The Cleridae are predaceous, and their larvae are very
active; they are specially fond of wood-boring Insects; that of _Tillus
elongatus_ (Fig. 131) enters the burrows of _Ptilinus pectinicornis_ in
search of the larva. The members of the group Corynetides frequent animal
matter, carcases, bones, etc., and, it is said, feed thereon, but Perris's
recent investigations[130] make it probable that the larvae really eat the
innumerable Dipterous larvae found in such refuse; it is also said that the
larvae of Cleridae spin cocoons for their metamorphosis; but Perris has
also shown that the larvae of _Necrobia ruficollis_ really use the puparia
formed {254}by Diptera. Some of the species of _Necrobia_ have been spread
by commercial intercourse, and _N. rufipes_ appears to be now one of the
most cosmopolitan of Insects. The beautifully coloured _Corynetes
coeruleus_ is often found in our houses, and is useful, as it destroys the
death-watches (_Anobium_) that are sometimes very injurious. _Trichodes
apiarius_, a very lively-coloured red and blue beetle, destroys the larvae
of the honey-bee, and Lampert has reared _Trichodes alvearius_ from the
nests of _Chalicodoma muraria_, a mason-bee; he records that one of its
larvae, after being full grown, remained twenty-two months quiescent and
then transformed to a pupa. Still more remarkable is a case of fasting of
the larva of _Trichodes ammios_ recorded by Mayet;[131] this Insect, in its
immature form, destroys _Acridium maroccanum_; a larva sent from Algeria to
M. Mayet refused such food as was offered to it for a period of two and a
half years, and then accepted mutton and beef as food; after being fed for
about a year and a half thereon, it died. Some Cleridae bear a great
resemblance to Insects of other families, and it appears probable that they
resemble in one or more points the Insects on which they feed. The species
are now very numerous, about 1000 being known, but they are rare in
collections; in Britain we have only nine species, and some of them are now
scarcely ever met with.
[Illustration: Fig. 131—Larva of _Tillus elongatus_. (New Forest). A, Head;
B, front leg; C, termination of the body, more magnified.]
FAM. 57. LYMEXYLONIDAE.—_Elongate beetles, with soft integuments, front and
middle coxae exserted, longitudinal in position; tarsi slender,
five-jointed; antennae short, serrate, but rather broad._ Although there
are only twenty or thirty species of this family, they occur in most parts
of the world, and are remarkable on account of their habit of drilling
cylindrical holes in hard wood, after the manner of Anobiidae. The larva of
_Lymexylon navale_ was formerly very injurious to timber used for
constructing ships, but of late years its ravages appear to have been of
little importance. The genus _Atractocerus_ consists of a few species of
very abnormal {255}Coleoptera, the body being elongate and vermiform, the
elytra reduced to small, functionless appendages, while the wings are
ample, not folded, but traversed by strong longitudinal nervures, and with
only one or two transverse nervures. Owing to the destruction of our
forests the two British Lymexylonidae—_L. navale_ and _Hylecoetus
dermestoides_—are now very rarely met with.
[Illustration: Fig. 132—_Hydrocyphon deflexicollis._ Britain. A, Larva
(after Tournier); B, imago.]
FAM. 58. DASCILLIDAE.—_Small or moderate-sized beetles, with rather flimsy
integuments, antennae either serrate, filiform, or even made flabellate by
long appendages; front coxae elongate, greatly exserted; abdomen with five
mobile ventral segments; tarsi five-jointed._ This is one of the most
neglected and least known of all the families of Coleoptera, and one of the
most difficult to classify; though always placed amongst the Serricornia,
it is more nearly allied to Parnidae and Byrrhidae, that are placed in
Clavicornia, than it is to any of the ordinary families of Serricornia. It
is probable that careful study will show that it is not natural as at
present constituted, and that the old families, Dascillidae and Cyphonidae,
now comprised in it, will have to be separated. Only about 400 species are
at present known; but as nearly 100 of these have been detected in New
Zealand, and 17 in Britain, doubtless the numbers in other parts of the
world will prove very considerable, these Insects having been neglected on
account of their unattractive exterior, and fragile structure. The few
larvae known are of three or four kinds. That of _Dascillus cervinus_ is
subterranean, and is believed to live on roots; in form it is somewhat like
a Lamellicorn larva, but is straight, and has a large head. Those of the
Cyphonides are aquatic, and are remarkable for possessing antennae
consisting of a great many joints (Fig. 132, A). Tournier describes the
larva of _Helodes_ as possessing abdominal but not thoracic spiracles, and
as breathing by coming to the surface of the water and carrying down a
bubble of air adhering to the posterior part of the body; the larva of
_Hydrocyphon_ (Fig. 132, A) {256}possesses several finger-like pouches that
can be exstulpated at the end of the body. It is probable that these larvae
are carnivorous. The imago of this Insect abounds on the bushes along the
banks of some of the rapid waters of Scotland; according to Tournier, when
alarmed, it enters the water and goes beneath it for shelter. The third
form of larva belongs to the genus _Eucinetus_, it lives on fungoid matter
on wood, and has ordinary antennae of only four joints.[132] It is very
doubtful whether _Eucinetus_ is related to other Dascillidae; some
authorities indeed place it in Silphidae.
FAM. 59. RHIPICERIDAE.—_Tarsi five-jointed, furnished with a robust
onychium (a straight chitinous process bearing hairs) between the claws;
antennae of the male bearing long processes, and sometimes consisting of a
large number of joints. Mandibles robust, strongly curved, and almost
calliper-like in form._ This small family of less than 100 species is
widely distributed, though confined to the warmer regions of the earth, a
single species occurring in the extreme south of Eastern Europe. Very
little is known as to the natural history. The larva of _Callirhipis
dejeani_ (Fig. 133, A) is described by Schiödte as hard, cylindrical in
form, and peculiarly truncate behind, so that there appear to be only eight
abdominal segments, the ninth segment being so short as to look like an
operculum at the extremity of the body. It lives in wood.
[Illustration: Fig. 133—A, Larva of _Callirhipis dejeani_ (after Schiödte);
B, _Rhipicera mystacina_ male, Australia; C, under side of its hind foot.]
{257}[Illustration: Fig. 134—_Athous rhombeus._ New Forest. A, Larva; B,
female imago.]
FAM. 60. ELATERIDAE (_Click-beetles_).—_Antennae more or less serrate along
the inner margin, frequently pectinate, rarely filiform. Front coxae small,
spherical. Thorax usually with hind angles more or less prolonged
backwards; with a prosternal process that can be received in, and usually
can move in, a mesosternal cavity. Hind coxa with a plate, above which the
femur can be received. Visible ventral segments usually five, only the
terminal one being mobile. Tarsi five-jointed._ This large family of
Coleoptera comprises about 7000 species. Most of them are readily known by
their peculiar shape, and by their faculty of resting on the back,
stretching themselves out flat, and then suddenly going off with a click,
and thus jerking themselves into the air. Some, however, do not possess
this faculty, and certain of these are extremely difficult to recognise
from a definition of the family. According to Bertkau[133] our British
_Lacon murinus_ is provided near the tip of the upper side of the abdomen
with a pair of eversible glands, comparable with those that are better
known in Lepidopterous larvae. He states that this Insect does not try to
escape by leaping, but shams death and "stinks away" its enemy. The glands,
it would appear, become exhausted after the operation has been repeated
many times. The extent of the leap executed by click-beetles differs
greatly; in some species it is very slight, and only just sufficient to
turn the Insect right side up when it has been placed on its back. In some
cases the Insects go through the clicking movements with little or no
appreciable result in the way of consequent propulsion. Although it is
difficult to look on this clicking power as of very great value to the
Elateridae, yet their organisation is profoundly modified so as to permit
its accomplishment. The junction of the prothorax with the after-body
involves a large number of pieces which are all more or less changed, so
that the joint is endowed with greater mobility than usual; while in the
position of repose, on the other hand, the two parts are firmly locked
together. The thoracic stigma is of a highly remarkable nature, and the
extensive {258}membrane in which it is placed appears to be elastic.
Although the mechanics of the act of leaping are still obscure, yet certain
points are clear; the prosternal process possesses a projection, or notch,
on its upper surface near the tip; as a preliminary to leaping, this
projection catches against the edge of the mesosternal cavity, and as long
as this position is maintained the Insect is quiescent; suddenly, however,
the projection slips over the catch, and the prosternal process is driven
with force and rapidity into the mesosternal cavity pressing against the
front wall thereof, and so giving rise to the leap.
Several larvae are well known; indeed the "wire-worms" that are sometimes
so abundant in cultivated places are larvae of Elateridae. In this instar
the form is usually elongate and nearly cylindrical; the thoracic segments
differ but little from the others except that they bear rather short legs;
the skin is rather hard, and usually bears punctuation or sculpture; the
body frequently terminates in a very hard process, of irregular shape and
bearing peculiar sculpture on its upper surface, while beneath it the
prominent anal orifice is placed: this is sometimes furnished with hooks,
the function of which has not yet been observed. The majority of these
larvae live in decaying wood, but some are found in the earth; as a rule
the growth is extremely slow, and the life of the larva may extend over two
or more years. Some obscurity has prevailed as to their food; it is now
considered to be chiefly flesh, though some species probably attack
decaying roots; and it is understood that wire-worms destroy the living
roots, or underground stems, of the crops they damage. Various kinds of
Myriapods (see Vol. V. p. 29) are often called "wire-worm," but they may be
recognised by possessing more than six legs. The larvae of the genus
_Cardiophorus_ are very different, being remarkably elongate without the
peculiar terminal structure, but apparently composed of twenty-three
segments.
The genus _Pyrophorus_ includes some of the most remarkable of light-giving
Insects. There are upwards of 100 species, exhibiting much diversity as to
the luminous organs; some are not luminous at all; but all are peculiar to
the New World, with the exception that there may possibly be luminous
species, allied to the American forms, in the Fiji Islands and the New
Hebrides. In the tropics of America the _Pyrophorus_, or Cucujos, form one
of the most remarkable of the natural phenomena. {259}The earliest European
travellers in the New World were so impressed by these Insects that
descriptions of their wondrous display occupy a prominent position in the
accounts of writers like Oviedo, whose works are nearly 400 years old. Only
one of the species has, however, been investigated. _P. noctilucus_ is one
of the most abundant and largest of the _Pyrophorus_, and possesses on each
side of the thorax a round polished space from which light is given forth;
these are the organs called eyes by the older writers. Besides these two
eye-like lamps the Insect possesses a third source of light situate at the
base of the ventral surface of the abdomen; there is no trace of this
latter lamp when the Insect is in repose; but when on the wing the abdomen
is bent away from the breast, and then this source of light is exposed;
hence, when flying, this central luminous body can be alternately displayed
and concealed by means of slight movements of the abdomen. The young larva
of _P. noctilucus_ is luminous, having a light-giving centre at the
junction of the head and thorax; the older larva has also numerous luminous
points along the sides of the body near the spiracles. It is remarkable
that there should be three successive seats of luminescence in the life of
the same individual. The eggs too are said to be luminous. The light given
off by these Insects is extremely pleasing, and is used by the natives on
nocturnal excursions, and by the women for ornament. The structure of the
light-organs is essentially similar to that of the Lampyridae. The light is
said to be the most economical known; all the energy that is used being
converted into light, without any waste by the formation of heat or
chemical rays. The subject has been investigated by Dubois,[134] who comes,
however, to conclusions as to the physiology of the luminous processes
different from those that have been reached by Wielowiejski and others in
their investigations on Glow-worms. He considers that the light is produced
by the reactions of two special substances, luciferase and luciferine.
Luciferase is of the nature of an enzyme, and exists only in the luminous
organs, in the form, it is supposed, of extremely minute granules.
Luciferine exists in the blood; and the light is actually evoked by the
entry of blood into the luminous organ.
We have given to this family the extension assigned to it by {260}Schiödte.
Leconte and Horn also adopt this view, except that they treat Throscides as
a distinct family. By most authors Eucnemides, Throscides, and Cebrionides
are all considered distinct families, but at present it is almost
impossible to separate them on satisfactory lines. The following table from
Leconte and Horn exhibits the characters of the divisions so far as the
imago is concerned:—
Posterior coxae laminate; trochanters small.
Labrum concealed; antennae somewhat distant from the eyes,
their insertion narrowing the front Eucnemides.
Labrum visible, free; antennae arising near the eyes under
the frontal margin Elaterides.
Labrum transverse, connate with the front.
Ventral segments six; claws simple; tibial spurs well
developed. Cebrionides.
Ventral segments five; claws serrate; tibial spurs moderate.
Perothopides.
Posterior coxae not laminate; trochanters of middle and
posterior legs very long Cerophytides.
[Illustration: Fig. 135—Larva of _Fornax_ n. sp. Hawaii. A, Upper side; B,
under side: _s_ _s_, position of spiracles; C, head more enlarged; D, under
side of terminal segment; _a_, anus.]
Throscides are considered to be distinguished by the mesosternum being
impressed on each side in front for the accommodation of the posterior face
of the front coxae. The genus _Throscus_ has the antennae clavate. The
classification of the Elaterides and these forms is a matter of the
greatest difficulty, and, if the larvae are also considered, becomes even
more complex. Cebrionid larvae are different from those of any of the other
divisions, and possess laminate, not calliper-like, mandibles. The larvae
of Eucnemides (Fig. 135) are very little known, but are highly remarkable,
inasmuch as it is very difficult to find any mouth-opening in some of them,
and they have no legs. The other divisions possess very few species
compared with Elaterides. In Britain we have about sixty species of
Elaterides, four of Throscides and three of Eucnemides; _Cerophytum_ was
probably a native many years ago. Neither Perothopides {261}nor Cebrionides
are represented in our fauna; the former of these two groups consists only
of four or five North American species, and the Cerophytides are scarcely
more numerous.
FAM. 61. BUPRESTIDAE.—_Antennae serrate, never elongate; prothorax fitting
closely to the after-body, with a process received into a cavity of the
mesosternum so as to permit of no movements of nutation. Five visible
ventral segments, the first usually elongate, closely united with the
second, the others mobile. Tarsi five-jointed, the first four joints
usually with membranous pads beneath._ This family is also of large extent,
about 5000 species being known. Many of them are remarkable for the
magnificence of their colour, which is usually metallic, and often of the
greatest brilliancy; hence their wing-cases are used by our own species for
adornment. The elytra of the eastern kinds of the genus _Sternocera_ are of
a very brilliant green colour, and are used extensively as embroidery for
the dresses of ladies; the bronze elytra of _Buprestis (Euchroma) gigantea_
were used by the native chieftains in South America as leg-ornaments, a
large number being strung so as to form a circlet. The integument of the
Buprestidae is very thick and hard, so as to increase the resemblance to
metal. The dorsal plates of the abdomen are usually soft and colourless in
beetles, but in Buprestidae they are often extremely brilliant. The
metallic colour in these Insects is not due to pigment, but to the nature
of the surface. Buprestidae appear to enjoy the hottest sunshine, and are
found only where there is much summer heat. Australia and Madagascar are
very rich in species and in remarkable forms of the family, while in
Britain we possess only ten species, all of which are of small size, and
nearly all are excessively rare. The family is remarkably rich in fossil
forms; no less than 28 per cent of the Mesozoic beetles found by Heer in
Switzerland are referred to Buprestidae.
[Illustration: Fig. 136—A, Larva of _Euchroma goliath_ (after Schiödte); B,
imago of _Melanophila decostigma_. Europe.]
The larvae (Fig. 136, A) find nourishment in living vegetable matter, the
rule being that they form galleries in or under the {262}bark of trees and
bushes, or in roots thereof; some inhabit the stems of herbaceous plants
and one or two of the smaller forms have been discovered to live in the
parenchyma of leaves. A few are said to inhabit dead wood, and in Australia
species of _Ethon_ dwell in galls on various plants. Buprestid larvae are
of very remarkable shape, the small head being almost entirely withdrawn
into the very broad thorax, while the abdomen is slender.[135] A few,
however, depart from this shape, and have the thoracic region but little or
not at all broader than the other parts. The larvae of _Julodis_—a genus
that inhabits desert or arid regions—are covered with hair; they have a
great development of the mandibles; it is believed that they are of
subterranean habits, and that the mandibles are used for burrowing in the
earth. Only the newly hatched larva is, however, known.
SERIES IV. HETEROMERA.
_Tarsi of the front and middle legs with five, those of the hind legs with
four, joints._
This series consists of some 14,000 or 15,000 species. Twelve or more
families are recognised in it, but the majority of the species are placed
in the one great family, Tenebrionidae. The number of visible ventral
segments is nearly always five. Several of the families of the series are
of doubtful validity; indeed beyond that of Tenebrionidae the taxonomy of
this series is scarcely more than a convention. The larvae may be
considered as belonging to three classes; one in which the body is
cylindrical and smooth and the integument harder than usual in larvae; a
second in which it is softer, and frequently possesses more or less
distinct pseudopods, in addition to the six thoracic legs; and a third
group in which hypermetamorphosis prevails, the young larvae being the
creatures long known as Triungulins, and living temporarily on the bodies
of other Insects, so that they were formerly supposed to be parasites.
{263}FAM. 62. TENEBRIONIDAE.—_Front coxae short, not projecting from the
cavities, enclosed behind. Feet destitute of lobed joints. Claws smooth._
This is one of the largest families of Coleoptera, about 10,000 species
being already known. A very large portion of the Tenebrionidae are entirely
terrestrial, wings suitable for flight being absent, and the elytra
frequently more or less soldered. Such forms are described in systematic
works as apterous. Unfortunately no comprehensive study has ever been made
of the wings or their rudiments in these "apterous forms."[136] it is
probable that the wings, or their rudiments or vestiges, always exist, but
in various degrees of development according to the species, and that they
are never used by the great majority of the terrestrial forms. Many of the
wood-feeding Tenebrionidae, and the genera usually placed at the end of the
family, possess wings well adapted for flight. The apterous forms are
chiefly ground-beetles, living in dry places; they are very numerous in
Africa, California, and North Mexico. Their colour is nearly always black,
and this is probably of some physiological importance; the integuments are
thick and hard, and if the wing-cases are taken off, it will be found that
they are usually more or less yellow on the inner face, even when jet-black
externally; the external skeleton is very closely fitted together, the
parts that are covered consisting of very delicate membrane; the transition
between the hard and the membranous portions of the external skeleton is
remarkably abrupt. These ground-Tenebrionidae form a very interesting
study, though, on account of their unattractive appearance, they have not
received the attention they deserve.
[Illustration: Fig. 137—_Tenebrio molitor._ Europe, etc. A, Larva
(meal-worm); B, pupa (after Schiödte); C, imago.]
Many of the Tenebrionidae, notwithstanding their dark {264}colours, are
diurnal in habits, and some of them run with extreme velocity in places so
bare and desert that the means of existence of the Insects is a mystery.
Most of the Tenebrionidae, however, shun the light. The food is usually
vegetable matter, and it is apparently preferred in a very dry state. Mr.
Gahan has recently recorded that in _Praogena_ the under surface of the
head has the gular region striate for stridulating purposes. This is the
only instance known of a voice-organ in this situation, and moreover is the
only case in all the Tenebrionidae in which any sound-producing organ has
been discovered. The larvae exhibit but little variety, they are elongate
and cylindrical, with harder integument than is usual in Coleopterous
larvae; they have six thoracic legs, and at the under side of the posterior
extremity the anus serves as a very short pseudopod. The resemblance of
these larvae to those of Elateridae is considerable; but though the body is
terminated by one or two small processes, these never attain the complexity
of the terminal segment of Elateridae. The common meal-worm—_i.e._ the
larva of _Tenebrio molitor_—is a very characteristic example of the group.
The pupae are remarkable on account of peculiar projections, of varied and
irregular form, that exist on the sides of the abdominal segments. Britain
is very poor in these Insects; our list of them scarcely attains the number
of thirty species.
FAM. 63. CISTELIDAE.—_Claws comb-like._ The very obscure beetles forming
this family are only separated from Tenebrionidae on account of their
pectinate claws. About 500 species of Cistelidae are recorded; the early
instars, so far as known, do not differ from those of Tenebrionidae; the
larvae are believed to live on dead wood.
FAM. 64. LAGRIIDAE.—_Anterior coxal cavities closed, tips of the front
coxae free, claws smooth, penultimate joint of the tarsi broader, pubescent
beneath._ This family has very little to distinguish it from Tenebrionidae,
and the group Heterotarsini appears to connect the two. It is a small
family of about 200 species, widely distributed, and represented in Britain
by one species, _Lagria hirta_. The early instars are similar to those of
the Tenebrionidae, except that the larva is less retiring in its habits and
wanders about on foliage: it is of broader form than that of most of the
Tenebrionidae. The pupa has long projections at the sides of the abdominal
segments.
{265}FAM. 65. OTHNIIDAE.—Only about ten species are known of this dubious
family. They are small Insects with weak integument, and are said by
Leconte and Horn to be distinguished from "degraded Tenebrionidae" by the
more mobile abdominal segments, the hind-margins of which are
semi-membranous. The antennae are of the clubbed shape, characteristic of
"Clavicornia," but this also occurs in numerous undoubted Tenebrionidae.
Species of _Othnius_ have been found in Japan and Borneo, as well as in
North America. Nothing is known as to their metamorphoses.
FAM. 66. ÆGIALITIDAE.—_All the coxae very widely separated; no
co-adaptation between the sides of the abdomen and the edges of the
wing-cases; five ventral segments and tip of a sixth visible._ Two minute
and rare Insects from North-West America constitute this family. It is
distinguished from Pythidae by the minute front coxae, widely separated,
completely closed in, and deeply embedded in the prosternum.
FAM. 67. MONOMMIDAE.—This is a small family of less than 100 species, the
members of which have the details of their external structure much
modified, permitting the Insect to pack itself up in repose in a very
perfect manner. They are of small size and oval form; and are absent from
Europe and the Antipodes. Nothing appears to be known as to the
metamorphosis.
FAM. 68. NILIONIDAE.—_Broad, circular Heteromera, of moderate size, with
the front coxae but little separated, and the anterior acetabula closed,
though having the appearance of being open in consequence of the tips of
the epimera being free. The inflexed portion of the wing-cases remarkably
broad._ A small family of less than fifty species, found on fungi, chiefly
in South America. The metamorphoses are not known. It is of very doubtful
validity.
FAM. 69. MELANDRYIDAE.—_Head not constricted behind the eyes; anterior
acetabula not closed; claws smooth. Prothorax broad behind._ These are
loosely-fitted-together Insects, of moderate or small size, frequenting dry
wood or fungi. About 200 species are known, found chiefly in temperate
regions. The few described larvae are rather varied in their details and
cannot be generalised at present. The characters of the members of this
family require fresh investigation.
FAM. 70. PYTHIDAE.—Distinguished from Melandryidae by the {266}prothorax
being narrow behind. This is a small family of about 100 species, found in
temperate regions in connection with timber. The species of _Rhinosimus_
have the head prolonged in front of the antennae so as to form a beak. The
larva of _Pytho depressus_ is flat and has parallel sides; the body is
terminated by two widely-separated sharp processes. It is found
occasionally under the bark of firs in Scotland.
FAM. 71. PYROCHROIDAE.—Differs from Melandryidae by the head forming a very
narrow neck behind, and by the penultimate tarsal joints being broad. They
are feeble Insects, though active on the wing. They are destitute of any of
the various remarkable structures found in Mordellidae. Only about forty
species are known, and the family is confined to the north temperate
region, being best represented in Japan. _Pyrochroa rubens_ is common in
some parts of England; the larva is found under the bark of tree-stumps; it
is remarkably flat, and has the eighth abdominal segment unusually long,
while the ninth terminates the body in the form of two long sharp
processes.
FAM. 72. ANTHICIDAE.—_Head with an abrupt narrow neck; prothorax narrower
than the elytra. Middle and hind coxae placed in definite acetabula. Claws
simple._ These little Insects are numerous in species; they have little
resemblance to Pyrochroidae, though the characters of the two families
cause us to place them in proximity. There are about 1000 species known;
though we have only about 12 in Britain, they are very numerous in the
Mediterranean region. The family Pedilidae of Lacordaire and some others is
now merged in Anthicidae. Thomson and Champion, on the other hand, separate
some very minute Insects to form the family Xylophilidae, on account of
certain differences in the form of the abdomen and tarsi. The Xylophilidae
live in dead wood; the Anthicidae, on the surface of the earth, after the
manner of ground-beetles; very little is, however, known as to their
natural history.
FAM. 73. OEDEMERIDAE.—_Prothorax not forming sharp edges at the sides, head
without a narrow neck. Penultimate tarsal joint broad; claws smooth._ These
Insects usually have a feeble integument, and bear a certain resemblance to
Malacodermidae. Less than 500 species are known, but they are widely
distributed, and occur in both temperate and tropical regions. The larvae
live in old wood. _Nacerdes melanura_ is common on our {267}coasts, where
its larva lives in timber cast up by the sea, or brought down by floods,
and it is able to resist immersion by the tide. It is remarkable from the
possession of five pairs of dorsal false feet on the anterior segments, and
two pairs on the ventral aspect. In _Asclera caerulea_ there are six dorsal
and three ventral pairs of these remarkable pseudopods. We have six species
of Oedemeridae in Britain, including _Asclera_ as well as _Nacerdes_.
[Illustration: Fig. 138—_Asclera caerulea._ A, Larva; B, pupa (after
Schiödte); C, imago. Cambridge.]
FAM. 74. MORDELLIDAE (incl. RHIPIPHORIDAE).—_Head peculiarly formed, vertex
lobed or ridged behind, so that in extension it reposes on the front edge
of the pronotum; capable of great inflection and then covering the
prosternum; hind coxae with laminae forming a sharp edge behind, frequently
very large._ This family is a very distinct one, though it exhibits great
variety. Lacordaire has pointed out that Rhipiphoridae cannot at present be
satisfactorily distinguished from Mordellidae. Leconte and Horn separate
the two by the fact that the sides of the prothorax form a sharp edge in
Mordellidae, but not in Rhipiphoridae. A better character would perhaps be
found by a study of the head, but as this would clearly result in a radical
change in the composition of the two families it is preferable to treat
them at present as only sub-families: if placed on a similar basis to the
preceding families, the group would however form, not two, but several
families. Besides the unusual shape of the head (Fig. 139, D) the ventral
region of the body is remarkably formed, being very convex, and in many
Mordellides terminating in a strong spinous process (Fig. 139, C). The
elytra are, in several Rhipiphorids, of the groups Myoditini and
Rhipidiini, reduced to a very small size, and the wings are not folded. The
Mordellidae are remarkable for their activity; in the perfect state they
usually frequent flowers, and fly and run with extreme rapidity.
Mordellides are amongst the most numerous and abundant of the European
Coleoptera, and in Britain the Anaspini swarm on the flowers of bushes and
Umbelliferae. The {268}life-histories appear to be singularly varied; but
unfortunately they are incompletely known. The larvae of some of the
Mordellids have been found in the stems of plants, and derive their
nutriment therefrom. This is said by Schwarz to be undoubtedly the case
with _Mordellistena floridensis_. Coquillett has found the larvae of _M.
pustulata_ in plant-stems under circumstances that render it highly
probable that they were feeding on a Lepidopterous larva contained in the
stems; and Osborn found a similar larva that was pretty certainly a
_Mordellistena_, and fed voraciously on Dipterous larvae in the stems of a
plant. The little that is known as to the metamorphoses of _Mordella_ and
_Anaspis_ shows that they live in old wood, but does not make clear the
nature of their food.
[Illustration: Fig. 139—_Mordellistena floridensis._ America. (After
Riley.) A, Larva; B, pupa; C, imago; D, outline of detached head of imago
of _M. pumila_, to show the neck.]
Although it has been ascertained that the Rhipiphorides exhibit instances
of remarkable metamorphosis, their life-histories are still very
imperfectly known. Dr. Chapman has ascertained some particulars as to
_Metoecus paradoxus_, which has long been known to prey in the larval state
on the larvae of the common social wasps.[137] The eggs are apparently not
deposited in the nests of the wasps, but in old wood. The young larva is a
triungulin, similar to that of the Cantharidae, we shall subsequently
describe. It is not known how it makes its way to the wasps' nests, but it
is possible that when a wasp visits some old wood haunted by these larvae,
some of them may attach themselves to it and be carried to the wasps'
nests. When {269}access is gained to the cells the little _Metoecus_
pierces the skin of one of the wasp-grubs, and entering in it feeds on the
interior; after it has increased in size it emerges, changes its skin, and
assumes a different form and habits; subsequently, as an external parasite,
entirely devouring the wasp-larva, and then becoming a pupa, and finally a
perfect _Metoecus_, in the cell of the wasp. The wasps, though they
investigate the cells, do not apparently entertain any objection to the
_Metoecus_, though there may be sometimes as many as twenty or thirty of
the destroyers in a single nest. A few hours after the _Metoecus_ has
become a winged Insect and has escaped from the cells, it appears however,
from the observations of Erné[138] on nests of wasps in captivity, that the
wasps become hostile to the foreigners, and it is probable that in a state
of nature these leave the nest as quickly as possible. _Emenadia
flabellata_, a genus allied to _Metoecus_, has been discovered by Chobaut
to have a similar life-history, except that it attacks a solitary wasp of
the genus _Odynerus_.[139] An old record to the effect that a second
species of _Emenadia_, _E. bimaculata_, lives in the stalks of _Eryngium
campestre_, on the pith, is now thought to be erroneous. Fabre has found
the larvae and pupae of another Rhipiphorid in the cells of a bee,
_Halictus sexcinctus_.
The most remarkable of the Rhipiphorids, from the point of view of its
habits, is certainly _Symbius blattarum_, which is now treated as the same
as an Insect previously described by Thunberg from specimens found in amber
and called _Ripidius pectinicornis_. This species is parasitic in
cockroaches; the male and female are very different, the former being an
active winged Insect, while the female is worm-like, differing but little
from the larva, and never leaving the body of the cockroach. It is to be
regretted that the life-history is not better known. The species has been
found on board ship in vessels coming from India; the male has been met
with in several European countries, but the female is excessively rare.
FAM. 75. CANTHARIDAE OR MELOIDAE (_Blister-beetles_, _Oil-beetles_).-_-Head
with an abrupt neck; elytra and sides of the abdomen without any
coadaptation; each claw of the feet with a long appendage closely applied
beneath it._ This distinct family consists of Heteromera with soft
integument, and is remarkable for the fact that many of its members contain
a substance that when extracted {270}and applied to the human skin,
possesses the power of raising blisters. The life-history is highly
remarkable, the most complex forms of hyper-metamorphosis being exhibited.
The species now known amount to about 1500; there can be no difficulty in
recognising a member of the family by the above characters, except that in
a very few cases each claw bears a projecting tooth, instead of an elongate
appendage parallel with itself. The penultimate tarsal joint scarcely ever
broader than the preceding; the colour and style of markings are extremely
varied. There are two very distinct sub-families, Cantharides and Meloides;
the former are winged Insects, and are frequently found on flowers or
foliage. The Meloides are wingless, and consequently terrestrial; they have
a very short metasternum, so that the middle coxae touch the hind; and they
also have very peculiar wing-cases, one of the two overlapping the other at
the base; in a few Meloids the wing-cases are merely rudiments.
The post-embryonic development of these Insects is amongst the most
remarkable of modern entomological discoveries. The first steps were made
by Newport in 1851,[140] and the subject has since been greatly advanced by
Fabre, Riley, and others. As an example of these peculiar histories, we may
cite Riley's account[141] of _Epicauta vittata_ (Fig. 140), a
blister-beetle living at the expense of North American locusts of the genus
_Caloptenus_. The locust lays its eggs underground, in masses surrounded by
an irregular capsule, and the _Epicauta_ deposits its eggs in spots
frequented by the locust, but not in special proximity to the eggs thereof.
In a few days the eggs of the blister-beetle hatch, giving rise to little
larvae of the kind called triungulin (Fig. 140, A), because each leg is
terminated by three tarsal spines or claws. In warm, sunny weather these
triungulins become very active; they run about on the surface of the ground
exploring all its cracks, penetrating various spots and burrowing, till an
egg-pod of the locust is met with; into this the triungulin at once eats
its way, and commences to devour an egg. Should two or more triungulins
enter the same egg-pod, battles occur till only one is left.
{271}[Illustration: FIG. 140.—Hypermetamorphosis of _Epicauta vittata_.
North America. (After Riley.) A, Young larva or triungulin; B, Caraboid
instar or second larva; C, coarctate larva, or instar between the
Scarabaeoid and Scolytoid larva; D, Scarabaeoid larva, from which the
Scolytoid, or sixth, instar differs but little; E, pupa; F, imago.]
After a few days passed in devouring a couple of eggs, the triungulin sheds
its skin and appears as a different larva (Fig. 140, B), with soft skin,
short legs, small eyes, and different form and proportions; a second moult
takes place after about a week, but is not accompanied by any very great
change of form, though the larva is now curved, less active, and in form
like a larva of Scarabaeidae; when another moult occurs the fourth instar
appears as a still more helpless form of larva (Fig. 140, D), which
increases rapidly in size, and when full grown leaves the remains of the
egg-pod it has been living on, and forms a small cavity near by; here it
lies on one side motionless, but gradually contracting, till the skin
separates and is pushed down to the end of the body, disclosing a
completely helpless creature that has been variously called a semi-pupa,
pseudo-pupa, or coarctate larva (Fig. 140, C); in this state the winter is
passed. In spring the skin of the coarctate larva bursts, and there crawls
out of it a sixth instar which resembles the fourth (Fig. 140, D), except
in the somewhat reduced size and greater whiteness. It is worthy of remark
that the skin it has deserted retains its original form almost intact. In
this sixth instar the larva is rather active and burrows about, {272}but
does not take food, and in the course of a few days again moults and
discloses the true pupa (Fig. 140, E). As usual in Coleoptera this instar
lasts but a short time, and in five or six days the perfect beetle appears
(Fig. 140, F). It is extremely difficult to frame any explanation of this
complex development; there are, it will be noticed, no less than five
stages interposed between the first larval instar and the pupal instar, and
the creature assumes in the penultimate one a quasi-pupal state, to again
quit it for a return to a previous state. It is possible to look on the
triungulin and the pupal instars as special adaptations to external
conditions; but it is not possible to account for the intermediate instars
in this way, and we must look on them as necessitated by the physiological
processes going on internally. Nothing, however, is known as to these. It
may be well to mention that, after describing and figuring (_loc. cit._)
this series of instars, Riley changed his views as to their
nomenclature.[142] The following summary of the metamorphosis, to which we
have added the two nomenclatures of Riley—the original one, when different
from the amended one, being given in square brackets—may therefore be
useful, viz.—Egg; 1, triungulin-larva—moult; 2, Caraboid larva [second
larva, Caraboid stage]—moult; 3, Scarabaeoid larva [second larva,
Scarabaeoid stage]—moult; 4, Scarabaeoid larva [second larva, ultimate
stage] (large amount of food and much growth)—moult; 5, coarctate larva
[pseudo-pupa, or semipupa]; 6, Scolytoid larva [third larva] (active, but
little or no food taken)—moult; 7, pupa—moult; 8, perfect Insect.
M. Fabre has succeeded in elucidating the history of _Sitaris humeralis_, a
Cantharid that lives at the expense of bees of the genus _Anthophora_.[143]
The eggs of the _Sitaris_ are deposited in the earth in close proximity to
the entrances to the bees' nests, about August. They are very numerous, a
single female producing, it is believed, upwards of 2000 eggs. In about a
month—towards the end of September—they hatch, producing a tiny triungulin
of black colour; the larvae do not, however, move away, but, without taking
any food, hibernate in a heap, remaining in this state till the following
April or May, when they become active. Although they are close to the
abodes of the bees they do not enter them, but seek to attach themselves
{273}to any hairy object that may come near them, and thus a certain number
of them get on to the bodies of the _Anthophora_ and are carried to its
nest. They attach themselves with equal readiness to any other hairy
Insect, and it is probable that very large numbers perish in consequence of
attaching themselves to the wrong Insects. The bee in question is a species
that nests in the ground and forms cells, in each of which it places honey
and lays an egg, finally closing the receptacle. It is worthy of remark
that in the case of the _Anthophora_ observed by M. Fabre, the male appears
about a month before the female, and it is probable that the vast majority
of the predatory larvae attach themselves to the male, but afterwards seize
a favourable opportunity, transfer themselves to the female, and so get
carried to the cells of the bee. When she deposits an egg on the honey, the
triungulin glides from the body of the bee on to the egg, and remains
perched thereon as on a raft, floating on the honey, and is then shut in by
the bee closing the cell. This remarkable act of slipping on to the egg
cannot be actually witnessed, but the experiments and observations of the
French naturalist leave little room for doubt as to the matter really
happening in the way described. The egg of the bee forms the first
nutriment of the tiny triungulin, which spends about eight days in
consuming its contents; never quitting it, because contact with the
surrounding honey is death to the little creature, which is entirely
unfitted for living thereon. After this the triungulin undergoes a moult
and appears as a very different creature, being now a sort of vesicle with
the spiracles placed near the upper part; so that it is admirably fitted
for floating on the honey (Vol. V. Fig. 86, 10). In about forty days, that
is, towards the middle of July, the honey is consumed, and the vesicular
larva after a few days of repose changes to a pseudo-pupa (11 of the fig.
cited) within the larval skin. After remaining in this state for about a
month, some of the specimens go through the subsequent changes, and appear
as perfect Insects in August or September. The majority delay this
subsequent metamorphosis till the following spring, wintering as
pseudo-pupae and continuing the series of changes in June of the following
year; at that time the pseudo-pupa returns to a larval form (12 of the fig.
cited), differing comparatively little from the second instar. The skin,
though detached, is again not shed, so that this ultimate larva is enclosed
in two {274}dead skins; in this curious envelope it turns round, and in a
couple of days, having thus reversed its position, becomes lethargic and
changes to the true pupa, and in about a month subsequent to this appears
as a perfect Insect, at about the same time of the year as it would have
done had only one year, instead of two, been occupied by its metamorphosis.
M. Fabre employs the term, third larva, for the instar designated by Riley
Scolytoid larva, but this is clearly an inconvenient mode of naming the
instar. _Sitaris humeralis_ is now very rare in Britain, but it seems
formerly to have been more common, and it is not improbable that its
triungulin may have been the "_Pediculus melittae_," that was believed by
Kirby to be a sort of bee-louse. Some species of the genus _Meloe_ are
still common in Britain, and the Insects may be seen with heavy distended
abdomen grazing on herbage in the spring. The females are enormously
prolific, a single one producing, it is believed, about 10,000 eggs.
_Meloe_ is also dependent on _Anthophora_, and its life-history seems on
the whole to be similar to that of _Sitaris_; the eggs are, however, not
necessarily deposited in the neighbourhood of the bees' nests, and the
triungulins distribute themselves on all sorts of unsuitable Insects, so
that it is possible that not more than one in a thousand succeeds in
getting access to the _Anthophora_ nest. It would be supposed that it would
be a much better course for these bee-frequenting triungulins to act like
those of _Epicauta_, and hunt for the prey they are to live on; but it must
be remembered that they cannot live on honey; the one tiny egg is their
object, and this apparently can only be reached by the method indicated by
Fabre. The history of these Insects certainly forms a most remarkably
instructive chapter in the department of animal instinct, and it is a
matter for surprise that it should not yet have attracted the attention of
comparative psychologists. The series of actions, to be performed once and
once only in a lifetime by an uninstructed, inexperienced atom, is such
that we should _a priori_ have denounced it as an impossible means of
existence, were it not shown that it is constantly successful. It is no
wonder that the female _Meloe_ produces 5000 times more eggs than are
necessary to continue the species without diminution in the number of its
individuals, for the first and most important act in the complex series of
this life-history is accomplished by an extremely indiscriminating
instinct; the {275}newly hatched _Meloe_ has to get on to the body of the
female of one species of bee; but it has no discrimination whatever of the
kind of object it requires, and as a matter of fact, passes with surprising
rapidity on to any hairy object that touches it; hence an enormous majority
of the young are wasted by getting on to all sorts of other Insects; these
larvae have been found in numbers on hairy Coleoptera as well as on flies
and bees of wrong kinds; the writer has ascertained by experiment that a
camel's-hair brush is as eagerly seized, and passed on to, by the young
_Meloe_ as a living Insect is.
The histories of several other Cantharids have been more or less completely
discovered. Fabre has found the larva of _Cerocoma schaefferi_ attacking
the stores of provisions laid up by a fossorial wasp of the genus
_Tachytes_, and consisting of Orthoptera of the family Mantidae. The
student who wishes for further information may refer to M. Beauregard's
work on this family.[144]
Some half-dozen species of the genus _Cephaloon_ found in Siberia, Japan,
and North America, have, by some authorities, been separated as the family
Cephaloidae. Nothing is known as to the metamorphosis of these rare
beetles; and at present it is not necessary to distinguish them from
Cantharidæ.
FAM. 76. TRICTENOTOMIDAE.—_Large Heteromera, with powerful free projecting
mandibles; the antennae long, but with the terminal three joints short,
with angular projections on one side._ This family includes only two genera
and seven or eight species. They are very remarkable Insects; _Autocrates
aenea_ being three inches long. The family is of considerable interest, as
it seems to have no affinity with any other Coleoptera. The appearance of
the species somewhat reminds one of Lucanidae, or Prionides; but
Trictenotomidae have even less relation to those beetles than they have to
the members of the Heteromerous series. The Trictenotomidae appear to be
found only in the primitive forests of the Indian and Indo-Malayan regions.
Nothing is known as to their life-histories.
{276}SERIES V. PHYTOPHAGA.
_Tarsi apparently four-jointed, the three basal joints usually densely
set with cushion-like pubescence beneath; the third joint different in
form, being divided into two lobes, or grooved on its upper surface so as
to allow of the fourth joint being inserted near its base instead of at
its extremity. Head not forming a definite prolonged beak; its labrum
visible, the palpi rarely (and even then not completely) occluded in the
mouth._
This great series of beetles includes something like 35,000 species. It
approaches, like all the other series, the Polymorpha, especially the
family Erotylidae placed therein, but in the great majority of cases there
is no difficulty in recognising its members. The tarsi have never the
Heteromerous formula, the head is not constructed like that of
Rhynchophora, nor the mouth and feet like those of Adephaga; the antennae
are different from those of the Lamellicorns. The tarsi are really
five-jointed, for careful inspection shows that the long claw-joint has at
its extreme base a small nodule, which is undoubtedly the fourth joint
(Fig. 142, B). In speaking of the joints it is, however, customary not to
refer to this small and functionally useless joint at all, and to call the
claw-joint the fourth; when the little joint is referred to it may be
called the true fourth joint.
Nearly the whole of the enormous number of species of this series are
directly dependent on the vegetable kingdom for their nutriment; they are
therefore well styled Phytophaga. This term is, however, restricted by some
systematists to the family we have called Chrysomelidae. Although there is
enormous variety in this series, three families only can be at all
naturally distinguished, and this with difficulty. Of these the Bruchidae
are seed-feeders, the Chrysomelidae, as a rule, leaf-feeders, the
Cerambycidae wood and stem-feeders. The number of exceptions to this rule
is but small, though certain Cerambycidae and certain Chrysomelidae live on
roots.
FAM. 77. BRUCHIDAE.—_Prosternum extremely short; in front perpendicular;
behind the coxae, forming merely a transverse lamina with pointed
extremity. Hind femora more or less {277}thickened._ This comparatively
small family includes about 700 species of small, unattractive beetles. The
larvae live in seeds; hence some of the species are liable to be
transported by means of commerce; some of them do considerable injury; peas
and beans being specially subject to their attacks. They are able to
complete their growth with a very small amount of nutriment, some of them
consuming only a portion a little larger than themselves of a bean or pea.
The larvae are fat maggots without legs, but Riley has discovered that the
young larvae of _Bruchus pisi_ and _B. fabae_ have, when first hatched,
three pairs of legs which are subsequently lost. They also have peculiar
spinous processes on the pronotum. Both of these characteristics may be
correlative with the transient differences in the activities of the larva,
for the little creature is not at first located in the pea, but mines a
gallery in the pod, in which it moves about, subsequently entering the pea
and losing its legs. There is a good deal of difference in these respects
between the two species—_B. pisi_ and _B. fabae_—examined by Riley, and as
but little is known of the life-histories of other Bruchidae it is probable
that still greater variety prevails. Heeger has found that _Bruchus lentis_
sometimes requires two seeds to enable it to complete its growth; it is,
notwithstanding its legless state when half-grown, able to migrate by
dropping to the earth, and dragging itself along by its mandibles till it
comes to another pod into which it bites its way.
[Illustration: Fig. 141—_Bruchus pisi_ or pea-weevil. A, Young larva; B,
prothoracic spinous process; C, post-embryonic leg, greatly magnified; D,
pea-pod, with tracks of entry; E, portion of pod, with egg, and the
subsequently formed track, magnified; F, imago. (After Riley.)]
The family has, until recently, been placed in the {278}Rhynchophorous
series, with which it has, however, no direct connection. On the other
hand, it is so closely connected with Chrysomelidae that it is not possible
to indicate good characters to distinguish the two at present. The
Australian genus _Carpophagus_, and the large South American species of
_Caryoborus_ appear to be quite indistinguishable as families, though
Lacordaire and Chapuis placed one in Bruchidae, the other in Chrysomelidae.
The definition we have given applies, therefore, to the majority of the
family, but not to the aberrant forms just mentioned. The European genus
_Urodon_ appears to belong to Anthribidae, not to Bruchidae. The family
Bruchidae is called Mylabridae by some.
FAM. 78. CHRYSOMELIDAE.—_Antennae moderately long; eyes moderately large,
usually not at all surrounding the insertion of the antennae; upper surface
usually bare, frequently brightly coloured and shining._ This enormous
family comprises about 18,000 species of beetles, in which the form and
details of structure are very varied. No satisfactory character for
distinguishing Chrysomelidae from Cerambycidae has yet been discovered,
although the two families are certainly distinct and natural. Most of the
Chrysomelidae live on foliage; few of them are more than half an inch long,
whereas the Cerambycidae are wood-feeders and usually of more elongate form
and larger size. The potato beetle, or Colorado beetle, that occasioned so
much destruction in North America some thirty years ago, and the
introduction of which into Europe was anticipated with much dread, is a
good example of the Chrysomelidae. The turnip flea, a tiny hopping beetle,
is among the smallest forms of the family, and is a member of another very
extensive subdivision of Chrysomelidae, viz. Halticides. The term
Phytophaga is by many naturalists limited to Chrysomelidae, the
Cerambycidae being excluded. The classification of the family is but little
advanced, but the enormous number of species of Chrysomelidae are placed in
four divisions, viz.:—
[Illustration: Fig. 142—_Doryphora decemlineata_, the potato beetle. North
America. A, Imago; B, hind-tarsus. 3, third joint; 4, true fourth joint; 5,
so-called fourth joint.]
{279}Prothorax much narrower at the base than the elytra, and usually
without side-margins (raised edges). Sub-fam. 1. Eupoda; with three
divisions, Sagrides, Donaciides, Criocerides.
The basal ventral plates of the abdominal segments are somewhat shorter
in the middle than at the sides, the fourth one being often invisible in
the middle, while the fifth is very large. Sub-fam. 2. Camptosomes; with
six divisions, Megascelides, Megalopides, Clythrides, Cryptocephalides,
Chlamydes, Sphaerocarides.
In the other two groups there is no great disparity between the fourth
and fifth ventral plates.
Prothorax not greatly narrower at the base than the elytra, and usually
with distinct edges at the outsides. Sub-fam. 3. Cyclica; with four
divisions, Lamprosomides, Eumolpides, Chrysomelides, Galerucides.
Front of the head bent downwards or inflexed, so that the mouth is on the
lower aspect. Antennae inserted close together on the most anterior part
of the head, so that they are more forward than the mouth. Sub-fam. 4.
Cryptostomes; with two divisions Hispides, Cassidides.
In the other three divisions the mouth is placed as usual, but the
insertion of the antennae varies a good deal.
The larvae of about 100 species of the family are known; they are arranged
in accordance with their habits, by Chapuis,[145] in six groups, viz.:
1. Elongate larvae, living under water, and there undergoing their
metamorphosis. (Donaciides.)
2. Larvae mining in leaves, and undergoing their metamorphosis in the
leaf. (Hispides and some Halticides.)
3. Short convex larvae, frequently with leathery and pigmented
integuments, living exposed on plants. (Most of the Cyclica.)
4. Larvae of short form; covering the body with excrementitious matter.
(Some Criocerides.)
5. Peculiar larvae of short form, spiny, and protecting their bodies by
excrementitious matter attached by a special apparatus, the excrement
itself being modified so as to be suitable for retention. (Cassidides.)
6. Elongate, pallid, larvae with curved abdomen; living in shell-like
cases, and undergoing metamorphosis therein. (Most of the Camptosomes,
the habits of which are known.)
Though our knowledge of these larvae extends to only about 100 out of
18,000 species, the above category by no means includes all the kinds of
larvae; Captain Xambeu having recently discovered that the larva of
_Chrysochus pretiosus_ lives in the earth feeding on roots after the manner
of a _Rhizotrogus_ larva, which it resembles. The larva of _Sagra
splendida_ lives {280}inside the stems of _Dioscorea batatas_, in
swellings; the group Sagrides, to which it belongs, is a very anomalous
one.
i. Eupoda. The beetles of the genus _Donacia_ are of special interest. They
form, with the genus _Haemonia_, a peculiar group, well represented in
Europe, and also in our own country. They are all connected with aquatic
plants, the species of _Haemonia_ living entirely under water, while the
_Donacia_ live in the imago-state an aërial life, though many of them enter
the water with great readiness, and, it is said, are able to take wing from
the surface. The larvae live on the roots of aquatic plants, and derive not
only nutriment but air therefrom; they pass several months as pupae (or as
resting larvae waiting for pupation), under water in cocoons which they
construct, and which, incredible as it may seem, are filled with air, not
water. Exact details as to the construction of these cocoons are wanting.
It was formerly absurdly supposed that the larva swelled itself out to the
size of the cocoon it was about to make, and so served as a mould,
subsequently contracting. The observations of Schmidt-Schwedt[146] make it,
however, more probable that the plant itself furnishes the air which, under
pressure of the water (so he supposes), fills the cocoon; the larva wounds
the root, piercing to an air-vessel and then constructs the cocoon on this
spot, leaving to the last moment an orifice, according to Schmidt, as an
exit for the water. The larva uses a similar artifice for obtaining air; it
has no gills, but is provided near the extremity of the body with two sharp
chitinous processes which it drives into the root of the plant till it
penetrates an air-vessel. Schmidt thinks the processes serve as conduits to
conduct the air to the tracheae, but Dewitz thinks the air enters the larva
in a more normal manner, by means of a stigma placed at the base of the
piercing process. A similar larva exists in _Haemonia_; which genus is
additionally interesting from the fact that the imago lives entirely
submerged. It is not known how it breathes. This genus is the only member
of the Chrysomelidae that does not possess the structure of the feet that
is characteristic of the Phytophaga. The late Professor Babington about
sixty years ago found _H. curtisi_ at Cley on the Norfolk coast on
submerged _Potamogeton pectinatus_, but it has not been met with there for
a great many years.
The larvae of Criocerides are of two kinds, in one of which the {281}body
is peculiarly shaped in conformity with the curious habit of using the
excrement as a covering. The larva is less elongate than usual, and has the
anus placed on the upper surface, and formed so that the excrement when
voided is pushed forward on to the Insect; here it is retained by means of
a slimy matter, and a thick coat entirely covering the creature, is
ultimately formed. The larva of _Lema melanopa_ is not uncommon about
Cambridge, where it feeds on the leaves of growing corn. It is a remarkable
fact that even in one genus the species have some of them this habit, but
others not. The species of _Crioceris_ living on lilies—_C. merdigera_,
_e.g._—are noted for possessing it; while _C. asparagi_ does not protect
itself in this way, but emits fluid from its mouth when disturbed. This
larva is a serious nuisance in some localities to the cultivators of
asparagus. The eggs are deposited on the stems of the plant—as shown in our
figure—sometimes in great numbers.
The perfect Insects of many of the Criocerides possess a stridulating
organ. Two contiguous areas at the base of the last dorsal segment, where
they can be rubbed by the tips of the elytra, are slightly elevated and
bear very close and fine straight lines.
[Illustration: Fig. 143—_Crioceris asparagi._ A, Eggs in position on stem
of asparagus; B, one egg much enlarged; C, young larva. Cambridge.]
ii. The Camptosomes, as we have already noticed, are distinguished by a
peculiar structure of the abdomen. This character appears to be connected
with a very remarkable habit, viz. the formation of a case to envelop the
egg. The tip of the abdomen is somewhat curved downwards, and, in the
female, bears a hollow near the extremity; when an egg is extruded the
female holds it in this hollow by means of the hind legs, and envelops it
with a covering said to be excrementitious. When the larva hatches, it
remains within this case, and {282}subsequently enlarges it by additions
from its own body. The beautiful Insects of the genus _Cryptocephalus_,
which is fairly well represented in Britain, belong to this division. The
exotic group Megalopodes is incorrectly placed in Camptosomes; the side
pieces of the prothorax meet in it behind the middle coxae, as they do in
Rhynchophora. The species of Megalopodes stridulate by means of an area on
the base of the meso-scutellum rubbed by a ridge inside the pronotum, as in
the Cerambycidæ.
iii. The division Cyclica includes the great majority of Chryomelidae; we
have not less than 170 species in Britain. The larvae live, like those of
Lepidoptera, at the expense of foliage, and the species frequently multiply
to such an extent as to be injurious. Some of them are destroyed in great
numbers by Hymenopterous parasites, the Braconid genus _Perilitus_ being
one of the best known of these; in some cases the parasite deposits its
eggs in either the larva or perfect Insect of the beetle, and the
metamorphoses of the parasites in the latter case are sometimes, if not
usually, completed, the larvae emerging from the living beetles for
pupation.
iv. The Cryptostomes, though comparatively few in number of species,
include some very remarkable beetles. There are two groups, Hispides and
Cassidides. The former are almost peculiar to the tropics and are not
represented by any species in the British fauna. The head in this group is
not concealed; but in the Cassidides the margins of the upper surface are
more or less expanded, so that the head is usually completely hidden by the
expansion of the pronotum. Both the groups are characterised by the
antennae being inserted very near together, and by the short claw-joint of
the feet. _Hispa_ is one of the most extensive of the numerous genera of
Hispides, and is remarkable from the imago being covered on the surface
with long, sharp spines. But little is known as to the metamorphosis,
beyond the fact already alluded to, that the larvae of several species mine
the interior of leaves. The larva of _Hispa testacea_, according to
Perris,[147] makes use of the leaves of _Cistus salvifolius_ in Southern
Europe; it is broad and flat, and possessed of six short legs. The eggs are
not deposited by the parents inside the leaves, but are probably attached
to various parts of the plant. After hatching, the young larva enters a
leaf, and feeds on the parenchyma without rupturing {283}the epidermis; but
when it has consumed about three-fourths of the soft interior of the leaf
it ruptures the epidermis of the upper surface, and seeks another leaf;
this found, it places itself on the midrib, tears the upper epidermis, and
lodges itself in the leaf. In the case of this second leaf it attacks the
parenchyma in the neighbourhood of the petiole, and so forms an irregular
tube which has an open mouth, the point of entry. In this tube it undergoes
its metamorphosis. Each larva, it is said, always makes use of two leaves,
and of two opposed leaves. A knowledge of the habits of some of the larger
of the exotic Hispides would be of much interest.
[Illustration: Fig. 144—Pupa of Cassidid beetle (? _Aspidomorpha_ sp.). A,
With appendage extended; B, with the appendage reposing on the back. New
Britain.]
The Cassidides, in addition to the curious marginal expansion of their
upper surface, have the power of withdrawing the head into the thorax, and
hence they are often called shield or tortoise-beetles. They exhibit
considerable variety in form and colour, and some of them display a
peculiar metallic reflection of great delicacy and beauty; this disappears
entirely after death, but it may be restored by thoroughly moistening the
dead Insect. The colour, therefore, probably depends on the presence of
water in the integument. The larvae of Cassidides are notorious on account
of their habit of covering their bodies with dried excrement, for which
purpose they are provided with a forked {284}process at the posterior
extremity; this serves to place the protecting matter in a proper position
and to retain it there. The excrement assumes in various species forms so
peculiar that they cannot be considered merely incidental. In several
species this covering-matter is like lichen. This is the case with
_Dolichotoma palmarum_, the larva of which has, in place of the usual fork,
a more complex appendage on the back for the purpose of preparing and
retaining its peculiar costume. The pupae, too, sometimes retain the larval
skin. An extremely remarkable pupa of a Cassidid—possibly of the genus
_Aspidomorpha_—was recently found by Dr. Arthur Willey in New Britain (Fig.
144). The back of the pupa is covered with a complex appendage, so that the
creature has no resemblance to an Insect; this appendage is perhaps capable
of being moved, or even extended (Fig. 144, A), during life. Whether it may
be formed by the retention of portions of the moulted skins of the larva we
cannot say with certainty.
[Illustration: Fig. 145—Nest of intestinally-made filaments under which the
larva of _Porphyraspis tristis_ lives.]
The most remarkable of the Cassidid coverings yet discovered are those
formed by certain small beetles of the tropical American genus
_Porphyraspis_. _P. tristis_ is apparently a common Insect at Bahia, where
it lives on a cocoa-palm. The larva is short and broad, and completely
covers itself with a very dense coat of fibres, each many times the length
of the body, and elaborately curved so as to form a round nest under which
the larva lives. On examination it is found that these long threads are all
attached to the anal extremity of the Insect, and there seems no
alternative to believing that each thread is formed by small pieces of
fibre that have passed through the alimentary canal, and are subsequently
stuck together, end to end. The process of forming these long fibres, each
one from scores of pieces of excrement, and giving them the appropriate
curve, is truly remarkable. The fibres nearest to the body of the larva are
abruptly curled so as to fit exactly, and make an even surface; but the
outside fibres stand out in a somewhat bushy fashion. The construction is
much like that of a tiny bird's nest. Señor Lacerda informed the writer
that the larva makes a nest as soon as it is hatched. Another
_Porphyraspis_—_P. palmarum_—has been recorded as {285}forming similar
nests on a species of _Thrinax_ in St. Domingo. Candèze says[148] that when
it has completed its growth the larva ejects on to the leaf a quantity of
semi-liquid matter, and this, on drying, sticks the nest to the leaf, so
that the metamorphosis is effected under shelter.
FAM. 79. CERAMBYCIDAE (_Longicorns_).—_Form usually oblong, not much curved
in outline at the sides; surface very frequently rendered dull by a very
minute hairiness, which often forms a pattern; antennae usually long, and
their insertion much embraced by the eyes._ This great family of beetles
includes some 12,000 or 13,000 known species. The elegance and variety of
their forms and the charm of their colours have caused them to attract much
attention, so that it is probable that a larger proportion of the existing
species have been obtained than is the case in any other of the great
families of Coleoptera. Still it is not likely that one-half of the living
forms are known. It is not possible at present to point out any one
character of importance to distinguish Cerambycidae from Chrysomelidae,
though the members of the two families have, as a rule, but little
resemblance in external appearance. Most of them live on, or in, wood,
though many are nourished in the stems of herbaceous plants. The larvae
live a life of concealment, and are soft, whitish grubs with powerful
mandibles, and usually with a comparatively small head, which is not much
exserted from the thorax. Most of them are without legs, but a good many
have three pairs of small legs, and there are numerous cases in which the
surface of the body is furnished above or below with swellings believed to
act as pseudopods (Fig. 84), and help the larvae to move about in their
galleries; but this is probably not the sole function of these organs, as
their surface is varied in character, and often not of a kind that appears
specially adapted to assist in locomotion. There is a slight general
resemblance between the larvae of Cerambycidae and those of Buprestidae,
and when the thorax of a Longicorn larva is unusually broad, _e.g._
_Astynomus_, this similarity is very pronounced.
[Illustration: Fig. 146—_Saperda populnea._ Britain.]
{286}The modes of life of Cerambycid larvae exhibit considerable variety,
and much perfection of instinct is displayed by the larvae, as well as by
the mother beetles. The larvae of _Saperda populnea_, are common in certain
woods in the South of England in the stems of aspen; they consume only a
small quantity of the interior of the stem, and are probably nourished by
an afflux of sap to the spot where they are situated. _Elaphidion villosum_
is called the oak-pruner in North America. The parent beetle lays an egg
near the axilla of a leaf-stalk or small stem, and the young larva enters
this and feeds on the tender material; as it grows it enters a larger limb,
and makes an incision within this in such a manner that the wood falls to
the ground with the larva within it, the dead wood serving subsequently as
pabulum and as a shelter, within which the metamorphosis is completed. The
species of the American genus _Oncideres_ are called girdlers, because the
parent beetle, after laying an egg in a small branch, girdles this round
with a deep incision, so that the portion containing the larva sooner or
later falls to the ground. The growth of a Longicorn larva frequently takes
more than a year, and under certain circumstances it may be enormously
prolonged. _Monohammus confusus_ has been known to issue from wooden
furniture in a dwelling-house when the furniture was fifteen years old.
Individuals of another Longicorn have issued from the wood of a table,
twenty and even twenty-eight years after the felling of the tree from which
the furniture was made. Sereno Watson has related a case from which it
appears probable that the life of a Longicorn beetle extended over at least
forty-five years.[149] It is generally assumed that the prolongation of
life in these cases is due to the beetle resting quiescent for long after
it has completed the metamorphosis. Recent knowledge, however, renders it
more probable that it is the larval life that is prolonged; the larva
continuing to feed, but gaining little or no nutriment from the dry wood in
these unnatural conditions. Mr. C. O. Waterhouse had for some years a
Longicorn larva under observation, feeding in this way in the wood of a
boot-tree;[150] the burrows in the wood contained a great deal of minute
dust indicating that the larva passed much matter through the alimentary
canal, probably with little result in the way of nutriment.
{287}There are numerous Longicorns that bear a great resemblance in form
and colour to Insects to which they are not related. Haensch[151] has
noticed that species of the genus _Odontocera_ resemble various
Hymenoptera, one species being called _O. braconoides_; he also observed
that these Hymenoptera-like Longicorns, instead of withdrawing their
underwings under the elytra as beetles generally do, vibrate them rapidly
like Hymenoptera. A large number of Longicorns stridulate loudly by rubbing
a ridge inside the pronotum on a highly specialised, striate surface at the
base of the scutellum, and therefore covered up when the Insect is
contracted in repose. A few produce noise by rubbing the hind femora
against the edges of the elytra, somewhat after the fashion of
grasshoppers. In this case there appears to be comparatively little
speciality of structure, the femora bearing, however, more or less distinct
small granules. The species of the Hawaiian genus _Plagithmysus_ produce
sound in both these manners, the thoracic stridulating organ being
beautifully developed, while in some species the margin of the elytra and
base of the femora are also well adapted for the purpose of
sound-production, and in a few species of the genus there are also
highly-developed stridulating surfaces on the hind and middle coxae. This
is the only case in which a beetle is known to possess more than one set of
sound-organs in the imago state.
Three divisions of this family are distinguished, viz.—
1. Front coxae large and transverse; prothorax with distinct side
margins. Sub-fam. 1. Prionides.
2. Front coxae not greatly extended transversely, thorax not margined;
last joint of maxillary palpus not pointed, usually broader (more or
less) than the preceding joint. Sub-fam. 2. Cerambycides.
3. Front coxae usually round and deeply embedded; last joint of maxillary
palpus pointed; front tibiae with a more or less distinct, slanting
groove on the inner side. Sub-fam. 3. Lamiides.
The Prionides are on the average considerably larger in size than the
members of the other divisions, and they include some of the largest of
Insects. The Amazonian _Titanus giganteus_ and the Fijian _Macrotoma heros_
are amongst the most gigantic. Some of the Prionides have a great
development of the mandibles in the male sex analogous to that we have
already noticed in Lucanidae. The larvae of the large Prionides appear in
various parts of the world to have been a favourite food with native
{288}tribes, and Lumholz states that they are really good eating. In
consequence of the destruction of forests that has progressed so largely of
late years these gigantic Prionides have become much rarer.
Several aberrant forms are included in Prionides. The genus _Parandra_ has
five-jointed tarsi; the third joint being much smaller than usual, so that
the fourth joint is not concealed by it. The Brazilian _Hypocephalus
armatus_ was for long a subject of dispute as to its natural position, and
was placed by different authorities in widely-separated families of
Coleoptera. The structure of this aberrant Longicorn seems to be only
explicable on the hypothesis of warfare amongst the males.[152] Nothing is,
however, known as to the habits and history of the Insect, and only one or
two specimens of the female have yet been obtained.
The family Spondylidae has been proposed for some of these aberrant
Longicorns, but as it includes but very few, and highly discrepant,
species, it is neither natural nor of much use for systematic purposes.
The Lamiides are the most highly specialised division of the Longicorns,
and includes the larger number of the species. The front of the head is
usually placed at right angles to the vertex, and in some cases (groups
Hippopsini, Spalacopsini) it is strongly inflexed, so that the mouth is
placed on the under side of the head. The extension of the eyes round the
antennae is accompanied by very curious shapes of those organs, and not
infrequently each eye is divided into two more or less widely-separated
parts, so that the Insect has, on the external surface, four eyes.
SERIES VI. RHYNCHOPHORA.
_Head more or less prolonged in front to form a snout or beak, called
rostrum. Tarsi four-jointed, usually at least the third joint broad and
densely pubescent beneath._
This enormous series includes about 25,000 species, and as may well be
imagined shows a great variety of structure amongst its forms. The vast
majority may, however, be readily recognised by the two characters
mentioned above. There are some cases in which the beak is indistinct, and
others in which the tarsi are {289}five-jointed (_Dryophthorus_), and even
slender (Platypides). In these cases a close examination shows that the
gular region on the middle of the back of the under surface of the head
cannot be detected, and that the back of the prosternum is very strongly
consolidated by the side-pieces of the thorax meeting together and being
very firmly joined behind the coxae. The beak is in the great majority
perfectly distinct, though it varies so extremely in form that it can only
be briefly described by saying that it is a prolongation of the head in
front of the eyes, or that the antennae are inserted on its sides near to,
or far from, the tip. It has been ascertained in many cases that the
rostrum is used by the female to assist in placing the eggs in suitable
places, a hole being bored with it; in some cases it is also used to push
the egg far into the hole in which it has previously been placed by the
ovipositor; but there are many forms in which it is fairly certain that it
is not so used. What purpose it serves in the male is totally unknown. In
many members of the series, the rostrum differs in form in the two sexes,
and in most, if not in all, these cases it is clear that the distinctions
tend in the direction of making the beak of the female more efficient for
the mechanical purpose we have mentioned.
[Illustration: Fig. 147.—_Eugnoristus monachus_ ♀. Madagascar. A, The
imago; B, front of pronotum, head, and rostrum.]
It was proposed by Leconte and Horn to separate this series from all the
other Coleoptera as a primary division, and they looked on it as of lower
or more imperfect structure. Packard has very properly protested against
this interpretation; and there seems to be no reason whatever for
considering the Rhynchophora as "lower" than other beetles; indeed we
should be inclined to place such forms as Calandrides {290}amongst the most
perfect of Insects; their external structure (as shown by _Eugnoristus
monachus_, Fig. 147) being truly admirable.
Only four families of Rhynchophora can be at present accepted as
satisfactory; one of these—Curculionidae—includes an enormous majority of
the whole series. Though it is probable that it will ultimately be divided
into several families, the attempts to that end that have already been made
are not satisfactory.
FAM. 80. ANTHRIBIDAE.—_Palpi usually not covered, but distinct and
flexible. Antennae often long, not elbowed, the first joint not very long.
Third joint of tarsus small, usually much concealed by being embraced by
the second joint. Pygidium exposed; propygidium deeply grooved in the
middle._ This family includes 800 or more species, which are mostly
tropical; it is very sparsely represented in the faunas of Europe and North
America. It is quite distinct from Curculionidae with which it was formerly
associated. It contains many graceful Insects having a certain resemblance
with Longicorns on account of the large development of the antennae. The
habits and metamorphoses are but little known. It seems probable that many
species find their nutriment in old wood or boleti The larvae of some
genera (_Cratoparis_ and _Araeocerus_) have legs, but in others the legs
are wanting, and the larvae are said to completely resemble those of
Curculionidae. In the larva of our tiny British species, _Choragus
sheppardi_, the legs are replaced by three pairs of thoracic, sac-like
pseudopods. This Insect makes burrows in dead branches of hawthorn. The
larvae of the genus _Brachytarsus_ have been ascertained to prey on
Coccidae.
[Illustration: Fig. 148—_Platyrhinus latirostris_, Anthribidae. Britain. A,
the perfect Insect; B, tarsus and tip of tibia.]
FAM. 81. CURCULIONIDAE (Weevils).—_The beak of very variable length and
thickness; the palpi small, nearly always concealed within the mouth,
short, and rigid. Labrum absent. Antennae of the majority elbowed,_ i.e.
_with the basal joint longer, and so formed that when it is laterally
extended the other joints can be placed in a forward direction._ This
enormous family includes {291}about 20,000 known species, and yet a large
portion of the species yearly brought from the tropics still prove to be
new. The rostrum or beak exhibits excessive variety in form, and is in many
cases different in the sexes; in this case it is usually longer and thinner
in the female. As the rostrum is one of the chief characters by which a
member of the family may be recognised, it is necessary to inform the
student that in certain forms (the Australian Amycterides, _e.g._) the
organ in question may be so short and thick that it is almost absent. In
these cases the Insect may be identified as a Curculionid by the gular area
being absent on the under side of the head, and by the concealment of the
palpi. The tarsi are usually of the same nature as those of Phytophaga,
already described, but the true fourth joint is less visible. In the
Brachycerides this joint is not present, and the third joint is not lobed.
The palpi are flexible and more or less exserted in a very few species
(Rhynchitides); in Rhinomacerides there is also present a minute labrum.
The front coxae are deeply embedded, and in many forms the prosternum is
peculiar in structure; the side-pieces (epimera) meeting at the back of the
prosternum in the middle line. This, however, is not universal in the
family, and it occurs in some other beetles (_e.g._, Megalopodides of the
Phytophaga). The larvae are without legs. They are vegetarian, the eggs
being deposited by the mother-beetle in the midst of the food. These larvae
may be distinguished from those of Longicorns by the general form, which is
sub-cylindric or rather convex, not flattened, and more particularly by the
free, exserted head, the mouth being directed downwards; the attitude is
generally a curve, and the anterior part of the body is a little the
thicker. No part of plants is exempt from the attacks of the larvae of
Curculionidae; buds, twigs, leaves, flowers, fruits, bark, pith, roots and
galls may each be the special food of some Curculionid. Certain species of
the sub-families Rhynchitides and Attelabides prepare leaves in an
elaborate manner to serve as food and dwelling for their young. If young
birches, or birch bushes from 5 to 10 feet in height, be looked at in the
summer, one may often notice that some of the leaves are rolled so as to
form, each one, a little funnel. This is the work of _Rhynchites_ (or
_Deporaus_) _betulae_, a little Curculionid beetle (Fig. 149). An
inspection of one of these funnels will show that it is very skilfully
constructed.
{292}[Illustration: Fig. 149.—The leaf-rolling of _Rhynchites betulae_.
Britain. A, Female beetle, magnified; B, the beetle forming the first
incision on a leaf; C, the completed roll. (B and C after Debey.)]
The whole of a leaf is not used in the formation of a funnel, cuts being
made across the leaf in suitable directions. The beetle standing on a leaf,
as shown in the figure, proceeds to cut with its mandibles an incision
shaped like an erect S, commencing at a certain part of the circumference,
and ending at the midrib of the leaf; the beetle then goes to the other
side of the midrib, and continues its incision so as to form another S-like
curve considerably different from the first; being prostrate and less
abrupt. Thus the blade of the leaf is divided into two halves by certain
curved incisions, the midrib remaining intact. The little funnel-twister
now commences to roll up the leaf to form the funnel; and this part of the
work is greatly facilitated by the shape of the incisions. Going back to
the spot where it commenced work, by the aid of its legs it rolls one side
of the leaf round an ideal axis, somewhat on the same plan as that adopted
by a grocer in forming a paper-funnel for sugar. The incisions are found to
be just of the right shape to make the overlaps in the rolling, and to
retain them rolled-up with the least tendency to spring back. After some
other operations destined to facilitate subsequent parts of its task, the
beetle enters the rolled-up part of the leaf and brings it more perfectly
together; it again comes out and, pursuing a different system, holds on
with the legs of one side of the body {293}to the roll, and with the other
legs drags to it the portion of the leaf on the other side of the midrib so
as to wrap this part (_i.e._ the result of its second incision) round the
part of the funnel already constructed. This being done the Insect again
enters the funnel, bites three or four small cavities on the inside of the
leafy wall and deposits an egg in each. Afterwards it emerges and fits the
overlaps together in a more perfect manner so as to somewhat contract the
funnel and make it firmer; then proceeding to the tip, this is operated on
by another series of engineering processes and made to close the orifice;
this part of the operation being analogous to the closing by the grocer of
his paper-funnel after the sugar has been put in. The operation of the
beetle is, however, much more complex, for it actually makes a sort of
second small funnel of the tip of the leaf, bends this in, and retains it
by tucking in some little projections. The work, which has probably lasted
about an hour, being now completed, the creature takes a longer or shorter
rest before commencing another funnel. We have given only a sketch of the
chief points of the work, omitting reference to smaller artifices of the
craft master; but we may remark that the curved incisions made by the
beetle have been examined by mathematicians and duly extolled as being
conducted on highly satisfactory mathematical principles. It is impossible
at present for us to form any conception as to the beetle's conceptions in
carrying out this complex set of operations. Our perplexity is increased if
we recollect its life-history, for we then see that neither precept or
example can have initiated its proceedings, and that imitation is out of
the question. The eggs hatch in their dark place, giving rise to an eyeless
maggot, which ultimately leaves the funnel for the earth. The parts of this
maggot subsequently undergo complete change to produce the motionless pupa
of entirely different form, from which emerges the perfect Insect. Hence
the beetle cannot be considered to have ever seen a funnel, and certainly
has never witnessed the construction of one, though, when disclosed, it
almost immediately sets to work to make funnels on the complex and perfect
system we have so imperfectly described. More general considerations only
add to the perplexity we must feel when reflecting on this subject. Why
does the Insect construct the funnel at all? As a matter of protection it
appears to be of little use, for the larvae are known to suffer from the
attacks {294}of parasites as other Insects do. We have not the least reason
for supposing that this mode of life for a larva is, so far as utility is
concerned, better than a more simple and usual one. Indeed, extraordinary
as this may appear, it is well known that other species of the same genus
adopt a simple mode of life, laying their eggs in young fruits or buds. We
think it possible, however, that a knowledge of the mode of feeding of this
larva may show that a more perfect nutrition is obtained from a
well-constructed cylinder, and if so this would to a slight extent satisfy
our longing for explanation, though throwing no light whatever on the
physiology or psychology of the artificer, and leaving us hopelessly
perplexed as to why a beetle in ages long gone by should or could adopt a
mode of life that by long processes of evolution should, after enormous
difficulties have been overcome, attain the perfection we admire.[153]
FAM. 82. SCOLYTIDAE.—_Rostrum extremely short, broad; tibiae frequently
denticulate externally; antennae short, with a broad club._ This family is
not at all sharply distinguished from certain groups of Curculionidae (from
Cossonides _e.g._), but as the species have somewhat different habits, and
in the majority of cases can be readily distinguished, it is an advantage
to separate the two families. About 1400 species are at present known. Most
of them are wood- and bark-feeders; some bore into hard wood; a few mine in
twigs or small branches of trees, but the majority live in the inner layers
of the bark; and this also serves as the nidus of the larvae. A small
number of species have been found to inhabit the stems of herbaceous
plants, or to live in dry fruits. Owing to their retiring habits they are
rarely seen except by those who seek them in their abodes, when they may
often be found in great profusion. The mother-beetle bores into the
suitable layer of the bark, forming a sort of tunnel and depositing eggs
therein. The young larvae start each one a tunnel of its own, diverging
from the parent tunnel; hence each batch of larvae produces a system of
tunnels, starting from the parents' burrow, and in many species these
burrows are {295}characteristic in form and direction, so that the work of
particular Scolytids can be recognised by the initiated.
The Platypides bore into the wood of trees and stumps; they are chiefly
exotic, and little is known about them. They are the most aberrant of all
Rhynchophora, the head being remarkably short, flat in front, with the
mouth placed on the under surface of the head, there being no trace of a
rostrum: the tarsi are elongate and slender, the third joint not being at
all lobed, while the true fourth joint is visible. Hence they have not the
appearance of Rhynchophora. Some authorities treat the Platypides as a
distinct family.
Some of the members of the group Tomicides also bore into the wood. Recent
observations have shown that there is an important feature in the economy
of certain of these wood-borers, inasmuch as they live gregariously in the
burrow, and feed on peculiar fungi that develop there, and are called
ambrosia. According to Hubbard[154], some species cultivate these fungi,
making elaborate preparations to start their growth. The fungi, however,
sometimes increase to such an extent as to seal up the burrows, and kill
the Insects by suffocation.
Scolytidae sometimes multiply to an enormous extent, attacking and
destroying the trees in wooded regions. Much discussion has taken place as
to whether or not they are really injurious. It is contended by one set of
partisans that they attack only timber that is in an unhealthy, dying, or
dead condition. It may be admitted that this is usually the case; yet when
they occur in enormous numbers they may attack timber that is in a sort of
neutral state of health, and so diminish its vigour, and finally cause its
destruction. Hence it is of great importance that they should be watched by
competent foresters.
The larvae of Scolytidae are said to completely resemble those of
Curculionidae: except in the group Platypides, where the body is straight
and almost cylindrical, and terminates in an oblique truncation bearing a
short hard spine.[155]
FAM. 83. BRENTHIDAE.—_Form elongate; rostrum straight, directly continuing
the long axis of the body, often so thick as to form an elongate head;
antennae not elbowed._ The Brenthidae form a family of about 800 species,
remarkable for the excessive {296}length and slenderness of some of its
forms, and for the extreme difference in the sexes that frequently exists.
It is well represented in the tropics only, and very little is known as to
the natural history and development. These beetles are stated to be
wood-feeders, and no doubt this is correct in the case of the majority of
the species; but Mr. Lewis observed in Japan that _Zemioses celtis_ and
_Cyphagogus segnipes_ are predaceous, and enter the burrows of wood-boring
Insects to search for larvae as prey: they are very much modified in
structure to permit this; and as the other members of the group
Taphroderides are similar in structure, it is probable that they are all
predaceous. Nothing whatever is known as to the larval history of these
carnivorous forms. Indeed an uncertainty, almost complete, prevails as to
the early stages of this family. Riley has given a sketch of a larva which
he had no doubt was that of _Eupsalis minuta_, the North American
representative of the family; if he is correct the larva differs from those
of Curculionidae by its elongate form, and by the possession of thoracic
legs: these, though small, are three-jointed. Descriptions, supposed to be
those of Brenthid larvae, were formerly published by Harris and
Motschoulsky; but it is now clear that both were mistaken.
[Illustration: Fig. 150—_Eupsalis minuta_. North America. A, Larva; B,
pupa; C, female imago; D, head of male. (After Riley.)]
In the higher forms of Brenthidae the rostrum of the female is perfectly
cylindrical and polished, and the mandibles are minute, hard, pointed
processes placed at its tip. This organ is admirably adapted to its
purpose; it being used for boring a hole in wood or bark, in which an egg
is subsequently deposited. The males in these cases are extremely
different, so that considerable curiosity is felt as to why this should be
so. In some cases their head is thick, and there may be no rostrum, while
large powerful mandibles are present.
In other cases the rostrum is slender, but of enormous length, so that it
may surpass in this respect the rest of {297}the body, although this itself
is so drawn out as to be quite exceptional in the Insect world:[156] the
antennae are inserted near the tip of the rostrum instead of near its base,
as they are in the female. The size of the males is in these cases usually
much larger than that of the female.[157] The males of some species fight;
they do not, however, wound their opponent, but merely frighten him away.
In _Eupsalis_ it appears that the rostrum of the female is apt to become
fixed in the wood during her boring operations; and the male then
extricates her by pressing his heavy prosternum against the tip of her
abdomen; the stout forelegs of the female serve as a fulcrum and her long
body as a lever, so that the effort of the male, exerted at one extremity
of the body of the female, produces the required result at the other end of
her body. The New Zealand Brenthid, _Lasiorhynchus barbicornis_, exhibits
sexual disparity in an extreme degree: the length of the male is usually
nearly twice that of the female, and his rostrum is enormous. It is at
present impossible to assign any reason for this; observations made at the
request of the writer by Mr. Helms some years ago, elicited the information
that the female is indefatigable in her boring efforts, and that the huge
male stands near by as a witness, apparently of the most apathetic kind.
COLEOPTERA OF UNCERTAIN POSITION.
There are three small groups that it is impossible at present to place in
any of the great series of beetles.
FAM. 84. AGLYCYDERIDAE.—_Tarsi three-jointed, the second joint lobed; head
not prolonged to form a beak._ The two most important features of
Rhynchophora are absent in these Insects, while the other structural
characters are very imperfectly known, many parts of the external skeleton
being so completely fused that the details of structure are difficult of
appreciation. Westwood considered the tarsi to be really four-jointed, but
it is not {298}at all clear that the minute knot he considered the third
joint is more than the articulation of the elongate terminal joint. The
family consists only of two or three species of _Aglycyderes_, one of which
occurs in the Canary Islands, and one or two in New Zealand and New
Caledonia. The former is believed to live in the stems of _Euphorbia
canariensis_; a New Zealand species has been found in connection with the
tree-ferna. _Cyathea dealbata_
[Illustration: Fig. 151—_Aglycyderes setifer_. Canary Islands. A, Imago; B,
tarsus according to Westwood; C, according to nature; D, maxilla; E,
labium.]
FAM. 85. PROTERHINIDAE.—_Tarsi three-jointed, the second joint lobed; head
of the male scarcely prolonged, but that of the female forming a definite
rostrum; maxillae and ligula entirely covered by the mentum._ As in the
preceding family the sutures on the under side of the head and prosternum
cannot be detected. The minute palpi are entirely enclosed in the buccal
cavity. There is a very minute true third joint of the tarsus, at the base
of the terminal joint, concealed between the lobes of the second joint. The
family consists of the genus _Proterhinus_; it is confined to the Hawaiian
Islands, where these Insects live on dead wood in the native forests. The
genus is numerous in species and individuals.
[Illustration: Fig. 152—_Proterhinus lecontei_. Hawaiian Islands. A, Male;
B, female; C, front foot, more magnified.]
STREPSIPTERA (or RHIPIPTERA, Stylopidae).—_Male small or minute; prothorax
extremely small; mesothorax moderate, the elytra reduced to small, free
slips; metathorax and wings very large; nervuration of the latter
radiating, without cross nervules. Female a mere sac, with one extremity
smaller and forming a sort of neck or head._
{299}[Illustration: Fig. 153.—Sexes of Strepsiptera. A, Male of _Stylops
dalii_ (after Curtis); B, female of _Xenos rossii_ (after von Siebold).]
These curious Insects are parasitic in the interior of other Insects, of
the Orders Hymenoptera and Hemiptera. Their structure and their
life-histories entitle them to be ranked as the most abnormal of all
Insects, and entomologists are not agreed as to whether they are aberrant
Coleoptera or a distinct Order. The newly-hatched larva is a minute
triungulin (Fig. 154), somewhat like that of _Meloe_; it fixes itself to
the skin of the larva of a Hymenopterous Insect, penetrates into the
interior, and there undergoes its metamorphoses, the male emerging to enjoy
a brief period of an abnormally active, indeed agitated, existence, while
the female never moves. It is important to note that these Strepsiptera do
not, like most other internal parasites, produce the death of their hosts;
these complete their metamorphosis, and the development of the parasite
goes on simultaneously with that of the host, so that the imago of the
Strepsipteron is found only in the imago of the host.[158] After the young
_Stylops_ has entered its host it feeds for a week or so on the fat-body
(apparently by a process of suction), then moults and assumes the condition
of a footless maggot, in which state it remains till growth is completed.
At the latter part of this period the history diverges according to sex;
the female undergoes only a slight metamorphic development of certain
parts, accompanied apparently by actual degradation of other parts; while
the male goes on to pupation, as is normal in Insects. (We may remark that
the great features of the development of the sexes are parallel with those
of Coccidae in Hemiptera.) When the Hymenopterous larva changes to a pupa,
the larva of the Strepsipteron pushes one extremity of its body between two
of the abdominal rings of its host, so that this extremity becomes
external, and in this position it completes its metamorphosis, the
{300}male emerging very soon after the host has become an active winged
Insect, while the female undergoes no further change of position, but
becomes a sac, in the interior of which young develop in enormous numbers,
finally emerging from the mother-sac in the form of the little triungulins
we have already mentioned. This is all that can be given at present as a
general account; many points of the natural history are still obscure,
others have been merely guessed; while some appear to differ greatly in the
different forms. A few brief remarks as to these points must suffice.
Bees carrying, or that have carried, Strepsiptera, are said to be
stylopised (it being a species of the genus _Stylops_ that chiefly infests
bees); the term is also used with a wider application, all Insects that
carry a Strepsipterous parasite being termed stylopised, though it may be a
Strepsipteron of a genus very different from _Stylops_ that attacks them.
The development of one or more Strepsiptera in an Insect usually causes
some deformity in the abdomen of its host, and effects considerable changes
in the condition of its internal organs, and also in some of the external
characters. Great difference of opinion prevails as to what these changes
are; it is clear, however, that they vary much according to the species,
and also according to the extent of the stylopisation. Usually only one
_Stylops_ is developed in a bee; but two, three, and even four have been
observed:[159] and in the case of the wasp, _Polistes_, Hubbard has
observed that a single individual may bear eight or ten individuals of its
Strepsipteron (_Xenos_, n. sp.?).
[Illustration: Fig. 154—Young larva of _Stylops_ on a bee's-hair. Greatly
magnified. (After Newport.)]
There is no exact information as to how the young triungulins find their
way to the bee-larvae they live in. Here again the discrepancy of opinion
that prevails is probably due to great {301}difference really existing as
to the method. When a _Stylops_ carried by an Insect (a Hymenopteron, be it
noted, for we have no information whatever as to Hemiptera) produces young,
they cover the body of the host as if it were powdered, being excessively
minute and their numbers very great; many hundreds, if not thousands, of
young being produced by a single _Stylops_. The species of the wasp genus
_Polistes_ are specially subject to the attacks of _Stylops_; they are
social Insects, and a stylopised specimen being sickly does not as a rule
leave the nest; in this case the _Stylops_ larva may therefore have but
little difficulty in finding its way to a Hymenopterous larva, for even
though it may have to live for months before it has the chance of attaching
itself to a nest-building female, yet it is clearly in the right
neighbourhood. The bee genus _Andrena_ has, however, quite different
habits; normally a single female makes her nest underground; but in the
case of a stylopised female it is certain that no nest is built, and no
larvae produced by a stylopised example, so that the young triungulins must
leave the body of the bee in order to come near their prey. They can be
active, and have great powers of leaping, so that it is perhaps in this way
possible for them to attach themselves to a healthy female bee.
[Illustration: Fig. 155.—Portion of early stages of _Xenos rossii_. (After
von Siebold.) A, Small male larva; B, small female larva; C, full-grown
male larva; D, full-grown female larva; E, the so-called "cephalothorax"
and adjacent segment of adult female. (The newly-hatched larva is very much
like that of _Stylops_ shown in Fig. 154.)]
We have still only very imperfect knowledge as to the structure and
development of Strepsiptera. Indeed but little information has been
obtained since 1843.[160] Before that time the mature female was supposed
to be a larva, and the triungulins found in it to be parasites. Although
the erroneous character of these views has been made clear, the problems
that have been suggested present great difficulties. Apparently the change
from the triungulin condition (Fig. 154) to the parasitic larvae (Fig. 155,
A, B) is extremely great and abrupt, and it appears also that during
{302}the larval growth considerable sexual differentiation occurs (Fig.
155, C, D); details are, however, wanting, and there exists but little
information as to the later stages. Hence it is scarcely a matter for
surprise that authorities differ as to which is the head and which the anal
extremity of the adult female. Von Siebold apparently entertained no doubt
as to the part of the female that is extruded being the anterior extremity;
indeed he called it a cephalothorax. Supposing this view to be correct, we
are met by the extraordinary facts that the female extrudes the head for
copulatory purposes, that the genital orifice is placed thereon, and that
the young escape by it. Meinert[161] contends that the so-called
cephalothorax of the adult is the anal extremity, and that fertilisation
and the escape of the young are effected by the natural passages, the
anterior parts of the body being affected by a complete degeneration.
Nassonoff, in controversion of Meinert, has recently pointed out that the
"cephalothorax" of the young is shown by the nervous system to be the
anterior extremity. It still remains, however, to be shewn that the
"cephalothorax" of the adult female corresponds with that of the young, and
we shall not be surprised if Meinert prove to be correct. The internal
anatomy and the processes of oogenesis appear to be of a very unusual
character, but their details are far from clear. Brandt has given some
particulars as to the nervous system; though he does not say whether taken
from the male or female, we may presume it to be from the former; there is
a supra-oesophageal ganglion, and near it a large mass which consists of
two parts, the anterior representing the sub-oesophageal and the first
thoracic ganglia, while the posterior represents two of the thoracic and
most of the abdominal ganglia of other Insects; at the posterior extremity,
connected with the other ganglia by a very long and slender commissure,
there is another abdominal ganglion.[162]
It is a matter of great difficulty to procure material for the prosecution
of this study; the fact that the instars to be observed exist only in the
interior of a few Hymenopterous larvae, which in the case of the bee,
_Andrena_, are concealed under ground; and in the case of the wasps,
_Polistes_, placed in cells in a nest of wasps, adds greatly to the
difficulty. It is therefore of interest to know that Strepsiptera occur in
Insects with incomplete {303}metamorphosis. They have been observed in
several species of Homoptera; and the writer has a large Pentatomid bug of
the genus _Callidea_, which bears a female Strepsipteron apparently of
large size. This bug[163] is abundant and widely distributed in Eastern
Asia, and it may prove comparatively easy to keep stylopised examples under
observation. Both v. Siebold and Nassonoff think parthenogenesis occurs in
Strepsiptera, but there appear to be no facts to warrant this supposition.
Von Siebold speaks of the phenomena of Strepsipterous reproduction as
paedogenesis, or pseudo-paedogenesis, but we must agree with Meinert that
they cannot be so classed.
The males of Strepsiptera live for only a very short time, and are very
difficult of observation. According to Hubbard the males of _Xenos_ dash
about so rapidly that the eye cannot see them, and they create great
agitation amongst the wasps in the colonies of which they are bred.
Apparently they are produced in great numbers, and their life consists of
only fifteen or twenty minutes of fiery energy. The males of _Stylops_ are
not exposed to such dangers as those of _Xenos_, and apparently live
somewhat longer—a day or two, and even three days are on record. The
individuals of _Andrena_ parasitised by _Stylops_ are apparently greatly
affected in their economy and appear earlier in the season than other
individuals; this perhaps may be a reason, coupled with their short lives,
for their being comparatively rarely met with by entomologists.
[Illustration: Fig. 156.—Abdomen of a wasp (_Polistes hebraeus_) with a
Strepsipteron (_Xenos_ ♀) in position, one of the dorsal plates of the
wasp's abdomen being removed. _a_, Projection of part of the parasite; _b_,
line indicating the position of the removed dorsal plate.]
It is not possible at present to form a valid opinion as to whether
Stylopidae are a division of Coleoptera or a separate Order. Von Siebold
considered them a distinct Order, and Nassonoff, who has recently discussed
the question, is also of that opinion.
{304}CHAPTER VI
LEPIDOPTERA—OR BUTTERFLIES AND MOTHS
ORDER VI. LEPIDOPTERA.
_Wings four; body and wings covered with scales usually variegate in
colour, and on the body frequently more or less like hair: nervures
moderate in number, at the periphery of one wing not exceeding fifteen,
but little irregular; cross-nervules not more than four, there being
usually only one or two closed cells on each wing, occasionally none.
Imago with mouth incapable of biting, usually forming a long coiled
proboscis capable of protrusion. Metamorphosis great and abrupt; the
wings developed inside the body; the larva with large or moderate head
and strong mandibles. Pupa with the appendages usually adpressed and
cemented to the body so that it presents a more or less even, horny
exterior, occasionally varied by projections that are not the appendages
and that may make the form very irregular: in many of the smaller forms
the appendages are only imperfectly cemented to the body._
Lepidoptera, or butterflies and moths, are so far as ornament is concerned
the highest of the Insect world. In respect of intelligence the Order is
inferior to the Hymenoptera, in the mechanical adaptation of the parts of
the body it is inferior to Coleoptera, and in perfection of metamorphosis
it is second to Diptera. The mouth of Lepidoptera is quite peculiar; the
proboscis—the part of the apparatus for the prehension of food—is
anatomically very different from the proboscis of the other Insects that
suck, and finds its nearest analogue in the extreme elongation of the
maxillae of certain Coleoptera, e.g. _Nemognatha_. {305}The female has no
gonapophyses, though in certain exceptional forms of Tineidae, there are
modifications of structure connected with the terminal segments, that have
as yet been only imperfectly investigated. As a rule, the egg is simply
deposited on some living vegetable and fastened thereto. Lepidoptera are
the most exclusively vegetarian of all the Orders of Insects; a certain
number of their larvae prey on Insects that are themselves filled with
vegetable juices (Coccidae, Aphidae) and a very small number (_Tinea_,
etc.) eat animal matter. In general the nutriment appears to be drawn
exclusively from the fluids of the vegetables, the solid matter passing
from the alimentary canal in large quantity in the form of little pellets
usually dry, and called frass. Hence the quantity of food ingested is
large, and when the individuals unduly increase in number, forest trees
over large areas are sometimes completely defoliated by the caterpillars.
[Illustration: Fig. 157.—Metamorphosis of a Lepidopteron (_Rhegmatophila
alpina_, Notodontidae). (After Poujade, _Ann. Soc. ent. France_, 1891.)
Europe. A, Egg; B, young larva, about to moult; C, adult larva; D, head and
first body-segment of adult larva, magnified; E, pupa, × 2/1; F, male moth
in repose; G, female moth in repose.]
Lepidoptera pass a larger portion of their lives in the pupal stage than
most other Insects do; frequently during nine months of the year the
Lepidopteron may be a pupa. In other Orders of {306}Insects it would appear
that the tendency of the higher forms is to shorten the pupal period, and
when much time has to be passed between the end of the feeding up of the
larva and the appearance of the imago, to pass this time as much as
possible in the form of a resting-larva, and as little as may be in the
form of a pupa; in Lepidoptera the reverse is the case; the resting-larva
period being usually reduced to a day or two. Hence we can understand the
importance of a hard skin to the pupa. There are, however, numerous
Lepidopterous pupae where the skin does not attain the condition of
hardness that is secured for the higher forms by the chitinous exudation we
have mentioned; and there are also cases where there is a prolonged
resting-larva period: for instance _Galleria mellonella_ spins a cocoon in
the autumn and remains in it as a resting larva all the winter, becoming a
pupa only in the spring. In many of these cases the resting-larva is
protected by a cocoon. It is probable that the chief advantage of the
perfect chitinous exudation of the Lepidopterous pupa is to prevent the
tiny, complex organisation from the effects of undue transpiration.
Bataillon has suggested that the relation of the fluid contents of the pupa
to air and moisture are of great importance in the physiology of
metamorphosis.
The duration of life is very different in various forms of Lepidoptera. It
is known that certain species (_Ephestia kuehniella_, _e.g._) may go
through at least five generations a year. On the other hand, certain
species that feed on wood or roots may take three years to complete their
life-history; and it is probable that some of the forms of Hepialidae are
even longer lived than this.
Lepidoptera have always been a favourite Order with entomologists, but no
good list of the species has ever been made, and it would be a difficult
matter to say how many species are at present known, but it can scarcely be
less than 50,000. In Britain we have about 2000 species.
The close affinity of the Order with Trichoptera has long been recognised:
Réaumur considered the latter to be practically Lepidoptera with aquatic
habits, and Speyer pointed out the existence of very numerous points of
similarity between the two. Brauer emphasised the existence of mandibles in
the nymph of Trichoptera as an important distinction: the pupa {307}of
_Micropteryx_ (Fig. 211) has however been recently shown to be similar to
that of Trichoptera, so that unless it should be decided to transfer
_Micropteryx_ to Trichoptera, and then define Lepidoptera and Trichoptera
as distinguished by the condition of the pupa, it would appear to be very
difficult to retain the two groups as distinct.
STRUCTURE OF IMAGO.—The head of a Lepidopteron is in large part made up of
the compound eyes; in addition to these it frequently bears at the top a
pair of small, simple eyes so much concealed by the scales as to cause us
to wonder if seeing be carried on by them. The larger part of the front of
the head is formed by the clypeus, which is separated by a well-marked line
from the epicranium, the antennae being inserted on the latter near its
point of junction with the former. There is sometimes (_Saturnia_,
_Castnia_) on each side of the clypeus a deep pocket projecting into the
head-cavity. The other parts of the head are but small. The occipital
foramen is very large.[164]
[Illustration: Fig. 158—External structure of a female butterfly, _Anosia
plexippus_. (After Scudder.) _a_, Base of antenna; _b_, pronotum; _b^2_,
scutum of mesothorax; _c_, clypeus; _cx_, coxa; _d_, scutellum; _d^1_,
scutellum of metathorax; _e_, post-scutellum (= base of phragma); _em_,
epimeron; _ep_, episternum; _f_, scutum of metathorax; _m_, basal part of
proboscis (= maxilla); _o_, eye; _p_, labial palp; _r_, mesosternum; _s_,
prothoracic spiracle; _t_, tegula; _tr_, trochanter; 1-9, dorsal plates of
abdomen.]
The antennae are always conspicuous, and are very various in form; they are
composed of numerous segments, and in the males of many species attain a
very complex structure, especially in Bombyces and Psychidae; they
doubtless function in such cases as sense-organs for the discovery of the
female.
The largest and most important of the mouth-parts are the maxillae and the
labial palpi, the other parts being so small as to render their detection
difficult. The labrum is a very short, {308}comparatively broad piece,
visible on the front edge of the clypeus; its lateral part usually forms a
prominence which has often been mistaken for a mandible; Kellogg has
applied the term "pilifer" to this part. In the middle of the labrum a
small angular or tongue-like projection is seen just over the middle of the
base of the proboscis; this little piece is considered by several
authorities to be an epipharynx.
[Illustration: Fig. 159—Mouth of Lepidoptera. Tiger-moth, _Arctia caja_. A,
Seen from front; B, from front and below, _a_, Clypeus; _b_, labrum; _c_,
epipharynx; _d_, mandibular area; _d′_, prominence beneath mandibular area;
_e_, one side of haustellum or proboscis; _f_, maxillary palp; _g_, labial
palp.]
MANDIBLES.—Savigny, Westwood, and others considered the parts of the labrum
recently designated pilifers by Kellogg to be the rudimentary mandibles,
but Walter has shown that this is not the case.[165] The mandibles are
usually indistinguishable, though they, or some prominence possibly
connected with them,[166] may frequently be detected in the neighbourhood
of the pilifers; they are, according to Walter, largest and most perfectly
developed in _Eriocephala_, a genus that was not distinguished by him from
_Micropteryx_ and was therefore termed "niedere Micropteryginen," _i.e._
lower Micropteryges. The opinion entertained by Walter that _Micropteryx_
proper (his "höhere Micropteryginen") also possesses rudimentary mandibles
is considered by Dr. Chapman, no doubt with reason, to be erroneous.[167]
The mandibles, however, in the vast majority of Lepidoptera can scarcely be
said to exist at all in the imago; there being only an obtuse
projection—without trace of {309}articulation—on each side of the labrum;
and even this projection is usually absent. Meinert recognised these
projections as mandibles in _Smerinthus populi_, and Kellogg in _Protoparce
carolina_, another large Sphinx moth. They appear to be unusually well
developed in that group. In _Castnia_ they are even more definite than they
are in Sphingidae.
The MAXILLAE are chiefly devoted to the formation of the proboscis. Their
basal portions are anatomically very indefinite, though they exist very
intimately connected with the labium. Each usually bears a small tubercle
or a segmented process, the representative of the maxillary palpus. The
proboscis itself consists of the terminal, or outer, parts of the two
maxillae, which parts are closely and beautifully coadapted to form the
spirally coiled organ, that is sometimes, though incorrectly, called the
tongue. The exact morphology of the Lepidopterous proboscis has not been
established. The condition existing in the curious family Prodoxidae (see
p. 432), where a proboscis coexists with another structure called a
maxillary tentacle, suggests a correspondence between the latter and the
galea of a typical maxilla; and between the proboscis and the lacinia or
inner lobe of a maxilla: but J. B. Smith is of opinion that the tentacle in
question is a prolongation of the stipes. The condition of the parts in
this anomalous family (Prodoxidae) has not, however, been thoroughly
investigated, and Packard takes a different view of the proboscis; he
considers that "it is the two galeae which become elongated, united and
highly specialised to form the so-called tongue or glossa of all
Lepidoptera above the Eriocephalidae."[168] The proboscis in some cases
becomes very remarkable, and in certain Sphingidae is said to attain, when
unrolled, a length of ten inches. In some cases the maxillary lobes do not
form a proboscis, but exist as delicate structures, pendulous from the
mouth, without coadaptation (_Zeuzera aesculi_, the Wood-leopard moth). In
other forms they are absent altogether (_Cossus_, _e.g._), and in
_Hepialus_ we have failed to detect any evidence of the existence of the
maxillae. On the other hand, in _Micropteryx_ the maxillae are much more
like those of a mandibulate Insect; and various other Microlepidoptera
approach more or less a similar condition. In the genus last mentioned
{310}the maxillary palpi are largely developed, flexible and slender.
According to Walter various forms of palpus intermediate between that of
_Micropteryx_ and the condition of rudimentary tubercle may be found
amongst the Microlepidoptera.[169]
LABIUM.—The labial palpi are usually largely developed, though but little
flexible; they form conspicuous processes densely covered with scales or
hairs, and curve forwards or upwards, rarely downwards, from the under side
of the head, somewhat in the fashion of tusks. The other parts of the
labium are frequently represented merely by a membranous structure, united
with the maxillae and obstructing the cavity of the pharynx. Where the
proboscis is absent it is difficult to find any orifice leading to the
alimentary canal, such opening as may exist being concealed by the
overhanging clypeus and labium. In some forms, _Saturnia_, _e.g._, there
appears to be no buccal orifice whatever. In _Hepialus_ the labium is in a
very unusual condition; it projects externally in the position usually
occupied by the labial palpi, these organs being themselves extremely
short. It is very difficult to form an opinion as to the structure of the
labium and other mouth-parts when the maxillae are not developed, as in
these cases the parts are of a delicate membranous nature, and shrivel
after death. This is the explanation of the fact that in descriptive works
we find vague terms in use such as "mouth aborted" or "tongue absent."
The mouth of the Lepidopterous imago is a paradoxical structure; it differs
very greatly from that of the larva, the changes during metamorphosis being
extreme. We should thus be led to infer that it is of great importance to
the creatures; but, on the other hand, the various structures that make up
the mouth, as we have remarked, are frequently absent or reduced to
insignificant proportions; and even in forms where the apparatus is highly
developed the individuals seem to be able to accomplish oviposition without
taking food, or after taking only very minute quantities. It is therefore
difficult to understand why so great a change should occur during the
metamorphosis of the Insects of this Order. It has been ascertained that in
some forms where the mouth is atrophied the stomach is in a correlative
condition; but we are not aware that any investigations have been made as
to whether this correspondence is general or exceptional.
{311}The exact mode in which the proboscis acts is in several respects
still obscure, the views of Burmeister and Newport being in some points
erroneous. Towards the tip of the proboscis there are some minute but
complex structures considered by Fritz Müller to be sense-organs, and by
Breitenbach to be mechanical instruments for irritating or lacerating the
delicate tissues of blossoms. It is probable that Müller's view will prove
to be correct. Nevertheless the proboscis has considerable power of
penetration; there being a moth, "_Ophideres fullonica_" that causes
considerable damage to crops of oranges by inserting its trunk through the
peel so as to suck the juices.[170] The canal formed by each maxilla opens
into a cavity inside the front part of the head. This cavity, according to
Burgess,[171] is a sort of sac connected with five muscles, and by the aid
of this apparatus the act of suction is performed: the diverticulum of the
alimentary canal, usually called a sucking-stomach, not really possessing
the function formerly attributed to it.
The PROTHORAX is very small, being reduced to a collar, between the head
and the alitrunk, of just sufficient size to bear the front pair of legs.
Its most remarkable feature is a pair of processes, frequently existing on
the upper surface, called "patagia." These in many cases (especially in
Noctuidae) are lobes capable of considerable movement, being attached only
by a narrow base. In _Hepialus_, on the contrary, they are not free, but
are merely indicated by curved marks on the dorsum. The patagia are styled
by many writers "tegulae." They are of some interest in connection with the
question of wing-like appendages on the prothorax of Palaeozoic insects,
and they have been considered by some writers[172] to be the equivalents of
true wings. The Mesothorax is very large, especially its upper face, the
notum, which is more or less convex, and in the higher forms attains a
great extension from before backwards. The notum consists in greater part
of a large anterior piece, the meso-scutum, and a {312}smaller part, the
meso-scutellum behind. In front of the scutum there is a piece termed
prae-scutum by Burgess. It is usually small and concealed by the front part
of the scutum; but in _Hepialus_ it is large and horizontal in position. It
is of importance as being the chief point of articulation with the
prothorax. The scutellum is more or less irregularly rhomboidal in form;
its hinder margin usually looks as if it were a lobe or fold placed in
front of the base of the abdomen or metathorax, according to whether the
latter is concealed or visible. In some of the higher forms this
meso-scutellar lobe is prominent, and there may be seen under its
projection a piece that has been called the post-scutellum, and is really
the base of the great mesophragma, a chitinous piece that descends far down
into the interior of the body. In addition to the front pair of wings the
mesothorax bears on its upper surface another pair of appendages, the
tegulae: in the higher forms they are of large size; they are fastened on
the front of the mesothorax, and extend backwards over the joint of the
wing with the body, being densely covered with scales so that they are but
little conspicuous. These appendages are frequently erroneously called
patagia, but have also been called scapulae, pterygodes, paraptera, and
shoulder-tufts, or shoulder-lappets. The lower surface of the mesothorax is
much concealed by the large and prominent coxae, but the sternum and the
two pleural pieces on each side, episternum and epimeron, are easily
detected. The area for attachment of the anterior wing on each side is
considerable, and appears to be of rather complex structure; its anatomy
has been, however, but little studied.
The METATHORAX is small in comparison with the preceding segment, to which
it is intimately co-adapted, though the two are really connected only by
delicate membrane, and can consequently be separated with ease by
dissection. The metanotum consists of (1) the scutum, which usually appears
externally as an anterior piece on each side; (2) the scutellum, forming a
median piece placed behind the scutum, which it tends to separate into two
parts by its own extension forwards. In order to understand the structure
of the metathorax it is desirable to dissect it off from the larger
anterior segment, and it will then be found that its appearance when
undissected is deceptive, owing to its being greatly arched, or folded in
the {313}antero-posterior direction. A broad, but short phragma descends
from the hind margin of the metascutellum into the interior of the body. It
should be noted that though the metanotum is forced, as it were, backwards
by the great extension of the mesonotum in the middle line of the body, yet
at the sides the metanotum creeps forward so as to keep the points of
attachment of the hind wings near to those of the front wings. In many
forms of Hesperiidae, Sphingidae, Noctuidae, etc. the true structure of the
metanotum is further concealed by the back of the mesoscutellum reposing
on, and covering it.
Difference of opinion exists as to the thoracic Spiracles; there is one
conspicuous enough in the membrane behind the pronotum, and it is thought
by some writers that no other exists. Westwood and Scudder, however, speak
of a mesothoracic spiracle, and Dr. Chapman considers that one exists.
Minot describes[173] a structure behind the anterior wing, and thinks it
may be an imperfect spiracle, and we have found a similar stigma in
_Saturnia pavonia_. At the back of the thorax there is on each side in some
Lepidoptera (Noctuidae, _Arctia_, etc.), a curious large cavity formed by a
projection backwards from the sides of the metasternum, and a corresponding
development of the pleura of the first abdominal segment. Minot and others
have suggested that this may be an organ of hearing.
The ABDOMEN differs according to the sex. In the female seven segments are
conspicuous dorsally, but only six ventrally, because the first segment is
entirely membranous beneath, and is concealed between the second abdominal
ventral plate and the posterior coxae. Besides these segments there are at
the hind end two others smaller, more or less completely withdrawn into the
body, and in certain cases forming an ovipositor. These nine segments are
usually considered to constitute the abdomen; but according to
Peytoureau,[174] a tenth dorsal plate is represented on either side of the
anal orifice, though there is no trace of a corresponding ventral plate. In
the male the segments, externally conspicuous, are one more than in the
female. According to the authority quoted,[175] this sex has also truly ten
abdominal segments, the ninth segment being withdrawn to a greater or
{314}less extent to the inside of the body, and modified to form part of a
copulatory apparatus; its dorsal portion bears a process called the
"uncus"; the anal orifice opens on the inner face of this process, and
below it there is another process—developed to a greater or less
extent—called the "scaphium." The ventral portion of the ninth segment
bears a lobe, the "saccus" (Peytoureau, _l.c._). On each side of the ninth
abdominal segment there is a process called the "valve," the internal wall
of which bears some hook-like or other processes called "harpes"; it is
continued as a membrane surrounding the "oedeagus," or penis, and—bearing
more or less distinct prominences—connects with the scaphium. In many forms
the parts alluded to, other than the valves, are concealed by the latter,
which come together when closed, and may be covered externally with scales
like the rest of the abdomen. Peytoureau considers that the uncus is really
the dorsal plate of a tenth segment, and that the scaphium is the tenth
ventral plate. Thus, according to this view, the ninth segment is extensive
and complex, being very highly modified in all its parts: while the tenth
segment is greatly reduced. The structure of the male organs is simpler in
Lepidoptera, and less varied than it is in the other great Orders of
Insects. There are seven pairs of abdominal spiracles on the upper parts of
the membranous pleurae.
[Illustration: Fig. 160—_Acherontia atropos._ The termination of ♂ body,
one side removed. _IX_, Ninth dorsal plate; _IX’_, ninth ventral; _s_,
lobe, saccus, of ninth ventral plate; _X_, tenth dorsal plate, or uncus;
_sc_, scaphium, or tenth ventral plate; _a_, position of anus; _b_,
chitinised band of scaphium; _V_, valve or clasper; _c_, hooks, or harpes,
of clasper; _p_, penis (or oedeagus). (After Peytoureau.)]
LEGS.—The legs are long, slender, covered with scales, and chiefly
remarkable from the fact that the tibiae sometimes bear articulated spurs
on their middle as well as at the tip. The front tibia usually possesses on
its inner aspect a peculiar mobile pad; this seems to be in some cases a
combing organ; it also often acts as a cover to peculiar scales. The tarsi
are five-jointed, with two small claws and a small apparatus, {315}the
functional importance of which is unknown, between the claws.
WINGS.—The wings are the most remarkable feature of this Order; it is to
them that butterflies owe their beauty, the surfaces of the wings being
frequently adorned with colours and patterns of the most charming and
effective nature. These effects are due to minute scales that are implanted
in the wing-membrane in an overlapping manner, somewhat similar to the
arrangement of slates on the roof of a house. The scales are very readily
displaced, and have the appearance of a silky dust. We shall describe their
structure and allude to their development subsequently. The wings are
usually of large size in comparison with the Insect's body: in the genus
_Morpho_, the most gorgeous of the butterflies, they are enormous, though
the body is small; so that when deprived of these floats the Insect is
insignificant. The great expanse of wing is not correlative with great
powers of flight, though it is perhaps indicative of flying with little
exertion; for the small-winged Lepidoptera, Sphingidae, etc., have much
greater powers of aërial evolution than the large-winged forms. The area of
the wing is increased somewhat by the fact that the scales on the outer
margin, and on a part or on the whole of the inner margin, project beyond
the edges of the membrane that bears them: these projecting marginal scales
are called fringes. In many of the very small moths the actual size of the
wing-membranes is much reduced, but in such cases the fringes may be very
long, so as to form the larger part of the surface, especially of that of
the hind wings. Frequently the hind wings are of remarkable shape, being
prolonged into processes or tails, some of which are almost as remarkable
as those of _Nemoptera_ in the Order Neuroptera.
The wings are very rarely absent in Lepidoptera; this occurs only in the
female sex, no male Lepidopterous imago destitute of wings having been
discovered. Although but little is known of the physiology of flight of
Lepidoptera, yet it is clearly important that the two wings of the same
side should be perfectly coadapted or correlated. This is effected largely
by the front wing overlapping the hind one to a considerable extent, and by
the two contiguous surfaces being pressed, as it were, together. This is
the system found in butterflies and in some of the large moths, such as
Lasiocampidae and Saturniidae; in these cases the hind {316}wing always has
a large shoulder, or area, anterior to its point of insertion. In most
moths this shoulder is absent, but in its place there are one or more stiff
bristles projecting forwards and outwards, and passing under a little
membranous flap, or a tuft of thick scales on the under face of the front
wing; the bristle is called the "frenulum," the structure that retains it a
"retinaculum." In _Castnia_ (Fig. 162) and in some Sphingidae there is the
unusual condition of a highly-developed shoulder (_s_) coexisting with a
perfect frenulum (_f_) and retinaculum (_r_). The frenulum and retinaculum
usually differ in structure, and the retinaculum in position, in the two
sexes of the same moth; the male, which in moths has superior powers of
flight, having the better retaining organs. Hampson says "the form of the
frenulum is of great use in determining sex, as in the males of all the
forms that possess it, it consists of hairs firmly soldered together so as
to form a single bristle, whilst in nearly all females it consists of three
or more bristles which are shorter than that of the male; in one female
Cossid I have found as many as nine. Also in the large majority of moths
the retinaculum descends from the costal nervure in the male, while in the
female it ascends from the median nervure."[176] This sexual difference in
a structure for the discharge of a function common to the two sexes is a
very remarkable fact. There are a few—very few—moths in which the bases of
the hind wings are not well coadapted with the front wings, and do not
possess a frenulum, and these species possess a small more or less free
lobe at the base of the front wing that droops towards the hind wing, and
may thus help to keep up an imperfect connexion between the pair; this lobe
has been named a jugum by Professor Comstock. Occasionally there is a jugum
on the hind as well as on the front wing. There is usually a very great
difference between the front and the hind wings; for whereas in the front
wing the anterior portion is doubtless of great importance in the act of
flight and is provided with numerous veins, in the hind wing, on the other
hand, the corresponding part has not a similar function, being covered by
the front wing; hence the hind wing is provided with fewer nervures in the
anterior region, the divisions of the subcostal being less numerous than
they are in the front wing. In the moths possessing a jugum the two wings
differ but little from one {317}another, and it is probable that they
function almost as four separate wings instead of as two pairs.
WING-NERVURES.—The nervures or ribs of the wings are of great importance in
Lepidoptera, as at present they furnish the chief characters for
classification and for the discussions of phylogeny that are so numerous in
entomological literature. On looking at wings that have been deprived of
their scales it will be noticed (Fig. 161) that the ribs are much more
numerous at the outer margins than they are near the points of attachment
of the wings, and that there is usually but one cell (or area completely
enclosed by ribs). This latter point is one of the chief peculiarities of
the Lepidopterous wing; in Insect-wings generally the number of cells in
proportion to the area of the wings and to the number of nervures is
greater than it is in Lepidoptera, for in the latter there are few or no
cross-nervures. Hence there is sometimes no closed cell at all on the wing
(Fig. 161, II. B). The maximum number of closed cells is six; this is found
in some species of _Micropteryx_, while in _Hepialus_ there may be three or
four; but the rule is that there is only one cell in the Lepidopterous
wing. When the number of cells is increased this is not necessarily due to
an increase in the cross-nervures; and in fact it is generally due to
irregular forking or to the sinuous form of the longitudinal nervures
themselves (see wing of _Castnia_, Fig. 162, A.). Some authorities consider
that all transverse or cross-veins in Lepidoptera are merely portions of
longitudinal veins having diverted courses. When a portion of a nervure
beyond the basal or primary portion serves as a common piece to two forked
parts external to it, it is called a stalk (Fig. 162, A, _e_). There are
cases in which the furcation takes place in the opposite direction, so that
a nervure is double at the base of the wing (Fig. 161, I, A, 1_a_, and B,
1_b_). This important condition has not yet been adequately discussed.
{318}[Illustration: Fig. 161.—Wing-nervuration of Lepidoptera. I, Diagram
of moths' wings (after Hampson); II, of a butterfly's wings (_Morpho
menelaus_ ♂, after Staudinger and Schatz). A, front, B, hind wing. I.—_c_,
costal; _sc_, subcostal; _m_, median; 1_a_, 1_b_, 1_c_, internal nervures;
_f_, frenulum; 2, 3, 4, branches of median nervure; 5, lower radial; 6,
upper radial; 7-11, divisions of the subcostal; 12, termination of costal;
_c_, cell; _d_, discocellular nervure. II.—C, costal; SC, subcostal; M,
median; SM and SN, submedian nervures; 1A, inner-margin nervure; UR, lower
radial; OR, upper radial; SC^1 to SC^5, divisions of subcostal; M^1 to M^3,
divisions of median nervure; C, cell; DC, discocellulars.]
Turning to the mode of designation of the nervures,[177] we may commence by
remarking that no system satisfactory from a practical as well as from a
theoretical point of view has yet been devised. The diagrams given in
figure 161 will enable us to explain the methods actually in vogue; I.
representing the system, dating from the time of Herrich-Schaeffer, chiefly
used by British naturalists, and II. that adopted by Staudinger and Schatz
in their recent great work on the Butterflies of the world. The three
anterior nervures in both front and hind wings correspond fairly well, and
are called, looking at them where they commence at the base of the wing,
"costal," "subcostal," and "median" nervures. The nervures near the inner
margin of the wing (that is the lower part in our figures) differ much in
the front and hind wings, consisting either of two or of three separate
portions not joined even at the base. British entomologists call these
"branches or divisions of the internal nervure": the Germans call the more
anterior of them the "submedian," and the more internal the "inner-margin
nervure"; they are also frequently called anal nervures. The cross-nervure
that closes the cell is called discocellular; when apparently composed of
two or three {319}parts joined so as to form angles, the parts are called,
according to position, upper, lower, and middle discocellulars. One or more
short spurs may exist on the front part of the basal portion of the hind
wing; these are called praecostal. The branches or terminal divisions of
the nervures should be called nervules; they are usually mentioned by the
numbers shewn in the diagram (Fig. 161, I.). In addition to this, it is
only necessary to remember that number 2 is always assigned to the
posterior division of the median nervure, the nervules below this being all
called 1, and distinguished by the addition of _a_, _b_, _c_ when
requisite. This course is necessary, because if it were not adopted the
corresponding nervules on the front and hind wings would bear different
numbers.
The use of this system of numbers for the nervules is becoming general, and
it answers fairly well for practical purposes. On the other hand, extreme
discrepancy exists as to the nomenclature of the nervures and nervules, and
there are almost as many systems as there are authorities.
The normal number of nervules is, on the front wing, 11 + 1 or 2 inner
marginal, and on the hind wing 7 + 2 or 3 inner marginal. In the aberrant
moths of the genus _Castnia_ the nervuration is unusually complex and
irregular (Fig. 162), and an analogous condition occurs in our common
Goat-moth (_Cossus ligniperda_). In _Hepialus_ and _Micropteryx_ (the
jugate moths of Comstock) the hind wings are less dissimilar in nervuration
from the front wings than they are in other Lepidoptera.[178]
[Illustration: Fig. 162—Wing-nervuration of _Castnia_. Undersides of, A,
front, B, hind wings. 1_a_, 1_b_, 1_c_, 1_d_, Inner marginal nervures; 2,
lower branch of median; 8, subcostal of hind wing; 12, subcostal of front
wing; _e_, "stalk" of 8 and 9; _f_, frenulum; _r_, retinaculum; _s_,
shoulder; _g_, articulation of wing.]
INTERNAL ANATOMY.[179]—The alimentary canal extends as a long, {320}slender
oesophagus through the length of the thorax, dilating when it reaches the
abdomen to form a tubular stomach; before this it is somewhat enlarged to
form an indistinct crop, and gives off a large diverticulum usually called
a sucking stomach. According to Burgess, this structure does not possess
the function ascribed to it by this name, and he terms it a food-reservoir.
The Malpighian tubes are six in number, three on each side, and each set of
three unite to form a common tube opening into the posterior extremity of
the stomach; behind them the alimentary canal continues in the form of a
slender, tortuous intestine, expanding at the extremity of the body to form
a rectum. The dorsal or circulatory vessel commences near the posterior
extremity of the body, but in the front part of the abdomen is deflexed to
pass under the great phragma into the thorax, where it rises abruptly to
the dorsal wall, but is again abruptly deflexed, forming a loop, and is
then prolonged above the oesophagus into the head: at the summit of the
thoracic loop there may be a dilatation called the aortal chamber. The
supra- and infra-oesophageal ganglia are consolidated into a mass pierced
by the oesophagus: there is a minute frontal ganglion; the ventral chain
consists of three much approximated thoracic ganglia and four abdominal
ganglia separated from the thoracic by a long interval.
[Illustration: Fig. 163—Internal anatomy of Lepidoptera. Section of the
body of a female butterfly, _Anosia plexippus_. (After Scudder.) The
portion to the left of the vertical line more magnified. I. II. III.
thoracic segments; 1-9, abdominal segments; _a_, antenna; _a_, anus; _ac_,
aortal chamber; _ag^1_, etc., abdominal ganglia; _agl^1_, _agl^2_,
accessory glands; _ao_, aorta; _br_, brain; _c_, colon; _cp_, copulatory
pouch; _cx^1_, _cx^2_, _cx^3_, coxae; _fr_, food-reservoir; _g^1_,
suboesophageal ganglion; _h_, dorsal vessel; _i_, intestine; _lm_, area
filled by wing muscles; _l.or_, ovary, or egg-tubes of left side; _mv_,
Malpighian tube (the two others of the right side cut away, except small
portions); _mx_, maxilla; _o_, oviduct; _oo_, its orifice; _oe_,
oesophagus; _ov.c_, end of left ovary; _p_, labial palp; _ph_, pharynx;
_r.ov_, terminal parts of right ovarian tubes, turned to one side, after
the tubes have been cut away; _sd_, salivary duct; _sgl_, salivary gland;
_sp_, spermatheca; _st_, stomach; _tg_, thoracic ganglia; _v_, copulatory
orifice.]
{321}The male sexual organs consist of the two testes placed in a common
capsule, from which proceed a pair of contiguous vasa deferentia (dilated
soon after their origin to form the vesiculae seminales); into each vas
there opens a long, tubular gland; the two vasa subsequently unite to form
a long, coiled, ejaculatory duct. It is in the structure of the female
sexual organs that the most remarkable of the anatomical characters of
Lepidoptera is found, there being two external sexual orifices. The imago
has, in the great majority of cases, four egg-tubes in each ovary; the pair
of oviducts proceeding from them unite to form a single unpaired (azygos)
oviduct which terminates by an orifice quite at the posterior extremity of
the body. There is a sac, the bursa copulatrix or copulatory pouch, which
is prolonged in a tubular manner, to open externally on the eighth ventral
plate: a tube, the seminal duct, connects the bursa with the oviduct, and
on this tube there may be a dilatation—the spermatheca. Besides these
structures two sets of accessory glands open into the oviduct, an unpaired
gland, and a pair of glands. The development of these structures has been
described by Hatchett Jackson,[180] and exhibits some very interesting
features. The exact functions of the bursa copulatrix and of the other
structures are by no means clear. According to Riley,[181] the spermatheca
in _Pronuba_ contains some curious radiate bodies, and Godman and Salvin
describe something of the same sort as existing in butterflies. Several
variations in the details of the structure of these remarkably complex
passages have been described, and the various ducts are sometimes rendered
more complex by diverticula attached to them. Some noteworthy diversities
in the main anatomical features exist. According to Cholodkovsky, there is
but one sexual aperture—the posterior one—in _Nematois metallicus_; while,
according to Brandt, the number of egg-tubes in a few cases exceeds the
normal—four—being in _Sesia scoliaeformis_ fourteen. In _Nematois
metallicus_ there is individual variation, the number of tubes varying from
twelve to twenty.
The EGG has been more extensively studied in Lepidoptera than in any other
Order of Insects. It displays great variety: we meet with elongate forms
(Fig. 164) and flat forms like buttons, while in _Limacodes_ (Fig. 83, Vol.
V.) the egg is a {322}transparent scale of somewhat inconstant outline.
Some are coloured and mottled somewhat after the fashion of birds'-eggs;
this is the case with some eggs of Lasiocampidae and Liparidae; in some the
sculpture of the egg-shell is of the most elaborate character (Figs. 77,
78, Vol. V.). The egg-shell or chorion is, according to Korschelt[182] and
others, a cuticular product of the epithelium of the egg-chambers of the
ovaries. The number of eggs deposited by an individual differs greatly in
different species, and has been ascertained to be variable within certain
limits in the same species. Speyer thought about 250 to be the average
number of eggs deposited by an individual. The number in the case of
_Aporia crataegi_ is believed to be from 60 to 100, and in some _Hepialus_
to be several thousands. The mode of deposition also differs greatly; where
the eggs are very numerous they seem to be discharged almost at random in
suitable spots; but moths such as _Clisiocampa neustria_ fasten their eggs
round the stems of the food-plant in a very perfect and artistic manner.
Butterflies seem as a rule to prefer to oviposit by placing an egg here and
there rather than risk many in one situation; but to this there are many
conspicuous exceptions especially in the cases where the larvae live
gregariously, as in the Vanessae. Some moths cover the eggs with fur from
their own body, which, in the case of certain of the Eggers
(Lasiocampidae), seems to have a special supply for the purpose. The period
that intervenes between deposition and hatching of the eggs varies from a
few days to many months. There seems to be, as a rule, comparatively little
power of extending the period of latency beyond a single season; though
certain facts have been recorded that would lead us to believe that in
Australia eggs may last over the proper time during a drought, and be
hatched as soon as rain falls.
[Illustration: Fig. 164—Egg of Orange-tip butterfly, _Euchloe cardamines_,
magnified. _a_, The egg of natural size on a stalk.]
LARVA.—The young condition or larva of the Lepidopterous Insect is commonly
called a caterpillar. It is a somewhat worm-like creature—in old English
it was sometimes called {323}palmer-worm—and is composed of a head and
thirteen divisions or segments of the body; the first three of the latter
are called thoracic, the other ten, abdominal segments; in most
caterpillars the terminal two or three abdominal segments are more or less
run together, and the ninth may be very small, so that the true number is
indistinct. The first three segments bear each, on either side, a short
limb, ending in a curved spine; the next two (or three or more) segments
are destitute of legs, but on some of the following divisions another kind
of leg of a more fleshy character appears, while the body is terminated by
a pair of these thick legs of somewhat different form. The front legs are
usually called the true legs, the others prolegs, but this latter
designation is a most unfortunate one, the term "pro" being in entomology
used to signify anterior; it is therefore better to call the three anterior
pairs thoracic legs, and the others abdominal feet, distinguishing the hind
pair of these latter as claspers. There is, too, an unfortunate discrepancy
amongst entomologists in their manner of counting the body-segments, some
count the head as the first segment, while others apply this term to the
first thoracic segment. The latter is the more correct course, for, as the
head is not a single segment it should not be called such in a terminology
that affects to be morphologically exact, not simply descriptive. The
thoracic legs are transversely jointed (Fig. 165, B), but this is not the
case with the abdominal feet, which are usually armed beneath with a
circle, or with rows, of little hooks. The thoracic legs are, independent
of their form, of a different nature from the abdominal, for these latter
disappear subsequently, while the former give rise to the legs of the
imago. The number of thoracic legs is always six, except in a few cases
where there are none at all; the abdominal feet are much more variable, and
exhibit so many distinctions that we cannot here attempt to deal with them.
M. Goossens has given a concise and interesting account of this
subject,[183] and Speyer[184] a summary of the variety in number and
position.
The anatomy of the larva is simple in comparison with that of the perfect
Insect; its main features will be appreciated from Fig. 165, from which it
will be seen that the stomach is enormous, and the silk-vessels are also
very extensive.
{324}[Illustration: Fig. 165.—A, Section of male caterpillar of _Anosia
plexippus_—muscular and tracheal systems and fat-body not shown: I, pro-,
II, meso-, III, meta-thorax; 1-10, abdominal segments; _b_,
supra-oesophageal ganglion; _c_, rectum; _d.v_, dorsal vessel; _g^3-g^9_,
ganglia of ventral chain; _h_, head; _i_, intestine; _m.v_, Malpighian
tube; _n.c_, nerve-cord of ventral chain; _oe_, oesophagus; _s_, spinneret;
_s.o.g_, infra-oesophageal ganglion; _st_, stomach; _s.v_, silk-vessel;
_t_, testis. B, One of the jointed prothoracic legs. C, An abdominal foot
with its hooks. (After Scudder and Burgess, magnification about 2/1.)]
There are three sets of glands opening by canals on the head, viz. the
salivary glands proper, which open into the cavity of the mouth, one close
to the base of each mandible; the silk-glands, which terminate by a common
canal, continued externally as the spinneret; and the glands of Filippi
situate in the head itself, and opening into the ducts of the silk-glands,
near their union into a common duct. It should be recollected that Fig. 165
does not indicate all the details of the anatomy; the muscular system, for
instance, being entirely omitted, though there are an enormous number of
muscles; these however are not very complex, they being mostly repetitions
in the successive segments.[185] The mouth-parts are very different from
those of the perfect Insect, inasmuch as the maxillae and labial palpi,
which are the most remarkable structures of the imago, are small, and are
differently constructed in the caterpillar, while the mandibles, which are
the largest organs of the caterpillar, disappear in the adult. The little
organ by which the caterpillar exudes its silk is called a spinneret;
according to Packard it is a "homologue of the hypopharynx." It is a more
or less prominent point on the middle of the labium (Fig. 166, _g_) and
sometimes forms a conspicuous spine projecting downwards. The eyes are
extremely imperfect organs, consisting merely of six, in some cases
{325}fewer, transparent, somewhat prominent, little spaces placed on each
side of the lower part of the head; they are called "ocelli," by Landois
"ocelli compositi." Under each of these external facets there are placed
percipient structures, apparently very imperfect functionally, the
caterpillar's sight being of the poorest character.[186] The spiracles of
the caterpillar are nine on each side, placed one on the first thoracic
segment and one on each of the first eight abdominal segments; there are no
true stigmata on the second and third thoracic segments, though traces of
their rudiments or vestiges are sometimes visible.
[Illustration: Fig. 166—Front view of head of a caterpillar, with the jaws
partially opened, _a_, Labrum; _b_, mandible; _c_, antenna; _d_, ocelli;
_e_, maxilla; _f_, lingua; _g_, spinneret; _h_, labial palp.]
In the caterpillar there are no traces of the external sexual organs, so
that the two sexes cannot be distinguished on superficial inspection; it
was however long ago demonstrated by Herold[187] that the ovaries and
testes exist in the youngest caterpillars, and undergo a certain amount of
growth and development in the larval instars; the most important feature of
which is that the testes are originally separate but subsequently coalesce
in the middle line of the body, and become enclosed in a common capsule. In
a few forms—especially of Liparidae—(Lymantriidae of modern authors)—the
caterpillars are said to be of different colours in the two sexes. Most of
what is known on this point has been referred to by Hatchett Jackson.[188]
The Silk-glands of Lepidoptera are of great interest from the physiological
point of view, as well as from the fact that they have furnished for many
ages one of the most beautiful of the adornments made use of by our own
species. The sericteria, or vessels that secrete silk, are of simple
structure, and differ greatly in their size in the various forms of the
Order; they sometimes become of great length; in the Silk-worm each of the
two vessels is nearly five times as long as the body, while in _Bombyx
yamamai_ and others, even this is exceeded. They {326}grow with remarkable
rapidity, being in the young silk-worm only 3 mm. long, in the adult 22 mm.
The increase in weight is still more remarkable; when the silk-worm is
thirty-one days old, the sericteria weigh only 3 mgr., but when the age is
fifty days their weight has increased to 541 mgr., being then ⅖ of the
whole weight of the body. In the pupa they undergo a gradual atrophy, and
in the moth they are, according to Helm, no longer to be found, though
earlier authors were of a contrary opinion.[189] According to Joseph,[190]
the silk-vessels begin to develop at an extremely early age of the embryo,
and are very different in their nature from the salivary glands, the former
being derivatives of the external integument (ectoderm), while the salivary
glands belong to the alimentary system. This view is to some extent
confirmed by the observations of Gilson as to the different manner in which
these two sets of glands discharge their functions.
The chief feature in the anatomy of the larva is the great size of the
stomach. There is a very short oesophagus and crop; the latter becomes
enlarged, spreading out so as to form the stomach, a great sac occupying
the larger part of the body-cavity (Fig. 165). On the hinder end of this
sac the Malpighian tubes open; they are similar in their disposition to
those of the imago; behind the stomach the canal expands into two
successive, short dilatations, the first called an intestine, the second a
rectum; they are connected by very short isthmuses. The dorsal vessel is a
simple, slender tube, extending from the eighth abdominal segment to the
head. The main nervous system consists of supra- and infra-oesophageal
ganglia, a small frontal ganglion, and a ventral chain of eleven ganglia,
three thoracic and eight abdominal, the last of these latter being double.
The sexual organs are quite rudimentary, and the passages connected with
them very incompletely developed.
PUPA.—The pupa, which is one of the most remarkable of the instars of an
Insect's life, attains its highest development in Lepidoptera. The
Lepidopterous pupa is frequently called a "chrysalis," a term originally
applied to certain metallic butterfly pupae. The Lepidopterous pupa differs
from that of other Insects in the fact that its outer skin forms a hard
shell, all the appendages of {327}the body being glued together by an
exudation so as to form a single continuous outer skin. This form of
perfect pupa is called "pupa obtecta." The obtected pupa is exhibited in
various stages of perfection in the Lepidoptera; the maximum of perfection
is attained by the pupae of such butterflies as are exposed without
protection or concealment; on the other hand, we find in various small
moths conditions of the pupa that do not differ in any marked manner from
the pupae of Insects of other Orders. Moreover, certain Coleoptera and
Diptera exhibit obtected pupae of a more or less perfect kind. Hence the
pupa obtecta is to be considered as a perfected condition that exists more
frequently in the Lepidoptera than in other Orders.
[Illustration: Fig. 167.—Section of female pupa of _Anosia plexippus_, 3-4
days old. I, pro-, II, meso-, III, meta-thorax; 1-9, abdominal segments;
_a_, antenna(?); _ac_, aortal chamber; _ag^1-ag^5_, abdominal ganglia;
_agl_, accessory glands; _ao_, aorta; _br_, brain; _c_, colon; _cp_, bursa
copulatrix; _cr_, cremaster; _f^1_, first femur; _fr_, food-reservoir; _h_,
dorsal vessel; _i_, part of intestine; _mv_, Malpighian tube; _mx_, base of
maxilla; _oe_, oesophagus; _ov_, ovary; _ph_, pharynx; _sd_, salivary duct;
_sgl_, salivary gland; _st_, stomach; _t^1_ first tarsus; _tg_, compound
thoracic ganglion; _ts^2_, _ts^3_, second and third tarsus. (After
Scudder.)]
The pupa has no orifices to the alimentary canal or sexual organs, but the
respiratory openings are pervious. It has no means of locomotion, but it
can move a certain number of the posterior segments (the number variable
according to kind). In some cases it is provided with spines, "adminicula,"
by means of which, aided by the wriggling movements of the abdominal
segments, considerable changes of position can be effected. The pupae of
the genus _Micropteryx_ apparently use the legs for locomotion, as do the
pupae of Trichoptera.
The study of the pupa of Lepidoptera is less advanced than that of the
imago and larva, between which it is, in many points of structure,
intermediate.[191] The interior of the pupa contains a {328}quantity of
cream-like matter, including the results of histolysis—but this, as well as
the condition of the internal organs, differs much according to whether the
change from the caterpillar to the moth is much or little advanced.
Many pupae are protected by cocoons. These are masses of silk—very various
in form—disposed by the caterpillar around itself during the last stage of
its existence. Some of these cocoons are so perfect that the moth has
considerable difficulty in escaping when the metamorphosis is complete.
Various devices are used for the purpose of emergence; the Puss-moth
excretes a corrosive fluid, containing potassium hydroxide, and then
protects itself from this by retaining on the head while passing through it
a shield formed of a portion of the pupa-skin.[192] Lepidopterous pupae
usually have the body terminated by a projection of very various and
peculiar form called "cremaster." In certain cases these projections are
used for the suspension of the pupa, and are then frequently provided with
hooks (Fig. 177, C, D). In other cases the cremaster is frequently called
the anal armature (Fig. 205, B).
[Illustration: Fig. 168—Wing-rudiments of _Pieris brassicae_. A, Rudiments
of a wing before the first moult of the caterpillar: _ce_, embryonic cells;
_ch_, external cuticle; _h_, hypodermis; _o_, opening of the invagination;
_tr_, trachea. B, posterior wing-rudiment of full-grown caterpillar; _b_,
semicircular pad; _c_, a bundle of the rolled tracheae; _e_, envelope; _i_,
pedicel; _tr_, trachea. (After Gonin.)]
The DEVELOPMENT of the WINGS of Lepidoptera has recently been much studied.
It has been known since the time of Lyonnet, that the rudiments of the
wings exist inside the body of the caterpillar when it is nearly adult.
Verson considers that he has detected the rudiments in the silk-worm larva
even before hatching, and he attributes their origin to a modification of
form of those hypodermal cells that occupy the spots where the spiracles of
the second and third thoracic segments might be looked for. (It will be
recollected that there are no spiracles on these two thoracic segments in
Lepidopterous larvae). Gonin has examined the wing-rudiments in the
caterpillar, a few days old, of {329}_Pieris brassicae_,[193] and finds
that the future wing is then indicated by a thickening and bagging inwards
of the hypodermis, and by some embryonic cells and a trachea in close
relation with this mass (Fig. 168, A). The structure grows so as to form a
sac projecting to the interior of the body, connected with the body-wall by
a pedicel, and penetrated by a trachea forming branches consisting of
rolled and contorted small tracheae (Fig. 168, B). If the body-wall be
dissected off the caterpillar immediately before pupation the wings appear
in crumpled form, as shown in Fig. 169. This fact was known to the older
entomologists, and gave rise to the idea that the butterfly could be
detected in a caterpillar by merely stripping off the integument.
The exact mode by which the wings become external at the time of appearance
of the chrysalis is not ascertained; but it would appear from Gonin's
observations that it is not by a process of evagination, but by destruction
of the hypodermis lying outside the wing. However this may be, it is well
known that, when the caterpillar's skin is finally shed and the chrysalis
appears, the wings are free, external appendages, and soon become fastened
down to the body by an exudation that hardens so as to form the shell of
the chrysalis.
[Illustration: Fig. 169—Anterior parts of a caterpillar of _P. brassicae_,
the body-wall having been dissected off, immediately before pupation. _a_,
_a′_, Anterior and posterior wings; _st I_, first spiracle; _p_, _p′_,
second and third legs. (After Gonin.)]
SCALES AND NERVURES.—Before tracing the further development it will be well
to discuss the structure of the scales and nervures that form such
important features in the Lepidopterous wing.
If a section be made of the perfect wing of a Lepidopteron, it is found
that the two layers or walls of the wing are firmly held together by
material irregularly arranged, in a somewhat columnar manner. The thickness
of the wing is much greater where the section cuts through a nervure (Fig.
170, A). The nervures apparently differ as to the structures found in them.
Spuler observed in a nervure of _Triphaena pronuba_, a body having in
section a considerable diameter, that he considered to be a {330}trachea,
and also a "wing-rib" and blood-cells. He remarks that even in nervures,
perfectly formed as to their chitinous parts, either wing-rib or trachea or
both may be absent.[194] Schäffer[195] was unable to find any tracheae in
the completed wings he examined, and he states that the matrix of the
tracheae and even their inner linings disappear. The wing-ribs were,
however, found by him to be present (Fig. 170, A and B).
[Illustration: Fig. 170.—Structure of wing of imago. A, Transverse section
of basal portion of wing [of _Vanessa_?] containing a nervure; _c_,
cuticle; _fr_, wing-rib; _g_, wall of nervure ("Grundmembran"); _h_,
hypodermis; _p_, connecting columns: _r_, lumen of nervure; B, section of a
rib; _b_, one of the chitinous projections; _str_, central rod. (After
Schäffer.)]
[Illustration: Fig. 171—Scales of male _Lepidoptera_. A, Scale from upper
surface of _Everes comyntas_; B, from upper surface of _Pieris rapae_; C,
from inner side of fold of inner margin of hind wing of _Laertias
philenor_; D, one of the cover-scales from the costal androconium of
_Eudamus proteus_; E, F, G, scales from androconium of _Thorybes pylades_.
(After Scudder).]
The scales that form so conspicuous a feature in Lepidoptera exist in
surprising profusion, and are of the most varied forms. They may be briefly
described as delicate, chitinous bags; in the completed state these bags
are flattened, so as to bring the sides quite, or very nearly, together.
Their colour is due to contained pigments, or to striation of the exposed
surface of the scale; the latter condition {331}giving rise to metallic
"interference-colours." The walls of the scales are themselves, in some
cases, tinted with pigment. It is said that some of the scales contain
air, and that the glistening whiteness of certain scales is due to this.
The exposed surface of the scale usually differs from the surface that is
pressed down on the wing in being delicately and regularly striated; the
colours of the upper and under surfaces of a scale may also be quite
different. Scales are essentially of the nature of hairs, and all the
transitions between hairs and true scales may be found on the wings of
certain Lepidoptera that bear both hairs and scales, e.g. _Ithomia_. It has
been calculated that there are a million and a half of scales on the wings
of an individual of the genus _Morpho_. The scales are arranged on the wing
in an overlapping manner, somewhat like slates on the roof of a house.
Each scale has a short stalk, and is maintained in position by the stalk
fitting into a cavity in a projection of the wing-membrane (Fig. 172).
[Illustration: Fig. 172—Insertion of scales. A, Socket holding the stalk in
_Galleria mellonella_; B, insertion of the scale of _Polyommatus phloeas_.
_b_, Base of scale; _r_, holding-ring; _w_, surface of wing. (After
Spuler.)]
ANDROCONIA.—The males of numerous butterflies possess scales peculiar in
kind and various in arrangement. They may be either irregularly scattered
over the wing, or they may form very complex definite structures (Fig.
173). They were formerly called "plumules," but Scudder has replaced this
name by the better one, "androconia." The function of the androconia is
still obscure. An odour is believed to be connected with them. Thomas
supposes[196] that these scales are hollow tubes in connection with glands
at their bases, and that matter secreted by the glands passes through the
scales and becomes diffused. In nearly all Lepidoptera it is the male that
seeks the female; if therefore odorous scales were present in one sex only
we should have supposed that this would have been the female rather than
the male. As, however, the reverse is the case, the function of the
androconia is supposed to be that of charming the female. Scudder considers
that the covering part of the androconial {332}structures is sometimes
ornamental. As a rule, however, the "brands" of male Lepidoptera detract
from their beauty to our eyes.
[Illustration: Fig. 173—A, section of part of wing showing the complex
androconia of _Thanaos tages_, a Skipper butterfly. The turning over of the
costal margin of the wing is in this case part of the arrangement. _a_,
Upper covering-scales attached to the costal portion of the under surface
of the wing; _b_, edge of costal margin of the wing; _c_, costal nervure
with its scales; _d_, field of the wing next the costal nervure, bearing
stunted scales; _e_, the androconia proper, or male scales; _f_, posterior
covering scales; _g_, lumen of the costal nervure: B, a portion of the
costal area flattened out and seen from above; lettering as before: C,
section of androconium on the second nervure of _Argynnis paphia_. (After
Aurivillius.)]
Resuming our consideration of the DEVELOPMENT of the WINGS, we may remark
that the history of the changes during the pupal state is still imperfect.
By the changes of relative size of the thoracic segments the hind wing is
brought to lie under the anterior one (_i.e._ between it and the body), so
that in the newly formed pupa the arrangement is that shown in Fig. 174.
The wings are two sacs filled with material surrounding peritracheal spaces
in which run tracheae. The subsequent history of the tracheae is very
obscure, and contrary opinions have been expressed as to their growth and
disappearance. We have alluded to the fact that in some nervures tracheae
are present, while in others they are absent; so that it is quite possible
that {333}the histories of the formation of the nervures and of their
relation to tracheae are different in various Lepidoptera. This conclusion
is rendered more probable by the statement of Comstock and Needham,[197]
that in some Insects the "peritracheal spaces" that mark out the position
of the future nervures are destitute of tracheae. Gonin thinks the nervures
are derived from the sheaths of the peritracheal spaces, and a review of
all the facts suggests that the tracheae have only a secondary relation to
the nervures, and that the view that a study of the pupal tracheae may be
looked on as a study of the preliminary state of the nervures is not
sufficiently exact. It is, however, probable that in Lepidoptera the pupal
tracheae play an important though not a primary part in the formation of
the nervures; possibly this may be by setting up changes in the cells near
them by means of the air they supply. Semper long ago discovered hypodermal
cylinders traversed by a string (Fig. 170, B), placed near the tracheae in
the pupa.[198] It appears probable that the "wing-ribs" found in the
nervures (Fig. 170, A _fr_ and B) are the final state of these cylinders,
but the origin and import of the cylinders are still unknown.
[Illustration: Fig. 174—Transverse section of part of the newly disclosed
chrysalis of _Pieris brassicae_, showing the position and structure of the
wings, hanging from one side of the body. _aa_, Anterior wing; _ap_,
posterior wing; _e_, _e_, peritracheal spaces; _t_, _t_, tracheae. (After
Gonin.)]
The formation of the scales of the wing commences very early—apparently
soon after the casting of the larval skin—though the completion of the
scales and their pigmentation is delayed to a late period of the pupal
life. The scales are formed by special cells of the hypodermis that are
placed deeper in the interior of the wing than the other hypodermal cells.
Each scale is formed by one cell, and protrudes through the overlying
hypodermis; the membrane into which the scales are inserted is a
subsequently developed structure, and the beautiful {334}articulation of
the scale with the wing takes place by a division of the stalk of the scale
where it is encompassed by the membrane. Semper was not able to show that
the scale-forming cells are certainly hypodermal cells, but this has since
been demonstrated by Schäffer, who also shows that each of the cells
contains an excretory vesicle.
[Illustration: Fig. 175.—Early condition of scales and nervures. (After
Semper.) A, Section of portion of wing of pupa of _Sphinx pinastri_; _a_,
basal membrane with trachea beneath it; _c_, scale-forming cell; _d_, early
state of a scale; _e_, _e_, more advanced stages; _f_, hypodermal cells. B,
part of a cellular cylinder that excretes the nervure [or more probably the
rib or "Rippe" of Schäffer; cf. Fig. 170, B]; _b_, epithelial [hypodermal]
cells; _a_, central string [supposed by Semper to be a nerve].]
Very little is positively known as to the development of the colour in the
wing-scales. It has been pointed out by Hopkins[199] that in some cases the
colours are of the nature of urates; that is, of excretory matter of the
kind that usually passes from the body by direct channels, and in the case
of Lepidoptera, by the Malpighian tubes. Miss Newbigin suggests that the
organic pigments used in scale-coloration will be found to be of two kinds,
urates and melanins, the urates being derivatives from nitrogenous, the
melanins from carbonaceous, matters.[200] Marchal, who has devoted a great
deal of attention to the study of the Malpighian tubes, informs us that the
subdermal pigments of caterpillars are frequently in large part deposits of
urates, and he is of opinion that, the function of the Malpighian tubes
being arrested at certain periods of the metamorphosis, elimination of the
matter they separate when functionally active then takes place in a variety
of other ways.[201] A similar condition as to the melanin-pigments and the
respiratory functions appears also {335}probable. The scales when first
formed are pallid, and the physiology of their pigmentation is not fully
ascertained; it is, however, known that when the scales are pallid the
hypodermis is either pigmented or in close contact with pigmentary matter,
and that as the scales become coloured this pigmentation of the hypodermis
diminishes; so that it is clear that the colour of the scales is obtained
from matter in the interior of the developing wing, and probably by the
agency of the hypodermis.
The pattern on the wings of Lepidoptera is formed before the emergence from
the pupa. In the Tortoiseshell butterfly, according to Schäffer, it
commences to appear about the ninth day of the pupal life, and the pattern
is completed about the eleventh or twelfth day. He also states that the
process varies in its rapidity, and this, he thinks, may depend on the
previous condition of the larva. According to Buckell the pupa of
_Nemeobius lucina_ is sufficiently transparent to allow the development of
the colour of the imago to be watched. He says that the coloration occurred
first in front; that its entire production occupied less than twenty-four
hours, and only commenced about forty-eight hours before the imago
emerged.[202] When the butterfly leaves the pupal skin the wings are soft,
crumpled sacs, of comparatively small size, but, as everyone knows, they
rapidly expand and become rigid; the physiology of this process is
apparently still unknown.
A great deal of evidence, both direct and indirect, has accumulated showing
that the organisation of many Lepidoptera is excessively sensitive, so that
slight changes of condition produce remarkable results; and it has also
been shown that in the early part of the life this sensitiveness is
especially great at the period of ecdysis. Numerous butterflies produce
more than one generation a year, and sometimes the generations are so
different that they have passed current with entomologists as distinct
species. The phenomena of this character are styled "seasonal variations"
or "seasonal dimorphism." It has, however, been shown that, by careful
management, the eggs of a generation (say form _a_) may be made to produce
form _a_, whereas in the usual course of nature they would produce form
_b_. A very remarkable condition is exhibited by the North American
_Papilio ajax_. There are three forms of the species, known as _P. ajax_,
_P. telamonides_, {336}and _P. marcellus_. It is uncertain how many
generations there may be in one year of this species, as the length of the
life-cycle varies greatly according to circumstances. But in West Virginia
all the butterflies of this species that emerge from the chrysalis before
the middle of April are the form _marcellus_; those produced between the
middle of April and the end of May are _telamonides_; while those that
appear after this are _ajax_. _P. telamonides_ is not, however, the
offspring of _marcellus_, for both forms emerge from pupae that have passed
through the winter (and are the offspring of _ajax_), those that emerge
early being _marcellus_, those that appear later _telamonides_.
In various parts of Asia and Africa the butterflies produced during the wet
season differ more or less markedly from those of the same species produced
during the dry season. These are called "wet" and "dry season" forms. Their
aetiology has not been investigated, this discovery being comparatively
recent.
Turning to the early life we find that some larvae vary in colour, and that
this variation is sometimes of a definite character, the larva being one of
two different colours—green or brown. In other cases the variation of the
species is less definitely dimorphic, a considerable range of variation
being exhibited by the species. In tracing the life-histories of
Lepidopterous larvae it is not rare to find species in which the larva
abruptly changes its form and colour in the middle of its life, and so
completely that no one would believe the identity of the individual in the
two successive conditions had it not been shown by direct observation; in
these cases the change in appearance is usually associated with a change in
habits, the larva being, perhaps, a miner in leaves in its first stages,
and an external feeder subsequently. In the case of the larval variation we
have alluded to above, it is understood that there is no marked change of
habits. Poulton has shown[203] that it is not infrequent for some of these
latter kinds of variable larvae to change colour during life, and he
considers that light or conditions of illumination, that he speaks of as
"phytoscopic," are the inducing causes. Great difference is, however,
exhibited according to species, some variable species not being so amenable
to these influences as others are. In dimorphic forms the change was
observed to take place at a moult, the larva changing its skin {337}and
appearing of another colour. In some cases the result of the change was to
bring the colour of the larva into harmony with its surroundings, but in
others it was not so. During the final stage many larvae are susceptible,
the result being made evident only when the pupa is disclosed. Variably
coloured pupae of certain species of butterflies have long been known, and
it has been shown that some of the varieties can be induced by changing the
surroundings. The result of the changes is in certain cases correspondence
between the colour of the individual and its surroundings. In the case of
other species having pupae of variable colour, the colour of the pupa is
without relation to, or harmony with, the surroundings.
Experiments have been made on pupae by Merrifield and others, with the
result of showing that by changes of temperature applied at certain moments
some of the colours or marks of the butterfly that will emerge can be
altered.
It is found that in certain localities the colour of various kinds of
butterflies more or less agrees, while it differs from that of the same
butterflies found in other localities. Thus Weir speaks of a duskiness
common to various butterflies in Java, and calls it "phaeism"; and Bates
states that in the Amazon valley numerous species of butterflies vary in a
similar manner, as regards colour, in a locality. This phenomenon is now
called "homoeochromatism," and is supposed to be due to the effect of local
conditions on a susceptible organisation, though there is no experimental
evidence of this.
MIMICRY.—There are many cases in Lepidoptera of species that depart more or
less strongly in appearance from those forms to which they are considered
to be allied, and at the same time resemble more or less closely species to
which they are less allied. This phenomenon is called mimicry.[204] Usually
the resembling forms are actually associated during life. Bates, who
observed this phenomenon in the Amazon valley, thought that it might be
accounted for by the advantage resulting to the exceptionally coloured
forms from the resemblance;[205] it being assumed that these were
unprotected, while the forms they resembled were {338}believed to be
specially protected by nauseous odours or taste. It was, in fact, thought
that the destroying enemies were deceived by the resemblance into supposing
that the forms that were in reality edible were inedible. This subject has
been greatly discussed, and in the course of the discussion numerous cases
that could not be accounted for by Bates's hypothesis have been revealed.
One of these is the fact that resemblances of the kind alluded to very
frequently occur amongst inedible forms. This also has been thought to be
accounted for by a supposed advantage to the Insects; it being argued that
a certain number of "protected" forms are destroyed by enemies the
instincts of which are faulty, and which therefore always require to learn
by individual experience that a certain sort of colour is associated with a
nasty taste. The next step of the argument is that it will be an advantage
to a protected butterfly to form part of a large association of forms
having one coloration, because the ignorant enemies will more easily learn
the association of a certain form of coloration with nastiness; moreover
such destruction as does occur will be distributed over a larger number of
species, so that each species of a large, similarly coloured, inedible
association will have a less number of its individuals destroyed. It is
scarcely a matter for surprise that many naturalists are very sceptical as
to these explanations; especially as the phenomena are supposed to have
occurred in the past, so that they cannot be directly verified or
disproved. It has not, however, been found, as a matter of fact, that even
unprotected butterflies are much destroyed in the perfect state by birds.
Moreover, in endeavouring to realise the steps of the process of
development of the resemblance, we meet with the difficulty that the amount
of resemblance to the model that is assumed to be efficient at one step of
the development, and to bring safety, is at the next step supposed to be
inefficient and to involve destruction. In other words, while analysis of
the explanation shows that it postulates a peculiar and well-directed
discriminative power, and a persistent selection on the part of the birds,
observation leads to the belief that birds have been but little concerned
in the matter. If we add to this that there is no sufficient evidence that
the species now similar were ever dissimilar (as it is supposed they were
by the advocates of the hypothesis), we think it is clear that the
explanation from our point of view is of but {339}little importance.[206]
The comparatively simple, hypothetical explanation, originally promulgated
by Bates, is sometimes called Batesian mimicry; while the "inedible
association" hypothesis is termed Müllerian mimicry.
There is one branch of the subject of mimicry that we think of great
interest. This is the resemblance between Insects of different Orders; or
between Insects of the same Order, but belonging to groups that are
essentially different in form and appearance. It is not infrequent for
beetles to resemble Hymenoptera, and it is still more frequent for
Lepidoptera to resemble Hymenoptera, and that not only in colour and form,
but also in movements and attitude. Druce says: "Many of the species of
Zygaenidae are the most wonderful of all the moths; in some cases they so
closely resemble Hymenoptera that at first sight it is almost impossible to
determine to which Order they belong."[207] W. Müller says: "The little
Lepidoptera of the family Glaucopides, that are so like certain wasps as to
completely deceive us, have when alive exactly the same manner of holding
their wings, the same restless movements, the same irregular flight as a
wasp."[208] Seitz and others record a case in which a Brazilian
_Macroglossa_ exactly resembles a humming-bird, in company with which it
flies; and the same naturalist also tells us[209] of a Skipper butterfly
that greatly resembles a grasshopper of the genus _Tettix_, and that
moreover makes movements like the jumping of grasshoppers. In most of these
cases the probabilities of either original similarity, arrested evolution,
or the action of similar conditions are excluded: and the hypothesis of the
influence, by some means or other, of one organism on another is strongly
suggested.
The CLASSIFICATION of Lepidoptera was said by Latreille a century ago to be
a reproach to entomologists. Since that time an enormous number of new
species and genera have been described, but only recently has much advance
been made in {340}the way of improvement of classification. The progress
made has been limited to a better comprehension and definition of the
families. The nervuration of the wings is the character most in vogue for
this purpose. As regards the larger groups, and Phylogeny, there is a
general opinion prevalent to the effect that Micropterygidae,
Eriocephalidae and Hepialidae are in a comparatively primitive condition,
but as to the relations of these families one with the other, or with other
Lepidoptera, there is a wide difference of opinion.
[Illustration: Fig. 176—Clubs of butterflies' antennae. Terminal portions
of antenna of, 1, _Pieris brassicae_; 2, _Styx infernalis_; 3, _Hestia
idea_ (sub-family Danaides); 4, _Eudamus proteus_, and 5, _Limochores
taumas_ (Hesperiidae). (After Schatz and Scudder.)]
The primary divisions of the family most often met with in literature
are:—either Rhopalocera (= butterflies) and Heterocera (= moths); or
Macrolepidoptera and Microlepidoptera; the Macrolepidoptera including the
butterflies and large moths, the Microlepidoptera being limited to the
families Tineidae (now itself in process of division into numerous
families) and Tortricidae; some entomologists including also Pyralidae,
Pterophoridae and Orneodidae in Microlepidoptera. The division of all
Lepidoptera into two series is merely a temporary device necessitated by
imperfect acquaintance with morphology. The division into Macro- and Micro-
lepidoptera is entirely unscientific.
Series 1. _Rhopalocera_ or Butterflies.—Antennae knobbed at the tip or
thickened a little before the tip, without pectinations, projecting
processes, or conspicuous arrangements of cilia. Hind wings without a
frenulum, but with the costal nervure strongly curved at the base (Fig.
161, II, B).
Series II. _Heterocera_ or Moths.—Antennae various in form, only rarely
knobbed at the tip, and in such cases a frenulum present. In the large
majority a frenulum is present, and the costal nervure of the hind-wing
is either but little arched at the base (as in Fig. 161, I, B) or it has
a large area between it and the front margin; but in certain families the
hind wing is formed much as in Rhopalocera.
{341}It may be inferred from these definitions that the distinction between
the two sub-Orders is neither sharply defined nor of great importance. The
club of the antenna of the Rhopalocera exhibits considerable variety in
form (Fig. 176).[210] Butterflies are as a rule diurnal in their activity
and moths nocturnal; but in the tropics there are numerous Heterocera that
are diurnal, and many of these resemble butterflies not only in colour but
even in the shapes of their wings.
SERIES I. RHOPALOCERA. BUTTERFLIES.
CLASSIFICATION AND FAMILIES OF BUTTERFLIES. Although considerable unanimity
exists as to the natural groups of butterflies, there is much diversity of
opinion as to what divisions are of equivalent value—some treating as
sub-families groups that others call families—and as to the way the
families should be combined. There is, however, a general agreement that
the Hesperiidae are the most distinct of the families, and E. Reuter
considers them a distinct sub-Order with the name Grypocera.[211]
Four categories may be readily distinguished, as follows, viz:—
1. The majority of butterflies; having the first pair of legs more or
less strikingly different from the other pairs; frequently very much
smaller and not used as legs; when not very small, then differing
according to sex of the same species, being smaller in the male than in
the female; the part most peculiar is the tarsus, which is modified in
various manners, but in the males of this great series is always
destitute of its natural form of a succession of simple joints five in
number. There is no pad on the front tibia.
Fam. Nymphalidae, Erycinidae, Lycaenidae.
[The distinctions between these three families are found in the amount
and kind of the abortion of the front legs; for definition refer to the
heading of each of the families.]
2. The front legs are in general form like the other pairs; their tibiae
have no pads; the claws of all the feet are bifid, and there is an
empodium in connection with them. Fam. Pieridae.
3. The front legs are like the other pairs; their tibiae however
possess{342}
pads; the claws are large, not bifid, and there is no empodium; the
metanotum is completely exposed at the base of the abdomen.
Fam. Papilionidae.
4. The front legs are like the other pairs; their tibiae however possess
pads; the claws are small, toothed at the base, and there is an empodium;
the metanotum is concealed by the prolonged and overhanging mesonotum.
Fam. Hesperiidae.
The relations between the families Erycinidae, Lycaenidae, and Nymphalidae
are very intimate. All these have the front legs more or less modified, and
the distinctions between the families depend almost entirely on
generalisations as to these modifications. These facts have led Scudder to
associate the Lycaenidae and Erycinidae in one group, which he terms
"Rurales." It is however difficult to go so far and no farther; for the
relations between both divisions of Rurales and the Nymphalidae are
considerable. We shall subsequently find that the genus _Libythea_ is by
many retained as a separate family, chiefly because it is difficult to
decide whether it should be placed in Erycinidae or in Nymphalidae. Hence
it is difficult to see in this enormous complex of seven or eight thousand
species more than a single great Nymphalo-Lycaenid alliance. The forms
really cognate in the three families are however so few, and the number of
species in the whole is so very large, that it is a matter of great
convenience in practice to keep the three families apart. It is sufficient
for larger purposes to bear in mind their intimate connexions.
The Papilionidae and Pieridae are treated by many as two sub-divisions of
one group. But we have not been able to find any justification for this in
the existence of forms with connecting characters. Indeed it would, from
this point of view, appear that the Pieridae are more closely connected
with the Lycaenidae and Erycinidae than they are with Papilionidae; in one
important character, the absence of the pad of the front tibia, the
Nymphalo-Lycaenids and the Pierids agree. It has also been frequently
suggested that the Papilionidae (in the larger sense just mentioned) might
be associated with the Hesperiidae. But no satisfactory links have been
brought to light; and if one of the more lowly Hesperiids, such as
_Thanaos_, be compared with one of the lower Papilionidae, such as
_Parnassius_, very little approximation can be perceived.
{343}It appears, therefore, at present that Hesperiidae, Papilionidae,
Pieridae, and the Nymphalo-Lycaenid complex are naturally distinct. But in
the following review of the families and sub-families of butterflies, we
shall, in accordance with the views of the majority of Lepidopterists,
treat the Lycaenidae and Erycinidae as families distinct from both
Nymphalidae and Pieridae.[212]
The number of described species of butterflies is probably about 13,000;
but the list is at present far from complete; forms of the largest size and
most striking appearance being still occasionally discovered. Forty years
ago the number known was not more than one-third or one-fourth of what it
is at present, and a crowd of novelties of the less conspicuous kinds is
brought to light every year. Hence it is not too much to anticipate that
30,000, or even 40,000 forms may be acquired if entomologists continue to
seek them with the enthusiasm and industry that have been manifested of
late. On the other hand, the species of Rhopalocera seem to be peculiarly
liable to dimorphic, to seasonal and to local variation; so that it is
possible that ultimately the number of true species—that is, forms that do
not breed together actually or by means of intermediates, morphological or
chronological—may have to be considerably reduced.
In Britain we have a list of only sixty-eight native butterflies, and some
even of these are things of the past, while others are only too certainly
disappearing. New Zealand is still poorer, possessing only eighteen; and
this number will probably be but little increased by future discoveries.
South America is the richest part of the world, and Wallace informs us that
600 species of butterflies could, forty years ago, be found in the environs
of the city of Pará.
FAM. 1. NYMPHALIDAE.—_The front pair of legs much reduced in size in each
sex, their tarsi in the male with but one joint, {344}though in the female
there are usually five but without any claws. Pupa suspended by the tail so
as to hang down freely._ We include in this family several sub-families
treated by some taxonomists as families; in this respect we follow Bates,
whose arrangement[213] still remains the basis of butterfly classification.
With this extension the Nymphalidae is the most important of the families
of butterflies, and includes upwards of 250 genera, and between 4000 and
5000 species. There are eight sub-families.
It is in Nymphalidae that the act of pupation reaches its acme of
complication and perfection; the pupae hang suspended by the tail, and the
cremaster, that is the process at the end of the body, bears
highly-developed hooks (Fig. 177, C, D). The variety in form of the
chrysalids is extraordinary; humps or processes often project from the
body, making the Insect a fantastic object; the strange appearance is
frequently increased by patches like gold or silver, placed on various
parts of the body. It is believed that the term chrysalid was first
suggested by these golden pupæ. The Purple Emperor, _Apatura iris_, differs
strikingly in the pupa as well as in the larva-stage from all our other
Nymphalids; it is of green colour, very broad along the sides, but narrow
on the dorsal and ventral aspects (Fig. 177). The skin of this pupa is less
hard than usual, and the pupa seems to be of a very delicate constitution.
The Purple Emperor, like some of the Satyrides as well as some of its more
immediate congeners, hibernates in our climate as a partially grown larva
and passes consequently only a very brief period of its existence in the
form of a pupa.
[Illustration: Fig. 177.—Pupa of the Purple Emperor butterfly, _Apatura
iris_. New Forest. A, Lateral, B, dorsal aspect; C, enlarged view of
cremaster with the suspensory hook; D, one hook still more enlarged.]
SUB-FAM. 1. DANAIDES.—_Front wing with inner-margin {345}(submedian)
nervure, with a short fork at the base. Cell of hind wing closed. Front
foot of the female ending in a corrugate knob. Caterpillars smooth,
provided with a few long fleshy processes._ The claws are in a variable
state, being sometimes simple, as in Papilionidae, sometimes with an
empodium, apparently of an imperfect kind. The Danaides are usually large
Insects with an imperfect style of ornament and colour; they have a great
deal of black or very dark scaling, and in some _Euploea_ this is agreeably
relieved by a violet or purple suffusion, and these are really fine
Insects. Usually there are large pale spaces, of some neutral indefinite
tint, on which black blotches are distributed in a striking but inartistic
manner. In many of the species the markings are almost spot for spot the
same on the upper and under sides. About seven genera and 250 species are
recognised. Danaides occur in all the warmer parts of the world, but are
most numerous in the Eastern tropics. In Europe the family is represented
only by an Asiatic and African species, _Limnas chrysippus_, that has
extended its range to Greece. Besides this another species, _Anosia
erippus_, Cr. (unfortunately also called _Anosia menippe_, Hb., and _Danais
archippus_ or even _D. plexippus_) has in the last two or three decades
extended its range to various islands and distant localities,
concomitantly, it is believed, with an extension of the distribution of its
food-plant, _Asclepias_. This Insect has several times been taken in this
country, and may probably be a natural immigrant. It is a common butterfly
in North America, where it is called the Monarch.[214]
Some, at least, of the Danaides are unpleasant to birds in odour or in
taste, or both. Among them there occur, according to Moore[215] and others,
numerous cases of resemblance between forms that are thus protected. It is
possible that the odour and taste are of some value to the Insects;[216]
as, however, butterflies of any kind appear to be but rarely attacked in
the imago-state by birds, and as their chief enemies are parasitic Insects
that attack the larval instar, it is impossible to consider this protection
of such prime importance to the species as many theorists assume it to be.
{346}[Illustration: Fig. 178—_Ithomia pusio._ Brazil.]
SUB-FAM. 2. ITHOMIIDES.—_Differs from Danaides by the female front foot
having a true, though somewhat abbreviate tarsus. The caterpillers have no
long processes._ There has been considerable difference of opinion as to
this division of butterflies. It is the family Neotropidae of Schatz, the
Mechanitidae of Berg; also the "Danaioid Heliconiidae" of several previous
writers, except that _Ituna_ and _Lycorea_ do not belong here but to
Danaides. Godman and Salvin treat it as a group of the Danaid sub-family.
The Ithomiides are peculiar to tropical America, where some 20 or 30 genera
and about 500 species have been discovered. There is considerable variety
amongst them. _Ithomia_ and _Hymenitis_ are remarkable for the small area
of their wings, which bear remarkably few scales, these ornaments being in
many cases limited to narrow bands along the margins of the wings, and a
mark extending along the discocellular nervule. Wallace says they prefer
the shades of the forest and flit, almost invisible, among the dark
foliage. Many of these species have the hind-wings differently veined in
the two sexes on the anterior part, in connection with the existence in the
male of peculiar fine hairs, placed near the costal and subcostal veins.
_Tithorea_ and other forms are, however, heavily scaled insects of stronger
build, their colours usually being black, tawny-red or brown, yellow, and
white. In the sub-fam. Danaides, according to Fritz Müller, the male has
scent-tufts at the extremity of the abdomen, whereas in Ithomiides
analogous structures exist on the upper side of the hind-wing. Ithomiides
have various colour-resemblances with members of the Heliconiides and
Pieridae; _Tithorea_ has colour analogues in _Heliconius_, and _Ithomia_ in
_Dismorphia_ (formerly called _Leptalis_). Crowds of individuals of certain
species of _Ithomia_ are occasionally met with, and mixed with them there
are found a small number of examples of _Dismorphia_ coloured like
themselves. They are placed by Haase in his category of secondary models.
Belt states that some Ithomiides are distasteful to monkeys and spiders,
but are destroyed by Fossorial Hymenoptera, which use the butterflies as
food for their young; and he also says that {347}they are very wary when
the wasp is near, and rise off their perches into the air, as if aware that
the wasp will not then endeavour to seize them. Much information is given
about the habits by Bates in the paper in which he first propounded the
"theory of mimicry."[217] The larvae are said to live on Solanaceae.
The genus _Hamadryas_ is placed by some writers in Danaides, by others in
Ithomiides; and Haase has proposed to make it the group "Palaeotropinae."
The species are small, black and white Insects, somewhat like Pierids. They
are apparently hardy Insects, and are abundant in certain parts of the
Austro-Malay region.
SUB-FAM. 3. SATYRIDES.—_Palpi strongly pressed together, set in front with
long, stiff hairs. Front wings frequently with one or more of the nervures
swollen or bladder-like at the base of the wing. Cells of both wings
closed. Caterpillar thickest at the middle, the hind end of the body bifid.
Pupa generally suspended by the cremaster, without girth: but sometimes
terrestrial._ This is a very extensive group, consisting of upwards of 1000
species. The Insects are usually of small size, of various shades of brown
or greyish colours, with circular or ringed marks on the under sides of the
wings. It is found all over the world, and is well represented in Europe;
our Meadow-browns, Heaths, and Marbled-whites, as well as the great genus
_Erebia_ of the highlands and mountains belonging to it. Most of these
Insects have but feeble powers of flight, and rise but little from the
surface of the ground. The caterpillars live on various grasses. They are
usually green or brown, destitute of armature, and a good deal like the
caterpillars of Noctuid moths, but the hind end of the body is thinner and
divided to form two corners, while the head is more or less free, or
outstanding. The pupae are of great interest, inasmuch as in a few cases
they do not suspend themselves in any way, but lie on the ground; sometimes
in a very feeble cocoon or cell. There are no cremasteral hooks. The pupae
of the Grayling butterfly, _Hipparchia semele_, has been found in loose
soil a quarter of an inch below the surface. The chrysalis of the Scotch
Argus, _Erebia aethiops_, was found by Mr. Buckler to be neither suspended
nor attached, but placed in a perpendicular position, head upwards, amongst
the grass. {348}In the majority of cases the pupa is, however, suspended as
is usual in Nymphalidae. Nothing is known as to the nature of the peculiar
inflation of the bases of the nervures of the front wings; it is well shown
in our common species of _Coenonympha_; this character is not, however,
constant throughout the family. There is in South America a very remarkable
group of Satyrides consisting of the genera _Cithaerias_ and _Haetera_, in
which the wings are very delicate and transparent, bearing on the greater
part of their area remote fine hairs instead of scales; there are
nevertheless some scaled patches about the margins, and one or more of the
ringed marks characteristic of the Satyrides; while in some species the
distal portions of the hind wings are tinted with carmine. The species of
the genus _Pierella_ connect these transparent Satyrids with the more
ordinary forms. According to Wallace the habits of these fairy-like forms
are those characteristic of the family in general. The genus _Elymnias_ has
been separated by some authorities as a sub-family, or even as a family,
Elymniidae, chiefly on the ground of a slight peculiarity in the
termination of the branches of the veins at the outer angle of the front
wings. The _Elymnias_ are said to be of a mimetic nature, having a greater
or less resemblance to butterflies of various other divisions; there is
also a considerable difference in appearance between their own sexes. The
larva of _E. undularis_ is known; it is of the form usual in Satyrides, and
lives on the palm _Corypha_. About 50 species, ranging from India to
Australia, with two in Africa, are known of this interesting group.
SUB-FAM. 4. MORPHIDES.—_There is no cell on the hind wing, the
discocellular nervule being absent_ (Fig. 161, II. B). _Caterpillars smooth
or spiny, with the extremity of the body divided; frequently gregarious._
These Insects have become notorious from the extraordinary brilliancy of
blue colour exhibited by the upper surface of the wings of the typical
genus _Morpho_. The species of _Morpho_ are all Insects of large size, but
with wings enormous in proportion to the body; this latter part is carried
in a sort of cradle formed by the inner parts of the margins of the hind
wings. Although an arrangement of this kind is seen in numerous other
butterflies, yet there is perhaps none in which it is carried to quite such
a pitch of perfection as it is in _Morpho_, where, on the under surface no
part of the body behind the posterior legs can {349}be seen. There are only
about 100 species of Morphides, and 50 of these are included in _Morpho_,
which is peculiar to tropical and sub-tropical America; the other half of
the family is divided among ten or twelve genera, found in the Indo-Malay
region; there being none in Africa. The eastern Morphides, though fine
Insects, are not to be compared, either in size or brilliancy, with their
American allies. The species of _Morpho_ are apparently found only in the
great forests of South America, where they are far from rare; some have a
flapping and undulating flight, straight onwards along the alleys of the
forest, and near the ground; others are never seen except steadily gliding
with outstretched wings from 20 to 100 feet above the ground, where they
move across sunny spaces between the crowns of the taller trees; the
low-flyers settle frequently on the ground to suck the juices from fallen
fruit, but the members of the other section never descend to the ground. As
regards the caterpillars, W. Müller tells us[218] that the spines they are
armed with break off, and enter the skin, if the creatures are carelessly
handled. Four of the five species known to him are conspicuously coloured
with black, red, yellow and white. The individuals are gregarious. The
larvae of _M. achilles_ sit in companies, often of more than 100
individuals, on trunks of trees, and so form a conspicuous patch. The
caterpillars of _M. epistrophis_ hang together as red clumps on the twigs
of their food-plants. Hence it appears that in this genus we have an
exception to the rule that night-feeding caterpillars rest in a hidden
manner during the day.
SUB-FAM. 5. BRASSOLIDES.—_Large butterflies, with the cell of the hind wing
closed, and usually with a small adjoining prediscoidal cell. Larva not
very spiny; thinner at the two ends, the tail bifid, the head perpendicular
and margined with spines._ This small sub-family includes less than 100
species arranged in about eight genera, all South American. They have the
very unusual habit of resting during the day like moths, becoming active
only late in the afternoon. They are truly noble Insects; although not
possessed of the brilliant colours of _Morpho_, they are adorned,
especially on the under surface, with intricate lines and shades most
harmoniously combined, while the upper surface is frequently suffused with
blue or purple. This sub-family {350}attains its highest perfection in the
genus _Caligo_; they are enormous Insects, and some of them not rare. The
larva of _C. eurylochus_ (Fig. 179) during early life is green, and sits on
the leaf of a _Musa_, but after the third moult it becomes brown and hides
itself among the dry leaves. It is common in the gardens of Rio de Janeiro,
where its pupae are found on the walls, like those of our white butterflies
here.
SUB-FAM. 6. ACRAEIDES.—_Submedian nervure of fore wings not forked at the
base; the median without spur. Cells closed. Palpi in section cylindric,
sparingly set with hairs. Larva armed with branched spines._ A somewhat
monotonous and uninteresting division; the size is moderate or small, and
the colours not artistic, but consisting of ill-arranged spots; the under
side of the hind wings very frequently diversified by numerous line-like
marks, radiately arranged, and giving place at the base to a few spots.
There are about 200 species known, of which the majority are African; there
are but few Oriental or South American species. Some authorities consider
there is only one genus, but others prefer to adopt seven or eight
divisions. _Alaena_ is now placed in Lycaenidae, though until recently it
was considered to belong here. The females of some species possess an
abdominal pouch somewhat similar to that of _Parnassius_.
The members of this sub-family are considered to be of the protected kind.
[Illustration: Fig. 179—Larva of _Caligo_ (_Pavonia_) _eurylochus_. Rio de
Janeiro. × 1. (After Burmeister.)]
{351}SUB-FAM. 7. HELICONIIDES.—_Submedian nervure of front wing not forked;
median with a short spur near the base. Cell of hind wing closed by a
perfect nervule. Palpi compressed, with scales at the sides, in front
covered with hairs. Male with an elongate unjointed, female with a
four-jointed, front tarsus. Caterpillars set with branched spines._ This
family is peculiar to tropical America and consists of only two genera,
_Heliconius_ and _Eueides_, with about 150 species; but it is one of the
most characteristic of the South American groups of Butterflies. It is very
closely allied to the Nymphalides, especially to the genera _Metamorpha_
and _Colaenis_, but is readily distinguished by the perfectly-formed
nervules that close the wing-cells. The wings are longer and narrower than
in Nymphalides, and the colour, though exhibiting much diversity, is on the
whole similar to that of the heavily-scaled forms of Ithomiides of the
genera _Tithorea_, _Melinaea_, _Melanitis_; there being in several cases a
great resemblance between species of the two groups. A frequent feature in
one group of _Heliconius_ is that the hind wing bears a patch of red
prolonged outwards by angular radiating marks. The individuals of certain
species—_H. melpomene_ and _H. rhea_—are known to execute concerted dances,
rising and falling in the air like gnats; when some of them withdraw from
the concert others fill their places. _H. erato_ exhibits the very rare
condition of trichroism, the hind wings being either red, blue, or green.
Schatz states that the different forms have been reared from a single brood
of larvae. The caterpillars of Heliconiides live on Passiflorae, and are
said to be very similar to our European _Argynnis_-caterpillars. The
chrysalids are very spinous. We may here remark that considerable confusion
exists in entomological literature in consequence of Ithomiides having been
formerly included in this sub-family; for remarks formerly made as to
"Heliconiides," but that really referred only to Ithomiides, have been
interpreted as referring to Heliconiides of the present system.
The Heliconiides seem remarkably plastic as regards colour, and are
therefore exponents of "homoeochromatism." Bates says, as regards them: "In
tropical South America a numerous series of gaily-coloured butterflies and
moths, of very different families, which occur in abundance in almost every
locality a naturalist may visit, are found all to change their hues and
markings together, as if by the touch of an enchanter's wand, at {352}every
few hundred miles, the distances being shorter near the eastern slopes of
the Andes than nearer the Atlantic. So close is the accord of some
half-dozen species (of widely different genera) in each change, that he had
seen them in large collections classed and named respectively as one
species."[219] Many of them are believed to be permeated by nauseous
fluids, or to possess glands producing ill-smelling secretions.
SUB-FAM. 8. NYMPHALIDES.—_Cells, of both front and hind wing, either closed
only by imperfect transverse nervules or entirely open. Front tarsus of the
male unjointed and without spines, of the female four- or five-jointed.
Caterpillar either spined or smooth; in the latter case the head more or
less strongly horned or spined, and the apex of the body bifid._ This
sub-family is specially characterised by the open cells of the wings; the
discocellulars, even when present, being frequently so imperfect as to
escape all but the most careful observation. The Nymphalides include
upwards of 150 genera and 2000 species. The divisions having smooth larvae
are separated by Kirby[220] and others as a distinct sub-family
(Apaturides). In Britain, as in most other parts of the world, Nymphalides
is the predominant group of butterflies. We have eighteen species, among
which are included the Fritillaries, Admirals, Purple Emperor, and the
various _Vanessa_—Peacock, Camberwell Beauty, Red Admiral, Tortoise-shells,
and Painted Lady. All have spined caterpillars except the Emperor. In the
temperate regions of the northern hemisphere Vanessa may be considered the
dominant butterflies, they being very numerous in individuals, though not
in species, and being, many of them, in no wise discomfited by the
neighbourhood of our own species. Several of them are capable of prolonging
and interrupting their lives in the winged condition to suit our climate;
and this in a manner that can scarcely be called hibernation, for they
frequently take up the position of repose when the weather is still warm,
and on the other hand recommence their activity in the spring at a very
early period. This phenomenon may frequently be noticed in the
Tortoise-shell butterfly; it is as if the creature knew that however warm
it may be in the autumn there will be no more growth of food for its young,
and that in the spring vegetation {353}is sure to be forthcoming and
abundant before long, although there may be little or none at the time the
creature resumes its activity. It is probable that the habit may be in some
way connected with an imperfect activity of the sexual organs. It should,
however, be recollected that many larvae of butterflies hibernate as young
larvae after hatching, and, sometimes, without taking any food. _Pyrameis
cardui_, the Painted Lady, is, taking all into consideration, entitled to
be considered the most ubiquitous of the butterfly tribe. Its distribution
is very wide, and is probably still extending. The creature is found in
enormous numbers in some localities, especially in Northern and Eastern
Africa; and when its numbers increase greatly, migration takes place, and
the Insect spreads even to localities where it cannot maintain itself
permanently. In Britain it is probably during some years nearly or quite
absent, but may suddenly appear in large numbers as an immigrant. The
favourite food of the larva is thistles, but many other plants serve the
Insect at times.
_Vanessa_, or _Pyrameis_,[221] _atalanta_, the Red Admiral, is common in
the Palaearctic and Nearctic regions, and extends its range to various
outlying spots. The most remarkable of these is the remote Hawaiian
Islands, where the Insect appears really to be now at home, though it is
associated with a larger and more powerful congener, _P. tameamea_. Another
interesting Vanessid is _Araschnia levana_, which is peculiar to Europe,
where it produces annually two generations so dissimilar to one another
that they passed current as two species, _V. levana_ and _V. prorsa_.
Although intermediate forms are rare in nature they can be induced by
certain treatments applied to the larvae under human control.
The dead-leaf butterflies of the genus _Kallima_ belong to Nymphalides.
They are so shaped and coloured that when settled, with wings closed, on a
twig, the appearance is exactly that of a dry leaf; the exposed surface is
mottled with spots that look just like the patches of minute fungi, etc.
that are so common on decaying vegetation. The colour and the spots on the
under surface of this butterfly are very variable. According to Mr.
Skertchly,[222] we may presume that in the minute details of {354}these
resemblances we have a case of hypertely similar to that of the resemblance
to Insects' minings exhibited by certain marks on the tegmina of
_Pterochroza_ (mentioned in Vol. V. p. 322).
In South America there is a somewhat peculiar genus of
Nymphalides—_Ageronia_—that delights in settling on the trunks of trees
rather than on flowers or leaves. It was long since noticed that the the
species of _Ageronia_ make a clicking noise; in some cases when on the
wing, in other cases by moving the wings when the Insect is settled. The
object of the noise is quite uncertain; it has been suggested that it is
done in rivalry or courtship, or to frighten away enemies. Bigg-Wether
found, however, that in South Brazil there is a lazy little bird to which
this sound serves as a signal, inducing it to descend from its perch and
eat the clicker. The mode in which the noise is produced is not quite
clear. Sir George Hampson has pointed out[223] that the fore wing bears at
the extreme base a small appendage bearing two hooks, and that two other
processes on the thorax play on these when the wing moves. His suggestion
that these hooks are the source of the sound seems highly probable.
There is a great variety in the larvae of Nymphalides. In the _Vanessa_
group the body is armed with spines, each one of which bears shorter
thorns, the head being unadorned. The Fritillaries (_Argynnis_, _Melitaea_)
also have caterpillars of this kind. In many other forms the head itself is
armed with horns or spines of diverse, and frequently remarkable,
character. In _Apatura_ and its allies the body is without armature, but
the head is perpendicular, the vertex bifid and more or less prolonged. The
caterpillar of our Purple Emperor, _Apatura iris_, is quite unlike any
other British caterpillar; in colour it is like a Sphingid larva—green with
oblique lateral stripes of yellow and red—but in form it is slug-like,
pointed behind, and it has on the head two rather long tentacle-like horns.
In the South American genus _Prepona_, the larva of which in general form
resembles that of _Apatura_ there are no anal claspers, but the extremity
of the body is prolonged, forming a sort of tail.
FAM. 2. ERYCINIDAE (LEMONIIDAE of some authors).—_The female has six
perfectly formed legs, though the front pair is smaller. The male has the
coxae of the front legs forming a spine, and the tarsi unjointed, without
claws._ This family consists of about 1000 {355}species, usually of rather
small size, exhibiting a great variety of shape and coloration, some of
them being remarkably similar to some of the gay, diurnal moths of South
America. The palpi are usually small, but in _Ourocnemis_ they are large
and porrect. The family is specially characteristic of tropical America,
but there is one small group of 30 or 40 species, _Nemeobiides_, in the
Eastern Hemisphere. We have one species in Britain, _Nemeobius lucina_, the
Duke of Burgundy Fritillary. Neither the larvae nor the pupae of Erycinidae
present any well-marked characteristic feature, but exhibit considerable
variety. According to Bar,[224] some of the larvae are like those of moths;
the caterpillar of _Meliboeus_ is said to be like that of a _Liparis_: the
chrysalis has the short, rounded form of that of the _Lycaenidae_, and is
suspended with the head down, and without a band round the body. The larvae
of _Eurygona_ are gregarious. The pupae of some other forms adhere, heads
downwards, to branches. Scudder considers that this family is not distinct
from Lycaenidae, and that the Central American genus _Eumaeus_ connects the
two. Reuter also treats Erycinidae as a division of Lycaenidae.
SUB-FAM. 1. ERYCINIDES.—[_Characters of the family._] _Palpi not unusually
large._ We place all the Erycinidae in this sub-family except the
following—
SUB-FAM. 2. LIBYTHEIDES.—_Butterflies of average size, with the palpi large
and porrect: the front legs of the male small, the tarsus reduced to one
joint: the front leg of the female of the normal structure, and but little
reduced in size._ This division consists of the single genus _Libythea_,
with only a score of species. They are Insects somewhat like _Vanessa_ in
appearance, but cannot fail to be recognised on account of the peculiar
palpi. The genus is of very wide distribution, occurring in most parts of
the warm and temperate continental regions, and it also occurs in Mauritius
and the Antilles.
The Libytheides have given rise to much difference of opinion amongst
systematists, some of whom assign them as a sub-family to the Erycinidae,
some to the Nymphalidae; while others treat them as a family apart. The
families Nymphalidae, Erycinidae and Lycaenidae are so intimately allied,
that Scudder is probably correct in considering them to form really one
huge family; if this view were adopted there would be no difficulty {356}in
locating _Libythea_ therein. If they be kept apart, it is almost necessary
to separate _Libythea_ also; though possibly its claims to be placed in
Erycinidae slightly preponderate. The recently described genus _Ourocnemis_
to some extent connects Erycinides with Libythaeides.[225]
FAM. 3. LYCAENIDAE.—_The front legs but little smaller than the others: in
the male, however, the tarsus, though elongate, is only of one joint, and
is terminated by a single claw. No pad on the front tibia. Claws not
toothed._ The Lycaenidae, or Blues, are, as a rule, of small size, but in
the tropics there are many that reach the average size of butterflies,
_i.e._ something about the stature of the Tortoise-shell butterfly. The
family is one of the larger of the divisions of butterflies, considerably
more than 2000 species being at present known, and this number is still
rapidly increasing. Although blue on a part of the upper surface is a very
common feature in the group, it is by no means universal, for there are
many "Coppers," as well as yellow and white Lycaenidae. Many species have
delicate, flimsy appendages—tails—to the hind wings, but in many others
these are quite absent; and there are even tailed and tailless forms of the
same species. The members of the group Lipteninae (_Liptena_, _Vanessula_,
_Mimacraea_, etc.) resemble members of other sub-families of Nymphalidae,
and even of Pieridae. Lycaenidae are well represented wherever there are
butterflies; in Britain we have 18 species.
The larvae of this family are very peculiar, being short, thicker in the
middle, and destitute of the armature of spines so remarkable in many other
caterpillars. It has of late years been frequently recorded that some of
these larvae are attended by ants, which use their antennae to stroke the
caterpillars and induce them to yield a fluid of which the ants are fond.
Guénée had previously called attention[226] to the existence of peculiar
structures contained in small cavities on the posterior part of the
caterpillar of _Lycaena baetica_. These structures can be evaginated, and,
it is believed, secrete a fluid; Edwards and M‘Cook are of opinion that
they are the source of the matter coveted by the ants. The larvae are
without spines.
The caterpillars of the Blues have some of them strange tastes; more than
one has been recorded as habitually feeding on Aphidae {357}and
scale-Insects. The pupae are, like the larvae, of short inflated form. By a
remarkable coincidence, the pupae of two species bear a considerable
resemblance to the heads of monkeys, or mummies. The Lycaenid pupa is
usually extremely consolidated, destitute of movement, and is supported—in
addition to the attachment by the cremaster—by a silk thread girdling the
middle. There are exceptions to these rules, and according to Mr. Robson
the pupa of _Tajuria diaeus_ hangs free, suspended from a leaf, and can
move the body at the spot where the abdominal segments meet the wing-cases
in the dorsal line.[227]
FAM. 4. PIERIDAE.—_The six legs well developed, and similar in the sexes;
there is no pad on the front tibia. The claws of all the feet are bifid, or
toothed, and there is an empodium._ There are upwards of 1000 species of
Pieridae already known. Although several taxonomists treat the Pieridae and
Papilionidae as only subdivisions of one family, yet they appear to be
quite distinct, and the relationships of the former to be rather with
Lycaenidae. In Pieridae, white, yellow, and red are the predominant
colours, though there is much black also. It has recently been ascertained
that the yellow and red pigments, as well as the white, are uric acid or
derivatives therefrom.[228] The physiology of this peculiarity has not yet
been elucidated, so that we do not know whether it may be connected with
some state of the Malpighian vessels during metamorphosis.
Our Garden-White, Brimstone, Clouded-yellows and Orange-tip butterflies
belong to this family; as does also the South American genus formerly
called _Leptalis_. This generic name, which is much mentioned in literature
owing to the resemblance of the species of the genus to _Heliconiides_, has
now disappeared; _Leptalis_ having been divided into various genera, while
the name itself is now considered merely a synonym of _Dismorphia_.
The African Insect, _Pseudopontia paradoxa_, has nearly transparent wings,
no club to the antennae, a remarkably small cell on the wing, and an
arrangement of the nervules not found in any other butterfly; there being
only ten nervules at the periphery of the front wing, and both upper and
lower radial nervules uniting with the posterior branch of the subcostal.
It has been treated as a moth by several entomologists. Aurivillius
considers that it {358}is certainly a butterfly; but as the metamorphoses
are unknown, we cannot yet form a final opinion as to this curious form.
The extraordinary Peruvian Insect, _Styx infernalis_, is also placed in
this family by Staudinger; it is a small, pale Insect, almost white, and
with imperfect scales; a little recalling a Satyrid. It appears to be
synthetic to Pieridae and Erycinidae.
[Illustration: Fig. 180—Pupation of the Orange-tip butterfly, _Euchloe
cardamines_. A, The completed pupa; B, the larva, with its girdle, prepared
for the change.]
The caterpillars of Pieridae are perhaps the least remarkable or attractive
of all butterfly-caterpillars; their skins are as a rule bare, or covered
only with fine, short down or hair; their prevalent colour is green, more
or less speckled with black and yellow, and they are destitute of any
prominent peculiarities of external structure. Pupation is accomplished by
the larva fixing itself to some solid body by the posterior extremity, with
the head upwards (or the position may be horizontal), and then placing a
girdle round the middle of the body. The pupa never hangs down freely as it
does in Nymphalidae. It has been ascertained by experiment that if the
girdle round the larva be cut, the pupation can nevertheless be
accomplished by a considerable proportion of larvae. Some of the pupae are
of very peculiar form, as is the case in the Orange-tip (Fig. 180, A) and
Brimstone butterflies. The Orange-tip butterfly passes nine or ten months
of each year as a pupa, which is variable in colour; perhaps to some extent
in conformity with its surroundings. The North American _E. genutia_ has a
similar life-history, but the larva leaves its Cruciferous food-plant,
wanders to an oak tree, and there turns to a pupa, resembling in colour the
bark of the tree.
[Illustration: Fig. 181—Newly-hatched larva of _Euchloe cardamines_. A, The
larva in profile; B, one segment more magnified, showing the liquid-bearing
setae; C, one of the setae still more magnified, and without liquid.]
It is not unusual for caterpillars to change their habits and
{359}appearance in a definite manner in the course of the larval life. The
caterpillar of _Euchloe cardamines_ exhibits a larval metamorphosis of a
well-marked character. The young larva (Fig. 181) is armed with peculiar
setae, furcate at the tip, each of which bears a tiny ball of fluid. In
this stage the caterpillar makes scarcely any movement. In the middle of
the caterpillar's life a new vestiture appears after an ecdysis; numerous
fine hairs are present, and the fluid-bearing spines nearly disappear,
being reduced to a single series of spines of a comparatively small size on
each side of the upper middle region of the body (Fig. 182). The colour is
also a good deal changed, and concomitantly there is a much greater
voracity and restlessness.
[Illustration: Fig. 182—Larva of _Euchloe cardamines_ in middle life. A,
the larva in profile; B, one segment more magnified.]
FAM. 5. PAPILIONIDAE.—_All the legs well developed. Claws large, simple,
without empodium. Front tibiae with a pad. The metanotum free,
conspicuously exposed between mesonotum and abdomen._ This series of
butterflies includes some of the most magnificent of the members of the
Insect world. It is considered by some authorities to be the highest family
of butterflies; and in one very important feature—sexual differentiation—it
certainly is entitled to the rank. There are about 700 recorded species,
the larger portion of which are included in the genus _Papilio_. The great
variety of form has led to this genus being divided; the attempts have,
however, been partial, with the exception of an arrangement made by Felder,
who adopted 75 sections, and a recent consideration of the subject by
Haase, who arranges Felder's sections into three sub-genera. Many of the
sections have received names, and are treated by some authors as genera, so
that an unfortunate diversity exists as to the names used for these
much-admired Insects. The genus is distributed all over the world, but is
perhaps nowhere more numerous in species than in South America.
{360}[Illustration: Fig. 183—_Ornithoptera_ (_Schoenbergia_) _paradisea_,
male. New Guinea. × 1. (Colours, velvet-black, golden-yellow and green.)]
Wallace informs us that the great majority of the species of the Amazon
valley frequent the shady groves of the virgin forest. In many cases the
sexes are extremely different in appearance and habits, and are but rarely
found together in one spot. The genus _Ornithoptera_ is closely allied to
_Papilio_, and contains some of the most remarkable of butterflies, the
homes of the species being the islands of the Malay Archipelago, and
outlying groups of islands, there being a smaller number of species in the
neighbouring continents. The females are of great size, and are so
excessively different from their consorts of the other sex, as to arouse in
the student a feeling of surprise, and a strong desire to fathom the
mysteries involved. {361}[Illustration: Fig. 184—_Ornithoptera
(Schoenbergia) paradisea_, female. × 1. (The wings, on the right side,
detached, showing the under surface. Colours, black, white, and gray.)]
{362}It would be difficult to surpass the effective coloration of the males
in many of the species of _Ornithoptera_; they are, too, very diverse in
this respect; _O. brookiana_ is of an intense black colour, with a band of
angular green marks extending the whole length of its wings, while behind
the head there is a broad collar of crimson colour. Perhaps the most
remarkable of all is the _O. paradisea_, recently discovered in New Guinea;
in this species the sexual disparity reaches its maximum. The female (Fig.
184) is a large, sombre creature of black, white and grey colours, but the
male (Fig. 183) is brilliant with gold and green, and is made additionally
remarkable by a long tail of unusual form on each hind wing.
We may anticipate that these extraordinary cases of sexual total
dissimilarity in appearance are accompanied by equally remarkable habits
and physiological phenomena. In the case of _O. brookiana_ the female is
extremely rare, so that the collector, Künstler, could only obtain fifteen
females to a thousand males. According to Mr. Skertchly, instead of the
crowd of males being eager to compete for the females, the reverse is the
case; the female diligently woos the male, who exhibits a reluctance to
coupling. This observer apparently considered that the "emerald feathers"
of the male are a guide or incitement to the female.[229]
In Africa _Ornithoptera_ is to a certain extent represented by two
extremely remarkable forms, _Papilio zalmoxis_ and _P. (Drurya)
antimachus_. There are about a dozen other genera of Papilionidae; most of
them contain but few species. _Parnassius_, however, is rich in species
inhabiting the mountains and elevated plateaus of the northern hemisphere
in both the Old and New Worlds; it is remarkable for the small amount of
scales on the wings, and for the numerous variations of the species. The
female possesses a peculiar pouch at the end of the body; although only
formed during the process of coupling, it has a special and characteristic
form in most of the species. The curious Indian genus _Leptocircus_ has
parts of the front wings transparent, while the hind pair form long tails.
This genus is of interest in that {363}it is said to connect Papilionidae
to some extent with Hesperiidae. The larvae of this family are remarkable
on account of a curious process on the thoracic segment called an
"osmeterium." It is usually retracted, but at the will of the caterpillar
can be everted in the form of a long furcate or Y-shaped process; there is
a gland in the osmeterium, and as a result a strong odour is emitted when
the exstulpation occurs.
The pupation of Papilionidae is similar to that of Pieridae, the pupa being
placed with the head upwards, fixed by the tail, and girt round the middle.
A very curious diversity of pupation occurs in the genus _Thais_, in which
the pupa is attached by the tail as usual, and—which is quite
exceptional—also by a thread placed at the top of the head. Scudder thinks
there is also a girdle round the middle, but Dr. Chapman inclines to the
view that the thread attaching the head is really the median girdle slipped
upwards. The pupation of _Parnassius_ is exceptional, inasmuch as, like
Satyrides, it is terrestrial, in a slight construction of silk.
FAM. 6. HESPERIIDAE (_Skippers_).—_Six perfect legs: metanotum not free,
largely covered by the mesonotum. A pad on the front tibia. Claws short and
thick; empodium present._ Although this family has been comparatively
neglected by entomologists, upwards of 2000 species and more than 200
genera are known, and it is not improbable that it may prove to be as
extensive as Nymphalidae. We have already said that Hesperiidae is
generally admitted to be the most distinct of the butterfly groups. It has
been thought by some taxonomists to be allied to Papilionidae, but this is
a mistake. It is undoubtedly more nearly allied to Heterocera, and when the
classification of Lepidoptera is more advanced, so that the various natural
groups placed in that sub-Order are satisfactorily distinguished, it is
probable that Hesperiidae will be altogether separated from Rhopalocera. We
have already mentioned that E. Reuter considers the Hesperiidae to be
phylogenetically unconnected with Rhopalocera proper; but though quite
ready to admit that he will probably prove correct in this, we think
Lepidopterists will not be willing to recognise the family as a sub-Order
equivalent in value to all Heterocera.
The body is shorter and thicker than it is in most butterflies, and is
pointed at the tip rather than knobbed or bent downwards; the wings are
less ample; the antennae are not truly {364}knobbed, but are thicker before
the actual tip, which is itself pointed and more or less bent backwards, so
that the antennae are somewhat hook-shaped.
In habits as well as structure the family is markedly distinct from
butterflies; the pupation is peculiar, and the name Skipper has been
applied to the perfect Insects, because so many of them indulge in a brief,
jerky flight, instead of the prolonged aerial courses characteristic of the
higher butterflies.
There is great difference among the members of the family, and some of them
possess a very high development of the powers of locomotion, with a
correspondingly perfect structure of the thoracic region, so that, after
inspection of these parts, we can quite believe Wallace's statement that
the larger and strong-bodied kinds are remarkable for the excessive
rapidity of their flight, which, indeed, he was inclined to consider
surpassed that of any other Insects. "The eye cannot follow them as they
dart past; and the air, forcibly divided, gives out a deep sound louder
than that produced by the humming-bird itself. If power of wing and
rapidity of flight could place them in that rank, they should be considered
the most highly organised of butterflies." It was probably to the genera
_Pyrrhopyge_, _Erycides_, etc., that Mr. Wallace alluded in the above
remarks. Although the Hesperiidae are not as a rule beautifully coloured,
yet many of these higher forms are most tastefully ornamented; parts of the
wings, wing-fringes, and even the bodies being set with bright but
agreeable colours. We mention these facts because it is a fashion to
attribute a lowly organisation to the family, and to place it as ancestral
to other butterflies. Some of them have crepuscular habits, but this is
also the case with a variety of other Rhopalocera in the tropics.
In their early stages the Skippers—so far as at present known—depart
considerably from the majority of butterflies, inasmuch as they possess in
both the larval and pupal instars habits of concealment and retirement. The
caterpillars have the body nearly bare, thicker in the middle, the head
free, and more or less notched above. They make much greater use of silk
than other butterfly-larvae do, and draw together leaves to form caves for
concealment, and even make webs and galleries. Thus the habits are almost
those of the Tortricid moths.
{365}[Illustration: Fig. 185—Pupation of _Badamia exclamationis_. (After
Dudgeon. _J. Bombay Soc._ x. 1895, p. 144). A, One side of the leaf-cradle,
the other (nearest to the observer) being broken away; B, transverse
section of entire cradle, _a_, The pupa; _b_, fastenings of perpendicular
threads round pupa; _c_, cross thread retaining the leaf in cradle form;
_d_, margins of the leaf; _e_, midrib of leaf.]
Pupation takes place under similar conditions; and it is interesting to
find that Chapman considers that the pupa in several points of structure
resembles that of the small moths. Not only does the larva draw together
leaves or stalks to make a shelter for the pupa, but it frequently also
forms a rudimentary cocoon. These arrangements are, however, very variable,
and the accounts that have been given indicate that even the same species
may exhibit some amount of variation in its pupation. Scudder considers
that, in the North American Skippers, the cremaster is attached to a single
Y-like thread. In other cases there is a silk pad on the leaf for the
cremaster to hook on. An interesting account given by Mr. Dudgeon of the
pupation of a common Indian Skipper, _Badamia exclamationis_, shows that
this Insect exercises considerable ingenuity in the structure of the
puparium, and also that the arrangements it adopts facilitate one of the
acts of pupation most difficult for such pupae as suspend themselves, viz.
the hooking the cremasters on to the pad above them. _Badamia_ uses a
rolled-up leaf (Fig. 185); the edges of the leaf are fastened together by
silk at _d_; from this spot there descends a thread which, when it reaches
the pupa, _a_, forks so as to form an inverted Y, and is fastened to the
leaf on either side; the two sides of the leaf are kept together by a cross
thread, _cc_. Mr. Dudgeon was fortunate enough to observe the act of
pupation, and saw that "although the anal prolegs of the larva were
attached to a tuft or pad of silk in the usual way, and remained so until
nearly the whole skin had been shuffled off, yet when the last segment had
to be taken out, the pupa drew it entirely away from the skin and lifted it
over the {366}empty skin, and by a series of contortions similar to those
made by an Insect in depositing an egg, it soon re-attached its anal
segment or cremaster to the web, throwing away the cast-off skin by
wriggling its body about."
SERIES II. HETEROCERA. MOTHS.
Although Rhopalocera—if exclusion be made of the Hesperiidae—is probably a
natural group, yet this is not the case with Heterocera. The only
definition that can be given of Heterocera is the practical one that all
Lepidoptera that are not butterflies are Heterocera. Numerous divisions of
the Heterocera have been long current, but their limits have become more
and more uncertain, so that at the present time no divisions of greater
value than the family command a recognition at all general. This is not
really a matter of reproach, for it arises from the desire to recognise
only groups that are capable of satisfactory definition.
Several attempts have recently been made to form a rough forecast of the
future classification of moths. Professor Comstock, struck by some
peculiarities presented by the Hepialidae, Micropterygidae (and
Eriocephalidae), recently proposed to separate them from all other
Lepidoptera as a sub-order Jugatae. Comstock's discrimination in making
this separation met with general approval. The character on which the group
Jugatae is based is, however, comparatively trivial, and its possession is
not sufficient, as pointed out by Packard,[230] to justify the close
association of Hepialidae and Micropterygidae, which, in certain important
respects, are the most dissimilar of moths. The characters possessed by the
two families in common may be summarised by saying that the wings and
wing-bearing segments remain in a low stage of development. In nearly all
other characters the two families are widely different. Packard has
therefore, while accepting Comstock's separation of the families in
question, proposed a different combination. He considers that
Eriocephalidae should be separated from all others as "Protolepidoptera" or
"Lepidoptera Laciniata," while the whole of the other Lepidoptera,
comprised under the term "Lepidoptera Haustellata," are divided into
Palaeolepidoptera (consisting only of Micropterygidae) and Neolepidoptera,
comprising all Lepidoptera {367}(inclusive of Hepialidae) except the
Eriocephalidae and Micropterygidae. The question is rendered more difficult
by the very close relations that exist between Micropterygidae and a
sub-Order, Trichoptera, of Neuroptera. Dr. Chapman, by a sketch of the
classification of pupae,[231] and Dyar, by one on larval stages,[232] have
made contributions to the subject; but the knowledge of early stages and
metamorphosis is so very imperfect that the last two memoirs can be
considered only as preliminary sketches; as indeed seem to have been the
wishes of the authors themselves.
Simultaneously with the works above alluded to, Mr. Meyrick has given[233]
a new classification of the Order. We allude, in other pages, to various
points in Mr. Meyrick's classification, which is made to appear more
revolutionary than it really is, in consequence of the radical changes in
nomenclature combined with it.
As regards the various aggregates of families that are widely known in
literature by the names Bombyces, Sphinges, Noctuae, Geometres, Pyrales, we
need only remark that they are still regarded as to some extent natural.
Their various limits being the subject of discussion and at present
undecided, the groups are made to appear more uncertain than is really the
case. The group that has to suffer the greatest changes is the old
Bombyces. This series comprises the great majority of those moths that have
diurnal habits. In it there were also included several groups of moths the
larvae of which feed in trunks of trees or in the stems of plants, such as
Cossidae, that will doubtless prove to have but little connection with the
forms with which they were formerly associated. These groups with aberrant
habits are those that give rise to the greatest difficulties of the
taxonomist.
The following key to the families of Heterocera is taken from Sir G. F.
Hampson's recent work, _Fauna of British India—Moths_.[234] It includes
nearly all the families at present recognised among the larger Lepidoptera;
certain families[235] not mentioned in this key are alluded to in our
subsequent remarks on the families:—
{368}Key to the Families of Moths[236]
N.B.—_This table is not simply dichotomic; three contrasted categories
are used in the case of the primary divisions, A, B, C, and the secondary
divisions, I, II, III_.
A. Fore wing with nervule 5 coming from the middle of the discocellulars,
or nearer 6 than 4 (Categories I, II, III = 1-18).
I. Frenulum rudimentary. Fam. 38. EPICOPEIIDAE, see p. 418.
II. Frenulum absent (Categories 1-8).
1. Proboscis present, legs with spurs (Cat. 2-5).
2. Hind wing with nervule 8 remote from 7 (Cat. 3 and 4).
3. Fore wing with nervule 6 and 7 stalked
Fam. 39. URANIIDAE, see p. 419.
4. Fore wing with nervules 6 and 7 not stalked
Fam. 5. CERATOCAMPIDAE, see p. 375.
5. Hind wing with nervule 8 nearly touching 7 beyond end of
cell Fam. 4. BRAHMAEIDAE, see p. 374.
6. Proboscis absent, legs without spurs (Cat. 7 and 8).
7. Hind wing with one internal nervure
Fam. 3. SATURNIIDAE, see p. 372.
8. Hind wing with two or three internal nervures
Fam. 6. BOMBYCIDAE, see p. 375.
III. Frenulum present (Cat. 9-18).
9. Antennae fusiform [spindle-shaped]
Fam. 9. SPHINGIDAE, see p. 380.
10. Antennae not fusiform (Cat. 11-18).
11. Proboscis absent Fam. 7. EUPTEROTIDAE, see p. 376.
12. Proboscis present (Cat. 13-18).
13. Hind wing with nervule 8 curved and almost touching 7
after end of cell; nervure 1a reaching anal angle
Fam. 12. CYMATOPHORIDAE, see p. 386.
14. Hind wing with nervule 8 remote from 7 after end of
cell (Cat. 15-18).
15. Tarsi as short as tibia, hairy; stoutly built
moths Fam. 11. NOTODONTIDAE,[237] see p. 383.
16. Tarsi long and naked; slightly built moths
(Cat. 17 and 18)
17. Fore wing with nervule 7 remote from 8, and
generally stalked with 6
Fam. 40. EPIPLEMIDAE, see p. 420.
18. Fore wing with nervule 7 given off from 8;
hind wing with nervure 1a short or absent
Fam. 36. GEOMETRIDAE, see p. 411.
B. Fore wing with nervule 5 coming from lower angle of cell or nearer
4{369}
than 6 [see figures 161 and 162, pp. 318, 319] (Categories 19-58).
19. Hind wing with more than 8 nervules (Cat. 20, 21).
20. Proboscis absent, no mandibles nor ligula; size not very
small Fam. 23. HEPIALIDAE, see p. 396.
21. Mandibles, long palpi and ligula present; size very small
Fam. 47. MICROPTERYGIDAE, see p. 435.
22. Hind wing with not more than 8 nervules (Cat. 23-58).
23. Hind wing with nervule 8 remote from 7 after origin of
nervules 6 and 7 (Cat. 24-51).
24. Frenulum absent (Cat. 25-29).
25. Hind wing with one internal nervure; nervule 8 with a
precostal spur, Fam. 31. PTEROTHYSANIDAE, see p. 406.
26. Hind wing with two internal nervures (Cat. 27
and 28).
27. Hind wing with a bar between nervules 7 and 8
near the base; nervure 1a directed to middle of
inner margin Fam. 30. ENDROMIDAE, see p. 406.
28. Hind wing with no bar between nervules 7 and 8;
nervure 1a directed to anal angle
Fam. 29. LASIOCAMPIDAE, see p. 405.
29. Hind wing with three internal nervures
Fam. 21. ARBELIDAE, see p. 396.
30. Frenulum present (Cat. 31-51).
31. Hind wing with nervule 8 aborted
Fam. 15. SYNTOMIDAE, see p. 388.
32. Hind wing with nervule 8 present (Cat. 33-51).
33. Antennae knobbed, Fam. 1. CASTNIIDAE, see p. 371.
34. Antennae filiform, or (rarely) dilated a little
towards the tip (Cat. 35-51).
35. Fore wing with nervure 1c present
(Cat. 36-43).
36. Hind wing with nervule 8 free from the
base or connected with 7 by a bar
(Cat. 37-42).
37. Proboscis present
Fam. 16. ZYGAENIDAE, see p. 390.
38. Proboscis absent (Cat. 39-42).
39. Palpi rarely absent; ♀
winged; larvae wood-borers
Fam. 20. COSSIDAE, see p. 395.
40. Palpi absent; ♀ apterous
(Cat. 41, 42).
41. ♀ rarely with legs; ♀ and
larvae case-dwellers
Fam. 19. PSYCHIDAE, see p. 392.
42. ♀ and larvae free[238]
Fam. 18. HETEROGYNIDAE, see p. 392.
43. Hind wing with nervule 8 {370}
anastomosing shortly with 7
Fam. 26. LIMACODIDAE, see. p. 401.
44. Fore wing with nervure 1c absent
(Cat. 45-51).
45. Hind wing with nervule 8 rising out of 7
Fam. 34. ARCTIIDAE, see p. 408.
46. Hind wing with nervule 8 connected with 7
by a bar, or touching it near middle of
cell (Cat. 47, 48).
47. Palpi with the third joint naked and
reaching far above vertex of head;
proboscis present
Fam. 33. HYPSIDAE, see p. 408.
48. Palpi not reaching above vertex of
head; proboscis absent or very minute
Fam. 32. LYMANTRIIDAE, see p. 406.
49. Hind wing with nervule 8 anastomosing
shortly with 7 near the base; proboscis
well developed (Cat. 50, 51).
50. Antennae more or less thick towards tip
Fam. 35. AGARISTIDAE, see p. 410.
51. Antennae filiform
Fam. 37. NOCTUIDAE, see p. 414.
52. Hind wing with nervule 8 curved and nearly or quite touching
nervure 7, or anastomosing with it after origin of nervules
6 and 7 (Cat. 53-58).
53. Hind wing with nervure 1c absent (Cat. 54-57).
54. Hind wing with nervule 8 with a precostal spur
Fam. 24. CALLIDULIDAE, see p. 400.
55. Hind wing with nervule 8 with no precostal spur
(Cat. 56, 57).
56. Hind wing with nervure 1a absent or very short
Fam. 25. DREPANIDAE, see p. 400.
57. Hind wing with nervure 1a almost or quite
reaching anal angle
Fam. 28. THYRIDIDAE, see p. 404.
58. Hind wing with nervure 1c present
Fam. 41. PYRALIDAE, see p. 420.
C. Fore wing with 4 nervules arising from the cell at almost even
distances apart (Cat. 59-66).
59. Wings not divided into plumes (Cat. 60-63).
60. Hind wing with nervule 8 coincident with 7
Fam. 13. SESIIDAE, see p. 386.
61. Hind wing with nervule 8 free (Cat. 62, 63).
62. Fore wing with nervure 1b simple or with a very minute
fork at base Fam. 14. TINAEGERIIDAE, see p. 387.
63. Fore wing with nervure 1a forming a large fork with 1b
at base Fam. 45. TINEIDAE, see p. 428.
64. Wings divided into plumes (Cat. 65, 66). {371}
65. Fore wing divided into at most two, hind wing into three
plumes Fam. 42. PTEROPHORIDAE, see p. 426.
66. Fore wing and hind wing each divided into three plumes
Fam. 43. ALUCITIDAE (= ORNEODIDAE), see p. 426.
FAM. 1. CASTNIIDAE.—_The Insects of this family combine to a large extent
the characters of butterflies and moths. The antennae are knobbed or hooked
at the tip, there is a large precostal area to the hind wing. The nervules
of the front wing are complex and anastomose so as to form one or more
accessory cells_ (Fig. 162). This important, but not extensive, family
consists chiefly of forms found in tropical America and Australia. The
diversity of size, form and appearance is very great, and it is probable
that the members of the family will be separated; indeed, taxonomists are
by no means in agreement as to the limits of the family. The Castniidae are
diurnal Insects, and the North American genus _Megathymus_ is by many
considered to belong to the Rhopalocera. _Euschemon rafflesiae_ (Fig. 186)
is extremely like a large Skipper with long antennae, but has a well-marked
frenulum. The members of the Australian genus _Synemon_ are much smaller,
but they also look like Skippers. Their habits are very like those of the
Hesperiidae; they flit about in the hot sunshine, and when settling after
their brief flights, the fore wings are spread out at right angles to the
body, so as to display the more gaily coloured hind wings; at night, or in
cloudy weather, the Insect rests on blades of grass with the wings erect,
meeting vertically over the back, like a butterfly. _Hecatesia_, another
Australian genus, is now usually assigned to _Agaristidae_; its members
look like moths. The male of _H. fenestrata_ is provided with a
sound-producing organ similar to that of the Agaristid genus _Aegocera_.
[Illustration: Fig. 186—_Euschemon rafflesiae._ Australia. (After
Doubleday.)]
The _Castnia_ of South America are many of them like {372}Nymphalid
butterflies, but exhibit great diversity, and resemble butterflies of
several different divisions of the family.[239]
The species are apparently great, lovers of heat and can tolerate a very
dry atmosphere.[240] The transformations of very few have been observed; so
far as is known the larvae feed in stems; and somewhat resemble those of
Goat-moths or Leopard-moths (Cossidae); the caterpillar of _C. therapon_
lives in the stems of Brazilian orchids, and as a consequence has been
brought to Europe, and the moth there disclosed. The pupae are in general
structure of the incomplete character, and have transverse rows of spines,
as is the case with other moths of different families, but having larvae
with similar habits.[241] _Castnia eudesmia_ forms a large cocoon of
fragments of vegetable matter knitted together with silk. These Insects are
rare in collections; they do not ever appear in numbers, and are generally
very difficult to capture.
FAM. 2. NEOCASTNIIDAE.—The Oriental genus _Tascina_, formerly placed in
Castniidae has recently been separated by Sir G. Hampson and associated
with _Neocastnia nicevillei_, from East India, to form this family. These
Insects have the appearance of Nymphalid butterflies. They differ from
Castniidae by the want of a proboscis.
FAM. 3. SATURNIIDAE.—This is a large and varied assemblage of moths; the
larvae construct cocoons; the products of several species being used as
silk. These moths have no frenulum and no proboscis. The hind wings have a
very large shoulder, so that the anterior margin or costa stretches far
forward beneath the front wing, as it does in butterflies. The antennae of
the males are strongly bipectinated and frequently attain a magnificent
development. The family includes some of the largest and most remarkable
forms of the Insect-world, _Coscinocera hercules_, inhabiting North
Australia, is a huge moth which, with its expanded wings and the long tails
thereof, covers a space of about 70 square inches. One of the striking
features of the family is the occurrence in numerous forms of remarkable
transparent spaces on the wings; these window-like areas usually occur in
the middle of the wing and form a most remarkable contrast to the rest of
the surface, which is very densely {373}scaled. In _Attacus_ these attain a
large size. In other species, such as the South African _Ludia
delegorguei_, there is a small letter-like, or symboliform, transparent
mark towards the tip of each front wing. We have at present no clue to the
nature or importance of these remarkable markings. In the genus
_Automeris_, and in other forms, instead of transparent spaces there are
large and staring ocellate marks or eyes, which are concealed when the
Insect is reposing. In _Arceina_, _Copiopteryx_, _Eudaemonia_ and others,
the hind wings are prolonged into very long tails, perhaps exceeding in
length those of any other moths.
[Illustration: Fig. 187—Larva of _Attacus atlas_, India. A, at end of 1st
instar, profile; B, 4th instar, dorsal view; C, full-grown larva, in
repose. (After Poujade.)]
The cocoons are exceedingly various, ranging from a slight open network to
a dense elaborate structure arranged as in our Emperor moth; in this latter
case an opening is left by the larva for its exit after it has become a
moth, but by an ingenious, chevaux-de-frise work, this opening is closed
against external enemies, though the structure offers no resistance at all
to the escape of the moth. Fabre has recorded some observations and
experiments which seem to show that the instinct predominating over the
formation of the cocoon is not cognoscent. The Insect, if interfered with,
displays a profound stupidity. Its method is blind perseverance in the
customary.[242] The cocoon of Saturniidae is more often continuous, _i.e._
entirely closed. Packard says that {374}_Actias luna_ effects its escape by
cutting through the strong cocoon with an instrument situate at the base of
the front wing. Other species were examined and were found to possess the
instrument; but Packard is convinced that the majority of the species
possessing the instrument do not use it, but escape by emitting a fluid
that softens the cocoon and enables the moth to push itself through.[243]
The cocoons of the species of _Ceranchia_ have a beautiful appearance, like
masses of filagree-work in silver. The pupa in _Ceranchia_ is very
peculiar, being terminated by a long, spine-like process. In _Loepa newara_
the cocoon is of a green colour and suspended by a stalk; looking like the
pod, or pitcher, of a plant. The silk of the Saturniidae is usually coarse,
and is known as Tusser or Tussore[244] silk.
The larvae of this family are as remarkable as the imagos, being furnished
with spine-bearing tubercles or warts, or long fleshy processes; the
colours are frequently beautiful. The caterpillar of _Attacus atlas_ (Fig.
187) is pale olive-green and lavender, and has a peculiar, conspicuous, red
mark on each flank close to the clasper.
About seventy genera and several hundred species are already known of this
interesting family. They are widely distributed on the globe, though there
are but few in Australia. Our only British species, the Emperor moth,
_Saturnia pavonia_, is by no means rare, and its larva is a beautiful
object; bright green with conspicuous tubercles of a rosy, or yellow,
colour. It affects an unusual variety of food-plants, sloe and heather
being favourites; the writer has found it at Wicken flourishing on the
leaves of the yellow water-lily. Although the Emperor moth is one of the
largest of our native Lepidopterous Insects, it is one of the smallest of
the Saturniidae.
The family Hemileucidae of Packard is included at present in Saturniidae.
FAM. 4. BRAHMAEIDAE.—The species forming the genus _Brahmaea_ have been
placed in various families, and are now treated by Hampson as a family
apart, distinguished from Saturniidae by the presence of a proboscis. They
are magnificent, large moths, of sombre colours, but with complex patterns
on the wings, looking as if intended as designs for {375}upholstery. About
fifteen species are recognised; the geographical distribution is
remarkable; consisting of a comparatively narrow belt extending across the
Old World from Japan to West Africa, including Asia Minor and the shores of
the Caspian Sea. Little has been recorded as to the life-histories of these
Insects. The larva is said to have the second and third segments swollen
and armed with a pair of lateral spines projecting forwards. A cocoon is
not formed.
FAM. 5. CERATOCAMPIDAE.—This is a small family. They are fine moths
peculiar to the New World, and known principally by scattered notices in
the works of North American entomologists. Seven genera and about sixty
species are known. The chief genus is _Citheronia_. Some of the larvae are
remarkable, being armed with large and complex spines. A cocoon is not
formed.
FAM. 6. BOMBYCIDAE.—In entomological literature this name has a very
uncertain meaning, as it has been applied to diverse groups; even at
present the name is frequently used for the Lasiocampidae. We apply it to
the inconsiderable family of true silkworm moths. They are comparatively
small and uninteresting Insects in both the larval and imaginal instars;
but the cocoons formed by the well-known silkworm are of great value, and
some other species form similar structures that are of more or less value
for commercial purposes. The silkworm has been domesticated for an enormous
period, and is consequently now very widely spread over the earth's
surface; opinions differ as to its real home, some thinking it came
originally from Northern China, while others believe Bengal to have been
its native habitat. The silkworm is properly called _Bombyx mori_, but
perhaps it is as often styled _Sericaria mori_. Besides being of so great a
value in commerce, this Insect has become an important object of
investigation as to anatomy, physiology and development. Its domestication
has probably been accompanied by a certain amount of change in habits and
instincts, the creature having apparently lost its appreciation of freedom
and its power of flight; it is also said to be helpless in certain respects
when placed on trees in the larval state; but the importance of these
points has been perhaps somewhat exaggerated.[245]
Although the family Bombycidae is very widely distributed in the warmer
regions of the world, it includes only 15 or 20 {376}genera, and none of
them have many species. The Mustiliidae of some entomologists are included
here. Like the Saturniidae, the Bombycidae are destitute of proboscis and
of frenulum to the wings, but they possess two or three internal nervures
on the hind wing instead of the single one existing in Saturniidae.
FAM. 7. EUPTEROTIDAE (Striphnopterygidae of Aurivillius).—This family has
only recently been separated from Lasiocampidae; its members, however,
possess a frenulum; while none is present in the larger family mentioned.
Its limits are still uncertain, but it includes several extremely
interesting forms. The larvae of the European processionary moth,
_Cnethocampa processionea_, are social in habits; they sometimes occur in
very large numbers, and march in columns of peculiar form, each band being
headed by a leader in front, and the column gradually becoming broader. It
is thought that the leader spins a thread as he goes on, and that the
lateral leaders of the succeeding files fasten the threads they spin to
that of the first individual, and in this way all are brought into unison.
The hairs of these caterpillars are abundant, and produce great irritation
to the skin and mucous membrane of any one unlucky enough to come into too
close contact with the creatures. This property is, however, not confined
to the hairs of the processionary moths, but is shared to a greater or less
extent by the hairs of various other caterpillars of this division of
Lepidoptera. In some cases the irritation is believed to be due to the form
of the hair or spine, which may be barbed or otherwise peculiar in form. It
is also thought that in some cases a poisonous liquid is contained in the
spine.
The larvae of other forms have the habit of forming dense webs, more or
less baglike, for common habitation by a great number of caterpillars, and
they afterwards spin their cocoons inside these receptacles. This has been
ascertained to occur in the case of several species of the genus _Anaphe_,
as has been described and illustrated by Dr. Fischer,[246] Lord
Walsingham,[247] and Dr. Holland.[248] The structures are said to be
conspicuous objects on trees in some parts of Africa. The common dwelling
of this kind formed by the caterpillars of _Hypsoides radama_ in Madagascar
is said to be several feet in length; but the structures of most of the
other species are of much smaller size.
{377}The larvae of the South American genus _Palustra_, though hairy like
other Eupterotid caterpillars, are aquatic in their habits, and swim by
coiling themselves and making movements of extension; the hair on the back
is in the form of dense brushes, but at the sides of the body it is longer
and more remote; when the creatures come to the surface—which is but
rarely—the dorsal brushes are quite dry, while the lateral hairs are wet.
The stigmata are extremely small, and the mode of respiration is not fully
known. It was noticed that when taken out of the water, and walking in the
open air, these caterpillars have but little power of maintaining their
equilibrium. They pupate beneath the water in a singular manner: a first
one having formed its cocoon, others come successively and add theirs to it
so as to form a mass.[249] Another species of _Palustra_, _P. burmeisteri_,
Berg,[250] is also believed to breathe by means of air entangled in its
long clothing; it comes to the surface occasionally, to renew the supply;
the hairs of the shorter brushes are each swollen at the extremity, but
whether this may be in connexion with respiration is not known. This
species pupates out of the water, between the leaves of plants.
_Dirphia tarquinia_ is remarkable on account of the great difference of
colour and appearance in the two sexes. In the Australian genus _Marane_
the abdomen is densely tufted at the extremity with hair of a different
colour.
FAM. 8. PEROPHORIDAE.—The moths of the genus _Perophora_ have for long been
an enigma to systematists, and have been placed as abnormal members of
Psychidae or of Drepanidae, but Packard now treats them as a distinct
family. The larvae display no signs of any social instincts, but, on the
contrary, each one forms a little dwelling for itself. Some twenty species
of _Perophora_ are now known; they inhabit a large part of the New World,
extending from Minnesota to Buenos Aires. The habits of _P. melsheimeri_
have been described by Harris, Packard[251] and Newman, and those of _P.
batesi_ by Newman.[252] The larva is very peculiar; there is a flexible
pair of appendages on the {378}head, the use of which is unknown;[253] they
arise by slender stalks behind and above the eyes, are about as long as the
head, and are easily broken off. After hatching, the young larva, when it
begins to feed, fastens two leaves together with silk threads, and so feeds
after the fashion of a Tortricid, rather than a case-making, larva.
Subsequently, however, the caterpillar entirely detaches two pieces of
leaves and fastens them together at the edges, thus constructing a case
that it lives in, and carries about; it can readily leave the case and
afterwards return to it. When at rest, the larva relieves itself from the
effort of supporting this case by the device of fastening it to a leaf with
a few silken threads; when the creature wished to start again, "it came out
and bit off these threads close to the case." Subsequently it changes
inside the case to a pupa armed with transverse rows of teeth, like so many
other pupae that are capable of a certain amount of movement. The larva is
of broad, short, peculiar form, and is said to be very bold in defending
itself when attacked. The moth is somewhat like the silkworm moth, though
of a more tawny colour. Newman does not allude to any cephalic appendages
as existing in the larva of _P. batesi_. If we accept the eggs figured and
described by Snellen,[254] as those of _P. batesi_, it is possible that
this Insect possesses a peculiar mode of oviposition, the eggs being placed
one on the other, so as to form an outstanding string; but we think this
example probably abnormal; the mode is not shared by _P. melsheimeri_. The
genus _Lacosoma_ is considered by Packard to be an ally of _Perophora_. The
caterpillar of _L. chiridota_ doubles a leaf at the mid-rib and fastens the
two edges together, thus forming an unsymmetrical case. Many larvae of
Microlepidoptera do something like this, but the _Lacosoma_ cuts off the
habitation thus formed and carries it about. Packard says it may have
descended from ancestors with ordinary habits and that certain peculiar
obsolete markings on the body of the caterpillar may be indications of
this.[255]
{379}[Illustration: Fig. 188—Larvae of Hammock-moth, _Perophora
sanguinolenta_, projecting from their Hammocks, built from their own
excrement. South America. (After Jones.)]
The Argentinian Insect _Mamillo curtisea_[256] is also probably an ally of
_Lacosoma_. The caterpillar of this moth spins a dwelling for itself, and
is remarkable from the bright colour of the thoracic segments, the
following somites being colourless; the head bears a pair of large
processes, quite different from those figured by Harris. The moth itself is
very Geometrid-like in colour and form. This species is now assigned to
_Perophora_, but it seems to be very doubtful whether many of the species
placed in this genus really belong to it. The diversity of habits and
instincts evinced by these moths of exceptional modes of life, but
considered to be closely allied, is very interesting. The most remarkable
of all is the Hammock-moth, _Perophora sanguinolenta_, of the centre of
South America, the larva of which constructs its portable habitations out
of its own {380}excrement, which is of peculiar form, specially suitable
for the purpose. The caterpillar, when wishing to enlarge its case, builds
it up from excrement "flattened at the sides, so as to adapt it for
building purposes."[257]
[Illustration: Fig. 189.—Antennae of Sphingidae. A, One joint of antenna of
_Choerocampa elpenor_ ♂, enlarged; B, three joints of antenna of _Sphinx
ligustri_, seen from one side, and enlarged.]
FAM. 9. SPHINGIDAE (_Hawk-moths_).—A very important family of moths of
large or moderate size. They have a proboscis which is frequently very
long; there is a frenulum; the body is stouter than in most other
Lepidoptera, and the wings are of small superficies in comparison with it;
the antennae are somewhat peculiar, having a thick, solid appearance,
pointed at the tip. This is usually somewhat hooked, and bears a few hairs.
In the males the antennae are formed in a manner specially characteristic
of the family. In section, each joint shows a chitinous process on the
under side (Fig. 189, A), forming with that of the other joints a
continuous ridge, and on each side of this ridge there exists a series of
short, delicate "cilia" arranged in a very beautiful manner (Fig. 189, B).
This structure, with some modifications, appears to be usually present in
the family; it attains a very perfect development in cases where the tips
of two rows of cilia bend towards one another, meeting so as to form an
arched cavity. This structure is different from what occurs in the males of
other families of Lepidoptera, for though cilia are very common, they are
usually placed either on two projections from the body of the antennae
(instead of on the two sides of a single projection), or there is but a
single whorl, or set, of them on each joint (_Catocala_, etc.). The front
wings are usually pointed at the tip, and are long in proportion to their
width; but in the Smerinthini they are of different form, with the outer
margin scalloped; the hind wings are remarkably small; the abdomen is
frequently pointed, but in the Macroglossini, or Humming-bird hawk-moths,
it is furnished at the {381}tip with a tuft, or with two tufts, of dense,
long scales, capable of expansion.
The larvae are remarkable for their colours and form. The anterior segments
are attenuated, but are capable of great retraction, so that in repose
(Fig. 190, A) this shape is concealed by the curious attitudes that are
assumed. There is in nearly all cases a conspicuous horn on the eleventh
segment, and the body at the extremity behind the horn is so much modified
that the terminal two segments look like little more than a pair of large
claspers. In the Choerocampini, the thoracic segments are retractile, and
can be withdrawn into the more or less inflated fourth segment, and give
the creature somewhat the appearance of a miniature hooded snake. The
larvae of Sphingidae do not bear any conspicuous hairs—except during the
first instar. They do not spin cocoons, but bury themselves in the earth.
The pupa is remarkable from the deep cleft that exists to admit air to the
first spiracle, and for a deep depression on each side of the anterior part
of abdominal segments 5-7; in some cases the proboscis projects on the
breast somewhat like the handle of a pitcher.
[Illustration: Fig. 190—Larva of the Poplar Hawk-moth, _Smerinthus populi_.
× 1. A, in repose; B, in movement.]
A great deal has been written on the colours, markings, and attitudes of
Sphingid larvae, and many interesting facts have been brought to light. We
may refer the reader to the writings of Weismann[258] and Poulton,[259]
without, however, recommending him to place an implicit confidence in their
somewhat metaphysical disquisitions; for the views there shadowed will
{382}necessarily became much modified with the advance of exact knowledge.
It is certain that the position assumed by the same individual varies much
according to age, and to the interval since the last moult; sometimes the
attitude is much more remarkable than that shown in Figure 190, A, for the
anterior segments are held erect, as well as contracted, the front part of
the body being curled, and the Insect supported by the claspers and two
pairs only of the abdominal feet. There is, too, a considerable difference
in colour before and after an ecdysis. Piepers, who has had a long
experience among Sphingid larvae in Java, considers that much of what has
been written as to the protective value of their colours and attitudes, is
mere fancy, and wild generalisation.[260]
Sphingidae have been recorded as capable of producing sounds in the larval
and pupal, as well as in the perfect, instars; but the method in which this
is done has not been ascertained, except in the case of the imago of the
Death's-head moth, which is well known to emit a very audible cry when not
on the wing; in this case it is highly probable that the method is the
friction of the palpi against the proboscis, as stated by Réaumur and
Landois; the inner face of the palp is said to be marked in this case with
fine ridges or striae.
[Illustration: Fig. 191—_Cocytia durvillii._ New Guinea. (After
Boisduval.)]
FAM. 10. COCYTIIDAE.—A single genus constitutes this family, and there are
only three or four species known; they come from the region of New Guinea,
whence the first was brought by D'Urville nearly a hundred years ago. They
are still amongst {383}the rarest of Insects. Nothing is known as to their
life-histories. In appearance they somewhat remind us of the Bee-hawk moths
and Zygaenidae. Butler says[261] the family is characterised by the palpi,
which differ much in the two sexes, and by the antennae resembling those of
Castniidae or Hesperiidae. The form, transparency, and coloration of the
wings reminds one vividly of the Sphingid genus _Hemaris_; the nervuration
is somewhat like that of _Hemaris_, but has certain features of Zygaenidae.
Butler places the family between Agaristidae and Zygaenidae.
[Illustration: Fig. 192—_Cerura vinula_ (Puss-moth) caterpillar. A,
Moulting; B, the same individual a few hours after the moult.]
FAM. 11. NOTODONTIDAE (_Prominents_, _Puss-moths_, etc.).—This is one of
the most extensive of the families of Bombyces; it consists in larger part
of obscure-coloured moths, somewhat like the ordinary Noctuidae of
temperate regions; to which family the Notodonts are indeed considered to
be very closely allied. The family contains, however, some very remarkable
forms. _Tarsolepis_ has an elongate body, terminated (in the female of _T.
fulgurifera_) by a very conspicuous tuft of enormously long, battledore
scales; while in the male of _T. sommeri_ the hind legs are provided with
an appendage of beautiful, roseate hairs. A few of the larger kinds bear a
considerable resemblance in form and proportions to the Sphingidae. Some of
the larvae are most interesting objects; the Puss-moth caterpillar, the
Lobster, and the Dragon larvae are of such strange forms that they have
already interested several generations of observers. The Puss-moth is
common in the southern half of England; its caterpillar (Fig. 192) has,
instead of the claspers, a pair of tubes in which are concealed {384}two
long, flexible whips, capable of being thrust out, and withdrawn, with
rapidity. The structure and the mode of action of these flagella have been
well elucidated by Professor Poulton.[262] The flagella are to be
considered as actual prolongations of the receptacle in which each is
placed, though they are of very different texture therefrom; they are
everted by blood-pressure and drawn in by muscular action; this latter
function is very perfectly accomplished, the amount of relaxation and
contraction of the muscle being very great. It has been maintained that the
whips have arisen as arms of protection against the attacks of Ichneumon
flies; observation shows, however, that the proportion of these "protected"
Insects destroyed by enemies of this sort is quite as large as it is in the
case of forms that are not so protected. The Puss-moth larva is also
believed to be protected by terrifying attitudes,[263] as well as by
ejection (like so many other larvae and insects generally) of fluid. There
is no reason for believing that these larvae are less eaten than others,
and consequently a further hypothesis has been proposed, to the effect that
if they had not acquired these means of defence they would have been
exterminated altogether. This supposition is considered to account for
their acquiring the defence by means of natural selection; realising the
dictum of D. O'Phace, Esq.—
Some flossifers think that a fakkilty's granted,
The minnit it's proved to be thoroughly wanted.
When the Puss-moth caterpillar is full grown it spins a peculiar cocoon of
a solid and impervious nature, which it manages to make look very like the
spots, crevices, or other places amongst which it is located; in this
prison the creature remains for nine or ten months—by far the larger part
of its existence. When it has changed to a moth it has to escape from the
cell in which it so effectually confined itself. This is effected by the
cocoon being thinner in front of the head of the moth, and by the emission
from the alimentary canal of a fluid that softens the cocoon at the spot
alluded to. Mr. Latter has ascertained[264] that this fluid is strongly
alkaline, and contains potassium hydroxide. The front of the head of the
moth is provided with a shield, consisting of a portion of the pupa shell,
which enables the moth to {385}push through in safety, and at the same time
protects the head from the emitted fluid. Figure 192 shows the great change
that occurs in the period of a few hours in the size of the head of the
larva, as well as in that of the spiracles: in A the old spiracles are seen
surrounded by the much larger new orifices, which are at the moment of
moulting quite visible through the skin that is about to be cast off.
The caterpillar of the Lobster-moth, _Stauropus fagi_, is more remarkable
than that of the Puss-moth, but is unfortunately very rare. It has
remarkably long thoracic legs, the abdomen is swollen at the tip, and
instead of the terminal claspers has two long slender processes. The effect
of these peculiarities is greatly enhanced by the extraordinary attitude
assumed by the caterpillar, which holds the first five segments erect, with
the second and third pairs of thoracic legs outstretched; the swollen
terminal segment is also held erect. Hermann Müller states[265] that when
seen from the front this caterpillar looks like a spider, and also that
when alarmed it moves the long legs after the fashion of an Arachnid. He
believes that it is thus effectually protected from the attacks of
Ichneumons. Birchall says[266] that the young larva, when at rest, closely
resembles, in colour and outline, one of the twigs of beech with unopened
buds, on which it frequently stations itself; and that, when feeding, its
likeness to a great earwig or to a _Staphylinus_ is very striking. Others
say that this caterpillar resembles a dead and crumpled beech leaf.
The larva of _Hybocampa milhauseri_—the Dragon of old Sepp—is highly
remarkable. When young it has grand lateral horns in front, and a dorsal
row; as it grows the lateral horns disappear. Dr. Chapman says[267] that he
could not understand at first why any larva should have such remarkable
angular outlines, curiously conspicuous corners and humps. But he
afterwards found that the creature exactly resembled a curled oak leaf,
eaten and abandoned by a _Tortrix_ larva. This caterpillar also constructs
an elaborate cocoon from which the moth escapes by an operation performed
by the pupa, which is provided with two hard spines, called by Dr. Chapman
sardine-openers. "By a lateral rotatory movement of the pupa, which obtains
its fulcrum {386}from the tightness with which it is grasped by the cocoon,
it traverses over and over again" the same part of the cocoon till it is
cut through; at the same time the spines act as guides to a fluid which is
emitted so as to soften the part that has to be sundered.
Though many other larvae of Notodontidae are of most curious form and
assume remarkable attitudes, yet this is not the case with all, and some
are quite ordinary and like the caterpillars of common Noctuidae. This is
the case with the species _Rhegmatophila alpina_ we have selected to
illustrate the metamorphosis of the Order (Fig. 157). Those who wish to
form an idea of the variety of larval forms in this family will do well to
refer to Packard's beautiful volume on the North American forms.[268] The
family has a very wide distribution, but is absent from New Zealand and
Polynesia, and appears to be but poorly represented in Australia. In
Britain we have about two dozen species.
FAM. 12. CYMATOPHORIDAE.—A small family of nocturnal moths that connect the
Bombyces with the Noctuids; they are usually associated with the latter,
but are widely separated in Hampson's arrangement because of a slight
difference of nervuration, nervule 5 being nearer to 6 than to 4, whereas
in Noctuidae the reverse is the case. The Insects, however, in certain
respects approach the Notodontidae, and are of interest if only as showing
that the linear sequences we adopt in books are necessarily conventional,
and to some extent deceptive. We have three genera in Britain; our pretty
Peach-blossom, _Thyatira batis_, and the very different Buff-arches, _T.
derasa_, being among them. Meyrick denies any connexion of this group with
Noctuidae, and in his nomenclature _Cymatophora_ becomes _Polyploca_, and
the family, consequently, Polyplocidae.
FAM. 13. SESIIDAE or AEGERIIDAE (_Clear-wings_).—A family of comparatively
small extent; its members have frequently one or both pairs of wings in
large part free from scales, the tip of the body tufted, the hind legs of
one sex peculiar. The size is usually small, but in the largest forms the
measurement may be but little less than two inches across the expanded
wings. The pupa is of the kind classed as "incompletae" by Chapman, the
appendages not being firmly glued to the body, and much {387}mobility
existing; an "eye-collar" is present, and the segments of the abdomen are
armed with series of teeth. The larva is a concealed feeder, nearly naked
and colourless, but with the legs normal in number—three thoracic, four
abdominal pairs of feet, and the terminal claspers; these are sometimes but
poorly developed; the larvae have a greater or less resemblance to those of
Longicorn beetles, the habits of which they share. The family was formerly
associated with the Sphingidae, with which it has no true relationship; it
is more closely allied to the Tineidae. Some of the species have a certain
resemblance to Hymenoptera, which is probably in most, if not in all cases
merely incidental. The proper position of the family was pointed out by
Butler,[269] but he did not distinguish it from Tinaegeriidae. Meyrick
calls the family Aegeriadae, and places it in his series Tineina.
[Illustration: Fig. 193—_Oedematopoda princeps._ Africa. (After
Walsingham.)]
We have two genera of these Clear-wings in Britain. They are _Trochilium_
(called variously _Sesia_, _Sphecia_, and _Aegeria_), with two species of
comparatively large size, and _Sesia_ (called variously _Trochilium_ and
_Aegeria_), with nearly a dozen species of smaller size. A third genus,
_Sciapteron_, is doubtfully native with us. They are much prized by
collectors on account of the rarity of the Insects and their great
difference in appearance from our other native Lepidoptera.
FAM. 14. TINAEGERIIDAE. This is one of the least known of the families of
Lepidoptera, and has only recently been distinguished from Sesiidae. It is
entirely exotic, and our knowledge of it is principally due to Lord
Walsingham.[270] Nothing is known as to the life-histories, except that it
has been stated by Stainton that a larva feeds in webs on shoots of a shrub
of the genus _Clerodendron_. The family is widely distributed, but its
metropolis will probably prove to be the tropics of Africa. It is of
considerable interest as showing that the Sesiidae really {388}belong to
the Tineid series of moths. The species we figure (Fig. 193) has a
character otherwise peculiar to Sesiidae in the wings being inserted on the
thorax remote from the head—a feature we do not find in the Tineidae
proper; while on the other hand it has the long wing-fringes, and the shape
of the wings that are characteristic of Tineidae. It is worth mentioning
that though these Insects are of excessive rarity and very peculiar, there
exists in the Solomon Islands[271] a species distinct from, though at first
sight excessively similar to, the S. African one we figure.
FAM. 15. SYNTOMIDAE.—This family has usually been associated with the
Zygaenidae. It includes a large number of moths having, as a rule, in
external appearance little to distinguish them from the family named. Many
of them are of gaudy colours, and probably of diurnal, but somewhat
sedentary, habits. The wings are less ample than usual, the hind pair
frequently very small, so that the Insects have somewhat the proportions of
Hymenoptera. In some cases the resemblance is made more remarkable by the
fact that the wings are transparent and bare of scales, or have scales only
at the margins, so as to be like the wings of Hymenoptera. Not less
remarkable is the fact that these Insects use the body itself for the
purposes of adornment or display; thus adopting a system prevalent in the
Hymenoptera, rather than that of their own Order, where the rule is that
the wings are more ornamented than the body. In many cases the shape of the
body is so very different from the normal that the disposition of the
organs of life in the interior of the body must be materially affected. In
some genera, such as _Andrenimorpha_, the form, colour and attitude of the
body and some of the limbs are plainly similar to Hymenoptera. These
Insects have a highly-developed frenulum, retinaculum, and proboscis;
bipectinate antennae in the male, a complex organ at the base of the
abdomen on each side, and are in fact highly-developed forms, except
perhaps as regards the structures in connexion with flight.
Unfortunately little or nothing is known as to the habits and metamorphoses
of these extraordinary creatures, but it is no doubt to them Seitz referred
in saying, "How far one may be deceived by appearances of a mimetic nature
can only be comprehended by visiting the tropics; in this part of the world
{389}[Europe] one is prepared by knowledge gained from books for the
appearance _Sesia_ presents. Had one no knowledge of this sort as to
Sesiidae he would actually in the field [in Brazil] overlook dozens of
these little creatures without being aware of his deception. The surprise
at finding a quite different being in the net from what one believes he has
caught occurs daily in Brazil, so rich in Lepidoptera."[272] The same
intelligent observer says[273] that a species of _Macrocneme_ was observed
by him to be exactly like one of the blue wasps of the genus _Pepsis_.
One remarkable point in these Hymenopteroid Syntomids is their complete
dissimilarity from their immediate allies. They resemble very different
Hymenoptera; and not only stinging Hymenoptera; the Sessiliventres have a
large share of their attentions; the numerous species of _Dycladia_
partaking the appearance of the South American Sawflies in a wonderful
manner. Bees, Wasps of the most different kinds, and a variety of Sawflies
are beautifully paralleled, if one may use such an expression, by these
Syntomids. That shown in Fig. 194 has the abdomen formed like that of a
Petiolate Hymenopteron; the base of this part, moreover, resembles in a
remarkable manner the "median segment" of that Order. The constriction is,
however, placed not at the base of the abdomen but beyond the second
segment. Thus the structure is not morphologically similar to that of the
Hymenoptera, for the median segment of Aculeate Hymenoptera consists of
only one abdominal segment, while in this moth the corresponding part is
formed of two segments. Though anatomically inexact, the resemblance is, as
to proportions, correct; and those who delight in the use of the
imagination will see that had the moth used only one segment for the
imitation, the result would have been less successful owing to insufficient
size. In his very interesting account of some Brazilian Syntomids,[274]
Seitz describes a species of _Trichura_ provided with a long appendage that
is held straight backwards during life; and he informs us that this
creature resembles a female Ichneumon, the long process looking like the
elongate ovipositor of the Hymenopteron. Possibly the species from Demerara
we figure may resemble an Ichneumon we are not acquainted with, though its
colour and form rather suggest a likeness to an Aculeate. {390}This case of
resemblance is of the most noteworthy character, for an appendage of this
kind in a Lepidopterous Insect is without parallel, and is almost
equivalent to the production of a new structure. An interesting feature of
the case is that Ichneumonidae do not sting, and there is no evident reason
why the enemies of the moth should be particularly afraid of an ovipositor.
The larvae appear to be in form somewhat like those of Zygaenidae; but with
the same sort of remarkable clothing, in the form of tufts and brushes,
that we find in Lymantriidae. A cocoon is formed. In Britain no member of
this family is to be met with, but _Naclia ancilla_ may formerly have been
a native; _Syntomis phegea_ has occurred here; probably an escaped example
that had been introduced in one of its earlier stages.
[Illustration: Fig. 194—_Trichura_, sp. × 2/1. Demerara.]
FAM. 16. ZYGAENIDAE (_Burnet-Moths_).—This family is one about the limits
and characters of which much difference of opinion prevails. As exemplified
by our Burnet-moths it is characterised (in addition to the points given in
the table) by the peculiar, flexible antennae; these are a little thicker
before the tip, but are curved and pointed at the extremity, and without
pectinations in the male. There is an elongate proboscis; bladder-like
organs at the sides of the first abdominal segment are not present. The
pupa is softer than is usual in the Macrolepidoptera, and the parts are
less firmly fixed together, so that unusual mobility exists; six of the
intersegmental membranes {391}are free, and the abdomen has much power of
movement; there is no eye-collar; the antennae, hind legs, and
proboscis-tips stretch backwards as far as the fifth or sixth abdominal
segment, the tips being quite free; on the dorsal plates of the abdomen
there are rows of minute elevations reminding one of the teeth existing in
pupae that live in stems or galleries. This is altogether a peculiar pupa;
it lives closely enclosed in a small hard cocoon, and its great capacity
for movement is perhaps connected with the fact that the pupa itself
manages to force its way through the cocoon in anticipation of the
emergence of the moth. This cocoon is fastened tightly to a stem, and is
covered with a substance that gives it a glazed appearance. The larvae are
objects of a baggy nature, with inferior coloration, consisting of large
dark blotches on a light ground, and without any remarkable development of
their somewhat feeble system of hairs. Numerous small moths from the
tropics are assigned to the family; they are most of them conspicuously
marked and coloured, and like our Burnets are probably diurnal.
[Illustration: Fig. 195—_Hampsonia pulcherrima._ Wings on right side
detached and denuded to show nervuration. India. (After Swinhoe.)]
The family Chalcosiidae is reduced by Hampson to the position of a
sub-family of Zygaenidae. It consists of a large variety of diurnal moths
of varied and brilliant colours, with an expanse of wing large in
comparison with the typical Zygaenae, and with the antennae pectinate or
flabellate to the tip. Some of these Insects (which are as conspicuous as
possible in appearance, at any rate in a cabinet, the East Indian
_Cadphises moorei_ _e.g._) are considered to be destitute of any special
"protection." _Histia_ is a genus of remarkable cruciform moths, of a
mixture of black and metallic colours, with carmine-tinted bodies.
_Hampsonia pulcherrima_ (East India) is a curious moth of butterfly form
and coloration, red and black with yellow patches, and with some of the
nervules distorted, as if they had been forced apart in certain spots in
order to accommodate these patches.
Two or three hundred species of Chalcosiidae are recorded. They are
specially characteristic of the Indo-Malayan region.
{392}FAM. 17. HIMANTOPTERIDAE (THYMARIDAE of some authorities) are placed
by Hampson in the sub-family Phaudinae of Zygaenidae characterised by the
absence of the mouth-parts. The Himantopteridae are small moths, and have
the scales on the wings very imperfect and hair-like; the hind wings form
long slender tails, so that the Insects scarcely look like moths. They are
peculiar to India and Africa. In the South African genus _Dianeura_
(belonging really to Phaudinae) also the wings are scaleless and nearly
transparent.
FAM. 18. HETEROGYNIDAE.—Consists of the single genus _Heterogynis_ which
has hitherto been found only in the south of Europe. This is an important
form connecting Zygaenidae and Psychidae. The larvae resemble those of
Zygaena, and construct an oval cocoon for their metamorphosis. The male
issues as a small moth of smoky colour, the scales being but imperfect; the
female chrysalis shows no trace of any appendages, and the imago is
practically a maggot, and never leaves the cocoon; in it she deposits her
eggs, and the young larvae hatch there.[275]
FAM. 19. PSYCHIDAE.—Small, or moderate-sized moths, with imperfect scales,
and little or no colour beyond certain shades of duskiness; the sexes very
different, the female being wingless and sometimes quite maggot-like; the
male often with remarkable, bipectinate antennae, the branches sometimes
very long and flexible. Larva inhabiting a case that it carries about. This
family consists of Insects unattractive in appearance but presenting some
points of great interest. It is frequently stated that the Psychidae are
destitute of scales, but Heylaerts states[276] that, in addition to hairs,
scales of a more or less imperfect formation are present in all, but that
they are, like those of some Sphingidae (_Macroglossa_), very easily
detached. There is much difference in the females, some having
well-developed legs, while others are not only apterous, but are bare and
destitute of appendages like a maggot, while in certain cases (Fig. 196,
G), the head is reduced in size and is of peculiar form so as to make the
Insect look really like the larva of one of the parasitic Diptera. These
females never leave their cases, but deposit their eggs {393}therein, and
inside, also, their former pupa-skin; and here the young hatch; the
peculiar little larvae are very numerous, and it is suggested that they
make a first meal on the body of their parent, but this we believe has not
been satisfactorily ascertained. Great differences as to the condition of
the legs, antennae, etc., are said to exist in species of the same genus.
There is also a remarkable diversity in the pupae of the females; the male
sex being normal in this respect. Some of the female pupae are destitute of
wing-sheaths and all other appendages, while others are said to possess
them, though there are no wings at all in the imago (_Fumea_, _e.g._).[277]
Great difficulties attend the study of these case-bearing Insects, and
several points require careful reconsideration, amongst them the one we
have just mentioned. The males fly rapidly in a wild manner, and may
sometimes be met with in swarms; their lives are believed to be very brief,
rarely exceeding a couple of days, and sometimes being limited to a few
hours.
[Illustration: Fig. 196—Metamorphosis of _Monda rhabdophora_. Ceylon. A,
Larva in case, nat. size; B, larva itself, magnified; C, case of female
during pupation; D, case of male during pupation; E, female pupa,
magnified; F, male moth, nat. size; G, female moth, magnified. (From
unpublished drawings by Mr. E. E. Green).]
The larvae are called basket-worms, and their baskets or cases are well
worthy of attention. Their variety is remarkable; the most extraordinary
are some of the genus _Apterona_ Fig. 197, B, which perfectly resemble the
shells of Molluscs such as snails; indeed, the specimens in the collection
at the British Museum were sent there as shells. This case is not, like
those of other Psychidae, constructed of earth or vegetable matter, but is
of silk and is in texture and appearance exactly {394}like the surface of a
shell. _Psyche helix_ is, according to Ingenitzky,[278] found in great
numbers near Lake Issyk-kul in Central Asia, where the larvae feed, in
their snail-shell-like cases, on a grass, just like snails. Only females
could be reared from these larvae. The case of _Chalia hockingi_ (Fig. 197,
C) consists of little pieces of wood cut to the proper lengths, and
spirally arranged, so as to form a construction that would be quite a
credit to our own species. In some of the Canephorinae we meet with long
cylindrical cases, like those of Caddis-worms, or of Tineid larvae.
[Illustration: Fig. 197—Baskets, or cases, of Psychidae. A, _Amicta
quadrangularis_; B, _Apterona_ (or _Cochlophora_) _valvata_; C, _Chalia
hockingi_.]
Riley has given an account of several points in the structure and natural
history of one of the North American basket- or bag-worms, _Thyridopteryx
ephemeraeformis_; one of his points being the manner in which the newly
hatched larva forms its case.[279] This question has also been discussed by
Packard.[280] The larvae when hatched in unnatural conditions will make use
of fragments of paper, cork, etc., for the case; the act of construction
takes one or two hours, and the larva does not eat till the case is
completed. It walks in a peculiar manner, the legs of the third pair being
moved forwards together, as if they were the prongs of a fork.
This family is already one of considerable extent, but its study, as
already remarked, is but little advanced. Some naturalists are inclined to
place it among the Tineidae, but it is connected with Zygaenidae by means
of Heterogynidae. Mr. Meyrick divides it, placing _Psyche_ and
_Sterrhopteryx_ (the forms representing, according to his ideas, the family
Psychidae in Britain) in the series Psychina which includes Zygaenidae. He
{395}removes the other British genera, _Fumea_, and _Epichnopteryx_, to
Tineidae near _Solenobia_ and _Taleporia_. The group Canephorinae, to which
the two genera in question belong, was long since separated from Psychidae
by Herrich-Schäffer, but this course was condemned by Heylaerts.
Parthenogenesis has been thought by some to occur in numerous species in
this family, but Heylaerts says that it is limited to _Apterona crenulella_
var. _helix_, and even of this species males are found in certain
localities.
FAM. 20. COSSIDAE (_Goat-Moths_, or _Carpenter-Worms_).—Moths of moderate,
or rather large size, without proboscis, frequently with a dense covering
of matted, imperfect scales; the pattern being vague. The larvae bore into
trees in which they often make large burrows, leaving holes from which sap
exudes. Our common Goat-moth is a good specimen of this family, which is a
very widely distributed one. The Australian genus _Ptilomacra_ has very
large, pectinated antennae in the male. The larvae of Cossidae are nearly
bare of clothing and are unadorned; they form a slight cocoon of silk mixed
with gnawed wood. The pupa of the Goat-moth is remarkable for the great
development of the rows of teeth on the dorsal aspects of the segments of
the abdomen, and for the absence of consolidation in this part, six of the
intersegmental incisions being free, and the ventral aspect almost
membranous. Very little is known as to other pupae of the family. It is
believed that the generations of these Insects are fewer than usual, the
growth of the larva occupying a period of two or three years. The larva of
_Zeuzera aesculi_ forms a temporary cocoon in which it passes a
winter-sleep, before again feeding in the spring.[281] It is a moot
question whether the Zeuzeridae should be separated from the Cossidae or
not. The group includes our Wood-leopard moth, which, like many other
Zeuzerids, is spotted in a very striking but inartistic manner. The
position the family Cossidae should occupy in an arrangement of the
Lepidoptera is a very difficult question. Some consider the Insects to be
allied to Tortricidae. The wing-nervuration of _Cossus_ is very peculiar
and complex, there being four or five cells on the front wing, and three on
the hind one. Meyrick places Zeuzeridae as a family of his series Psychina,
but separates Cossidae proper (he calls them Trypanidae) as a family of the
series Tortricina.
{396}FAM. 21. ARBELIDAE.—Closely allied to Cossidae, but without frenulum,
and with less complex wing-nervures. A small family believed to be similar
to Cossidae in the life-history. The tropical African Arbelidae are
considered by Karsch to be a distinct family, Hollandiidae.
FAM. 22. CHRYSOPOLOMIDAE.—This family has been established by Dr.
Aurivillius[282] for an African genus, allied in wing-nervuration to
Cossidae; the Insects are like Lasiocampidae.
FAM. 23. HEPIALIDAE (_Ghost-_ and _Swift-Moths_).—Moths of very diverse
size, some gigantic; wings not fitting together well at the bases; without
a frenulum; no proboscis; the scales imperfect; the nervures complex. The
Hepialidae are extremely isolated amongst the Lepidoptera; indeed, they
have really no allies; the conclusion that they are connected with the
Micropterygidae being certainly erroneous. Although but small in
numbers—only about 150 species being known—they exhibit a remarkable
variety in size and colour. Many are small obscure moths, while others are
of gigantic size—six or seven inches across the wings—and are amongst the
most remarkably coloured of existing Insects. The great _Charagia_ of
Australia, with colours of green and rose, bearing white spots, are
remarkable. The South African _Leto venus_ is of large size, and has an
astonishing supply of glittering metallic splashes on the wings, making a
barbaric but effective display. The South Australian _Zelotypia staceyi_,
of enormous size, is also a handsome moth; but the majority of species of
the family are adorned only in the feeblest manner.
Very little is known as to the larvae; they are either subterranean,
feeding on roots, or they live in the wood of trees and shrubs. They are
nearly bare, and are apparently the lowest type of Bombycid larva. At the
same time, it would appear there is considerable variety amongst them.
Packard says[283] the young larva of _Hepialus mustelinus_ has the
arrangement of setae that is normal in Tineidae. The larva of _H. humuli_
seems to be a very simple form, but _H. hectus_ shows a considerable amount
of divergence from it. They probably live for several years; the larva of
_H. argenteo-maculatus_ in North America lives for three years, at first
eating the roots of Alder and then entering the {397}stems. The pupae are
also peculiar. They are of unusually elongate, cylindrical form, with
comparatively feeble integument, but with a considerable development of
chitinous, elevated, toothed ridges, on the dorsal aspect, and a very
strong ridge of this kind on the ventral surface of the seventh segment;
the wing-sheaths are short; it is very difficult to distinguish the full
number of abdominal segments. These pupae are remarkably agile, and by
wriggling and kicking are able to move a considerable distance; it is said
that they can force themselves to the surface even when the superficial
soil is quite hard. We cannot consider this pupa naturally placed amongst
either the pupae obtectae or incompletae of Chapman.
[Illustration: Fig. 198—Pupa of _Hepialus lupulinus_. Britain. A, Ventral;
B, dorsal aspect.]
We have already remarked that little is known as to the life-histories. The
species are probably prolific, a female of _H. thule_ having been known to
deposit more than 2000 eggs. Of the Australian forms little more is
known[284] than that they live in the wood of trees and shrubs, and are
rapidly disappearing; we may fear that some are extinct without ever having
been discovered, and others, also unknown but still existing, may disappear
only too soon; the wasteful destruction of timber in Australia having been
deplorable.
The peculiar habits of the Hepialidae are not likely to bring the Insects
to the net of the ordinary collector, and we believe they never fly to
light, hence it is probable that we are acquainted with only a small
portion of the existing species; their distribution is very wide, but
Australia seems to be their metropolis, and in New Zealand twelve species
are known. The genera as at present accepted are remarkable for their wide
distribution. _Leto_ is said to occur in South Africa and in the {398}Fiji
Islands; but we must repeat that the study of these interesting Insects is
in a very primitive state, and our present knowledge of their distribution
may be somewhat misleading.
The habits of the European _Hepialus_ in courtship have been observed to a
considerable extent and are of great interest, an astonishing variety and a
profound distinction in the methods by which the sexes are brought together
having been revealed.
_H. humuli_, our Ghost-moth, is the most peculiar. Its habits were detected
by Dr. Chapman.[285] The male is an Insect of exceptional colour, being
white above, in consequence of a dense formation of imperfect scales; the
female is of the brownish tints usual in Swift-moths. In the month of June
the male selects a spot where he is conspicuous, and hovers persistently
there for a period of about twenty minutes in the twilight; his colour has
a silvery-white, glistening appearance, so that the Insect is really
conspicuous notwithstanding the advanced hour. Females may be detected
hovering in a somewhat similar manner, but are not conspicuous like the
male, their colour being obscure; while so hovering they are ovipositing,
dropping the eggs amongst the grass. Females that have not been fertilised
move very differently and dash about in an erratic manner till they see a
male; they apparently have no better means of informing the hovering male
of their presence than by buzzing near, or colliding with him. Immediately
this is done, the male abandons his hovering, and coupling occurs. There
can be little doubt that the colour of the male attracts the female; but
there is a variety, _hethlandica_, of the former sex coloured much like the
female, and in some localities varieties of this sort are very prevalent,
though in others the species is quite constant. This variation in the
colour of the males is very great in Shetland,[286] some being quite like
the females. In _H. hectus_ the two sexes are inconspicuously and similarly
coloured. The male hovers in the afternoon or evening in a protected spot,
and while doing so diffuses an agreeable odour—said by Barrett to be like
pine-apple—and this brings the female to him, much in the same manner as
the colour of _H. humuli_ brings its female. The hind legs of the male
{399}are swollen, being filled with glands for secreting the odorous
matter.[287] This structure has led to the suggestion of the generic name
_Phymatopus_ for the Insect. Turning to other species of the genus, we find
that the normal relative rôles of the sexes are exhibited, but with
considerable diversity in the species. In _H. lupulinus_ the males fly
about with rapidity, while the female sits on a stem and vibrates her
wings; she thus attracts the males, but they do not perceive her unless
happening to come within three or four feet, when they become aware of her
proximity, search for and find her. It is doubtful whether the attraction
is in this case the result of an odour; it would appear more probable that
it may be sound, or that the vibration of the wings may be felt by the
male.
In _H. sylvinus_, _H. velleda_ and _H. pyrenaicus_ less abnormal modes of
attracting the males occur, the individuals of this latter sex assembling
in great numbers at a spot where there is a female. In the first of the
three species mentioned the female sits in the twilight on the stem of some
plant and vibrates the wings with rapidity; she does not fly; indeed,
according to Mr. Robson, she does not till after fertilisation move from
the spot where she emerged. In _H. pyrenaicus_ the female is quite
apterous, but is very attractive to the males, which as we have said,
assemble in large numbers near her. Thus within the limits of these few
allied forms we find radically different relations of the sexes.
1. The male attracts the female—(A) by sight (_H. humuli_); (B) by odour
(_H. hectus_).
2. The female attracts the male—(A) by vibration of wings (_H. lupulinus_
and _H. sylvinus_); (B) without vibration, but by some means acting at a
distance (_H. velleda_, _H. pyrenaicus_).
Little or nothing is known as to the habits of the great majority of the
more remarkable forms of the family. The gigantic Australian forms are
believed to be scarcely ever seen on the wing.
The Hepialidae differ from other Lepidoptera by very important anatomical
characters. The absence of most of the {400}mouth-parts is a character
common to them and several other divisions of Lepidoptera; but the labial
palpi are peculiarly formed in this family, being short and the greater
portion of their length consisting of an undivided base, which probably
represents some part of the labium that is membranous in normal
Lepidoptera. The thoracic segments are remarkably simple, the three
differing less from one another than usual, and both meso- and meta-notum
being much less infolded and co-ordinated. The wings are remarkable for the
similarity of the nervuration of the front and hind wings, and by the cell
being divided by longitudinal nervules so as to form three or four cells.
On the inner margin of the front wing there is near the base an incision
marking off a small prominent lobe, the jugum of Prof. Comstock. Brandt
mentions the following anatomical peculiarities,[288] viz. the anterior
part of the alimentary canal is comparatively simple; the respiratory
system is in some points like that of the larva; the heart is composed of
eight chambers; the appendicular glands of the female genitalia are
wanting. The testes remain separate organs throughout life. The chain of
nerve ganglia consists of the supra- and infra-oesophageal, three thoracic,
and five abdominal, ganglia, while other Lepidoptera have four abdominal.
FAM. 24. CALLIDULIDAE.—A small family of light-bodied diurnal moths having
a great resemblance to butterflies. In some the frenulum is present in a
very rudimentary condition, and in others it is apparently absent.
_Cleosiris_ and _Pterodecta_ are very like butterflies of the Lycaenid
genus _Thecla_. Although fifty species and seven or eight genera are known,
we are quite ignorant of the metamorphoses. Most of the species are found
in the islands of the Malay Archipelago, but there are a few in East India.
FAM. 25. DREPANIDAE (or DREPANULIDAE). (_Hook-tips_).—The larger moths of
this family are of moderate size; many of the species have the apex of the
front wing pointed or even hooked; some have very much the appearance of
Geometrid moths; they resemble very different members of that family.
_Oreta hyalodisca_ is remarkable on account of the very large, transparent
patch on each front wing, though the other species of the genus have
nothing of the sort. In the genus _Deroca_ we {401}find Insects with the
scales imperfect, they being few and small and approximating in form to
hairs; in _D. hyalina_ scales are nearly entirely absent. In other genera,
_e.g._ _Peridrepana_, _Streptoperas_, there is only a very inferior state
of scale-formation. The few larvae that are known are peculiar; they are
nearly bare of hair, without the pair of terminal claspers, while the body
is terminated by a long tubular process. They form a slight cocoon among
leaves.
The members of the family were formerly much misunderstood, and were
assigned to various positions in the Order. There are now about 30 genera,
and 150 species known, the geographical distribution of the family being
very wide. In Britain we have half a dozen species. _Cilix glaucata_
(better known as _C. spinula_) is said "to undoubtedly imitate" the
excrement of birds. No doubt the Insect resembles that substance so as to
be readily mistaken for it. This Insect has a very wide distribution in
North America, Europe and East India, and is said to vary so much in the
structure of its organs as to justify us in saying that the one species
belongs to two or three genera.
[Illustration: Fig. 199—Mature larva of _Apoda testudo_, on beech-leaf.
Britain.]
FAM. 26. LIMACODIDAE (or EUCLEIDAE).—These are somewhat small moths, of
stout formation, sometimes very short in the body, and with rather small
wing-area. The family includes however at present many Insects of diverse
appearance; there are numerous forms in which apple-green is a prominent
colour; some bear a certain resemblance to the Swifts, others to Noctuids;
some, _Rosema_ and _Staetherinia_, are of extraordinary shapes; certain
very small forms, _Gavara_, _Ceratonema_, resemble Tortricids or Tineids; a
few even remind one of Insects of other Orders; so that the group is a
mimetic one. _Nagoda nigricans_ (Ceylon) has the male somewhat like a
Psychid, while the female has a different system of coloration and
wing-form. In _Scopelodes_ the palpi are in both sexes remarkable;
elongated, stiff, directed upwards and brush-like at the tip. Altogether
there are about 100 genera and 400 species known; the distribution of the
family is very wide {402}in both hemispheres, but these Insects do not
occur in insular faunas. In Britain we have two genera, _Heterogenea_ and
_Apoda_ (better known as _Limacodes_[289]), each with a single species.
[Illustration: Fig. 200—Larva of _Apoda testudo_ just hatched. A, Dorsal
view of larva; B, C, D, a spine in different states of evagination. All
magnified. (After Chapman.)]
The early stages of these Insects are of great interest. The eggs, so far
as known, are peculiar flat oval scales, of irregular outline and
transparent; we have figured an example in Vol. V. Fig. 83. The eggs of the
same moth are said to vary much in size, though the larvae that emerge from
them differ little from one another in this respect. The latter are
peculiar, inasmuch as they have no abdominal feet, and the thoracic legs
are but small; hence the caterpillars move in an imperceptible gliding
manner that has suggested for some of them the name of slug-worms. The
metamorphoses of a few are known. They may be arranged in two groups; one
in which the larva is spinose or armed with a series of projections and
appendages persisting throughout life; while in the members of the second
group the spines have only a temporary existence. At the moment the young
larva of _Apoda testudo_ emerges from the egg it has no conspicuous spines
or processes, and is an extremely soft, colourless creature,[290] but it
almost immediately displays a remarkable system of complex spines. These
really exist in the larva when it is hatched, and are thrust out from pits,
as explained by Dr. Chapman. In the succeeding stages, the spines become
modified in form, and the colour of the body and the nature of {403}the
integument are much changed, so that in the adult larva (Fig. 199) the
spines have subsided into the condition of mere prominences, different in
colour from the rest of the surface. These larvae appear to be destitute of
a head, but there really exists a large one which is retracted, except
during feeding, into the body; the five pairs of abdominal feet of the
larvae of allied families are replaced by sucker-like structures on the
first eight abdominal segments. The spinneret of the mouth is not a pointed
tubular organ, but is fish-tailed in shape, and hence disposes the silky
matter, that aids the larva in moving on the leaves, in the form of a
ribbon instead of that of a thread. It has been stated that these peculiar
larvae "imitate" the coloured galls frequently found on the leaves of
trees. The North American forms of this family have very varied and most
extraordinary larvae.[291] In the pretty and conspicuous larva of _Empretia
stimulea_, the tubercles or processes of the body are, in the later stages,
armed with hairs, that contain a poisonous or irritating fluid, said to be
secreted by glands at the bases of the processes. These hairs are readily
detached and enter the skin of persons handling the caterpillars. The larva
of the North American Hag-moth, _Phobetron pithecium_, is a curious object,
bearing long, fleshy appendages covered with down. Hubbard makes the
following statement as to the instincts of this larva:[292]—"The hag-moth
larvae do not seek to hide away their cocoons, but attach them to leaves
and twigs fully exposed to view, with, however, such artful management as
to surroundings and harmonising colours that they are of all the group the
most difficult to discover. A device to which this Insect frequently
resorts exhibits the extreme of instinctive sagacity. If the caterpillar
cannot find at hand a suitable place in which to weave its cocoon, it
frequently makes for itself more satisfactory surroundings by killing the
leaves, upon which, after they have become dry and brown in colour, it
places its cocoon. Several of these caterpillars unite together, and
selecting a long and vigorous immature shoot or leader of the orange tree,
they kill it by cutting into its base until it wilts and bends over. The
leaves of a young shoot in drying turn a light tan-color, which
{404}harmonises most perfectly with the hairy locks of the caterpillar
covering the cocoon. The latter is, consequently, not easily detected, even
when placed upon the exposed and upturned surface of the leaf."
The cocoons of Limacodidae are unusually elaborate, the larva forming a
perfect lid in order to permit itself to escape when a moth. Chapman states
that the larva lies unchanged in the cocoon all winter, moulting to a pupa
in the spring, and that the pupa escapes from the cocoon previous to the
emergence of the moth.[293] Both Chapman and Packard look on the family as
really nearer to Microlepidoptera than to Bombyces; Meyrick (calling it
Heterogeneidae) places it at the end of his series Psychina next
Zygaenidae.
We may allude here to the little moths, described by Westwood under the
name of _Epipyrops_,[294] that have the extraordinary habit of living on
the bodies of live Homopterous Insects of the family Fulgoridae in India.
What their nutriment may be is not known. The larva exudes a white
flocculent matter, which becomes a considerable mass, in the midst of which
the caterpillar changes to a pupa. Westwood placed the Insect in Arctiidae;
Sir George Hampson suggests it may be a Limacodid, and this appears
probable.
FAM. 27. MEGALOPYGIDAE (or LAGOIDAE).—The American genera, _Megalopyge_ and
_Lagoa_, are treated by Berg and by Packard[295] as a distinct family
intermediate between Saturniidae and Limacodidae. The larva is said by the
latter authority to have seven pairs of abdominal feet instead of five
pairs—the usual number in Lepidoptera. When young the caterpillars of
_Lagoa opercularis_ are white and resemble a flock of cotton wool. When
full grown the larva presents the singular appearance of a lock of hair,
moving in a gliding, slug-like manner. Under the long silky hair there are
short, stiff, poison-hairs. The larva forms a cocoon, fitted with a hinged
trap-door for the escape of the future moth. This curious larva is
destroyed by both Dipterous and Hymenopterous parasites.
FAM. 28. THYRIDIDAE.—A small family of Pyraloid moths, exhibiting
considerable variety of form and colour, frequently with hyaline patches on
the wings. They are mostly small {405}Insects, and contain no very striking
forms. Some of them look like Geometrids of various groups. The family is
widely distributed in the tropical zone, and includes 25 genera, of which
_Rhodoneura_, with upwards of 100 species, is the chief one. The larvae are
said to be similar to those of Pyralidae. This family is considered by
Hampson and Meyrick to be ancestral to butterflies.[296]
[Illustration: Fig. 201.—Lappet-moth, _Gastropacha quercifolia_, ♀.
Britain.]
FAM. 29. LASIOCAMPIDAE (_Eggers_, _Lappet-moths_). Usually large Insects
densely covered with scales, without frenulum, but with the costal area of
the hind wing largely developed, and the male antennae beautifully
pectinate, Lasiocampids are easily recognised. They are well known in
Britain, though we have but few species. The flight of some of the species
is powerful, but ill-directed, and the males especially, dash about as if
their flight were quite undirected; as indeed it probably is. The
difference in the flight of the two sexes is great in some species. In the
genus _Suana_ and its allies we meet with moths in which the difference in
size of the two sexes is extreme; the males may be but 1½ inches across the
wings, while the very heavy females may have three times as great an
expanse. Kirby separates these Insects to form the family Pinaridae; it
includes the Madagascar silkworm, _Borocera madagascariensis_. The African
genus _Hilbrides_ is remarkable for the wings being destitute of scales,
and consequently transparent, and for being of very slender form like a
butterfly. The eggs of Lasiocampidae are smooth, in certain cases spotted
in an irregular manner like birds' eggs. Sometimes the parent covers them
with hair. The larvae are clothed with a soft, woolly hair, as well as with
a shorter and stiffer kind, neither beautifully arranged nor highly
coloured, and thus differing from the caterpillars of Lymantriidae; this
hair in some cases has very irritating properties. Cocoons of a close and
compact nature are formed, and hairs from the body are frequently mixed
with the cocoon. In {406}some species the walls of the cocoons have a firm
appearance, looking very like egg-shell—a fact which is supposed to have
given rise to the name of Eggers. Professors Poulton and Meldola have
informed us that this appearance is produced by spreading calcium oxalate
on a slight framework of silk, the substance in question being a product of
the Malpighian tubes.[297] In various families of Lepidoptera it happens
that occasionally the pupa exists longer than usual before the appearance
of the perfect Insect, and in certain members of this family—notoriously in
_Poecilocampa populi_, the December moth—this interval may be prolonged for
several years. There is not at present any explanation of this fact. It may
be of interest to mention the following case:—From a batch of about 100
eggs deposited by one moth, in the year 1891 (the Puss-Moth of the family
Notodontidae), some sixty or seventy cocoons were obtained, the feeding up
of all the larvae having been effected within fourteen days of one another;
fourteen of the Insects emerged as moths in 1892; about the same number in
1893; in 1894, twenty-five; and in 1895, eleven emerged. Lasiocampidae is a
large family, consisting of some 100 genera and 500 or more species, and is
widely distributed. It is unfortunately styled Bombycidae by some
naturalists.
FAM. 30. ENDROMIDAE.—The "Kentish glory," _Endromis versicolor_, forms this
family; it is a large and strong moth, and flies wildly in the daytime in
birch-woods. The larva has but few hairs, and is said when young to assume
a peculiar position, similar to that of saw-fly larvae, by bending the head
and thorax backwards over the rest of the body.
FAM. 31. PTEROTHYSANIDAE.—Consists of the curious East Indian genus
_Pterothysanus_, in which the inner margins of the hind wings are fringed
with long hairs. They are moths of slender build, with large wing-expanse,
black and white in colour, like Geometrids. There is no frenulum.
Metamorphoses unknown.
FAM. 32. LYMANTRIIDAE.—(Better known as LIPARIDAE). These are mostly small
or moderate-sized moths, without brilliant colours; white, black, grey and
brown being predominant; with highly-developed, pectinated antennae in the
male. The larva is very hairy, and usually bears tufts or brushes of
shorter hairs, {407}together with others much longer and softer, these
being sometimes also amalgamated to form pencils; the coloration of these
larvae is in many cases very conspicuous, the tufts and pencils being of
vivid and strongly contrasted colours. Some of these hairy larvae are
poisonous. A cocoon, in which much hair is mixed, is formed. The pupae are
remarkable, inasmuch as they too are frequently hairy, a very unusual
condition in Lepidoptera. The Lymantriidae is one of the largest families
of the old group Bombyces; it includes some 180 genera and 800 species, and
is largely represented in Australia. _Dasychira rossii_ is found in the
Arctic regions. In Britain we have eight genera represented by eleven
species; the Gold-tails, Brown-tails and Vapourer-moths being our commonest
Bombyces, and the latter being specially fond of the London squares and
gardens, where its beautiful larva may be observed on the leaves of roses.
Most of the Lymantriidae are nocturnal, but the male Vapourer-moth flies in
the daytime. In this family there are various species whose females have
the wings small and unfit for flight, the Insects being very sluggish, and
their bodies very heavy. This is the state of the female of the
Vapourer-moth. The males in these cases are generally remarkably active,
and very rapid on the wing.
Some of these moths increase in numbers to an enormous extent, and commit
great ravages. _Psilura monacha_—the Nun, "die Nonne" of the
Germans,[298]—is one of the principal troubles of the conservators of
forests in Germany, and great sums of money are expended in combating it;
all sorts of means for repressing it, including its infection by fungi,
have been tried in vain. The caterpillars are, however, very subject to a
fungoid disease, communicated by natural means. It is believed, too, that
its continuance in any locality is checked after a time by a change in the
ratio of the two sexes. It is not a prolific moth, for it lays only about
100 eggs, but it has been shown that after making allowance for the
numerous individuals destroyed by various enemies, the produce of one moth
amounts in five generations to between four and five million individuals.
The larva feeds on Coniferae, and on many leafy trees and shrubs. The young
{408}larva is provided with two sets of setae, one set consisting of very
long hairs, the other of setae radiating from warts; each one of this
second set of spines has a small bladder in the middle, and it has been
suggested that these assist in the dissemination of the young caterpillars
by atmospheric means.[299] These aerostatic setae exist only in the young
larva. The markings of the moth are very variable; melanism is very common
both in the larva and imago; it has been shown conclusively that these
variations are not connected, as black larvae do not give a larger
proportion of black moths than light-coloured caterpillars do. In England
this moth is never injurious. A closely allied form, _Ocneria dispar_, was
introduced by an accident into North America from Europe about thirty years
ago; for twenty years after its introduction it did no harm, and attracted
but little attention; it has, however, now increased so much in certain
districts that large sums of money have been expended in attempting its
extirpation.
_Dasychira pudibunda_ has occasionally increased locally to an enormous
extent, but in the limited forests of Alsace the evil was cured by the fact
that the caterpillars, having eaten up all the foliage, then died of
starvation.[300] _Teara melanosticta_ is said to produce columns of
processionary caterpillars in Australia.
FAM. 33. HYPSIDAE (or AGANAIDAE).—A family of comparatively small extent,
confined to the tropical and sub-tropical regions of the Eastern
hemisphere. The colours are frequently buff and grey, with white streaks on
the outer parts of the wings. We have nothing very like them in the
European fauna, our species of _Spilosoma_ are perhaps the nearest
approach. In _Euplocia_ the male has a pouch that can be unfolded in front
of the costa at the base of the anterior wing; it is filled with very long,
peculiar, hair-like scales growing from the costal margin; both sexes have
on each side of the second abdominal segment a small, projecting structure
that may be a sense-organ. The female is more gaily coloured than the male.
FAM. 34. ARCTIIDAE.—With the addition recently made to it of the formerly
separate family Lithosiidae, Arctiidae has become the most extensive family
of the old Bombycid series of moths, comprising something like 500 genera
and 3000 species. Hampson recognises four sub-families—Arctiinae,
Lithosiinae, {409}Nolinae, Nycteolinae,—to which may be added others from
America—Pericopinae, Dioptinae, Ctenuchinae; these sub-families being
treated as families by various authors. The sub-family Arctiinae includes
our Tiger- and Ermine-moths, and a great many exotic forms of very diverse
colours and patterns; the species of this division are, on the whole,
probably more variable in colour and markings than in any other group of
Lepidoptera. There are many cases of great difference of the sexes; in the
South American genus _Ambryllis_ the male is remarkable for its hyaline
wings with a few spots; while the female is densely scaled, and very
variegate in colour. There are some cases (the South European genus
_Ocnogyna_) where the female is wingless and moves but little, while the
male flies with great rapidity. _Epicausis smithi_, from Madagascar, one of
the most remarkable of moths, is placed in this division of Arctiidae; it
is of a tawny colour, variegate with black; the abdomen of this latter
colour is terminated by a large tuft of long scarlet hairs; the Insect has
somewhat the appearance of a Hummingbird-hawkmoth. _Ecpantheria_ is an
extensive genus of tropical American moths (having one or two species in
North America), of black and white or grey colours, with very complex
markings; the male in some species has a part of the hind wing produced as
a tail, or lobe, of a different colour.
The sub-family Pericopinae are almost peculiar to South America (two
species of _Gnophaela_ exist in North America); some of this sub-family
bear a great resemblance to Heliconiid butterflies.
The Dioptinae are likewise American moths of diurnal habits, and many of
them bear a striking resemblance to the Ithomiid butterflies they associate
with when alive.
The sub-family Lithosiinae is of great extent; our native "Footmen" give a
very good idea of it; the moths are generally of light structure, with
long, narrow front wings; a simple system of yellow and black colour is of
frequent occurrence. Many of this group feed in the larval state on
lichens. Hampson includes in this group the Nyctemeridae—light-bodied
diurnal moths, almost exclusively of black and white colours, of Geometrid
form, frequently treated as a distinct family.
The sub-family Nolinae is a small group of rather insignificant Insects, in
appearance like Pyralids or Geometrids; four or five {410}species are
native in Britain. Packard maintains the family Nolidae as distinct.[301]
The sub-family Nycteolinae consists of a few small moths the position of
which has always been uncertain; _Nycteola_ (better known as
_Sarrothripus_), _Halias_, and _Earias_ are all British genera that have
been placed amongst Tortrices, to which they bear a considerable
resemblance. _Sarrothripus_ is at present placed by Hampson in Noctuidae,
by others in Lithosiidae, by Meyrick in Arctiidae. The sub-family forms the
family Cymbidae of Kirby;[302] it includes at present only about 70
species, all belonging to the Eastern hemisphere. Two types of larvae are
known in it: one bare, living exposed on leaves; the other, _Earias_,
hairy, living among rolled-up leaves. _Halias prasinana_ is known from the
testimony of numerous auditors to produce a sound when on the wing, but the
_modus operandi_ has not been satisfactorily ascertained. Sound-production
seems to be of more frequent occurrence in Arctiidae than it is in any
other family of Lepidoptera; _Dionychopus niveus_ produces a sound by, it
is believed, friction of the wings. In the case of the genera _Setina_ and
_Chelonia_ the process is said to be peculiar to the male sex: Laboulbène
believes it to proceed from drum-like vesicles situate one on each side of
the base of the metathorax.[303]
FAM. 35. AGARISTIDAE.—An interesting assemblage of moths, many of them
diurnal and of vivid colours, others crepuscular. There is considerable
variety of appearance in the family, although it is but a small one, and
many of its members remind one of other and widely separated families of
Lepidoptera. The style and colour of the Japanese _Eusemia villicoides_ are
remarkably like our _Arctia villica_. In some forms the antennae are
somewhat thickened towards the tip and hooked, like those of the Skipper
butterflies. The family consists at present of about 250 species, but we
doubt its being a sufficiently natural one. It is very widely distributed,
with the exception that it is quite absent from Europe and the
neighbourhood of the Mediterranean Sea. In North America it is well
represented. The larvae, so far as known, are not very remarkable; they
have some lateral tufts of hair, as well as longer hairs scattered over the
body.
{411}The male of the Indian _Aegocera tripartita_ has been noticed to
produce a clicking sound when flying, and Sir G. Hampson has shown[304]
that there is a peculiar structure on the anterior wing; he considers that
this is rubbed against some spines on the front feet, and that the sound is
produced by the friction. Though this structure is wanting in the
acknowledged congeners of _A. tripartita_, yet it occurs in a very similar
form in the genus _Hecatesia_, already noticed under Castniidae.
FAM. 36. GEOMETRIDAE (_Carpets_, _Pugs_, _etc._)—This very extensive family
consists of fragile moths, only a small number being moderately stout
forms; they have a large wing-area; the antennae are frequently highly
developed in the males, but on this point there is much diversity. Either
the frenulum or the proboscis is absent in a few cases. The caterpillars
are elongate and slender, with only one pair of abdominal feet—placed on
the ninth segment—in addition to the anal pair, or claspers. They progress
by moving these two pairs of feet up to the thoracic legs, so that the body
is thrown into a large loop, and they are hence called Loopers or
Geometers. The family is universally distributed, and occurs even in remote
islands and high latitudes; in Britain we have about 270 species. The
family was formerly considered to be closely connected with Noctuidae, but
at present the opinion that it has more intimate relations with the
families we have previously considered is prevalent. Packard considers it
near to Lithosiidae, while Meyrick merely places the six families, of which
he treats it as composed, in his series Notodontina. Hampson adopts
Meyrick's six families as subfamilies, but gives them different names,
being in this respect more conservative than Meyrick, whose recent revision
of the European forms resulted in drastic changes in nomenclature.[305]
This classification is based almost exclusively on wing-nervuration. The
number of larval legs and the consequent mode of walking is one of the most
constant characters of the group; the few exceptions that have been
detected are therefore of interest. _Anisopteryx aescularia_ has a pair of
undeveloped feet on the eighth segment, and, according to Meyrick, its
allies "sometimes show rudiments of the other two pairs." The larva of
_Himera {412}pennaria_ is said to have in early life a pair of imperfect
feet on the eighth segment, which disappear as the larva approaches
maturity.
[Illustration: Fig. 202—Larva of _Amphidasis betularia_, reposing on a
rose-twig. × 1. Cambridge.]
The position of the abdominal feet and claspers throws the holding power of
the larva to the posterior part of the body, instead of to the middle, as
in other caterpillars. This, combined with the elongate form, causes these
larvae when reposing to assume attitudes more or less different from those
of other larvae; holding on by the claspers, some of these Insects allow
all the anterior parts of the body to project in a twig-like manner. The
front parts are not, however, really free in such cases, but are supported
by a thread of silk extending from the mouth to some point near-by. Another
plan adopted is to prop the front part of the body against a twig placed at
right angles to the supporting leaf, so that the caterpillar is in a
diagonal line between the two (Fig. 202). Other Geometers assume peculiar
coiled or spiral attitudes during a whole or a portion of their lives; some
doing this on a supporting object—leaf or twig—while others hang down
(_Ephyra pendularia_). Certain of the larvae of Geometridae vary in colour,
from shades of brown to green; there is much diversity in this variation.
In some species it is simple variation; in others it is dimorphism, _i.e._
the larvae are either brown or green. In other cases the larvae are at
first variable, subsequently dimorphic. In _Amphidasis betularia_ it would
appear that when the larva is hatched the dimorphism is potential, and that
the future colour, whether {413}green or brown, is settled by some
determining condition during the first period of larval life and cannot be
subsequently modified.[306] According to Poulton, the dark tint is due in
_A. betularia_ to colouring matter in the skin or immediately below it, and
the green tint to a layer of fat between the hypodermis and the superficial
muscles; this layer being always green, but more brightly green in the
larvae that are of this colour externally. Much discussion has occurred
about these larval attitudes and colours, and it seems probable that
Professor Poulton has overrated the value of protection from birds, mammals
and entomologists; the chief destroying agents being other than these, and
not liable to be thus deceived, even if the vertebrates are. In some cases
such resemblance as undoubtedly exists is not made the best use of. The
larva shown in figure 202 bore a wonderful resemblance, when examined, to
the rose-twigs it lived on, but the effect of this as a concealing agent
was entirely destroyed by the attitude; for this, being on different lines
to those of the plant, attracted the eye at once. This larva, and we may
add numerous other larvae, could have been perfectly concealed by adopting
a different attitude, but never did so; the position represented being
constantly maintained except while feeding.
In some species of this family the adult females are without wings, or have
them so small that they can be of no use for flight. This curious condition
occurs in various and widely-separated groups of the Geometridae; and it
would be naturally supposed to have a great effect on the economy of the
species exhibiting it, but this is not the case. Some of the flightless
females affect the highest trees and, it is believed, ascend to their very
summits to oviposit. It has been suggested that they are carried up by the
winged males, but this is probably only an exceptional occurrence; while,
as they are known to be capable of ascending with rapidity by means of
crawling and running, it may be taken for granted that this is the usual
method with them. Some of these wingless females have been found in numbers
on gas-lamps, and are believed to have been attracted by the light, as is
the case with very many of the winged forms.[307] {414}Neither is the
geographical distribution limited by this inferior condition of the most
important of the organs of locomotion, for _Cheimatobia brumata_ (the
Winter-moth) one of the species with flightless female, is a common and
widely distributed Insect in Europe and North America.
Although the classification of this family is based almost entirely on
wing-nervuration, yet there are some divisions of the Geometridae in which
this character is remarkably variable, certain individuals frequently
exhibiting considerable abnormality.[308] _Amphidasis betularia_ is
believed to have changed its variation considerably in the course of the
last fifty years. Previous to that time a black variety of the species was
unknown, but it has now become common; and it is believed that other
species of Geometridae are in process of exhibiting a similar
phenomenon.[309]
FAM. 37. NOCTUIDAE (_Owlet-Moths_, _Eulen_ of the Germans).—This very
extensive assemblage consists of moths rarely seen in the day-time, of
generally sombre colours, with antennae destitute of remarkable
developments in the male (except in a small number of forms); proboscis and
frenulum both present; a complex sense-organ on each side of the body at
the junction of the metathorax and abdomen. The number of species already
known can scarcely be less than 8000; owing to their large numbers and the
great general resemblance of the forms, their classification is a matter of
considerable difficulty. Although the peculiar structure at the base of the
thorax was long since pointed out, it has never received any thorough
investigation. Few other remarkable structures have yet been discovered:
the most interesting is perhaps the peculiarity in the hind wings of the
males of certain Ommatophorinae recently pointed out by Sir G. F.
Hampson[310]: in the genera _Patula_ and _Argiva_ the form of the hind
wings is normal in the females, but in the male the anterior one-half of
each of these wings is aborted, and the position of the nervures changed;
this condition is connected with the development of a glandular patch or
fold on the wing, and is remarkable as profoundly affecting a structure
which is {415}otherwise so constant that the classification of the family
is largely based on it.
[Illustration: Fig. 203—_Brephos notha._ Larva, newly hatched. Britain.]
The larvae are as a rule destitute of the remarkable adornments of hairs
and armatures of spines that are so common in many of the families we have
previously considered; they are fond of concealing themselves during the
day and coming out at night to feed; many of them pass most of their time
at, or beneath, the surface of the ground, finding nourishment in roots or
the lower parts of the stems of plants; this is notably the case in the
genus _Agrotis_, which is perhaps the most widely distributed of all the
genera of moths. Such caterpillars are known as Cut-worms in North
America.[311] The great resemblance, _inter se_, of certain of these
Cut-worms, much astonished the American naturalist Harris, who found that
larvae almost perfectly similar produced very different moths. The majority
of Noctuid larvae have the usual number of legs, viz., three pairs of
thoracic legs, four pairs of abdominal feet and the terminal claspers. In
some divisions of the family there is a departure from this arrangement,
and the abdominal feet are reduced to three, or even to two, pairs. One or
two larvae are known—e.g. _Euclidia mi_—in which the claspers have not the
usual function, but are free terminal appendages. When the abdominal legs
are reduced in number (_Plusia_, e.g.) the larvae are said to be
Half-loopers, or Semi-loopers, as they assume to some extent the peculiar
mode of progression of the Geometrid larvae, which are known as Loopers. In
the case of certain larvae, e.g. _Triphaena_, that have the normal number
of feet, it has been observed that when first hatched, the one or two
anterior pairs of the abdominal set are ill developed, and the larvae do
not use them for walking. This is the case with the young larva of our
British _Brephos notha_ (Fig. 203). Subsequently, however, this larva
undergoes a considerable change, and appears in the form shown in Fig. 204.
This interesting larva joins together two or three {416}leaves of aspen and
lives between them, an unusual habit for Noctuid larvae. When about to
pupate it bores into bark or soft wood to change to a pupa, Fig. 205; the
specimen represented closed the hole of entry by placing two separate doors
of silk across the burrow, as shown at _d_. The anal armature of this pupa
is terminated by a curious transverse process. The systematic position of
this interesting Insect is very uncertain: Meyrick and others associate it
with the Geometridae.
[Illustration: Fig. 204—_Brephos notha._ Adult larva.]
[Illustration: Fig. 205 —_Brephos notha._ A, Pupa, ventral aspect; B,
extremity of body, magnified; C, the pupa in wood; _d_, diaphragms
constructed by the larva.]
The larva of _Leucania unipunctata_ is the notorious Army-worm that commits
great ravages on grass and corn in North America. This species sometimes
increases in numbers to a considerable extent without being observed, owing
to the retiring habits of the larvae; when, however, the increase of
numbers has been so great that food becomes scarce, or for some other
cause—for the scarcity of food is supposed not to be the only reason—the
larvae become gregarious, and migrate in enormous swarms: whence its
popular name. The Cotton-worm, _Aletia xylinae_ is even more notorious on
account of its ravages. Riley states[312] that in bad years the mischief it
commits on the cotton crop causes a loss of £6,000,000, and that for a
period of fourteen successive years the annual loss averaged about
£3,000,000. This caterpillar strips the cotton plants of all but their
branches. It is assisted in its work by another highly destructive Noctuid
caterpillar, the Boll-worm, or larva of _Heliothis armigera_, which bores
into the buds and pods. This {417}latter Insect attacks a great variety of
plants, and has a very wide distribution, being found even in England,
where happily it is always a rare Insect.
In Britain, as well as in parts of Northern Europe, a Noctuid moth,
_Charaeas graminis_, occasionally increases to an enormous extent: its
larva is called the Hill-grub and lives on the grass of pastures,
frequently doing great damage in hill-lands. The increase of this moth
seems to take place after the manner of an epidemic; a considerable number
of years may pass during which it is scarcely seen, and it will then appear
in unusual numbers in widely separated localities. This moth lays a large
number of eggs, and is not completely nocturnal in habits; sometimes it may
be seen on the wing in great numbers in the hottest sunshine, and it has
been noticed that there is then a great disproportion of the sexes, the
females being ten or twenty times as numerous as the males. In Australia,
the Bugong moth, _Agrotis spina_, occurs in millions in certain localities
in Victoria: this moth hibernates as an imago, and it formerly formed, in
this instar, an important article of food with the aborigines. The powers
of increase of another Noctuid moth—_Erastria scitula_—are of great value.
Its habits have been described by Rouzaud.[313] On the shores of the
Mediterranean the larva of this little moth lives on a
Scale-Insect—_Lecanium oleae_—that infests the peach; and as the moth may
have as many as five generations in a year, it commits laudable havoc with
the pest. The larva is of remarkable form, very short and convex, with
small head, and only two pairs of abdominal feet. The scale of the
_Lecanium_ is of larger size than is usual in that group of Insects, and
the young larva of the _Erastria_ buries itself, as soon as hatched, in one
of the scales; it destroys successively numerous scales, and after having
undergone several moults, it finds itself provided, for the first time,
with a spinneret, when, with the aid of its silk, it adds to and adapts a
Coccid scale, and thus forms a portable habitation; this it holds on to by
means of the pair of anal claspers, which are of unusual form. The case is
afterwards subjected to further alteration, so that it may serve as a
protection to the creature when it has changed to a pupa. This moth is said
to be free from the attacks of parasites, and if this be the case it is
probable that its increase is regulated by the fact that {418}when the
creature becomes numerous it thus reduces the food supply, so that its own
numbers are afterwards in consequence diminished.
One of the most remarkable genera of British Noctuidae is _Acronycta_,[314]
the larvae of which exhibit so much diversity that it has been suggested
that the genus should be dismembered and its fragments treated as allied to
several different divisions of moths. There are many points of interest in
connection with the natural history of these _Acronycta_. _A. psi_ and _A.
ridens_ are practically indistinguishable as moths, though the larvae are
easily separated: the former species is said to be destroyed to an amazing
extent by parasites, yet it remains a common Insect. The genus _Apatela_ is
very closely allied to _Acronycta_, and Harris says that "_Apatela_
signifies deceptive, and this name was probably given to the genus because
the caterpillars appear in the dress of Arctians and Liparians, but produce
true owlet-moths or Noctuas."[315] The species of another British genus,
_Bryophila_, possess the exceptional habit of feeding on lichens. Some of
the American group Erebides are amongst the largest Insects, measuring
seven or eight inches across the expanded wings.
The Deltoid moths are frequently treated as a distinct family, Deltoidae,
perhaps chiefly because of their resemblance to Pyralidae. At present,
however, they are considered to be separated from Noctuidae by no valid
characters.
FAM. 38. EPICOPEIIDAE.—The genus _Epicopeia_ consists of only a few moths,
but they are amongst the most extraordinary known: at first sight they
would be declared without hesitation to be large swallow-tail butterflies,
and Hampson states that they "mimic" the Papilios of the _Polyxenus_ group.
Very little is known about these extremely rare Insects, but the larva is
stated, on the authority of Mr. Dudgeon, to surpass the moths themselves in
extravagance; to be covered with long processes of snow-white
efflorescence, like wax, exuded from the skin, and to "mimic" a colony of
the larva of a Homopterous Insect. Some ten species of this genus are known
from Java, India, China, and Japan. In this family there is said to be a
rudimentary frenulum, but it is doubtful whether the hairs that have given
rise to this definition really justify it.
{419}FAM. 39. URANIIDAE.—A family of small extent, including light-bodied
moths with ample wings and thread-like antennae; most of them resemble
Geometridae, but a few genera, _Urania_ and _Nyctalemon_, are like
Swallow-tail butterflies and have similar habits. The Madagascar moth,
_Chrysiridia madagascariensis_ (better known as _Urania rhipheus_), is a
most elegant and beautiful Insect, whose only close allies (except an East
African congener) are the tropical American species of _Urania_, which were
till recently treated as undoubtedly congeneric with the Madagascar moth.
The family consists of but six genera and some sixty species. The question
of its affinities has given rise to much discussion, but on the whole it
would appear that these Insects are least ill-placed near Noctuidae.[316]
The larva of the South American genus _Coronidia_ is in general form like a
Noctuid larva, and has the normal number of legs; it possesses a few
peculiar fleshy processes on the back. A description of the larva of
_Chrysiridia madagascariensis_ has been widely spread; but according to
Camboué,[317] the account of the metamorphoses, first given by Boisduval,
is erroneous. The larva, it appears, resembles in general form that of
_Coronidia_, and has sixteen feet; it is, however, armed with long,
spatulate black hairs; it changes to a pupa in a cocoon of open network.
[Illustration: Fig. 206—Abdomen of _Chrysiridia madagascariensis_. A,
Horizontal section showing the lower part of the male abdomen: 1, first
segment; 2, spiracle of second segment; 4-8, posterior segments. B, the
abdomen seen from the side, with the segments numbered. The section is that
of an old, dried specimen.]
In all the species of this family we have examined, we have noticed the
existence of a highly peculiar structure that seems hitherto to have
escaped observation. On each side of the second abdominal segment there is
an ear-like opening (usually {420}much concealed by overlapping scales),
giving entrance to a chamber in the body; this chamber extends to the
middle line, being separated from its fellow by only a thin partition. At
its anterior and lateral part there is a second vesicle-like chamber,
formed by a delicate membrane that extends as far forwards as the base of
the abdomen. There can be little doubt that this is part of some kind of
organ of sense, though it is much larger than is usual with Insect
sense-organs.
FAM. 40. EPIPLEMIDAE.—Under this name Hampson has assembled certain
Geometroid moths, some of them placed previously in Chalcosiidae, some in
Geometridae. They form a varied group, apparently closely allied to
Uraniidae, and having a similar peculiar sense-organ; but are distinguished
by the presence of a frenulum. The larva seems to be like that of
Uraniidae.
FAM. 41. PYRALIDAE.—This division is to be considered rather as a group of
families than as a family; it includes a very large number of small or
moderate-sized moths of fragile structure, frequently having long legs;
antennae simple, only in a few cases pectinate; distinguished from
Noctuidae and all the other extensive divisions of moths by the peculiar
course of the costal nervure of the hind wing, which either keeps, in the
middle of its course, near to the sub-costal or actually unites with it,
subsequently again separating. Members of the Pyralidae are found in all
lands; in Britain we have about 150 species. The larvae are usually nearly
bare, with only short, scattered setae, and little coloration; they have
most varied habits, are fond of concealment, and are very lively and abrupt
in movement, wriggling backwards as well as forwards, when disturbed; a
cocoon is formed for the metamorphosis.
The family as a whole consists of Insects of unattractive appearance,
although it contains some very elegant and interesting moths and numerous
forms of structural interest. In the genus _Thiridopteryx_ little
transparent spaces on the wings occur as a character peculiar to the males;
the spaces are correlative with a greater or less derangement of the
wing-nervures. In some other forms there is a remarkable retinaculum,
consisting of large scales, and this, too, is connected with a distortion
of the wing-nervures. The Pyralidae—Pyralites of Ragonot,[318] Pyralidina
of {421}Meyrick—have recently been revised by two naturalists of
distinction almost simultaneously; unfortunately their results are
discrepant, Meyrick including Pterophoridae and Orneodidae, and yet
admitting in all only eight families; while Ragonot does not include the
two groups named, but defines seventeen tribes of the two
families—Pyralidae and Crambidae—that he admits.
The Pyraustidae of Meyrick is an enormous division including the
Hydrocampidae and Scopariidae of many authors, as well as the Pyraustinae
proper and a small group of Ragonot's, the Homophysinae. The division
Scopariinae is believed to be amongst the "most ancient" of Lepidoptera;
the food of the larvae consists of moss and lichens. This group is widely
distributed, being richly represented in Australia, New Zealand, and the
Hawaiian Islands, as well as in Europe; and probably really occurs wherever
their food-plants exist accompanied by a tolerable climate. The statistics
of the distribution of this group, so far as at present known, have been
furnished by Mr. Meyrick, as follows:—European region, about 25 species;
Madeira, 3; St. Helena, 6; South Africa, 2 or 3; India, 9; Malayan region,
3 or 4; Australia, 24; New Zealand, 64; Hawaiian Islands, 50; North
America, 17 (one of them European); South America, 10. The
Hydrocampinae—the China-marks—are of great interest, as being amongst the
few forms of Lepidoptera adapted for aquatic life. It is believed that all
their larvae are aquatic, though of only a few is there much known. The
diversity amongst these forms is of considerable interest. The habits of
_Hydrocampa nymphaeata_ were long since described by Réaumur, and have more
recently been dealt with by Buckler,[319] W. Müller[320] and Prof.
Miall.[321] Although there are some discrepancies in their accounts, due we
believe to the observations being made at different periods of the life and
under somewhat different circumstances, yet the account given by Müller is
we feel no doubt substantially correct. The larvae when hatched mine in the
leaves of a water-plant for a short time—thirty hours to three days
according to Buckler—and are completely surrounded by water, which
penetrates freely into their burrows; at this period the caterpillar
breathes by its skin, the spiracles being very small, and the tubes leading
from {422}them closed and functionless. After this brief period of mining
life, the larva moults and then constructs a habitation by cutting a piece
out of a leaf, and fastening it to the under side of another leaf; it is
thus provided with a habitation, but it is one into which the water freely
enters, and the respiratory apparatus remains in the state we have
described. The Insect passes through several moults, and then hibernates in
the water. On its revival in the spring a change occurs, and the larva
constructs a portable, or we should rather say free, habitation out of two
large pieces of leaf of lens-shape, fastened together at the edges; but the
larva has some method of managing matters so that the water can be kept out
of this house; thus the creature lives in air though immersed in the water.
A correlative change occurs in the structure of the skin and tracheal
system. The former becomes studded with prominent points that help to
maintain a coat of air round the Insect, like dry velvet immersed in water;
the spiracles are larger than they were, and they and the tracheal tubes
are open. One or two moults take place and the creature then pupates. There
is a good deal of discrepancy in the accounts of this period, and it seems
probable that the pupa is sometimes aerial, sometimes aquatic. Buckler's
account of the formation of the case shows that the larva first cuts off,
by an ingenious process, one piece of leaf, leaving itself on this, as on a
raft; this it guides to a leaf suitable for a second piece, gets the raft
underneath, and fastens it with silk to the upper portion, and then severs
this, leaving the construction free; afterwards the larva goes through a
curious process of changing its position and working at the two extremities
of the case, apparently with the object of making it all right as regards
its capacity for including air and keeping out water. He believes that
Réaumur was correct in his idea that the larva regulates the admission of
air or of water to the case in conformity with its needs for respiration.
Müller calls special attention to the great changes in habit and in the
structure of the integument during the life of this larva; but the reader
will gather from what we relate as to various terrestrial Lepidopterous
larvae, that these phenomena are not very dissimilar from what frequently
take place in the latter; a change of habits at some particular moult,
accompanied by great changes in the integument, and even in the size of the
stigmata, being of frequent occurrence.
{423}The larva of _Nymphula stagnata_, a close ally of _H. nymphaeata_, has
aquatic habits of a somewhat similar but simpler nature; while _N._
(_Paraponyx_) _stratiotata_ is very different. This larva is provided with
eight rows of tufts of flexible branchiae, occupying the position of the
spots or setigerous warts usual in caterpillars, and reminding one of the
spines of certain butterfly-larvae, though they are undoubtedly respiratory
filaments. These caterpillars protect themselves by forming silken webs or
cases, or by adopting the case of some other larva, and are in the habit of
holding on by the anal claspers, and rapidly and energetically moving the
anterior parts of the body in an undulating fashion. The spiracles exist,
but are functionless. The pupa lives under water, and has no branchiae; but
three of the pairs of abdominal spiracles are open, and project from the
body. Müller informs us that in a Brazilian _Paraponyx_ these three pairs
of spiracles were already large in the larva, though the other pairs were
very small, or absent. He considers that the moth of this species descends
beneath the water of a rapid stream, and fastens its eggs on the stems of
plants therein. _Cataclysta lemnata_ lives in a case of silk with leaves of
duckweed attached to it, or in a piece of a hollow stem of some aquatic
plant; it is believed to breathe, like _H. nymphaeata_, at first by the
integument and subsequently by open stigmata; but particulars as to how it
obtains the requisite air-supply are not forthcoming: the aquatic pupa
breathes by three large abdominal spiracles like _Paraponyx_.
Musotimidae[322] is a small group of two or three genera found in Australia
and Polynesia; and the Tineodidae also consist of only two Australian
genera. Siculodidae is likewise a small Antarctic group, placed by Meyrick
in Pyralidina; but his view is not accepted by Snellen and Ragonot.
Epipaschiinae (formerly treated as a separate family) and Endotrichiinae
are, according to Meyrick, subdivisions of the family Pyralidae proper, an
enormous group of more than 100 genera. The Chrysauginae consist chiefly of
American forms, and have not been treated by Meyrick; some of this group
have been classed with Tortricidae or Deltoidae on account of the
undulating costa of the front wings and the long, peculiar palpi. The
Galleriidae are a small group including Insects that live in bees'-nests,
and feed on the wax {424}etc.; others eat seeds, or dried vegetable
substances. Three out of our five British species of this family occur
(usually gregariously) in bee-hives, and have the peculiar habit of
spinning their cocoons together. The mass of common cocoons formed in this
manner by _Aphomia sociella_ is remarkably tough and enduring; portions of
it are not infrequently picked up, and as the cocoons are of a peculiar
tubular form their nature gives rise to some perplexity.
Phycitidae[323] is another very large assemblage of Insects with very
diverse habits. The frenulum and retinaculum are similarly formed in the
two sexes: the males frequently have the basal-joint of the antennae
swollen; hence the term "Knot-horns" applied by collectors to these moths.
The larvae of the species of _Ephestia_ infest groceries, and most children
have become to a slight extent acquainted with them amongst dried figs;
that of _E. kuehniella_ has become very injurious in flour-mills, its
enormous increase being due in all probability to the fact that the
favourable and equable temperature maintained in the mills promotes a rapid
succession of generations, so that the Insect may increase to such an
extent as to entirely block the machinery. Many of the Phycitidae feed on
the bark of trees in galleries or tunnels constructed partially of silk. A
very peculiar modification of this habit in _Cecidipta excoecaria_ has been
described by Berg.[324] In Argentina this Insect takes possession of the
galls formed by a _Chermes_ on _Excoecaria biglandulosa_, a Euphorbiaceous
tree. The female moth lays an egg on a gall, and the resulting larva bores
into the gall and nourishes itself on the interior till all is eaten except
a thin external coat; the caterpillar then pupates in this chamber. The
galls vary in size and shape, and the larva displays much constructive
ability in adapting its home to its needs by the addition of tubes of silk
or by other modes. Sometimes the amount of food furnished by the interior
of the gall is not sufficient; the larva, in such cases, resorts to the
leaves of the plant for a supplement, but does not eat them in the usual
manner of a caterpillar; it cuts off and carries a leaf to the entrance of
its abode, fastens the leaf there with silk, and then itself entering,
feeds, from the interior, on the food it has thus acquired. Another
Phycitid, _Dakruma coccidivora_ is very {425}beneficial in North America by
eating large Scale-Insects of the _Lecanium_ group, somewhat after the
fashion of _Erastria scitula_; it does not construct a case, but shelters
itself when walking from one scale to another by means of silken tubes; it
suffers from the attacks of parasites.[325] Oxychirotinae, an Australian
group, is interesting because, according to Meyrick, it possesses forms
connecting the Pterophoridae with the more normal Pyralids.
Crambidae, or Grass-moths, are amongst the most abundant Lepidoptera in
this country, as they include the little pale moths that fly for short
distances amongst the grass of lawns and pastures; they fold their wings
tightly to their body, and have a head pointed in front, in consequence of
the form and direction of the palpi. They sit in an upright position on the
stems of grass, and it has been said that this is done because then they
are not conspicuous. Perhaps: but it would be a somewhat difficult
acrobatic performance to sit with six legs across a stem of grass. The
larvae are feeders on grass, and construct silken tunnels about the roots
at or near the surface. The Ancylolominae are included in Crambidae by
Meyrick and Hampson. Schoenobiinae[326] are included by Meyrick in
Pyraustidae, but this view appears not to meet with acceptance, and the
group is more usually associated with the Crambidae. Most writers place the
anomalous genus _Acentropus_ as a separate tribe, but it is associated by
both Meyrick and Hampson with _Schoenobius_. This Insect is apparently the
most completely aquatic of all the Lepidoptera, and was for long associated
with the Trichoptera in consequence of its habits and of the scaling of the
wings being of a very inferior kind. The males may sometimes be found in
large numbers fluttering over the surface of shallow, but large, bodies of
water; the females are rarely seen, and in some cases have no wings, or
have these organs so small as to be useless. The female, it would appear,
comes quite to the surface for coupling, and then takes the male beneath
the water. The larvae have the usual number of Lepidopterous feet, and
apparently feed on the leaves of plants below water just as Lepidopterous
larvae ordinarily do in the air.[327] They have no trace of gills, and
their {426}mode of respiration is unknown. A great deal has been written
about these Insects, but really very little is known. They are abundant,
though local in many parts of North and Central Europe; some of the females
have, as we have said, abbreviated wings, but how many species there are,
and whether the modifications existing in the development of the wings are
constant in one species or locality, are unknown as yet.
FAM. 42. PTEROPHORIDAE[328] (_Plume-moths_).—Elegant Insects of small size,
usually with the wings divided (after the fashion of a hand into fingers)
so as to form feathers: the extent of this division is diverse, but the
hind wings are more completely divided than the front, which indeed are
sometimes almost entire. The group is placed by Meyrick in his Pyralidina,
but there are many entomologists who look on it as distinct. It consists of
two sub-families, Agdistinae and Pterophorinae, that have been treated as
families by many entomologists. The Agdistinae (of which we have a British
representative of the only genus _Agdistes_) have the wings undivided.
Pterophorinae have the hind wings trifid or (rarely) quadrifid, the front
wings bifid or (rarely) trifid. The larvae of the Pterophorinae are
different from those of Pyralidae, being slow in movement and of heavy
form, covered with hair and living exposed on leaves; the pupae are highly
remarkable, being soft, coloured somewhat like the larvae, and also hairy
like the larvae, and are attached somewhat after the manner of
butterfly-pupae by the cremaster: but in some cases there is a slight
cocoon. There is, however, much variety in the larval and pupal habits of
the Pterophoridae, many having habits of concealment of divers kinds. We
have thirty species of these lovely Plume-moths in Britain. The family is
widely distributed, and will probably prove numerous in species when the
small and delicate Insects existing in the tropics are more appreciated by
collectors.
FAM. 43. ALUCITIDAE (ORNEODIDAE of Meyrick and others).—The genus _Alucita_
includes the only moths that have the front and hind wings divided each
into six feathers. Species of it, though not numerous, occur in various
regions. The larva and pupa are less anomalous than those of the
Pterophoridae, though the imago is more anomalous. The caterpillar of our
British _A. polydactyla_ feeds on the flower-buds of honey-suckle, and
forms a {427}cocoon. The moth with wings expanded is about an inch across,
and is a lovely object. It is not rare, though seldom numerous.
FAM. 44. TORTRICIDAE.—Moths of small size, with a rather ample wing area,
with the wing-fringes never as long as the wings are wide (long across),
the hind wings without a pattern: the anterior nervure on the hind wings is
simply divergent from that next to it, and the internal nervure, 1b, is
very evidently forked at the base. The larvae inhabit their food, which may
be rolled up or twisted leaves, or the interior of fruits and herbs, or
galls, or even roots; they exhibit less diversity than is usual in other
large series of moths; all have the normal complement of sixteen legs. This
group is a very extensive one, but is much neglected owing to the great
difficulties attending its study; it is not recognised in Hampson's Table
of families given on p. 370, being there merged in Tineidae. It appears,
however, to be a really natural group, and it is not desirable to merge it
in the sufficiently enormous assemblage of the Tineidae till this has been
shown to be necessary by the light of a greater knowledge of the external
anatomy than we possess at present. The term Microlepidoptera is frequently
met with in entomological literature, and should, we think, be confined to
the two series Tortricidae and Tineidae. The Pterophoridae, and even the
Pyralidae, have been, and still sometimes are, included under this term,
but at present it seems best to limit its application as is here suggested.
Three great divisions are at present recognised; these were formerly called
by Meyrick,[329] Tortricidae, Grapholithidae, Conchylidae;
subsequently,[330] he has adopted the names Tortricidae, Epiblemidae,
Phaloniadae. Lord Walsingham, who has devoted a great deal of time and
study to the elucidation of this most difficult group, has suggested[331]
that another change is desirable, and if so the nomenclature will be:—1.
Tortricidae [or Tortricinae, according to the view that may be taken as to
the group being family or sub-family]; 2. Phaloniidae [= the formerly used
name, Conchylidae]; 3. Olethreutidae [= the formerly used name
Grapholithinae = Epiblemidae, Meyr.]. We have upwards of 300 species in
Britain, nearly 200 of which belong to the last division. The name
Tortricidae refers to the habit the {428}larvae of these moths possess of
rolling up leaves, or twisting and distorting shoots and buds.
The mode in which leaves and shoots are twisted and rolled by the very
small larvae has been much discussed and is probably the result of two or
three distinct causes:—1, the immediate operations of the larva; 2, the
contraction of silk when drying; 3, changes in the mode of growth of the
parts of the vegetable, resulting from the interference of the caterpillar.
The larvae of this family that live in fruits are only too widely (we will
not say well) known. Stainton gives as the habitat of _Epinotia funebrana_,
"larva frequent in plum-pies"; the caterpillar of _Carpocapsa pomonella_
(the Codling-moth) mines in apples and pears, and its ravages are known
only too well in widely distant parts of the world where fruit-trees of
this kind are cultivated. _C. splendana_ lives in acorns and walnuts; _C.
juliana_ in Spanish chestnuts. Two, if not more, larvae live in the seeds
of Euphorbiaceous plants, and have become notorious under the name of
jumping-beans, on account of the movements they cause. As these latter show
no trace externally of being inhabited, the movements are supposed to be a
mysterious property of the seed; they are really due to its containing a
large cavity, extending, in one direction of the seed, nearly or quite from
skin to skin; in this the larva makes a movement sufficient to alter the
point of equilibrium of the quiescent seed, or as a free body to strike
some part of it. The exact nature of the movements of the larva have not,
we believe, been ascertained. There are, at least, two species of these
Insects, and two plants harbouring them, known in the United States and
Mexico, viz. _Carpocapsa saltitans_ living in the seeds of _Croton
colliguaja_ and _Grapholitha sebastianiae_ living in the seeds of
_Sebastiania bicapsularis_.
FAM. 45. TINEIDAE.—Small moths with the labial palpi more flexible and
mobile than in other moths; usually separated and pointed. Hind wings
frequently with very long fringes, the wing itself being proportionally
reduced in size, and in consequence pointed at the tip. Larvae very
diverse, almost always with habits of concealment. The series of forms
included under this head is very numerous, the British species alone
mounting up to 700, while the total described cannot be less than 4000.
This number, however, must be but a fragment of what exists, if Mr. Meyrick
be correct in supposing that a single one of the divisions of the
family—Oecophoridae—comprises 2000 species in Australia and New Zealand
alone.
{429}[Illustration: Fig. 207—_Diplosara lignivora_ (Gelechiides). Hawaiian
Islands.]
As the study of these Insects is attended with great difficulty on account
of their fragility and the minute size of the great majority, it is not a
matter for surprise that their classification is in a comparatively
rudimentary state. We shall not, therefore, deal with it here. Neither can
we attempt to give any idea of the extreme diversity in the colours, forms,
and attitudes of these small Insects. The one shown in Fig. 207, is
remarkable on account of the great accumulation of scales on the wings and
legs. As regards the pointed wings and the long fringes, we may remark that
it is probable that in many of these small forms the wings are passive
agents in locomotion; a similar condition of the wings is found in other
very minute Insects, _e.g._ Thysanoptera and Trichopterygidae; in all these
cases the framework of the wings is nearly absent: in some forms of the
Tineidae, _Opostega_, e.g. the nervules are reduced to three or four in
each wing. The variety in habits is as great as that of the external form,
and the larvae exceed in diversity those of any other group of Lepidoptera.
No doubt a corresponding amount of diversity will be discovered in the
details of structure of the perfect Insects, the anatomy of but few having
been at present investigated. _Tinea pellionella_ has two very important
peculiarities in its internal anatomy: the testes consist of four round
follicles on each side, and, contrary to the condition generally prevalent
in Lepidoptera, are not brought together in a common capsule: the two
groups are, however, not quite free (as they are in _Hepialus_), but are
connected by a loose tracheal network. Even more remarkable is the fact
also pointed out by Cholodkovsky[332] that the adult Insect possesses only
two Malpighian tubes instead of six, the normal number in Lepidoptera; in
the larva there are, however, six elongate tubes. The group of forms to
which {430}_Tinea_ belongs is remarkable for the diversity and exceptional
character of the food-habits of the larvae; species subsist on dried
camel's dung, various kinds of clothes, furs, and hair, and even about
horns of deer and horses' hoofs: one species has been found in abundance in
the hair of a live sloth, _Bradypus cuculliger_, under circumstances that
render it possible that the larva feeds on the creature's hair, though it
may feed on minute vegetable matter found in the hair. The larva of _Tinea
vastella_ is occasionally found feeding on the horns of living antelopes.
Several species of Tineidae are known to devour Scale-Insects.
_Lita solanella_ is notorious for the ravages it commits on stored
potatoes. Quite a number of species live on cryptogamic matter, or in old
wood; _Oinophila v-flavum_ feeds on the mould on the walls of cellars, and
is reputed to be injurious by occasionally also attacking the corks of
bottles containing wine. _Oecocecis guyonella_ is said to be the cause of
galls on _Limoniastrum guyonianum_, a plant that, growing in the deserts to
the south of Algeria, is a favourite food of camels, and is frequently
entirely covered with sand. The deposition of an egg by this moth is
believed by Guénée[333] to give rise to a gall in which the larva is
entirely enclosed (like the larvae of the gall-flies). Of Clothes-moths
there are at least three species widely distributed. _Trichophaga
tapetzella_ is perhaps entitled to be considered the Clothes-moth; its
caterpillar not only feeds on clothes, but spins webs and galleries amongst
them. _Tinea pellionella_ is also very common; its larva lives in a
portable case, while that of the third species, _Tineola biselliella_,
forms neither a case nor definite galleries. We have found this the most
destructive of the three at Cambridge. Clothes or valuable furs may be
completely protected by wrapping them in good sound paper in such a way
that no crevices are left at the places where the edges of the paper meet.
Garments that have become infested may be entirely cleared by free exposure
to air and sunshine.
Two species of _Tinea_ have been recorded as viviparous, viz. _Tinea
vivipara_ in Australia, and an undetermined species in South America. The
species of the genus _Solenobia_—in which the female is apterous—are
frequently parthenogenetic. The group Taleporiidae, to which this genus
belongs, is by some {431}classified with Psychidae, in which family, as we
have pointed out, one or two parthenogenetic forms are also known.
The larvae of Tineidae, though they do not exhibit the remarkable armature
found in so many of the larger caterpillars, are exceedingly diverse.[334]
Some are entirely destitute of feet (_Phyllocnistis_). Others are destitute
of the thoracic legs; _Nepticula_ is in this case, but it is provided with
an increased number of abdominal feet, in the form of more or less
imperfect ventral processes. Some mine in leaves, others live in portable
cases of various forms. Some are leaf-miners during their early life, and
subsequently change their habits by constructing a portable case. The genus
_Coleophora_ affords numerous instances of this mode of life; the habits of
these case-bearers exhibit considerable variety, and there are many points
of interest in their life-histories. Change of habit during the larval life
has already been alluded to as occurring in many Lepidoptera and is nowhere
more strikingly exemplified than in certain Tineidae. Meyrick mentions the
following case as occurring in an Australian Insect, _Nematobola
orthotricha_;[335] the larva, until two-thirds grown, is without feet, and
is almost colourless, and mines in the leaves of _Persoonia lanceolata_;
but when two-thirds grown it acquires sixteen feet, changes colour,
becoming very variegate, and feeds externally, unprotected, on the leaves.
The cases of the case-bearing Tineids are usually of small size, and do not
attract attention like those of Psychidae. A very remarkable one was
discovered by Mr. E. E. Green in Ceylon, and was at first believed to be
formed by a Caddis-worm. It has now been ascertained that the Insect
forming it is the caterpillar of _Pseudodoxia limulus_, a Tineid moth of
the group Depressariidae;[336] the case is composed of minute fragments of
moss, sand, and lichens; the anterior end is dilated into a shield-like
hood that covers and protects the anterior parts of the larva when feeding;
the food is mosses and lichens on rocks and trees. Before pupating, the
larva folds down the edges of the hood over the mouth of the tube, like an
envelope, fastening them with silk. The case is fixed to the rock or other
support and hangs there until the moth appears.
{432}[Illustration: Fig. 208—_Pronuba synthetica_. North America. A, Larva;
B, C, pupa, ventral and lateral aspects; D, female moth; E, head and part
of thorax of the female moth: _a_, labial palp; _b_, maxillary tentacle;
_c_, maxillary palp; _d_, proboscis; _e_, base of front leg. (After
Riley.)]
The family Prodoxidae consists of some Tineids, the larvae of which feed in
the pods and stems of the Yuccas of south-western North America; they have
the mouth of very unusual form (Fig. 208, E), and some of them, by aid of
this peculiar mouth, exhibit a remarkable modification of instinct. The
facts are chiefly known from the observations of Riley[337] on _Pronuba
yuccasella_, a moth living on _Yucca filamentosa_; this plant has been
introduced into our gardens in this country, where it never, we believe,
produces seed. The Yuccas are not fitted for self-fertilisation or for
fertilisation by Insect agency of an ordinary kind. The progeny of the moth
develops in the pods of the plant, and as these cannot grow until the
flowers have been fertilised, the moth has the habit of fertilising the
flowers at the time she lays her egg in the part that is to develop into
the pod, and to be the food for her own progeny. The female moth first
visits the stamens, and collects, by the aid of the {433}maxillae (which in
this sex are very remarkably formed),[338] a considerable mass of pollen,
which she holds by means of the peculiar maxillary tentacles; she then lays
an egg in the pistil, usually of some flower other than that from which she
has gathered the pollen; and after she has accomplished this act she
carefully applies the pollen she had previously collected to the pistil, so
as to secure the fertilisation of the flower and the development of the
pod.
The species of _Prodoxus_ stand in a very peculiar relation to _Pronuba_.
They also live in Yuccas, and have habits similar to those of _Pronuba_,
with the important exception that, being destitute of the requisite
apparatus, they do not fertilise the Yucca-flowers, and are thus dependent
on _Pronuba_ for the steps being taken that are necessary for the rearing
of the progeny of the two kinds of moth. Hence the name of Yucca-moth has
been bestowed on _Pronuba_, and that of "bogus Yucca-moth" on the
_Prodoxus_. The _Pronuba_ we figure is the largest and most remarkable
species of the genus and fertilises _Yucca brevifolia_; the larva is
destitute of abdominal feet, and in the pupa the spines on the back that
exist in nearly all pupae that live in stems are developed to an
extraordinary extent. The Yuccas do not flower every year, and the
Prodoxidae have a corresponding uncertainty as to their periods of
appearance, passing sometimes a year or two longer than usual in the pupal
stage.
FAM. 46. ERIOCEPHALIDAE.—This family has recently been proposed for some of
the moths formerly included in the genus _Micropteryx_.[339] They are
small, brilliant, metallic Insects, of diurnal habits, but are very rarely
seen on the wing, and it is doubtful whether they can fly much. These
little Insects are of peculiar interest, inasmuch as they differ from the
great majority of the Lepidoptera in at least two very important points,
viz. the structure of the wings and of the mouth-parts. The mouth shows
that we may consider that the Lepidoptera belong to the mandibulate
Insects, although in the great majority of them the mandibles in the final
instar are insignificant, functionless structures, or are entirely absent,
and although the maxillae are so highly adapted for the tasting of sweets
that it is difficult to recognise in them the parts usually found in the
maxilla of mandibulate Insects.
{434}[Illustration: Fig. 209.—Larva of _Eriocephala calthella_. (After
Chapman.) A, Young larva from side, × 50; B, portion of skin with a bulla
or ball-like appendage: C, abdominal foot of larva.]
_Eriocephala_ in both these respects connects the Lepidoptera with
Mandibulata: the mandibles have been shown by Walter[340] to be fairly well
developed; and the maxillae are not developed into a proboscis, but have
each two separate, differentiated—not elongated—lobes, and an elongate,
five-jointed, very flexible palpus. The moths feed on pollen, and use their
maxillae for the purpose, somewhat in the style we have mentioned in
Prodoxidae. The wings have no frenulum, neither have they any shoulder, and
they probably function as separate organs instead of as a united pair on
each side: the modification of the anterior parts of the hind wing—whereby
this wing is reduced as a flying agent to the condition of a subordinate to
the front wing—does not here exist: the hind wing differs little from the
front wing in consequence of the parts in front of the cell being well
developed. There is a small jugum. These characters have led Packard to
suggest that the Eriocephalidae should be separated from all other
Lepidoptera to form a distinct sub-Order, Lepidoptera Laciniata.[341] The
wing-characters of _Eriocephala_ are repeated—as to their main features—in
Hepialidae and Micropterygidae; but both these groups differ from
_Eriocephala_ as to the structure of the mouth-parts, and in their
metamorphoses. Although _Eriocephala calthella_ is one of our most abundant
moths, occurring in the spring nearly everywhere, and being easily found on
account of its habit of sitting in buttercup-flowers, yet its metamorphoses
were till recently completely unknown. Dr. Chapman has, however, been able
to give us some information as to the habits and structure of the larvae,
in both of which points the creature is most interesting. The eggs and
young larvae are "quite {435}unlike our ideas of a Lepidopterous Insect;"
the former have a snowy or mealy appearance, owing to a close coating of
minute rods standing vertically on the surface of the egg, and often tipped
with a small bulb. The larva lives amongst wet moss and feeds on the
growing parts thereof; it is not very similar to any other Lepidopterous
larva: Dr. Chapman suggests a similarity to the Slug-worms (Limacodids),
but Dyar is probably correct in thinking the resemblances between the two
are unimportant: the larva of _Eriocephala_ possesses three pairs of
thoracic legs, and eight pairs of abdominal appendages, placed on the
segments immediately following the thorax; on the under-surface of the
ninth and tenth abdominal segments there is a sucker, trifoliate in form;
this is probably really situate entirely on the tenth segment: the body
bears rows of ball-appendages, and the integument is beautifully
sculptured. The head is retractile and the antennae are longer than is
usual in caterpillars. This larva is profoundly different from other
Lepidopterous larvae inasmuch as the abdominal feet, or appendages, are
placed on different segments to what is customary, and are of a different
form. Unfortunately the pupa has not been procured, but there is some
reason for supposing that it will prove to be more like that of Tineidae
than like that of Micropterygidae.
The New Zealand genus _Palaeomicra_ is only imperfectly known. Meyrick
considers it the "most ancient" Lepidopteron yet discovered; and it would
appear that its relations are with _Eriocephala_ rather than with
_Micropteryx_. From information he has kindly given to us, we are able to
say that this moth possesses mandibles but no proboscis.
[Illustration: Fig. 210—Larva of _Micropteryx_ sp. A, Ventral view of the
larva, magnified; B, the same, with setae unduly magnified. Britain.]
FAM. 47. MICROPTERYGIDAE.—Small moths of metallic colours, without
mandibles, with elongate maxillary palpi: without frenulum: both wings with
a complex system of wing-veins: on the hind wings the area anterior to the
cell is large, and traversed by three or four elongate, parallel veins.
{436}[Illustration: Fig. 211—Pupa of _Micropteryx_ (_semipurpurella_?). A,
Dorsal aspect; B, C, D, views of head dissected off; B, profile; C,
posterior, D, anterior aspects; _m_, mandibles. Britain.]
There are no mandibles, but there is a short, imperfect proboscis. Larva
(Fig. 210) without any legs, mining in leaves. The pupa (Fig. 211) is not a
pupa obtecta, but has the head and appendages free, and is provided with
enormous mandibles. Although these Insects in general appearance resemble
_Eriocephala_ to such an extent that both have been placed in one genus,
viz. _Micropteryx_, yet the two forms are radically distinct. The most
remarkable point in _Micropteryx_ is the metamorphosis; the female moth is
furnished with a cutting ovipositor, by the aid of which she deposits an
egg between the two layers of a leaf after the manner of a saw-fly;[342]
the larva mines the newly-opened leaves in the early spring, and feeds up
with rapidity; it by some means reaches the ground, and there pupates in a
firm but thin cocoon, with grains of earth fastened to it; in this it
passes the greater part of its life as a larva, changing to a pupa very
early in the following spring. The pupa is unlike any other Lepidopterous
pupa, but is similar to those of Trichoptera; neither the head nor the
appendages are glued to the body or to one another, but are free, so that
the pupa can use the appendages to a considerable extent; it is furnished
with enormous mandibles (Fig. 211, C, D), which are detached and shed after
emergence.[343] In the interval between {437}the larval period of feeding
and the imaginal instar, the phenomena of life are essentially like those
of Trichoptera. The larva has not been at all satisfactorily studied; the
spiracles appear to be excessively minute, but have been ascertained by Dr.
Chapman to be normal in number and position.
All the information we possess points to profound distinctions between
_Micropteryx_ and _Eriocephala_, for whereas in the former the mandibles
drop off from the pupa, so that the imago has no mandibles, in the latter
the mandibles exist, as they do in several other true Lepidoptera. As the
history of the mandibles is not known in other Lepidoptera (where they are
present in the larva but wanting in the imago), it is premature to conclude
that no other Lepidoptera suffer the actual loss of the mandibles as
_Micropteryx_ does, though there is nothing to lead us to believe that in
any other Lepidopterous pupa are the mandibles specially developed as they
are in _Micropteryx_. This pupa is in fact quite unique in this Order of
Insects. When the history of the pupal mandibles is known, we shall be able
to decide whether they are secondary structures, like the deciduous,
supplementary mandibles found in Otiorhynchides (Coleoptera, Rhynchophora).
{438}CHAPTER VII
DIPTERA—OR FLIES; APHANIPTERA—OR FLEAS; THYSANOPTERA—OR THRIPS
ORDER VII. DIPTERA
_Wings two, membranous, usually transparent and never very large; behind
the wings a pair of small erect capitate bodies—halteres—frequently
concealed under membranous hoods. No distinct prothorax, all the
divisions of the thorax being united to form a large mass. Mouth-parts
very variable, formed for suction not for biting, frequently assuming the
form of a proboscis that can be retracted and concealed in a cleft of the
under side of the head. The metamorphosis is very great, the larvae
bearing no resemblance whatever to the perfect Insects, but being usually
footless grubs or maggots; frequently the head is indistinct, small, and
retracted. Pupa variable, either exposed and rather hard, with the
appendages of the body more or less adherent; or enclosed in a scaly
capsule looking like a seed, and when extracted, soft and delicate, with
the appendages not fastened to the body incapable of movement._
This definition of the Diptera, or two-winged flies, is framed without
reference to the fleas, which are wingless, or to a few other parasitic
wingless Diptera, such as the sheep-tick. Although the Order is of enormous
extent, these exceptional cases are remarkably few. About 40,000 species of
Diptera have been discovered, but these are only a tithe of what are still
unknown to science. The Order is not a favourite one with entomologists,
and by the rest of the world it may be said to be detested. Flies do not
display the sort of intelligence we appreciate, {439}or the kind of beauty
we admire, and as a few of the creatures somewhat annoy us, the whole Order
is only too frequently included in the category of nuisances that we must
submit to. Moreover, the scavenger-habits that are revealed, when we begin
to study their lives, are very repugnant to many persons. It is therefore
no wonder that flies are not popular, and that few are willing to study
them, or to collect them for observation. Nevertheless, Diptera have
considerable claims to be classed as actually the highest of Insects
physiologically, for it is certainly in them that the processes of a
complete life-history are carried on with the greatest rapidity and that
the phenomena of metamorphosis have been most perfected. A maggot, hatching
from an egg, is able to grow with such rapidity that the work of its life
in this respect is completed in a few days; then forming an impenetrable
skin it dissolves itself almost completely; solidifying subsequently to a
sort of jelly, it in a few days reconstructs itself as a being of totally
different appearance and habits, in all its structures so profoundly
changed from what it was that the resources of science are severely taxed
to demonstrate any identity of the organs of the two instars.
[Illustration: Fig. 212—A Dipteron (Fam. Syrphidae), _Cheilosia
chrysocoma_. Britain. A, Adult larva; B, the pupa; C, nymph, extracted from
pupa; D, imago. (From Weyenbergh.)]
A good study of the comparative anatomy of Diptera has never been made;
Baron Osten Sacken, one of our most accomplished Dipterologists, has
recently stated that "the external characters of the Diptera have as yet
been very insufficiently studied." We shall therefore only trouble the
student with a few observations on points of structure that are of special
importance, or that he will find frequently alluded to. The head is
remarkable {440}for its mobility, and is connected with the thorax by a
slender concealed neck that permits the head to undergo semi-rotation. A
large part—sometimes nearly the whole—of the exposed surface of the head is
occupied by the faceted eyes. It is usually the case that the eyes are
larger in the male than in the female, and the sexual discrepancy in this
respect may be very great. When the eyes of the two sides meet in a
coadapted line of union the Insect is said to be "holoptic," and when the
eyes are well separated "dichoptic."[344] The holoptic condition is
specially characteristic of the male, but in some forms occurs in both
sexes. There is no definite distinction between holoptic and dichoptic
eyes. The eyes may be enormous, Fig. 238, without actually uniting, and in
the cases where actual contiguity occurs, it takes place in different
manners.[345] The eyes are frequently during life of brilliant colours and
variegate with stripes or spots; this condition disappears speedily after
death, and it is uncertain what the use of this coloration may be.[346] The
eyes are frequently densely set with hairs between the almost innumerable
facets. These facets frequently differ in size according to their position
in the organ. The curious double eye of the male _Bibio_ (cf. Fig. 224) is
well worth notice. There are usually three small ocelli placed very near
together on the middle of the summit of the head.
The antennae are of considerable importance, as they offer one of the
readiest means of classification. The families placed by systematists at
the commencement of the Order have antennae similar to those of the
majority of Insects, inasmuch as they consist of a series of segments
approximately similar to one another, and arranged in a linear manner (Fig.
213, A). The number of these joints is never very great, but reaches
sixteen in certain Tipulidae, and falls as low as eight in some Bibionidae.
In certain cases where the antennae of the male are densely feathered
(_Chironomus_, e.g.), the number of joints is in that sex greatly
augmented, but they are imperfectly separated. This form of antenna gives
the name Nemocera to the first series of Diptera.
{441}[Illustration: Fig. 213—Antennae of flies. A, The two antennae of
_Glaphyroptera picta_ (Mycetophilidae); B, antenna of _Hexatoma pellucens_
(Tabanidae); C, of _Asilus crabroniformis_ (Asilidae); D, of _Leptis
scolopacea_ (Leptidae); E, of _Dolichopus undulatus_ (Dolichopidae); F, of
_Volucella bombylans_ (Syrphidae). (After Wandolleck.)]
The majority of flies have antennae of another form, peculiar to the Order,
viz. three segments, the outer one of which is of diverse form, according
to the genus or species, and bears on its front a fine projecting bristle,
frequently feathered, as in Fig. 213, F; and often distinctly divided into
two or more joints. This form of antenna is found in the series Aschiza and
Schizophora; it is well exemplified in the common house-fly, where the
organs in question hang from the forehead, and are placed in a hollow
formed for their reception on the front of the head. Flies with this form
of antennae are called Athericerous. Between the two forms of antennae we
have mentioned there exists what may, speaking roughly, be called an
intermediate condition, or rather a variety of intermediate conditions,
associated in the series Brachycera (Fig. 213, B to D).[347] Here there are
three (sometimes one or two) segments and a terminal appendage, but the
appendage is usually compound (often so distinctly compound that it is
evidently a series of partially, or even completely, separate joints, Fig.
213, B): the appendage in these cases is terminal, that is to say it is
placed, not as in the Eumyiidae on the front of the joint that bears it,
but (in the great majority of Brachycera) at the tip thereof; this
appendage is often conical and pointed, often hair-like. Exceptional forms
of antenna are found in the parasitic flies of the series Pupipara. In the
Order generally the two basal joints of the antennae are evidently distinct
in function from the others, and form the "scape"; the {442}part of the
antenna beyond the scape is called the "flagellum"; an appendage of the
flagellum is called "arista" when bristle-like, when thicker "style." In
the basal joint of the antenna there is a complex nervous structure known
as Johnston's organ. It is specially well developed in _Culex_ and
_Chironomus_, and is larger in the male than it is in the female. Child has
found something of the kind present in all the Diptera he has examined, and
he considers that an analogous structure exists in Insects of other Orders.
He thinks it is concerned with the perception of vibration, there being no
sharp distinction between auditory and tactile sensation.[348]
About one-half of the Diptera possess a peculiar structure in the form of a
head-vesicle called "ptilinum." In the fly emerging from the pupa this
appears as a bladder-like expansion of the front of the head; being
susceptible of great distension, it is useful in rupturing the hard shell
in which the creature is then enclosed. In the mature fly the ptilinum is
completely introverted, and can be found only by dissection; a little
space, the "lunula," just under an arched suture, extending over the point
of insertion of the antennae remains, however, and offers evidence of the
existence of the ptilinum. This structure is also of importance in
classification, though, unfortunately, it is difficult to verify.[349]
No point of Insect morphology has given rise to more difference of opinion
than the mouth of Diptera; and the subject is still very far from being
completely understood. The anatomy and morphology of the mandibulate
Insect-mouth are comparatively simple (though not without greater
difficulties than are usually appreciated); and it has been the desire of
morphologists to homologise the sucking mouth of Diptera with the biting
mouth; hence the view that the appendages of three segments are separate
and distinct in the fly's mouth is taken for granted, and it is further
assumed that some of the secondary parts of the appendages of the biting
mouth can also be recognised in the sucking mouth. The anatomy of the
mouth-parts is, however, {443}subject to great diversity of structure
within the limits of the Order itself, even the two sexes in some species
differing profoundly in this respect.[350] In the majority of the family
Oestridae the mouth-parts are practically absent, and no definite entry to
the alimentary canal can be perceived (Fig. 245). Besides this condition
and its antithesis (Fig. 214), the complex assemblage of lancets seen in
the Breeze-flies that draw blood, there is a great variety of other
anatomical conditions.
[Illustration: Fig. 214.—Mouth-parts of the common blood-sucking fly,
_Haematopota pluvialis_ ♀. A, Viewed from beneath, the proboscis removed;
_a_, labrum; _b_, _b_, cultelli (mandibles of other anatomists); _c_, _c_,
scalpella (maxillae of other anatomists); _d_, part of ventral scutum of
second metamere; _e_, _e_, _f_, _f_, parts of palpi; _g_, hypopharynx and
pellucid salivary duct; _h_, salivary receptacle; _i_, salivary duct; _k_,
membranous part of second metamere; _l_, pharynx: B, labrum, pharynx,
hypopharynx, separated, seen from beneath; _a_, labrum; _b_, hypopharynx;
_c_, salivary duct; _d_, pharynx; _e_, protractor muscles: C, proboscis
(labium) from beneath; _a_, scutum proboscidis; _c_, _c_, labella; _d_,
_d_, retractor muscles. (After Meinert).]
Although, as we have said, great diversity of opinion exists, yet on the
whole the majority of Dipterologists accept a view something to the
following effect:—the labrum, or the labrum combined with the epipharynx,
is frequently much prolonged; the tongue—hypopharynx—may also be much
prolonged, and may form, in apposition with the labrum, a more or less
imperfect tube for ingestion of the nutriment; the labium is more or less
membranous or fleshy, and acts as a sheathing organ, its tips—called
labella—-being in some cases developed to a quite extraordinary extent. As
to the other parts of the mouth there is less agreement; the pointed organs
(Fig. 214, A, _b_ _b_) are by {444}many identified as mandibles, while
another pair of pointed processes (_c_ _c_) are considered to be parts of a
maxilla, and the palpi (_f_ _f_) are by some considered to be maxillary
palps. The Danish entomologist, Meinert, has published the best anatomical
description of many of the diverse kinds of Dipterous mouth.[351] He,
however, takes a different view of the morphology; he considers that not
only may parts of the appendages of the mouth be much modified during the
early stages of the individual development, but that they may be
differently combined, even parts of the appendages of two segments being
brought together in intimate combination. He has also pointed out that the
mandibulate and sucking mouth are mechanical implements constructed on
opposed principles; the main object of a biting mouth being the fixing and
perfecting of the articulations of the mouth, so that great power of
holding may be attained with a limited but definite power of movement. In
the sucking mouth the parts are intimately associated for simple
protrusion. Hence the two kinds of mouth must have been distinguished very
early in the phylogeny, so that we must not expect to find a great
correspondence between the parts of biting and sucking mouths. He
apparently also considers that not only the appendages of a head-segment,
but also part of the body of the segment, may be used in the construction
of the mouth-organs. Meinert's views allow a much greater latitude of
interpretation of the parts of the Dipterous mouth; had he contented
himself with enunciating them in the manner we have followed him in
summarily describing, they would have been recognised as a formidable
obstacle to the facile adoption of the ordinary views. He has, however,
accompanied his general statement with a particular interpretation and a
distinct nomenclature, neither of which is it possible to adopt at present,
as they have no more justification than the ordinary view. So that instead
of one set of doubtful interpretations we have two.[352] In so difficult a
question as homologising the trophi of different Orders of Insects we ought
to use {445}exhaustively every method of inquiry: and from this point of
view the development is of great importance. This has, however, as yet
thrown but little light on the subject, this study being a very difficult
one owing to the profound changes that take place during metamorphosis, the
diversity of the parts in the early stages of Diptera, and the possibility
that the larval conditions may themselves have been greatly changed in the
course of the phylogeny. Miall informs us, however, that in _Chironomus_ as
well as in _Corethra_ the new parts of the mouth of the imago are developed
within those of the larva.[353] This may permit of an identification of the
main divisions of the mouth, at any rate in these cases. Lowne has to some
extent traced the development in the blowfly, and he does not agree with
the usual interpretation of the parts in the adult.
The mouth is of considerable importance in the classification of Diptera.
The Nemocera are remarkable from the linear development and flexibility of
the palpi, which are nearly always at least three- or four-jointed; this
condition occurring in no other Diptera. The palpi attain an extraordinary
development in some Culicidae; in the genus _Megarrhina_ they are nearly as
long as the body, and project in front of the head after the fashion of the
palpi of Lepidoptera. In the Brachycera the sclerites or hard parts of the
mouth reach a maximum of development, and in Tabanidae (Fig. 214),
Nemestrinidae and Bombyliidae are often quite disproportionate to the size
of the Insect. In many of the Eumyiid flies the soft parts are greatly
developed, and capable of a variety of movement, the proboscis as a whole
being protrusible, and having an elbow-joint in the middle.
The thorax is remarkable from the absence of distinct separation into the
three divisions that may usually be so easily distinguished in Insects. The
perfect combination of the three segments adds much to the difficulty of
arriving at general conclusions as to the identification of the parts;
hence considerable difference of opinion still prevails. It was formerly
supposed that a segment from the abdomen was added to the thorax of Diptera
as it is in Hymenoptera, but this has been shown by Brauer to be erroneous.
Indeed, according to Lowne, the abdominal cavity is increased by the
addition of the small posterior area of the thorax; it being the
mesophragma that separates the {446}second and third great divisions of the
body-cavity. The prothorax is always small, except in a few of the abnormal
wingless forms (_Melophagus_); in _Nycteribia_ (Fig. 248) the mesothorax
forms the anterior part of the body; the head and such parts of the
prothorax as may be subsequently discovered to exist being placed entirely
on the dorsum of the body. The mesothorax in all the winged Diptera forms
by far the larger portion of the thoracic mass, the prominent part of it,
that projects backwards to a greater or less extent over the base of the
abdomen, being the scutellum. The first or prothoracic stigma is remarkably
large and distinct, and is by some called mesothoracic. Another large
stigma is placed very near to the halter (or balancer); the metathorax
being very small. An imperfect stigma is said by Lowne to exist in the
blowfly near the base of the wing. The number of abdominal segments
externally visible is very diverse; there may be as many as nine (in the
male _Tipula_), or as few as five, or even four, when the basal segment is
much concealed; the diminution is due to certain segments at the extremity
being indrawn and serving as a sort of tubular ovipositor in the female, or
curled under the body and altered in form in the other sex, so as to
constitute what is called a "hypopygium." In the female of Tipulidae the
body is terminated by some horny pieces forming an external ovipositor. In
nearly all Diptera the feet are five-jointed; the claws are well developed,
there being placed under each of them a free pad or membrane, the
"pulvillus"; there may be also a median structure between each pair of
claws, of diverse form, the "empodium."
On the surface of the body of many flies there will be seen an armature of
pointed bristles; these flies are called "chaetophorous"; where no
regularly arranged system of such bristles exists the fly is
"eremochaetous." In some families the arrangement of these bristles is of
importance in classification, and a system of description has been drawn up
by Baron Osten Sacken: this branch of descriptive entomology is known as
chaetotaxy.[354]
The wings are of great importance in classifying Diptera; but
unfortunately, like the other parts, they have not received an exhaustive
anatomical study, and Dipterologists are not agreed as to the names that
should be applied to their parts.
{447}[Illustration: Fig. 215—Nervuration of Dipterous wing. A, Wing of a
Tipulid, according to Loew, who uses the following nomenclature: _a_,
costal nervure; _b_, mediastinal; _c_, subcostal; _d_, radial; _e_,
cubital; _f_, discoidal; _g_, postical; _h_, anal; _i_, axillar; _x_,
transverse, _y_, posterior transverse, nervure; 1, 2, mediastinal areas; 3,
subcostal; 4, cubital; 5, anterior basal; 6, posterior basal; 7, anal; 8,
posterior marginal; 9, discoidal. B, Wing of an Acalypterate Muscid
(_Ortalis_), according to Schiner, who uses the following nomenclature:
(nervures, small letters; cells, capital letters): _a_, transverse
shoulder; _b_, auxiliary; _c_ to _h_, first to sixth longitudinal; _i_,
middle transverse; _k_, posterior transverse; _l_, _m_, _n_, _o_, costa;
_p_, anterior basal transverse; _q_, posterior basal transverse; _r_,
rudiment of a fourth nervure; _s_, axillary incision: A, B, C, first,
second, and third costal cells; D, marginal; E, sub-marginal; F, G, H,
first, second, and third posterior; I, discal; K, L, M, first, second, and
third basal cells; N, anal angle; O, alula.]
We give below figures of two systems that have been used by eminent
Dipterologists for the description of the nervures and cells. The
comprehension of these features of the Dipterous wing will be facilitated
by noticing that the wing—being extended at right angles to the body—is
divided by the longitudinal nervures into two great fields, anterior and
posterior, with an interval between them: this interval is traversed only
by a short cross-vein (marked x in Fig. 215 A, and i in B). This cross-vein
may be placed near the base or nearer to the tip of the wing; it is of
importance because no nervure in front of the median area traversed by it
can correspond with a nervure placed behind it in another wing. The very
different nature of the nervuration in the two wings we have figured will
readily be appreciated by an inspection of the parts posterior to the
little cross-vein. On the hind margin of the wing, near the base, there is
often a more or less free lobe (Fig. 215, B, O) called the "alula": still
nearer to the base, or placed on the side of the body, may be seen one or
two other lobes, of which the one nearer the alula is called the "tegula,"
or (when a lobe behind it is also present) the "upper tegula," (the
"antitegula" of Osten Sacken); the other being the "lower tegula." These
two terms are erroneous, the word tegula being definitely applied to
another part of the Insect-body. In speaking of this structure in the
following pages, we have preferred to call it the {448}"squama."[355] Those
Muscidae in which the squama covers the halter like a hood are called
"calypterate." In Fig. 216, we represent these structures, and in the
explanation have mentioned the synonyms. The terms we think most applicable
to the three lobes are alula, antisquama, squama. The squama may be called
"calypter" when it covers the halter.
[Illustration: Fig. 216—Parts at the base of the wing in _Calliphora_. _a_,
Anal angle or lobe of the wing; _b_, alula; _c_, antisquama, squama alaris,
or antitegula; _d_, squama, squama thoracicalis, tegula, calypter, or
calyptron; _e_, posterior extremity (scutellum) of the mesothorax; _f_,
scutum of mesothorax.]
The halteres—commonly called balancers or poisers—are perhaps the most
characteristic of all the Dipterous structures, though they are absent in
most of the few wingless forms of the Order. Outside the Diptera similar
organs appear to exist only in male Coccidae. The pair of halteres is
placed on the metathorax, one on each of the pleural regions. They are
believed to be the homologues of the hind wings; Weinland states[356] that
certain canals existing in the interior of the halter correspond to
wing-nervures. The halter may be described as a small rod-like body with a
head like a pin, this terminal part being, however, rather variable in
form. We have already stated that in many Diptera the squama forms a hood,
the position of which leads to the belief that it is an important adjunct
to the halter. Although the exact functions of the halteres are far from
clear, it is certain that they are highly complex bodies, of extremely
delicate structure: they are doubtless sense-organs, possessing as they do,
groups of papillae on the exterior and a chordotonal organ (a structure for
assisting the perception of sound) in the basal part; each halter is
provided with four muscles at the base, and can, like the wings, execute
most rapid vibrations. Seeing that they are the homologues of wings, it is
a remarkable fact that in no Diptera are they replaced by wings, or by
structures intermediate between these two kinds of organs.
INTERNAL STRUCTURE.—Information about the internal anatomy {449}is by no
means extensive. The tracheal system is highly developed, and has air-sacs
connected with it; a large pair at the base of the abdomen being called
aërostats by Dufour. Inside the thoracic spiracles there are peculiar
structures supposed by some to be voice-organs, while the abdominal
spiracles are said to be remarkably simple in structure. Lowne says that
there are ten or eleven pairs of spiracles in the Blow-fly; one of these,
near the base of the wing, is peculiar in structure, and may not be a true
stigma; he calls it a tympanic spiracle; it seems doubtful whether there
are more than seven abdominal pairs. The alimentary canal is very elongate,
and is provided with a diverticulum, the crop; this is usually called the
sucking stomach, though its function is extremely doubtful. The Malpighian
tubes are four in number, and are very elongate; in several groups of
Nemocera there are, however, five Malpighian tubes, a number known to occur
in only very few other Insects. The nervous system is remarkable on account
of the concentration of ganglia in the thorax, so as to form a thoracic, in
addition to the usual cephalic, brain. For particulars as to the positions
of the ganglia and the great changes that occur in the lifetime, the
student should refer to Brandt, to Künckel, and to Brauer.[357] Much
information as to the internal anatomy of the Blowfly is given by Lowne,
but it is doubtful to what extent it is applicable to Diptera in
general.[358]
[Illustration: Fig. 217—Acephalous larva or maggot of the blow-fly, with
the head, _a_, extended. (After Lowne.)]
The LARVAE of Diptera are—so far as the unaided eye is concerned—without
exception destitute of any kind of adornment, the vast majority of them
being of the kind known as maggots. None of them have true thoracic legs;
though in the earlier groups, pseudopods or protuberances of the body that
serve as aids in locomotion are common. Unlike what occurs in other Orders
the arrangement of these pseudopods on the body differs greatly in various
forms; in a few cases they are surmounted by {450}curved hairs. The most
important distinction in external form in Dipterous larvae is that while
those that are thorough maggots possess no visible head, others have a
well-marked one (Fig. 225); these are therefore called "eucephalous": they
have a mouth of the mandibulate type. In some other Dipterous larvae the
head is more or less reduced in size, and in the acephalous forms there is
only a framework of a few chitinous rods to represent it. The nervous
system in the most completely headless larvae is very remarkable, all the
ganglia being concentrated in a single mass placed in the thorax. The
tracheal system exhibits a great variety; some larvae have stigmata
arranged along the sides of the body after the fashion normal in
Insect-larvae; these are called "peripneustic"; as many as ten pairs of
stigmata may be present in these cases, but nine pairs is much more common.
Other larvae have a pair of stigmata placed at the termination of the body,
and another pair near the anterior extremity, the two pairs communicating
by large tracheal trunks extending the length of the body; these larvae are
said to be "amphipneustic": this is the condition usual in the more
completely acephalous larvae. Others have only the terminal pair of
spiracles, and are styled "metapneustic." Some begin life in the
metapneustic state and afterwards become amphipneustic. In the aquatic
larva of _Corethra_ there are no spiracles, though there is an imperfect
tracheal system. Many Dipterous larvae that live in water or in conditions
that prevent access of air to the body have remarkable arrangements for
keeping the tip of the body in communication with the atmosphere. The
stigmata in metapneustic and amphipneustic larvae are very remarkable
compound structures, exhibiting however great diversity; their
peculiarities and uses are not well understood; it appears very doubtful
whether some of them have any external opening. Reference may be made, as
to the variety of structure, to Meijere's paper[359] from which we take the
accompanying figure of a posterior stigmatic apparatus in _Lipara lucens_.
It appears that there is a compound chamber—"Filzkammer"—terminating
externally in lobes or fingers—"Knospen" and appearing as marks on the
outer surface: this chamber is seated on a tracheal tube, and is, Meijere
thinks, probably a secondary growth of the trachea coming to the outer
surface. It is traversed by what may be {451}considered the original
tracheal tube, opening externally as an external stigmatic
scar—"Stigmennarbe"—and with a second or inner scar placed internally. We
may conclude from what is already known that these structures will be found
to differ in the same larva according to the stage of its development.
[Illustration: Fig. 218—The posterior stigma of the larva of _Lipara
lucens_. _a_, One of the three "Knospen" or lobes; _b_, external stigmatic
scar; _c_, internal scar; _d_, stigmatic chamber (Filzkammer); _e_,
trachea. (After Meijere.)]
An extremely valuable summary of the characters and variety of Dipterous
larvae has been given by Brauer,[360] from which it appears that the larvae
of the first half of the family exhibit great variety and have been much
studied, while the more purely maggot-like forms of the Muscidae have, with
one or two exceptions, been little investigated.
The PUPAL instar is of two distinct kinds. First, we meet with a pupa like
that of Lepidoptera, viz. a mummy-like object, or pupa obtecta, in which
there is a crisp outer shell, formed in part by the adherent cases of the
appendages of the future imago. This condition, with a few exceptions to be
subsequently noticed, obtains in the Nemocera and Brachycera. It is
exhibited in various degrees of perfection, being most complete in
Tipulidae; in other forms the shell is softer and the appendages more
protuberant. The second kind of pupa is found in the Cyclorrhaphous flies;
it has externally no marks except some faint circular rings and,
frequently, a pair of projections from near one extremity of the body;
occasionally there is a single prominence at the other extremity of the
body. This condition is due to the fact that the larva does not escape from
the skin at the last ecdysis, but merely shrinks within it, so that the
larval skin, itself contracted and altered by an excretion of chitin,
remains and forms a perfect protection to the included organism. This kind
of pupa looks like a seed, and is well exemplified by the common Blow-fly.
The capacity for entering on such a condition is evidently correlative with
the absence of a larval head. The metamorphosis in this curious little
barrel goes on in a different manner to what it does in the pupa
{452}obtecta. A good name for the whole structure of this instar has not
been found. Older authors called it "pupa coarctata," or "nympha inclusa";
Brauer speaks of it as a "compound pupa"; ordinarily in our language it is
called a "puparium," a term which is more applicable to the case alone.
In species having a pupa obtecta the larval skin is cast after the chief
processes of the external metamorphosis have occurred, and then an
exudation of chitin hardens the general surface. In the "compound pupa" of
the Blow-fly there is for a considerable period no formed pupa at all, but
merely a shell or case containing the results of histolysis and the centres
for regeneration of new organs; the chitin-exudation to the exterior of the
larval skin occurs in the early part of the series of metamorphic changes,
and the organism breaks down to a cream within the shell thus formed, and
then gradually assumes therein the condition of a soft, nymphoid pupa. The
exceptional conditions previously referred to as exhibited by a few forms
are certain cases in which a more or less perfect pupa obtecta is found
within the last larval skin, as is the case in _Stratiomys_. Another highly
remarkable condition exists in the Hessian fly, and a few other
Cecidomyiids, where the Insect apparently makes an exudation which it uses
as a covering case, independent of the larval skin; this latter being
subsequently shed inside the case, so that this condition of coarctate pupa
differs from that we have described as existing in Cyclorrhaphous flies,
although the two are superficially similar. In the Pupipara the larval
stage is passed in the body of the mother, which produces a succession of
young, nourished one at a time by the secretion of glands; this young is
born as a full-grown larva that becomes at once a pupa.
METAMORPHOSIS.—As it is in Diptera that the phenomena of
Insect-metamorphosis have reached their highest development we endeavoured
to give some idea of their nature in the previous volume, therefore we need
give only a brief sketch of the chief features of Dipterous metamorphosis.
The Blow-fly undergoes a rapid embryonic development, the later stages of
which are, on the whole, of a retrogressive nature. On the emergence of the
young maggot it feeds up rapidly, the rapidity varying greatly according to
circumstances, and then when full-grown rests. While resting, a process of
internal liquefaction, called histolysis, is going on, and the maggot
contracts and exudes an excretion {453}that hardens its skin. At the time
this hard skin has become complete, or soon after, the maggot inside has
dissolved into a cream contained in a sac inside the shell; this cream
becomes reconstituted into a fly by a gradual process of growth and
development of certain minute portions of the body—the imaginal discs or
folds, the histoblasts and neuroblasts that were exempt from the histolytic
process: in the early stages of the reconstitution the general structure
is, of course, altogether vague, and this condition—purely one of
transition—is called the pronymph; the nymph becomes gradually developed:
it corresponds vaguely with the pupa obtecta of the early groups of
Diptera, but is soft like the pupa of Hymenoptera. This nymph gradually
develops into the fly itself, the external parts being first completed and
the internal organs elaborated subsequently. The sexual organs do not
undergo metamorphosis like other internal organs, there being a gradual
(though irregular or interrupted) growth of them in the young larva, till
they are completed some time after the emergence of the perfect fly. The
processes in the Blow-fly have been studied by numerous able histologists
of various nationalities, and have recently been described by Lowne in our
own language.[361] Comparatively little has been done in studying the
corresponding phenomena in other Diptera. Weismann has investigated the
development of _Corethra_, and Miall that of _Chironomus_. These two flies
belong to a division of Diptera different from that which includes the
Blow-fly, and they display a condition of the metamorphic processes allied
to what occurs in Lepidoptera, as well as to that which takes place in the
Blow-fly. Imaginal folds are formed, but they only appear much later in the
life, and they are much less distant from the positions they will, when
developed, occupy in the imago. In _Chironomus_, according to Miall, the
imaginal folds only appear in the last larval instar, but they grow with
such rapidity that the legs and wings of the future fly can be
distinguished in the larva, even before pupation; thus when the activity of
the larva ceases but little change is required to complete the obtected
pupa. In the Blow-fly some of the imaginal folds have been {454}traced back
to the embryo; how many centres for the new growth there may be is
uncertain, for though there are upwards of sixty for the outer body, the
number of regenerative centres for the internal organs is not ascertained.
The peculiar central nervous mass, mentioned in our remarks on the larva,
consists of two kinds of tissue mixed together in a complex manner; one of
these kinds is functionally active during the larval life and at the
metamorphosis undergoes histolysis, while the other, or embryonic, portion
develops into the nervous system of the fly.
It forms no part of our task to deal with general subjects, but we may be
pardoned for calling attention to the bearing the metamorphosis of the
higher Diptera has on our ideas of heredity in Insects. The fly bears no
resemblance whatever to the larva, and is only obtained by the organic
destruction of the latter, which occurs before the perfection of the sexual
organs takes place, and yet the fly reproduces itself only secondarily, but
primarily gives rise to the totally different larva. It is supposed that
the larval structures have been gradually acquired, and yet they are
transmitted with the utmost faithfulness by the totally different fly. We
can only conclude that that which is bequeathed in each species is the
early state of a particular process of development from which the
subsequent stages follow necessarily if the developing organism be placed
in conditions having on it influences like to those that influenced the
ancestors.
CLASSIFICATION.—The classification of Diptera is as yet very imperfect.
Formerly they were divided into two great groups, Nemocera and Brachycera,
according to the structure of the antennae, as previously mentioned. This
division has been abandoned, and the term Brachycera is now applied to only
a small part of the old section that bore the name. The primary division
usually adopted at present is into Orthorrhapha and Cyclorrhapha. The
characters of these two groups are based on the nature of the
metamorphosis, and have been gradually elaborated by Brauer in various
memoirs.[362] The Orthorrhapha includes the forms with obtected pupae, the
Cyclorrhapha those with a nymph-compound, as previously described. This
distinction is of great importance, but unfortunately it is difficult to
apply to the fly itself; the only character that can be used in
{455}connection with the imago is the existence of a suture over the
insertion of the antennae in a portion, but not all, of the
Cyclorrhapha.[363] The next set of divisions used by Brauer divides the
Order into four sections, viz. 1. Orthorrhapha Nematocera, 2. O.
Brachycera, 3. Cyclorrhapha Aschiza, 4. C. Schizophora. As these four
groups are recognised more readily than the two major groups the student
will do well at first to disregard the primary division and consider the
Diptera as divisible into four great groups. To these four divisions we,
however, add temporarily a fifth, viz. Pupipara. This is included by Brauer
in Schizophora, but it appears to be really an unnatural complex, and had
better be kept separate till it has been entirely reconsidered. These great
sections may be thus summarised:—
Series 1. _Orthorrhapha Nemocera._—Antennae with more than 6 segments,
not terminated by an arista; with the segments of the flagellum more or
less similar to one another. Palpi slender and flexible, four- or
five-jointed.[364]
Series 2. _Orthorrhapha Brachycera._—Antennae variable, but never truly
Nemocerous nor like those of Cyclorrhapha; when an arista is present it
is usually placed terminally, not superiorly; when an arista is not
present the flagellum terminates as an appendage consisting of a variable
number of indistinctly separated segments; thus the flagellum is not
composed of similar joints; [rarely are the antennae as many as
seven-jointed]. Palpi only one- or two-jointed.[365] Around the insertion
of the antennae there is no definite arched suture enclosing a small
depressed space. The nervuration of the wings is usually more complex
than in any of the other divisions.
Series 3. _Cyclorrhapha Aschiza._—Antennae composed of not more than
three joints and an arista; the latter is not terminal. Front of head
without definite arched suture over the antennae, but frequently with a
minute area of different colour or texture there. This group consists of
the great family Syrphidae, and of four small families, viz. Conopidae,
Pipunculidae, Phoridae, and Platypezidae. The section is supposed to be
justified by its being Cyclorrhaphous in pupation, and by the members not
possessing a ptilinum (or having no trace of one when quite mature). The
Syrphidae are doubtless {456}a natural group, but the association with
them of the other families mentioned is a mere temporary device. The
greatest difficulty is experienced in deciding on a position for
Phoridae, as to which scarcely any two authorities are agreed.
Series 4. _Cyclorrhapha Schizophora_, or Eumyiid flies. The antennae
consist of three joints and an arista. In the Calyptratae the frontal
suture, or fold over the antennae, is well marked and extends downwards
along each side of the face, leaving a distinct lunule over the antennae.
In the Acalyptrate Muscids the form of the head and of the antennae vary
much and are less characteristic, but the wings differ from those of
Brachycera by their much less complex nervuration.
Series 5. _Pupipara._ These are flies of abnormal habits, and only found
in connection with living Vertebrates, of which they suck the blood (one
species, _Braula caeca_, lives on bees). Many are wingless, or have wings
reduced in size. The young are produced alive, full grown, but having
still to undergo a metamorphosis. This group consists of a small number
of flies of which some are amongst the most aberrant known. This is
specially the case with the Nycteribiidae. This Section will probably be
greatly modified, as it is far from being a natural assemblage.[366]
The Sub-Order _Aphaniptera_, or Fleas, considered a distinct Order by
many entomologists, may for the present be placed as a part of Diptera.
It must be admitted that these sections are far from satisfactory. Brauer
divides them into Tribes, based on the nature of the larvae, but these
tribes are even more unsatisfactory than the sections, hosts of species
being entirely unknown in the larval state, and many of those that are
known having been very inadequately studied. We must admit that the
classification of Diptera has at present advanced but little beyond the
stage of arranging them in natural families capable of exact definition. We
may, however, draw attention to the attempt that is being made by Osten
Sacken to remodel the classification of the Nemocera and Brachycera by the
combination of families into super-families.[367] He proposes to divide the
Nemocera into two super-families: 1. Nemocera Vera, including all the
families from Cecidomyiidae to Tipulidae; 2. Nemocera Anomala, consisting
of the small families Bibionidae, Simuliidae, Blepharoceridae, Rhyphidae
and Orphnephilidae.
For Orthorrhapha Brachycera he adopts the following {457}arrangement: 1.
Super-family Eremochaeta, for Stratiomyidae, Tabanidae, Acanthomeridae and
Leptidae; 2. Tromoptera, for Nemestrinidae, Acroceridae, Bombyliidae,
Therevidae, and Scenopinidae; 3. Energopoda, for Asilidae, Dolichopidae,
Empidae and Lonchopteridae, Phoridae being included with doubt; 4. Mydaidae
remains isolated.
This classification is based on the relations of the eyes and bristles of
the upper surface, and on the powers of locomotion, aërial or terrestrial.
At present it is not sufficiently precise to be of use to any but the very
advanced student.
BLOOD-SUCKING DIPTERA.—The habit of blood-sucking from Vertebrates is,
among Insects, of course confined to those with suctorial mouth, and is
exhibited by various Diptera. It is, however, indulged in by but a small
number of species, and these do not belong to any special division of the
Order. It is remarkable that as a rule the habit is confined to the female
sex, and that a large proportion of the species have aquatic larvae. This
subject has many points of interest, but does not appear to have yet
received the attention it merits. We give below a brief summary of the
facts as to blood-sucking Diptera.
Series I. Nemocera.—In this section the habit occurs in no less than five
families, viz.:
Blepharoceridae. _Curupira_; in the female only; larva aquatic.
Culicidae. _Culex_, Mosquitoes; in the female only; other genera, with
one or two exceptions, do not suck blood; larvae aquatic.
Chironomidae. _Ceratopogon_, Midge; in the female only; exceptional
even in the genus, though the habit is said to exist in one or two less
known, allied genera; larval habits not certain; often aquatic; in _C.
bipunctatus_ the larva lives under moist bark.
Psychodidae. _Phlebotomus_: in the female only (?); quite exceptional
in the family; larva aquatic or in liquid filth.
Simuliidae. _Simulium_, sand-flies; general in the family (?), which,
however, is a very small one; larva aquatic, food probably mixed
vegetable and animal microscopic organisms.
Series II. Brachycera. Tabanidae. Gad-flies: apparently general in the
females of this family; the habits of the exotic forms but little known;
in the larval state, scarcely at all known; some are aquatic.
{458}Series IV. Cyclorrhapha Schizophora: _Stomoxys_, _Haematobia_; both
sexes (?); larvae in dung. [The Tse-tse flies, _Glossina_, are placed in
this family, though their mode of parturition is that of the next
section].
Series V. Pupipara. The habit of blood-sucking is probably common to all
the group and to both sexes. The flies, with one exception, frequent
Vertebrates; in many cases living entirely on their bodies, and
apparently imbibing much blood; the larvae are nourished inside the
flies, not on the imbibed blood, but on a milky secretion from the
mother.
Sub-Order Aphaniptera. Fleas. The habit of blood-sucking is common to all
the members and to both sexes. The larvae live on dried animal matter.
FOSSIL DIPTERA.—A considerable variety of forms have been found in amber,
and many in the tertiary beds; very few members of the Cyclorrhaphous
Sections are, however, among them; the Tipulidae, on the other hand, are
richly represented. In the Mesozoic epoch the Order is found as early as
the Lias, the forms being exclusively Orthorrhaphous, both Nemocera and
Brachycera being represented. All are referred to existing families.
Nothing has been found tending to connect the Diptera with other Orders. No
Palaeozoic Diptera are known.
SERIES 1. ORTHORRHAPHA NEMOCERA
FAM. 1. CECIDOMYIIDAE.—_An extensive family of very minute and fragile
flies, the wings of which have very few nervures; the antennae are rather
long, and are furnished with whorls of hair._ In the case of some species
the antennae are beautiful objects; in _Xylodiplosis_ some of the hairs
have no free extremities, but form loops (Fig. 220). In the males of
certain species the joints appear to be double, each one consisting of a
neck and a body. Although comparatively little is known as to the flies
themselves, yet these Insects are of importance on account of their
preparatory stages. The larvae have very diverse habits; the majority live
in plants and form galls, or produce deformations of the leaves, flowers,
stems, buds, or roots in a great variety of ways; others live under bark or
in animal matter; some are predaceous, killing Aphidae or Acari, and even
other Cecidomyiids.
{459}[Illustration: Fig. 219—_Cecidomyia_ (_Diplosis_) _buxi_. Britain. A,
Larva, magnified; B, pupa; C, imago; D, portion of antenna. (After
Laboulbène.)]
[Illustration: Fig. 220—One segment of antenna of _Xylodiplosis_ sp.; _a_,
Tip of one segment; _b_, base of another. (After Janet.)]
The North American _Diplosis resinicola_ lives in the resin exuded as the
results of the attacks of a caterpillar. The larva burrows in the
semi-liquid resin, and, according to Osten Sacken,[368] is probably
amphipneustic. Cecidomyiid larvae are short maggots, narrowed at the two
ends, with a very small head, and between this and the first thoracic
segment (this bears a stigma), a small supplementary segment; the total
number of segments is thirteen, besides the head; there are eight pairs of
stigmata on the posterior part of the body. Brauer defines the Cecidomyiid
larva thus, "peripneustic, with nine pairs of stigmata, the first on the
second segment behind the head; two to nine on fifth to twelfth segments;
body as a whole fourteen-segmented without a fully-formed head." The most
remarkable peculiarity of Cecidomyiid larvae is that those of many species
possess a peculiar organ—called breast-bone, sternal spatula, or
anchor-process—projecting from the back of the lower face of the
prothoracic segment. The use of so peculiar a structure has been much
discussed. According to Giard,[369] in addition to the part {460}that
protrudes externally, as shown in Fig. 219, A, there is a longer portion
concealed, forming a sort of handle, having muscles attached to it. Some of
these larvae have the power of executing leaps, and he states that such
larvae are provided on the terminal segment with a pair of corneous
papillae; bending itself almost into a circle, the larva hooks together the
breast-bone and the papillae, and when this connection is broken the spring
occurs. This faculty is only possessed by a few species, and it is probable
that in other cases the spatula is used as a means for changing the
position or as a perforator. Some of the larvae possess false feet on
certain of the segments. Williston says they probably do not moult. In the
pupal instar (Fig. 219, B), the Cecidomyiid greatly resembles a minute
Lepidopterous pupa. The Hessian fly, _Cecidomyia destructor_, is frequently
extremely injurious to crops of cereals, and in some parts of the world
commits serious depredation. The larva is lodged at the point where a leaf
enwraps the stem; it produces a weakness of the stem, which consequently
bends. This Insect and _C. tritici_ (the larva of which attacks the flowers
of wheat) pupate in a very curious manner: they form little compact cases
like flax-seeds; these have been supposed to be a form of pupa similar to
what occurs in the Blow-fly; but there are important distinctions. The
larva, when about to undergo its change, exudes a substance from its skin,
and this makes the flax-seed; the larval skin itself does not form part of
this curious kind of cocoon, for it may be found, as well as the pupa, in
the interior of the "flax-seed." Other Cecidomyiids form cocoons of a more
ordinary kind; one species, described by Perris as living on _Pinus
maritima_, has the very remarkable faculty of surrounding itself, by some
means, with a cocoon of resin. Walsh describes the cocoon-forming process
of certain Cecidomyiids as one of exudation and inflation; Williston as
somewhat of the nature of crystallisation. Some Cecidomyiids are said to
possess, in common with certain other Diptera, the unusual number of five
Malpighian tubes; and Giard says that in the larva there is only a pair of
these tubes, and that their extremities are united so as to form a single
tube, which is twisted into an elegant double loop.
Thirty years or more ago the Russian naturalist, Wagner, made the very
remarkable discovery that the larva of a Cecidomyiid produces young; and it
has since been found by Meinert and {461}others that this kind of
paedogenesis occurs in several species of the genera _Miastor_ and
_Oligarces_. The details are briefly as follows:—A female fly lays a few,
very large, eggs, out of each of which comes a larva, that does not go on
to the perfect state, but produces in its interior young larvae that, after
consuming the interior of the body of the parent larva, escape by making a
hole in the skin, and thereafter subsist externally in a natural manner.
This larval reproduction may be continued for several generations, through
autumn, winter, and spring till the following summer, when a generation of
the larvae goes on to pupation and the mature, sexually perfect fly
appears. Much discussion has taken place as to the mode of origination of
the larvae; Carus and others thought they were produced from the
rudimental, or immature ovaries of the parent larva. Meinert, who has made
a special study of the subject,[370] finds, however, that this is not the
case; in the reproducing larva of the autumn there is no ovary at all; in
the reproducing larvae of the spring-time rudimentary ovaries or testes, as
the case may be, exist; the young are not, however, produced from these,
but from germs in close connection with the fat-body. In the larvae that go
on to metamorphosis the ovaries continue their natural development. It
would thus appear that the fat-body has, like the leaf of a _Begonia_,
under certain circumstances, the power, usually limited to the ovaries, of
producing complete and perfect individuals.
Owing to the minute size and excessive fragility of the Gall-midge flies it
is extremely difficult to form a collection of them; and as the larvae are
also very difficult of preservation, nearly every species must have its
life-history worked out as a special study before the name of the species
can be ascertained. Notwithstanding the arduous nature of the subject it
is, however, a favourite one with entomologists. The number of described
and named forms cannot be very far short of 1000, and each year sees some
20 or 30 species added to the list. The number of undescribed forms is
doubtless very large. The literature of the subject is extensive and of the
most scattered and fragmentary character.
The Cecidomyiidae have but little relation to other Nemocera, and are
sometimes called Oligoneura, on account of the reduced number of
wing-nervures. Their larvae are of a peculiar type {462}that does not agree
with the larvae of the allied families having well-marked heads (and
therefore called Eucephala), nor with the acephalous maggots of Eumyiidae.
FAM. 2. MYCETOPHILIDAE.—_These small flies are much less delicate creatures
than the Cecidomyiidae, and have more nervures in the wings; they possess
ocelli, and frequently have the coxae elongated, and in some cases the legs
adorned with complex arrangements of spines: their antennae have not whorls
of hair._ Although very much neglected there are probably between 700 and
1000 species known; owing to many of their larvae living in fungoid matter
the flies are called Fungus-gnats. We have more than 100 species in
Britain. _Epidapus_ is remarkable, inasmuch as the female is entirely
destitute of wings and halteres, while the male has the halteres developed
but the wings of very reduced size. _E. scabiei_ is an excessively minute
fly, smaller than a common flea, and its larva is said to be very injurious
to stored potatoes. The larvae of Mycetophilidae are usually very elongate,
worm-like maggots, but have a distinct, small head; they are peripneustic,
having, according to Osten Sacken, nine pairs of spiracles, one pair
prothoracic, the others on the first eight abdominal segments. They are
usually worm-like, and sometimes seem to consist of twenty segments. Some
of them have the faculty of constructing a true cocoon by some sort of
spinning process, and a few make earthen cases for the purpose of pupation.
The pupae themselves are free, the larval skin having been shed. The
Mycetophilidae are by no means completely fungivorous, for many live in
decaying vegetable, some even in animal, matter.
[Illustration: Fig. 221—_Mycetobia pallipes._ Britain. A, Larva; B, pupa;
C, imago. (After Dufour.)]
The habits of many of the larvae are very peculiar, owing to their spinning
or exuding a mucus, that reminds one of snail-slime; they are frequently
gregarious, and some of them have likewise, as we shall subsequently
mention, migratory habits. Perris has described the very curious manner in
which _Sciophila {463}unimaculata_ forms its slimy tracks;[371] it
stretches its head to one side, fixes the tip of a drop of the viscous
matter from its mouth to the surface of the substance over which it is to
progress, bends its head under itself so as to affix the matter to the
lower face of its own body; then stretches its head to the other side and
repeats the operation, thus forming a track on which it glides, or perhaps,
as the mucus completely envelops its body, we should rather call it a
tunnel through which the maggot slips along. According to the description
of Hudson[372] the so-called New Zealand Glow-worm is the larva of
_Boletophila luminosa_; it forms webs in dark ravines, along which it
glides, giving a considerable amount of light from the peculiarly formed
terminal segment of the body. This larva is figured as consisting of about
twenty segments. The pupa is provided with a very long, curiously-branched
dorsal structure: the fly issuing from the pupa is strongly luminous,
though no use can be discovered for the property either in it or in the
larva. The larva of the Australian _Ceroplatus mastersi_ is also luminous.
Another very exceptional larva is that of _Epicypta scatophora_; it is of
short, thick form, like Cecidomyiid larvae, and has a very remarkable
structure of the dorsal parts of the body; by means of this its excrement,
which is of a peculiar nature, is spread out and forms a case for
enveloping and sheltering the larva. Ultimately the larval case is
converted into a cocoon for pupation. This larva is so different from that
of other Mycetophilidae, that Perris was at first unable to believe that
the fly he reared really came from this unusually formed larva. The larva
of _Mycetobia pallipes_ (Fig. 221) offers a still more remarkable
phenomenon, inasmuch as it is amphipneustic instead of peripneustic (that
is to say, it has a pair of stigmata at the termination of the body and a
pair on the first thoracic segment instead of the lateral series of pairs
we have described as normal in Mycetophilidae). This larva lives in company
with the amphipneustic larva of _Rhyphus_, a fly of quite another family,
and the _Mycetobia_ larva so closely resembles that of the _Rhyphus_, that
it is difficult to distinguish the two. This anomalous larva gives rise,
like the exceptional larva of _Epicypta_, to an ordinary Mycetophilid
fly.[373]
{464}But the most remarkable of all the Mycetophilid larvae are those of
certain species of _Sciara_, that migrate in columns, called by the
Germans, Heerwurm. The larva of _Sciara militaris_ lives under layers of
decomposing leaves in forests, and under certain circumstances, migrates,
sometimes perhaps in search of a fresh supply of food, though in some cases
it is said this cannot be the reason. Millions of the larvae accumulate and
form themselves by the aid of their viscous mucus into great strings or
ribbons, and then glide along like serpents: these aggregates are said to
be sometimes forty to a hundred feet long, five or six inches wide, and an
inch in depth. It is said that if the two ends of one of these processions
be brought into contact, they become joined, and the monstrous ring may
writhe for many hours before it can again disengage itself and assume a
columnar form. These processional maggots are met with in Northern Europe
and the United States, and there is now an extensive literature about
them.[374] Though they sometimes consist of almost incredible numbers of
individuals, yet it appears that in the Carpathian mountains the
assemblages are usually much smaller, being from four to twenty inches
long. A species of _Sciara_ is the "Yellow-fever fly" of the Southern
United States. It appears that it has several times appeared in unusual
numbers and in unwonted localities at the same time as the dreaded disease,
with which it is popularly supposed to have some connection.
FAM. 3. BLEPHAROCERIDAE.[375]—_Wings with no discal cell, but with a
secondary set of crease-like lines._ The flies composing this small family
are very little known, and appear to be obscure Insects with somewhat the
appearance of Empidae, though with strongly iridescent wings; they execute
aerial dances, after the manner of midges, and are found in Europe (the
Pyrenees, Alps and Harz mountains) as well as in North and South America.
Their larvae are amongst the most remarkable of Insect forms; indeed, no
entomologist recognises them as belonging to a Hexapod Insect when he makes
a first {465}acquaintance with them. The larva of _Curupira_ (Fig. 222)
lives in rapid streams in Brazil, fixed by its suckers to stones or rocks.
It consists only of six or seven divisions, with projecting side-lobes; the
usual segmentation not being visible. There are small tracheal gills near
the suckers, and peculiar scale-like organs are placed about the edges of
the lobes. Müller considers that the first lobe is "cephalothorax,"
corresponding to head, thorax and first abdominal segment of other larvae,
the next four lobes he considers to correspond each to an abdominal
segment, and the terminal mass to four segments. He also says that certain
minute points existing on the surface, connected with the tracheal system
by minute strings, represent nine pairs of spiracles. These larvae and
their pupae can apparently live only a short time after being taken out of
the highly aërated water in which they exist, but Müller succeeded in
rearing several flies from a number of larvae and pupae that he collected,
and, believing them to be all one species, he announced that the females
exhibited a highly developed dimorphism, some of them being blood-suckers,
others honey-suckers. It is however, more probable that these specimens
belonged to two or three distinct species or even genera. This point
remains to be cleared up. The larva we have figured is called by Müller
_Paltostoma torrentium_. It is certain, however, that the Brazilian Insect
does not belong to the genus _Paltostoma_, and it will no doubt bear the
name used by Osten Sacken, viz. _Curupira_.
[Illustration: Fig. 222—Under surface of the larva of _Curupira_
(_Paltostoma_) _torrentium_, showing the suckers along the middle of the
body, much magnified. Brazil. (After Fritz Müller.)]
The metamorphoses of the European _Liponeura brevirostris_ have been
partially examined by Dewitz, who found the Insects in the valley of the
Ocker in September.[376] He does not consider the "cephalothorax" to
include an abdominal segment; and he found that two little, horn-like
projections from the thorax of the {466}pupa are really each four-leaved.
The pupa is formed within the larval skin, but the latter is subsequently
cast so that the pupa is exposed; its dorsal region is horny, but the under
surface, by which it clings firmly to the stones of the rapid brook, is
white and scarcely chitinised, and Dewitz considers that the chitinous
exudation from this part is used as a means of fastening the pupa to the
stones. Blepharoceridae possess, in common with _Culex_, _Psychoda_ and
_Ptychoptera_, the peculiar number of five Malpighian tubes, and it has
been proposed by Müller to form these Insects into a group called
Pentanephria.
FAM. 4. CULICIDAE (_Mosquitoes_, _Gnats_).—_Antennae with whorls of hair or
plumes, which may be very dense and long in the male, though scanty in the
female; head with a long, projecting proboscis._ Although there are few
Insects more often referred to in general literature than Mosquitoes, yet
the ideas in vogue about them are of the vaguest character. The following
are the chief points to be borne in mind as to the prevalence of
Mosquitoes:—The gently humming Gnat that settles on us in our apartments,
and then bites us, is a Mosquito; there are a large number of species of
Mosquitoes; in some countries many in one locality; in Britain we have ten
or a dozen; notwithstanding the multiplicity of species, certain Mosquitoes
are very widely diffused; the larvae are all aquatic, and specially
frequent stagnant or quiet pools; they are probably diffused by means of
the water in ships, it being known that Mosquitoes were introduced for the
first time to the Hawaiian Islands by a sailing vessel about the year 1828.
Hence it is impossible to say what species the Mosquitoes of a given
locality may be without a critical examination. No satisfactory work on the
Mosquitoes of the world exists. Urich states that he is acquainted with at
least ten species in Trinidad. The species common in our apartments in
Central and Southern England is _Culex pipiens_, Linn., and this species is
very widely distributed, being indeed one of the troublesome Mosquitoes of
East India. The term Mosquito is a Spanish or Portuguese diminutive of
Mosca. It is applied to a variety of small flies of other families than
Culicidae, but should be restricted to these latter. The irritation
occasioned by the bites of Mosquitoes varies according to several
circumstances, viz. the condition of the biter, the condition or
constitution of the bitten, and also the species of Mosquito. Réaumur and
{467}others believed that some irritating fluid is injected by the Mosquito
when it bites. But why should it want to irritate as well as to bite?
Macloskie, considering that the Mosquito is really a feeder on
plant-substances, suggests that the fluid injected may be for the purpose
of preventing coagulation of the plant-juices during the process of
suction. It is a rule that only the female Mosquito bites, the male being
an inoffensive creature, and provided with less effectual mouth-organs; it
has, however, been stated by various authors that male Mosquitoes do
occasionally bite. It is difficult to understand the blood-sucking
propensities of these Insects; we have already stated that it is only the
females that suck blood. There is reason to suppose that it is an acquired
habit; and it would appear that the food so obtained is not essential to
their existence. It has indeed been asserted that the act is frequently
attended with fatal consequences to the individual that does it. The proper
method of mitigating their nuisance is to examine the stagnant waters in
localities where they occur, and deal with them so as to destroy the
larvae. These little creatures are remarkable from the heads and thorax
being larger and more distinct than in other Dipterous larvae. Their
metamorphoses have been frequently described, and recently the numerous
interesting points connected with their life-histories have been admirably
portrayed by Professor Miall,[377] in an accessible form, so that it is
unnecessary for us to deal with them. _Corethra_ is placed in Culicidae,
but the larva differs totally from that of _Culex_; it is predaceous in
habits, is very transparent, has only an imperfect tracheal system, without
spiracles, and has two pairs of air-sacs (perhaps we should rather say
pigmented structures possibly for aerostatic purposes, but not suppliers of
oxygen). The kungu cake mentioned by Livingstone as used on Lake Nyassa is
made from an Insect which occurs in profusion there, and is compressed into
biscuit form. It is believed to be a _Corethra_. One of the peculiarities
of this family is the prevalence of scales on various parts of the body,
and even on the wings: the scales are essentially similar to those of
Lepidoptera. Though Mosquitoes are generally obscure plain Insects, there
are some—in the South American genus _Megarrhina_—that are elegant,
beautifully adorned creatures. Swarms of various species of Culicidae,
consisting sometimes of almost incalculable numbers {468}of individuals,
occur in various parts of the world; one in New Zealand is recorded as
having been three-quarters of a mile long, twenty feet high, and eighteen
inches thick. There is good reason for supposing that Mosquitoes may act as
disseminators of disease, but there is no certain evidence on the subject.
The minute _Filaria_ that occurs in great numbers in some patients, is
found in the human body only in the embryonic and adult conditions. Manson
considers that the intermediate stages are passed in the bodies of certain
Mosquitoes.[378]
FAM. 5. CHIRONOMIDAE (_Gnats_, _Midges_).—_Small or minute flies of slender
form, with narrow wings, without projecting rostrum, usually with densely
feathered antennae in the male, and long slender legs._ The flies of this
family bear a great general resemblance to the Culicidae. They are much
more numerous in species, and it is not improbable that we have in this
country 200 species of the genus _Chironomus_ alone. They occur in enormous
numbers, and frequently form dancing swarms in the neighbourhood of the
waters they live in. The species are frequently extremely similar to one
another, though distinguished by good characters; they are numerous about
Cambridge. Many of them have the habit of using the front legs as feelers
rather than as means of support or locomotion. This is the opposite of what
occurs in Culicidae, where many of the species have a habit of holding up
the hind legs as if they were feelers. The eggs of _Chironomus_ are
deposited as strings surrounded by mucus, and are many of them so
transparent that the development of the embryo can be directly observed
with the aid of the microscope. They are said to possess a pair of
air-sacs. The larvae, when born, are aquatic in habits, and are destitute
of tracheal system. They subsequently differ greatly from the larvae of
_Culex_, inasmuch as the tracheal system that develops is quite closed, and
in some cases remains rudimentary. There is, however, much diversity in the
larvae and also in the pupae. The little Blood-worms, very common in many
stagnant and dirty waters, and used by anglers as bait, are larvae of
_Chironomus_. They are said to be αἱ Ἐμπίδες of Aristotle. The red colour
of these larvae is due to haemoglobin, a substance which has the power of
attracting and storing oxygen, and giving it off to the tissues as they
require it. Such larvae are able to live in burrows they construct
{469}amongst the mud. Some of them, provided plentifully with haemoglobin,
are in consequence able to live at great depths, it is said even at 1000
feet in Lake Superior, and come to the surface only occasionally. A few are
able even to tolerate salt water, and have been fished up from considerable
depths in the sea. It is a remarkable fact that these physiological
capacities differ greatly within the limits of the one genus, _Chironomus_,
for some of these species are destitute of haemoglobin, and have to live
near the surface of the water; these have a superior development of the
tracheal system. The pupae of _Chironomus_ have the legs coiled, and the
thorax, instead of being provided with the pair of tubes or trumpets for
breathing that is so common in this division of Diptera, have a pair of
large tufts of hair-like filaments.[379] A very curious form of
parthenogenesis has been described by Grimm[380] as existing in an
undetermined species of _Chironomus_, inasmuch as the pupa deposits eggs.
Although this form of parthenogenesis is of much interest, it is not in any
way to be compared with the case, already referred to, of _Miastor_ (p.
461). The "pupa" is at the time of oviposition practically the imago still
covered by the pupal integument; indeed Grimm informs us that in some
cases, after depositing a small number of ova, the pupa became an imago.
This parthenogenesis only occurs in the spring-generation; in the autumn
the development goes on in the natural manner. The case is scarcely
entitled to be considered as one of paedogenesis.
Gnats of this family, and believed to be a variety of _Chironomus
plumosus_, are subject to a curious condition, inasmuch as individuals
sometimes become luminous or "phosphorescent"; this has been noticed more
specially in Eastern Europe and Western Asia. The whole of the body and
legs may exhibit the luminous condition, but not the wings. It has been
suggested by Schmidt that this condition is a disease due to bacteria in
the body of the gnat.[381]
_Ceratopogon_ is a very extensive genus, and is to some extent anomalous as
a member of Chironomidae. The larvae exhibit considerable variety of form.
Some of them are aquatic {470}in habits, but the great majority are
terrestrial, frequenting trees, etc. The former larvae are very slender,
and move after the manner of leeches; they give rise to imagos with naked
wings, while the terrestrial larvae produce flies with hairy wings. There
are also important distinctions in the pupae of the two kinds; the
correlation between the habits, and the distinctions above referred to, is,
however, far from being absolutely constant.[382] Certain species of midges
are in this country amongst the most annoying of Insects; being of very
minute size, scarcely visible, they settle on the exposed parts of the body
in great numbers, and by sucking blood create an intolerable irritation.
_Ceratopogon varius_ is one of the most persistent of these annoyers in
Scotland, where this form of pest is much worse than it is in England; in
Cambridgeshire, according to Mr. G. H. Verrall, the two troublesome midges
are the females of _C. pulicaris_ and _C. bipunctatus_.
FAM. 6. ORPHNEPHILIDAE.—_Small, brown or yellowish flies, bare of
pubescence, with very large eyes contiguous in both sexes, and with
antennae composed of two joints and a terminal bristle; both the second
joint and the bristle are, however, really complex._ One of the smallest
and least known of the families of Diptera, and said to be one of the most
difficult to classify. The nervures of the wings are very distinct. Nothing
is known of the habits and metamorphoses; there is only one
genus—_Orphnephila_; it is widely distributed; we have one species in
Britain.
FAM. 7. PSYCHODIDAE (_Moth-flies_).—_Extremely small, helpless flies,
usually with thickish antennae, bearing much hair, with wings broader than
is usual in small flies, and also densely clothed with hair, giving rise to
a pattern more or less vague._ These flies are very fragile creatures, and
are probably numerous in species. In Britain forty or fifty species have
been recognised.[383] A South European form is a blood-sucker, and has
received the appropriate name of _Phlebotomus_. The life-history of
_Pericoma canescens_ has recently been studied by Professor Miall.[384] The
larva is of aquatic habits, but is amphibious, being capable of existing in
the air; it has a pair of anterior spiracles, by means {471}of which it
breathes in the air, and a pair at the posterior extremity of the body,
surrounded by four ciliated processes, with which it forms a sort of cup
for holding air when it is in the water. The favourite position is amongst
the filaments of green algae on which it feeds. A much more extraordinary
form of larva from South America, doubtless belonging to this family, has
recently been portrayed by Fritz Müller, under the name of _Maruina_.[385]
These larvae live in rapid waters in company with those of the genus
_Curupira_, and like the latter are provided with a series of suctorial
ventral discs. Fritz Müller's larvae belong to several species, and
probably to more than one genus, and the respiratory apparatus at the
extremity of the body exhibits considerable diversity among them.
FAM. 8. DIXIDAE.—The genus _Dixa_ must, it appears, form a distinct family
allying the Culicid series of families to the Tipulidae. The species are
small, gnat-like Insects, fond of damp places in forests. We have four
British species (_D. maculata_, _D. nebulosa_, _D. aestivalis_, _D.
aprilina_). The genus is very widely distributed, occurring even in
Australia. The larvae are aquatic, and have been described by Réaumur,
Miall, and Meinert. The pupa has the legs coiled as in the Culicidae.
FAM. 9. TIPULIDAE (_Daddy-long-legs, or Crane-flies_).—_Slender Insects
with elongate legs, a system of wing-nervures, rather complex, especially
at the tip; an angulate, or open V-shaped, suture on the dorsum of the
thorax in front of the wings: the female with the body terminated by a pair
of hard, pointed processes, concealing some other processes, and forming an
ovipositor._ The curious, silly Insects called daddy-long-legs are known
all over the world, the family being a very large one, and found
everywhere, some of its members extending their range even to the most
inclement climates. It includes a great variety of forms that would not be
recognised by the uninitiated, but can be readily distinguished by the
characters mentioned above. It is impossible to assign any reason of
utility for the extreme elongation of the legs of these Insects; as
everyone knows, they break off with great ease, and the Insect appears to
get on perfectly well without them. It is frequently {472}the case that
they are much longer in the males than in the females. Other parts of the
body exhibit a peculiar elongation; in some forms of the male the front of
the head may be prolonged into a rostrum. In a few species the head is
separated by a great distance from the thorax, the gap being filled by
elongate, hard, cervical sclerites; indeed it is in these Insects that the
phenomenon, so rare in Insect-structure, of the elongation of these
sclerites and their becoming a part of the actual external skeleton,
reaches its maximum. In several species of _Eriocera_ the male has the
antennae of extraordinary length, four or five times as long as the body,
and, strange to say, this elongation is accompanied by a reduction in the
number of the segments of which the organ is composed, the number being in
the male about six, in the female ten, in place of the usual fourteen or
sixteen. In _Toxorrhina_ and _Elephantomyia_ the proboscis is as long as
the whole body. In other forms the wings become elongated to an unusual
extent by means of a basal stalk. It is probable that the elongation of the
rostrum may be useful to the Insects. Gosse,[386] indeed, describes
_Limnobia intermedia_ as having a rostrum half as long as the body, and as
hovering like a Syrphid, but this is a habit so foreign to Tipulidae, that
we may be pardoned for suspecting a mistake. The larvae exhibit a great
variety of form, some being terrestrial and others aquatic, but the
terrestrial forms seem all to delight in damp situations, such as shaded
turf or rotten tree-stems. They are either amphipneustic or metapneustic,
that is, with a pair of spiracles placed at the posterior extremity of the
body; the aquatic species frequently bear appendages or projections near
these spiracles. The pupae in general structure are very like those of
Lepidoptera, and have the legs extended straight along the body; they
possess a pair of respiratory processes on the thorax in the form of horns
or tubes.
There are more than 1000 species of these flies known, and many genera.
They form three sub-families, which are by some considered distinct
families, viz.: Ptychopterinae, Limnobiinae or Tipulidae Brevipalpi,
Tipulinae or Tipulidae Longipalpi.
The Ptychopterinae are a small group in which the angulate {473}suture of
the mesonotum is indistinct; the larvae are aquatic and have the head free,
the terminal two segments of the body enormously prolonged (Fig. 223),
forming a long tail bearing, in the North American _Bittacomorpha_, two
respiratory filaments. Hart[387] describes this tail as possessing a
stigmatal opening at the extremity; no doubt the structure is a compounded
pair of spiracles. The pupa (Fig. 223, B) has quite lost the respiratory
tube at the posterior extremity of the body, but has instead quite as long
a one at the anterior extremity, due to one tube of the pair normal in
Tipulidae being enormously developed, while its fellow remains small. This
is a most curious departure from the bilateral symmetry that is so
constantly exhibited in Insect-structure. Our British species of
_Ptychoptera_ have the pupal respiratory tube as extraordinary as it is in
_Bittacomorpha_, though the larval tail is less peculiar.[388] This group
should perhaps be distinguished from the Tipulidae as a separate family,
but taxonomists are not yet unanimous as to this. Brauer considers that the
head of the larva, and the condition of five Malpighian tubules in the
imago, require the association of Ptychopterinae with the preceding
families (Chironomidae, etc.), rather than with the Tipulidae.
[Illustration: Fig. 223.—_Bittacomorpha clavipes._ North America x 2/1.
(After Hart.) A, Larva; B, pupa: _l_, the left, _r_, the right respiratory
tube.]
The great majority of the Tipulidae are comprised in the sub-family
Limnobiinae—the Tipulidae Brevipalpi of Osten Sacken:[389] in them the last
joint of the palpi is shorter or not much longer than the two preceding
together. They exhibit great variety, and many of them are types of
fragility. The common winter gnats of the genus _Trichocera_ are a fair
sample of this sub-family. The species of this genus mostly inhabit high
latitudes, and delight in {474}a low temperature; it has been said that
they may be seen on the wing in the depth of winter when the temperature is
below freezing, but it is pretty certain that the spots chosen by the
Insects are above that temperature, and Eaton states that the usual
temperature during their evolutions is about 40° or 45° Fahr. They often
appear in the damp conditions of a thaw when much snow is on the ground.
_T. simonyi_ was found at an elevation of 9000 feet in the Tyrol, crawling
at a temperature below the freezing-point, when the ground was deeply
covered with snow. _T. regelationis_ occurs commonly in mines even when
they are 500 feet or more deep. The most extraordinary of the Limnobiinae
is the genus _Chionea_, the species of which are totally destitute of wings
and require a low temperature. _C. araneoides_ inhabits parts of northern
Europe, but descends as far south as the mountains near Vienna; it is
usually said to be only really active in the depth of winter and on the
surface of the snow. More recently, however, a large number of specimens
were found by Professor Thomas in the month of October in his garden in
Thuringia; they were caught in little pit-falls constructed to entrap
snails. The larva of this Insect is one of the interesting forms that
display the transition from a condition with spiracles at the sides of the
body to one where there is only a pair at the posterior extremity.
A very peculiar Fly, in which the wings are reduced to mere slips,
_Halirytus amphibius_, was discovered by Eaton in Kerguelen Land, where it
is habitually covered by the rising tide. Though placed in Tipulidae, it is
probably a Chironomid.
The group Cylindrotomina is considered by Osten Sacken[390] to be to some
extent a primitive one having relationship with the Tipulinae; it was, he
says, represented by numerous species in North America during the Oligocene
period. It is of great interest on account of the larvae, which are in
several respects similar to caterpillars of Lepidoptera. The larva of
_Cylindrotoma distincta_ lives upon the leaves of plants—_Anemone_,
_Viola_, _Stellaria_—almost like a caterpillar; it is green with a crest
along the back consisting of a row of fleshy processes. Though this fly is
found in Britain the larva has apparently not been observed here. The
life-history of _Phalacrocera replicata_ has been recently published by
Miall and Shelford.[391] The larva eats {475}submerged mosses in the South
of England, and bears long forked filaments, reminding one of those of
caterpillars. This species has been simultaneously discussed by Bengtsson,
who apparently regards these Tipulids with caterpillar-like larvae—he calls
them Erucaeformia[392]—as the most primitive form of existing Diptera.
The Tipulinae—Tipulidae Longipalpi, Osten Sacken[393]—have the terminal
joint of the palpi remarkably long, longer than the three preceding joints
together. The group includes the largest forms, and the true
daddy-long-legs, a Chinese species of which, _Tipula brobdignagia_,
measures four inches across the expanded wings. The group contains some of
the finest Diptera. Some of the exotic forms allied to _Ctenophora_ have
the wings coloured in the same manner as they are in certain Hymenoptera,
and bear a considerable resemblance to members of that Order.
[Illustration: Fig. 224—Head of _Bibio_. × 10. A, Of male, seen from the
front; C, from the side; _a_, upper, _b_, lower eye; B, head of female.]
FAM. 10. BIBIONIDAE.—_Flies of moderate or small size, sometimes of
different colours in the two sexes, with short, thick, straight, antennae;
front tibiae usually with a long pointed process; coxae not elongate. Eyes
of male large, united, or contiguous in front._ The flies of the genus
_Bibio_ usually appear in England in the spring, and are frequently very
abundant; they are of sluggish habits and poor performers on the wing.
{476}[Illustration: Fig. 225—Larva of _Bibio_ sp. Cambridge. × 5.]
The difference in colour of the sexes is very remarkable, red or yellow
predominating in the female, intense black in the male; and it is a curious
fact that the same sexual distinction of colour reappears in various parts
of the world—England, America, India, and New Zealand; moreover, this
occurs in genera that are by no means closely allied, although allied
species frequently have concolorous sexes. The eyes of the males are well
worth study, there being a very large upper portion, and, abruptly
separated from this, a smaller, differently faceted lower portion,
practically a separate eye; though so largely developed the upper eye is in
some cases so hairy that it must greatly interfere with the formation of a
continuous picture. Carrière considers that the small lower eye of the male
corresponds to the whole eye of the female. The larvae of _Bibio_ (Fig.
225) are caterpillar-like in form, have a horny head, well developed,
biting mouth-organs, and spine-like processes on the body-segments. They
are certified by good authorities[394] to possess the extremely unusual
number of ten pairs of spiracles; a larva found at Cambridge, which we
refer to _Bibio_ (Fig. 225) has nine pairs of moderate spiracles, as well
as a large terminal pair separated from the others by a segment without
spiracles. The genus _Dilophus_ is closely allied to _Bibio_, the larvae of
which (and those of Bibionidae in general) are believed to feed on
vegetable substances; the parasitism of _Dilophus vulgaris_ on the larva of
a moth, _Epinotia_ (_Chaetoptria_) _hypericana_, as recorded by Meade,[395]
must therefore be an exceptional case. In the genus _Scatopse_ there is a
very important point to be cleared up as to the larval respiratory system;
it is said by Dufour and Perris[396] to be amphipneustic; there are,
however, nine projections on each side of the body that were considered by
Bouché, and probably with good reason, to {477}be spiracles. The food of
_Scatopse_ in the larval state is principally vegetable. The larva of
_Scatopse_ changes to a pupa inside the larval skin; the pupa is provided
on the thorax with two branched respiratory processes that project outside
the larval skin.[397] Lucas has given an interesting account of the
occurrence of the larva of _Bibio marci_ in enormous numbers at Paris; they
lived together in masses, there being apparently some sort of connection
between the individuals.[398] In the following year the fly was almost
equally abundant.
[Illustration: Fig. 226—Portion of integument of _Bibio_ sp. Cambridge.
_p_, Intersegmental processes; _s_, spiracle.]
Owing to the great numbers in which the species of Bibionidae sometimes
appear, these Insects have been supposed to be very injurious. Careful
inquiry has, however, generally exculpated them as doers of any serious
injury, though _Dilophus febrilis_—a so-called fever-fly—appears to be
really injurious in this country when it multiplies excessively, by eating
the roots of the hop-plant.
FAM. 11. SIMULIIDAE (_Sand-flies_, _Buffalo-gnats_).—_Small obese flies
with humped back, rather short legs and broad wings, with short, straight
antennae destitute of setae; proboscis not projecting._ There is only one
genus, _Simulium_, of this family, but it is very widely spread, and will
probably prove to be nearly cosmopolitan. Some of the species are notorious
from their blood-sucking habits, and in certain seasons multiply to an
enormous extent, alight in thousands on cattle, and induce a disease that
produces death in a few hours; it is thought as the result of an instilled
poison. _S. columbaczense_ has occasioned great losses amongst the herds
near the Danube; in North America the Buffalo- and Turkey-gnats attack a
variety of mammals and birds. In Britain {478}and other parts of the world
they do not increase in numbers to an extent sufficient to render them
seriously injurious: their bite is however very annoying and irritating to
ourselves. In their early stages they are aquatic and require well aërated
waters: the larvae hold themselves erect, fixed to a stone or some other
object by the posterior extremity, and have on the head some beautiful
fringes which are agitated in order to bring food within reach; the pupae
are still more remarkable, each one being placed in a pouch or sort of
watch-pocket, from which projects the upper part of the body provided with
a pair of filamentous respiratory processes. For an account of the
interesting circumstances connected with the metamorphoses of this species
the reader should refer to Professor Miall's book; and for the life-history
of the American Buffalo-gnat to Riley.[399]
FAM. 12. RHYPHIDAE.—This is another of the families that have only two or
three genera, and yet are very widely distributed. These little flies are
distinguished from other Nemocera Anomala (cf. p. 456) by _the presence of
a discal cell; the empodia of the feet are developed as if they were
pulvilli, while the true pulvilli remain rudimentary_. The larvae are like
little worms, being long and cylindric; they are amphipneustic, and have
been found in decaying wood, in cow-dung, in rotten fruits, and even in
dirty water. The "petite tipule," the metamorphoses of which were described
and figured by Réaumur, is believed to be the common _Rhyphus
fenestralis_.[400] _R. fenestralis_ is often found on windows, as its name
implies.
SERIES 2. ORTHORRHAPHA BRACHYCERA
FAM. 13. STRATIOMYIDAE.—_Antennae with three segments and a terminal
complex of obscure joints, frequently bearing an arista: tibiae not spined;
wings rather small, the anterior nervures usually much more strongly marked
than those behind. The median cell small, placed near to the middle of the
wing. Scutellum frequently spined; terminal appendages of the tarsi small,
but pulvilli and a pulvilliform empodium are {479}present._ This is a large
family, whose members are very diversified, consequently definition of the
whole is difficult. The species of the typical sub-family Stratiomyinae
generally have the margins of the body prettily marked with green or
yellow, and the scutellum spined. In the remarkable American genus,
_Hermetia_, the abdomen is much constricted at the base, and the scutellum
is not spined; in the division Sarginae the body is frequently of brilliant
metallic colours. The species all have an only imperfect proboscis, and are
not blood-suckers. The larvae are also of diverse habits; many of those of
the Stratiomyinae are aquatic, and are noted for their capacity of living
in salt, alkaline, or even very hot water. Mr. J. C. Hamon found some of
these larvae in a hot spring in Wyoming, where he could not keep his hand
immersed, and he estimated the temperature at only 20° or 30° Fahr. below
the boiling-point. The larva of _Stratiomys_ is of remarkably elongate,
strap-like, form, much narrowed behind, with very small head; the terminal
segment is very long and ends in a rosette of hairs which the creature
allows to float at the surface. After the larval skin is shed the pupa,
though free, is contained therein; the skin alters but little in form, and
has no organic connection with the pupa, which merely uses the skin as a
shield or float. These larvae have been very frequently described; they can
live out of the water. Brauer describes the larvae of the family as
"peripneustic, some perhaps amphipneustic." Miall says there are, in
_Stratiomys_, nine pairs of spiracles on the sides of the body which are
not open, though branches from the longitudinal air-tubes pass to them.
There are probably upwards of 1000 species of Stratiomyidae known, and in
Britain we have 40 or 50 kinds. The American genus _Chiromyza_, Wied., was
formerly treated by Osten Sacken as a separate family, Chiromyzidae, but
Williston places it in Stratiomyidae.
FAM. 14. LEPTIDAE, including XYLOPHAGIDAE and COENOMYIIDAE.—_The Leptidae
proper are flies of feeble build; antennae with three joints and a terminal
bristle; in the Xylophagidae the antennae are longer, and the third joint
is complex. The wings have five posterior cells, the middle tibiae are
spined. Pulvilli and a pulvilliform empodium present._ The three families
are considered distinct by most authors, but there has always been much
difficulty about the Xylophagidae and Coenomyiidae, we therefore treat them
as sub-families.
{480}[Illustration: Fig. 227—_Atherix ibis._ A, The fly, nat. size; B, mass
of dead flies overhanging water, much reduced.]
The Xylophaginae are a small group of slender Insects, perhaps most like
the short-bodied kinds of Asilidae; the third joint of the antenna is
vaguely segmented, and there is no terminal bristle. _Rhachicerus_ is a
most anomalous little fly with rather long stiff antennae of an almost
nemocerous character, the segments of which give off a short thick
prolongation on each side, reminding one of a two-edged saw. The three or
four British species of Xylophaginae are forest Insects, the larvae of
which live under bark, and are provided with a spear-like head with which
they pierce other Insects. The Coenomyiinae consist of the one genus
_Coenomyia_, with two or three European and North American species. They
are remarkably thick-bodied, heavy flies, reminding one somewhat of an
imperfect Stratiomyid destitute of ornamentation. The metamorphosis of _C.
ferruginea_ has been described by Beling.[401] The larva is not aquatic,
but lives in burrows or excavations in the earth where there are, or have
recently been, rotten logs; it is probably predaceous. It is cylindric,
with an extremely small head and eleven other segments, the stigma on the
first thoracic segment distinct; the terminal segment is rather broad, and
the structures surrounding the stigma are complex. The pupa has stigmata on
each of abdominal segments 2 to 8. Notwithstanding that the fly is so
different to _Xylophagus_, the larvae indicate the two forms as perhaps
really allied. One of the Leptinae, _Atherix ibis_, has a singular mode of
oviposition (Fig. 227), the females of the species deposit their eggs in
common, and, dying as they do so, add their bodies to the common mass,
which becomes an agglomeration, it may be of thousands of individuals, and
of considerable size. The mass is attached to a branch of a bush or to a
plant overhanging water, into which it {481}ultimately falls. These curious
accumulations are occasionally found in England as well as on the
Continent, but no reason for so peculiar a habit is at present forthcoming.
Still more remarkable are the habits of some European Leptids of the genera
_Vermileo_ (_Psammorycter_ of some authors) and _Lampromyia_, slender
rather small flies of Asilid-like appearance, the larvae of which form
pit-falls after the manner of the Ant-lion. According to Beling[402] the
larva of _Leptis_ is very active, and is distinguished by having the
stigmatic orifice surrounded by four quite equal, quadrangularly placed
prominences; and at the other extremity of the body a blackish, naked,
triangular plate; on the under side of each of seven of the abdominal
segments there is a band of spines. The larva of _Atherix_ has seven pairs
of abdominal feet. Altogether there are some two or three hundred known
species of Leptidae; our British species scarcely reach a score. They are
destitute of biting-powers and are harmless timid creatures. _Leptis
scolopacea_, the most conspicuous of our native species, a soft-bodied fly
of rather large size, the wings much marked with dark colour, and the
thick, pointed body yellowish, marked with a row of large black spots down
the middle, is a common Insect in meadows.
[Illustration: Fig. 228.—Larva of _Vermileo degeeri_ (_Psammorycter
vermileo_). A, lateral, B, dorsal view: _p_, an abdominal pseudopod; _st_,
stigma. Europe. (After Réaumur and Brauer.)]
FAM. 15. TABANIDAE (_Breeze-flies_, _Cleggs_, or _Horse-flies_, also
frequently called _Gad-flies_).—_Proboscis fleshy, distinct, enwrapping
pointed horny processes, palpi distinct, terminal joint inflated, pendent
in front of proboscis. Antennae projecting, four-jointed, second joint very
short, third variable in form, fourth forming an indistinctly segmented
continuation of the third, but not ending in a bristle. A perfect squama in
front of the halter. Eyes large, very large in the males, but laterally
extending, rather than globose._
{482}[Illustration: Fig. 229—_Pangonia longirostris._ x 1. Nepal. (After
Hardwicke.)]
This large and important family of flies, of which Williston states that
1400 or 1500 species are named, is well known to travellers on account of
the blood-sucking habits of its members; they have great powers of flight,
and alight on man and animals, and draw blood by making an incision with
the proboscis; only the females do this, the males wanting a pair of the
lancets that enable the other sex to inflict their formidable wounds. They
are comparatively large Insects, some of our English species of _Tabanus_
attaining an inch in length. The smaller, grey _Haematopota_, is known to
every one who has walked in woods or meadows in the summer, as it alights
quietly on the hands or neck and bites one without his having previously
been made aware of its presence. The larger Tabani hum so much that one
always knows when an individual is near. The species of _Chrysops_, in
habits similar to _Haematopota_, are remarkable for their beautifully
coloured golden-green eyes. In Brazil the Motuca fly, _Hadrus lepidotus_,
Perty, makes so large and deep a cut that considerable bleeding may follow,
and as it sometimes settles in numbers on the body, it is deservedly
feared. The most remarkable forms of Tabanidae are the species of the
widely distributed genus _Pangonia_ (Fig. 229). The proboscis in the
females of some of the species is three or four times the length of the
body, and as it is stiff and needle-like the creature can use it while
hovering on the wing, and will pierce the human body even through clothing
of considerable thickness. The males suck the juices of flowers. The Seroot
fly, that renders some of the districts of Nubia uninhabitable for about
three months of the year, appears, from the figure and description given by
Sir Samuel Baker, to be a _Pangonia_. Tabanidae are a favourite food of the
fossorial wasps of the family Bembecidae. These wasps are apparently aware
of the blood-sucking habits of their favourites, and attend on travellers
and pick up the flies as they are about to settle down to their phlebotomic
operations. The larvae of the Tabanidae are some {483}of them aquatic, but
others live in the earth or in decaying wood; they are of predaceous
habits, attacking and sucking Insect-larvae, or worms. Their form is
cylindric, attenuate at the two extremities; the slender small head is
retractile, and armed with a pair of conspicuous, curved black hooks. The
body is surrounded by several prominent rings. The breathing apparatus is
apparently but little developed, and consists of a small tube at the
extremity of the body, capable of being exserted or withdrawn; in this two
closely approximated stigmata are placed. In a larva, probably of this
family, found by the writer in the shingle of a shallow stream in the New
Forest, the annuli are replaced by seven circles of prominent pseudopods,
on the abdominal segments about eight in each circle, and each of these
feet is surmounted by a crown of small hooks, so that there are fifty or
sixty feet distributed equally over the middle part of the body without
reference to upper or lower surface. The figures of the larva of _T.
cordiger_, by Brauer, and of _Haematopota pluvialis_, by Perris, are
something like this, but have no setae on the pseudopods. The metamorphoses
of several Tabanidae are described and figured by Hart;[403] the pupa is
remarkably like a Lepidopterous pupa. We have five genera and about a score
of species of Tabanidae in Britain.
[Illustration: Fig. 230—Larva of a Tabanid. [? _Atylotus fulvus._] A, the
larva, × 3; B, head; C, end of body; D, one of the pseudopods. New Forest.]
FAM. 16. ACANTHOMERIDAE.—A very small family of two genera (_Acanthomera_
and _Rhaphiorhynchus_) confined to America, and including the largest
Diptera, some being two inches long. The antenna is terminated by a
compound of seven segments and a style; the proboscis is short, and the
squama rudimentary. The general form reminds one of Tabanidae or Oestridae.
A dried larva exists in the Vienna collection; it is amphipneustic, and
very remarkable on account of the great size of the anterior stigma.
{484}FAM. 17. THEREVIDAE.—_Moderate-sized flies, with somewhat the
appearance of short Asilidae. They have, however, only a feeble fleshy
proboscis, and minute claws, with pulvilli but no empodium; the antennae
project, are short, three-jointed, pointed._—The flies of this family are
believed to be predaceous like the Robber-flies, but they appear to be very
feebly organised for such a life. We have about ten species in Britain, and
there are only some 200 known from all the world. But little is known as to
the metamorphoses. Meigen found larvae of _T. nobilitata_ in rotten stumps,
but other larvae have been recorded as devouring dead pupae or larvae of
Lepidoptera. The larvae are said to be elongate, very slender, worm-like,
and to have nineteen body-segments, the posterior pair of spiracles being
placed on what looks like the seventeenth segment, but is really the eighth
of the abdomen. The pupa is not enclosed in the larval skin; that of
_Psilocephala_ is armed with setae and spinous processes, and was found in
rotten wood by Frauenfeld.
[Illustration: Fig. 231—_Thereva (Psilocephala) confinis._ A, Pupa; B,
larva. Europe. (After Perris.)]
FAM. 18. SCENOPINIDAE.—_Rather small flies, without bristles. Antennae
three-jointed, the third joint rather long, without appendage. Proboscis
not projecting. Empodium absent._ These unattractive flies form one of the
smallest families, and are chiefly found on windows. _S. fenestralis_ looks
like a tiny Stratiomyid, with a peculiar, dull, metallic surface. The larva
of this species has been recorded as feeding on a variety of strange
substances, but Osten Sacken is of opinion[404] that it is really
predaceous, and frequents these substances in order to find the larvae that
are developing in them. If so, _Scenopinus_ is useful in a small way by
destroying "moth," etc. The larva is a little slender, cylindrical, hard,
pale worm of nineteen segments, with a small brown head placed like a hook
at one extremity of the body and with two short, divergent processes at the
other extremity, almost exactly like the larva of _Thereva_. Full
references to the literature about this Insect are given by Osten Sacken.
FAM. 19. NEMESTRINIDAE.—These Insects appear to be allied to the
Bombyliidae. _They are of medium size, often pilose, and {485}sometimes
with excessively long proboscis; antennae short, with a simple third joint,
and a jointed, slender, terminal appendage; the tibiae have no spurs, the
empodium is pulvillus-like. The wing-nervuration is perhaps the most
complex found in Diptera, there being numerous cells at the tip, almost
after the fashion of Neuroptera._ With this family we commence the aerial
forms composing the Tromoptera of Osten Sacken. Nemestrinidae is a small
family of about 100 species, but widely distributed. _Megistorhynchus
longirostris_ is about two-thirds of an inch long, but has a proboscis at
least four times as long as itself. In South Africa it may be seen
endeavouring to extract, with this proboscis, the honey from the flower of
a _Gladiolus_ that has a perianth just as long as its own rostrum; as it
attempts to do this when it is hovering on the wing, and as the proboscis
is, unlike that of the Bombylii, fixed, the Insect can only succeed by
controlling its movements with perfect accuracy; hence it has great
difficulty in attaining its purpose, especially when there is much wind,
when it frequently strikes the earth instead of the flower. M. Westermann
thinks[405] the life of the Insect and the appearance and duration of the
flower of the _Gladiolus_ are very closely connected. The life-history of
_Hirmoneura obscura_ has recently been studied in Austria by Handlirsch and
Brauer.[406] The larva is parasitic on the larva of a Lamellicorn beetle
(_Rhizotrogus solstitialis_); it is metapneustic, and the head is highly
modified for predaceous purposes. The young larva apparently differs to a
considerable extent from the matured form. The most curious fact is that
the parent fly does not oviposit near the Lamellicorn-larva, but places her
eggs in the burrows of some wood-boring Insect in logs; the larvae when
hatched come to the surface of the log, hold themselves up on their hinder
extremity and are carried away by the wind; in what manner they come into
contact with the Lamellicorn larva, which feeds in turf, is unknown. The
pupa is remarkable on account of the prominent, almost stalked stigmata,
and of two pointed divergent processes at the extremity of the body. This
life-history is of much interest, as it foreshadows to some extent the
complex parasitic life-histories of Bombyliidae. The Nemestrinidae are not
represented in the British fauna.
{486}[Illustration: Fig. 232—_Argyromoeba trifasciata._ A, Young larva; B,
adult larva; C, pupa. France. (After Fabre.) A, Greatly, B, C, slightly
magnified.]
FAM. 20. BOMBYLIIDAE.—_Body frequently fringed with down, or covered in
large part with hair. Legs slender, claws small, without distinct empodium,
usually with only minute pulvilli. Proboscis very long or moderate,
antennae three-jointed, terminal joint not distinctly divided, sometimes
large, sometimes hair-like._ This is a very large family, including 1500
species, and is of great importance to both naturalist and economist. Two
well-marked types, formerly treated as distinct families, are included in
it—(1) the Bombyliides with very long exserted rostrum, and humped thorax;
and (2) Anthracides, with a short beak, and of more slender and graceful
form. None of these flies are bloodsuckers, they frequent flowers only, and
use their long rostrums in a harmless manner. The members of both of these
groups usually have the wings ornamented with a pattern, which in _Anthrax_
is frequently very remarkable; in both, the clothing of the body is
frequently variegated. Their powers of flight are very great, and the
hovering _Bombylius_ of early spring is endowed with an unsurpassed
capacity for movement, remaining perfectly still on the wing, and darting
off with lightning rapidity; _Anthrax_ is also most rapid on the wing. In
Britain we have but few species of Bombyliidae, but in warm and dry
climates they are very numerous. The life-history of these Insects was till
recently unknown, but that of _Argyromoeba_ (_Anthrax_) _trifasciata_ has
been described by the French naturalist, Fabre, who ascertained that the
species is parasitic on the Mason-bee, _Chalicodoma muraria_, that forms
nests of solid masonry. He endeavoured to discover the egg, but failed; the
parent-fly oviposits, it appears, by merely dropping a minute egg while
flying over the surface of the mass of masonry by which the grubs of the
_Chalicodoma_ are protected. From this egg there is hatched a minute
delicate vermiform larva (Fig. 232, A). In order to obtain its food, it is
necessary for this feeble creature to penetrate the masonry; apparently a
hopeless task, the animal {487}being scarcely a twentieth of an inch long
and very slender; it is, however, provided with a deflexed horny head,
armed in front with some stiff bristles, while on the under surface of the
body there are four pairs of elongate setae serving as organs of
locomotion; thus endowed, the frail creature hunts about the surface of the
masonry, seeking to find an entrance; frequently it is a long time before
it is successful; but though it has never taken any food it is possessed of
great powers of endurance. Usually, after being disclosed from the egg, it
remains about fifteen days without stirring; and even after it commences
its attempts to enter the nest it is still capable of a long life without
taking any food. Possibly its organisation will not permit it to feed
(supposing any food were obtainable by it) without its growing somewhat
thereafter, and if so, its chance of obtaining entrance through the masonry
would be diminished. Abstention, it would appear, is the best policy,
whether inevitable or not; so the starving little larva continues its
endeavours to find a chink of entrance to the food contained in the
interior of the masonry. It has plenty of time for this, because it is
better for it not to get into the cell of the bee until the grub is quite
full grown, and is about to assume the pupal form, when it is quite
incapable of self-defence. Finally, after greater or less delay, the
persevering little larva succeeds in finding some tiny gap in the masonry
through which it can force itself. M. Fabre says that the root of a plant
is not more persistent in descending into the soil that is to support it
than is this little _Anthrax_ in insinuating itself through some crack that
may admit it to its food. Having once effected an entrance the organisation
that has enabled it to do so is useless; this primary form of the larva
has, in fact, as its sole object to enable the creature to penetrate to its
food. Having penetrated, it undergoes a complete change of form, and
appears as a creature specially fitted for feeding on the quiescent larva
of the bee without destroying it. To accomplish this requires an extreme
delicacy of organisation and instinct; to bite the prey would be to kill
it, and if this were done, the _Anthrax_ would, Fabre supposes, ensure its
own death, for it cannot feed on the dead and putrefying grub; accordingly,
the part of its body that does duty as a mouth is merely a delicate sucker
which it applies to the skin of the _Chalicodoma_-grub; and thus without
inflicting any perceptible wound it sucks day {488}after day, changing its
position frequently, until it has completely emptied the pupa of its
contents, nothing being left but the skin. Although this is accomplished
without any wound being inflicted, so effectual is the process that all the
_Chalicodoma_ is gradually absorbed. The time requisite for completely
emptying the victim is from twelve to fifteen days; at the end of this time
the _Anthrax_-larva is full grown, and the question arises, how is it to
escape from the cell of solid masonry in which it is imprisoned? It entered
this cell as a tiny, slender worm through a minute orifice or crack, but it
has now much increased in size, and exit for a creature of its organisation
is not possible. For some months it remains a quiescent larva in the cell
of the _Chalicodoma_, but in the spring of the succeeding year it undergoes
another metamorphosis, and appears as a pupa provided with a formidable
apparatus for breaking down the masonry by which it is imprisoned. The head
is large and covered in front with six hard spines, to be used in striking
and piercing the masonry, while the other extremity of the body bears some
curious horns, the middle segments being armed with rigid hairs directed
backwards, and thus facilitating movement in a forward direction and
preventing slipping backwards. The pupa is strongly curved, and fixes
itself by the aid of the posterior spines; then, unbending itself, it
strikes with the armour of the other extremity against the opposing wall,
which is thus destroyed piecemeal until a gallery of exit is formed; when
this is completed the pupa-skin bursts and the perfect fly emerges, leaving
the pupa-case still fixed in the gallery. Thus this species appears in four
consecutive forms—in addition to the egg—each of which is highly
specialised for the purposes of existence in that stage.
The habits of our British _Bombylius major_ have been partially observed by
Dr. Chapman,[407] and exhibit a close analogy with those of _Anthrax
trifasciata_. The bee-larva that served as food was in this case _Andrena
labialis_, and the egg was deposited by the fly, when hovering, by jerking
it against the bank in which the nest of the bee was placed.
It has recently been discovered that the larvae of various species of
Bombyliidae are of great service by devouring the eggs of locusts. Riley
found that the egg-cases of _Caloptenus {489}spretus_ are emptied of their
contents by the larvae of _Systoechus oreas_ and _Triodites mus_. A similar
observation has been made in the Troad by Mr. Calvert, who found that the
Bombyliid, _Callostoma fascipennis_, destroys large quantities of the eggs
of _Caloptenus italicus_. Still more recently M. Künckel d'Herculais has
discovered that the destructive locust _Stauronotus maroccanus_ is kept in
check in Algeria in a similar manner, as many as 80 per cent of the eggs of
the locust being thus destroyed in certain localities. He observes that the
larva of the fly, after being full fed in the autumn, passes the winter in
a state of lethargy—he calls it "hypnody"—in the egg-case of the locust,
and he further informs us that in the case of _Anthrax fenestralis_, which
devours the eggs of the large _Ocnerodes_, the lethargy may be prolonged
for a period of three years. After the pupa is formed it works a way out of
the case by means of its armature, and then again becomes for some days
immobile before the perfect fly appears. Lepidopterous larvae are also
attacked by Bombyliid flies. A species of _Systropus_ has been recorded as
destroying the larva of _Limacodes_. Several of the Bombyliids of the genus
just mentioned are remarkable for the great resemblance they display to
various Hymenoptera, some of them being very slender flies, like the thin
bodied fossorial Hymenoptera. The difference between the pupa and imago in
this case is very remarkable (Fig. 233).
[Illustration: Fig. 233—_Systropus crudelis._ South Africa. A, Pupa; B,
imago, appendages of the left side removed. (After Westwood.)]
FAM. 21. ACROCERIDAE or CYRTIDAE.—_Flies of the average size, of peculiar
form, the small head consisting almost entirely of the eyes, and bent down
under the humped thorax: wings small, halteres entirely concealed by the
very large horizontal squamae; antennae very diverse._ The peculiar shape
of these flies is an exaggeration of that we have already noticed in
_Bombylius_. The mouth in Acroceridae is very variable; there may be a very
long, slender proboscis (_Acrocera_), or the mouth-parts may be so
atrophied that it is doubtful whether even an orifice exists (_Ogcodes_).
There are but {490}few species known, and all of them are rare;[408] in
Britain we have but two (_Ogcodes gibbosus_, _Acrocera globulus_). The
genus _Pterodontia_, found in North America and Australia, an inflated
bladder-like form with a minute head, is amongst the most extraordinary of
all the forms of Diptera. The habits are very peculiar, the larvae, so far
as known, all living as parasites within the bodies of spiders or in their
egg-bags. It appears, however, that the flies do not oviposit in
appropriate places, but place their eggs on stems of plants, and the young
larvae have to find their way to the spiders. Brauer has described the
larva of the European _Astomella lindeni_,[409] which lives in the body of
a spider, _Cteniza ariana_; it is amphipneustic and maggot-like, the head
being extremely small. The larva leaves the body of the spider for
pupation; the pupa is much arched, and the head is destitute of the
peculiar armature of the Bombyliidae, but has a serrate ridge on the
thorax. Emerton found the larvae of an _Acrocera_ in the webs of a common
North American spider, _Amaurobius sylvestris_, they having eaten, it was
supposed, the makers of the cobwebs.
[Illustration: Fig. 234—_Megalybus gracilis._ × 4. (Acroceridae.) Chili.
(After Westwood.)]
FAM. 22. LONCHOPTERIDAE.—_Small, slender flies, with pointed wings, short,
porrect antennae, with a simple, circular third joint, bearing a bristle;
empodium very small, pulvilli absent._—Only one genus of these little flies
is known, but it is apparently widely distributed, and its members are
common Insects. They have the appearance of Acalyptrate Muscidae, and the
nervuration of the wing is somewhat similar, the nervures being simple and
parallel, and the minute cross-nervures placed near the base. The
systematic position is somewhat doubtful, and the metamorphoses are but
incompletely known, very little having been added to what was discovered by
Sir John Lubbock in 1862.[410] The larva lives on the earth under vegetable
matter; it is very transparent, amphipneustic, with a peculiar head, and
with fringes on the margins. This larva changes to a semi-pupa or apterous
maggot-like form, within the larval skin; the true pupa was {491}not
noticed by Lubbock, but Frauenfeld[411] has since observed it, though he
only mentions that it possesses differentiated limbs and segments. The
metamorphoses appear to be very peculiar. This fly requires a thorough
study.
FAM. 23. MYDAIDAE.—_Large flies of elongate form; the hind femora long and
toothed beneath; the antennae knobbed at the tip, projecting, rather long,
the basal joint definite, but the divisions of the subsequent joints more
or less indistinct. Empodium small. Wings frequently heavily pigmented;
with a complex nervuration._ These fine flies are exotic; a few species
occur in the Mediterranean region, even in the South of Europe; the chief
genus, _Mydas_, is South American, but most of the other genera are
Australian or African. But little is known as to the life-histories. The
larvae are thought to live in wood, and to prey on Coleopterous larvae.
FAM. 24. ASILIDAE (_Robber-flies_).—_Mouth forming a short, projecting
horny beak, the palpi usually only small; the feet generally largely
developed; the claws large, frequently thick and blunt, the pulvilli
generally elongate, the empodium a bristle; halteres free; no squama._ The
Asilidae is one of the largest families of flies, and probably includes
about 3000 described species: as will readily be believed, there is much
variety of form; some are short and thick and extremely hairy,
superficially resembling hairy bees, but the majority are more or less
elongate, the abdomen being specially long, and having eight segments
conspicuously displayed. The antennae are variable, but are three-jointed
with a terminal appendage of diverse form and structure. They belong to the
super-family Energopoda of Osten Sacken, but the association of Empidae and
Dolichopidae with them does not seem to be very natural. In their perfect
state these flies are most voracious, their prey being Insects, which they
seize alive and impale with the rostrum. They are amongst the most
formidable of foes and fear nothing, wasps or other stinging Insects being
attacked and mastered by the stronger species without difficulty. They have
been observed to capture even dragon-flies and tiger-beetles. As is the
case with so many other Insects that prey on living Insects, the appetite
in the Asilidae seems to be insatiable; a single individual has been
observed to kill eight moths in twenty minutes. They have {492}been said to
suck blood from Vertebrates, but this appears to be erroneous. The
metamorphoses of a few species have been observed. Perris has called
attention to the close alliance between the larvae of Tabanidae and of
Asilidae,[412] and it seems at present impossible to draw a line of
distinction between the two. So far as is known, the larvae of Asilidae are
terrestrial and predaceous, attacking more particularly the larvae of
Coleoptera, into which they sometimes bore; in _Laphria_ there are numerous
pseudopods, somewhat of the kind shown in Fig. 230, but less perfect and
without hairs; the head and breathing organs appear to be very different.
According to Beling's descriptions of the larvae of _Asilus_, the head in
this case is more like that of the figure, but there are no pseudopods. The
flies of Asilidae and Tabanidae are so very distinct that these
resemblances between their larvae are worthy of note.
FAM. 25. APIOCERIDAE.—_Moderate-sized flies marked with black and white,
with an appearance like that of some Muscidae and Asilidae; with clear
wings, the veins not deeply coloured; antennae short, with a short, simple
appendage; no empodium._ But little is known as to the flies of this
family, of which only two genera, consisting of about a dozen species, are
found in North America, Chili, and Australia. Osten Sacken is inclined to
treat them as an aberrant division of Asilidae. Brauer looks on them as
primitive or synthetic forms of much interest, and has briefly described a
larva which he considers may be that of _Apiocera_, but this is doubtful;
it is a twenty-segmented form, and may be that of a _Thereva_.[413]
FAM. 26. EMPIDAE.—_Small or moderate-sized flies of obscure colours, grey,
rusty, or black, with small head, somewhat globular in form, with
three-jointed antennae, the terminal joint long and pointed; usually there
is a long slender beak; the legs are elongate, frequently hairy; the tarsi
bear long pulvilli and a small empodium._ The Empidae are an extensive
family of flies, with predaceous habits, the rostrum being used by the
female as an instrument for impaling and sucking other flies. They are
occasionally very numerous in individuals, especially in wooded districts.
There is great variety; there are nearly 200 species in Britain. The forms
placed in the sub-family Hybotinae are curious slender little Insects, with
very convex thorax and {493}large hind legs. In _Hemerodromia_ the front
legs are raptorial, the femora being armed with spines on which the tibiae
close so as to form a sort of trap. Many Empidae execute aërial dances, and
some of the species of the genus _Hilara_ are notorious for carrying veils
or nets in the form of silken webs more or less densely woven. This subject
is comparatively new, the fact having been discovered by Baron Osten Sacken
in 1877,[414] and it is not at all clear what purpose these peculiar
constructions serve; it appears probable that they are carried by means of
the hind legs, and only by the males. Mik thinks that in _H. sartor_ the
veil acts as a sort of parachute, and is of use in carrying on the aërial
performance, or enhancing its effect; while in the case of other species,
_H. maura_ and _H. interstincta_, the object appears to be the capture or
retention of prey, after the manner of spiders. The source of the silk is
not known, and in fact all the details are insufficiently ascertained. The
larvae of Empidae are described as cylindrical maggots, with very small
head, and imperfect ventral feet; the stigmata are amphipneustic, the
thoracic pair being, however, excessively small; beneath the posterior pair
there is nearly always a tooth- or spine-like prominence present.
[Illustration: Fig. 235—A, Larva, B, pupa of _Medeterus ambiguus_. France.
(After Perris.)]
FAM. 27. DOLICHOPIDAE.—_Graceful flies of metallic colours, of moderate or
small size, and long legs; usually with bristles on the thorax and legs,
the halteres exposed, squamae being quite absent; antennae of two short
stout joints (of which the second is really two, its division being more or
less distinct), with a thread-like or hair-like appendage. Proboscis short,
fleshy. Claws, pulvilli, and empodium small; wings with a simple system of
nervures, those on the posterior part of the wing are but few, there is no
anterior basal cross-vein between the discal and second basal cells, which
therefore form but one cell._ This is also a very extensive family of
flies, of which we have probably about 200 species in Britain. They are
conspicuous on account of their golden, or golden-green colours, only a few
being yellow or black. {494}The males are remarkable for the curious
special characters they possess on the feet, antennae, face, or wings.
These characters are not alike in any two species; they are believed to be
of the nature of ornaments, and according to Professor Aldrich and others
are used as such in courtship.[415] This family of flies approaches very
closely to some of the Acalyptrate Muscidae in its characters. It is united
by Brauer with Empidae to form the tribe Orthogenya. Although the species
are so numerous and abundant in Europe, little is known as to their
metamorphoses. Some of the larvae frequent trees, living under the bark or
in the overflowing sap, and are believed to be carnivorous; they are
amphipneustic; a cocoon is formed, and the pupa is remarkable on account of
the existence of two long horns, bearing the spiracles, on the back of the
thorax; the seven pairs of abdominal spiracles being excessively
minute.[416]
[Illustration: Fig. 236—Wing of _Trineura aterrima_, one of the Phoridae.
Britain.]
SERIES 3. CYCLORRHAPHA ASCHIZA
FAM. 28. PHORIDAE.—_Small flies, with very convex thorax, small head, very
small two-jointed antennae, bearing a long seta; femora more or less broad;
wings with two dark, thick, approximate veins, meeting on the front margin
near its middle, and besides these, three or four very fine veins, that run
to the margins in a sub-parallel manner without forming any cells or
forks._ This obscure family of flies is of small extent, but its members
are extremely common in Europe and North America, where they often occur in
numbers running on the windows of houses. It is one of the most isolated
groups of Diptera, and great difference of opinion prevails as to its
classification. The wing-nervuration is peculiar (but varies somewhat in
the species), the total absence of any cross-veins even on the basal part
of the wing being remarkable. There are bristles on the head and thorax,
but they are not arranged in a regular manner. The larvae live in a great
variety of animal and vegetable decaying matter, {495}and attack living
Insects, and even snails, though probably only when these are in a sickly
or diseased condition. The metamorphoses of several species have been
described.[417] The larvae are rather slender, but sub-conical in form,
with eleven segments and a very small head, amphipneustic, the body behind
terminated by some pointed processes. The pupa is remarkable; it is
contained in a case formed by the contracted and hardened skin of the
larva; though it differs much in form from the larva the segmentation is
distinct, and from the fourth segment there project two slender processes.
These are breathing organs, attached to the prothorax of the imprisoned
pupa; in what manner they effect a passage through the hardened larval skin
is by no means clear. Perris supposes that holes for them pre-exist in the
larval skin, and that the newly-formed pupa by restless movements succeeds
in bringing the processes into such a position that they can pass through
the holes. The dehiscence of the puparium seems to occur in a somewhat
irregular manner, as in _Microdon_; it is never Cyclorrhaphous, and
according to Perris is occasionally Orthorrhaphous; probably there is no
ptilinum.
[Illustration: Fig. 237—_Aenigmatias blattoides._ × 27. Denmark. (After
Meinert.)]
The Insect recently described by Meinert as _Aenigmatias blattoides_,[418]
is so anomalous, and so little is known about it, that it cannot at present
be classified. It is completely apterous; the arrangement of the
body-segments is unlike that of Diptera, but the antennae and mouth-parts
are said to be like those of Phoridae. The Insect was found near Copenhagen
under a stone in the runs of _Formica fusca_. Meinert thinks it possible
that the discovery of the male may prove _Aenigmatias_ to be really allied
to Phoridae, and Mik suggests that it may be the same as _Platyphora
lubbocki_, Verrall, known to be parasitic on ants. Dahl recently described
a wingless Dipteron, found living as a parasite on land-snails in the
Bismarck archipelago, under the name of _Puliciphora lucifera_, {496}and
Wandolleck has recently made for this and some allies the new family
Stethopathidae. It seems doubtful whether these forms are more than
wingless Phoridae.
FAM. 29. PLATYPEZIDAE.—_Small flies, with porrect three-jointed antennae,
first two joints short, third longer, with a terminal seta; no bristles on
the back; hind legs of male, or of both sexes, with peculiar, broad, flat
tarsi; the middle tibiae bear spurs; there is no empodium._ Platypezidae is
a small family of flies, the classification of which has always been a
matter of considerable difficulty, and is still uncertain. The larvae are
broad and flat, fringed at the margin with twenty-six spines; they live
between the lamellae of Agaric fungi. At pupation the form alters but
little; the imago emerges by a horizontal cleft occurring at the margins of
segments two and four.[419] We have four genera (_Opetia_, _Platycnema_,
_Platypeza_, _Callomyia_), and nearly a score of species of Platypezidae in
our British list, but very little seems to be known about them. There is
much difference in the eyes of the sexes, in some at any rate of the
species, they being large and contiguous in the male, but widely separated
in the female.
[Illustration: Fig. 238—Head of _Pipunculus_ sp. A, Seen from in front; B,
side view, showing an antenna magnified. Pyrenees.]
FAM. 30. PIPUNCULIDAE.[420]—_Small flies, with very short antennae bearing
a long seta that is not terminal; head almost globular, formed, except at
the back, almost entirely by the large conjoined eyes; the head is only
slightly smaller in the female, but in the male the eyes are more
approximate at the top._ This is another of the small families of flies,
that seems distinct from any other, though possessing no very important
characters. In many of the flies that have very large eyes, the head is
either flattened (_i.e._ compressed from before backwards, as in Tabanidae,
Asilidae), or forced beneath the humped thorax (as in Acroceridae), but
neither of these conditions exists in _Pipunculus_; in them the head
extends far forwards, so that the area of the {497}eye compared with the
size of the body is perhaps greater than in any other Diptera. The general
form is somewhat that of _Anthrax_, but the venation on the hind part of
the wing is much less complex. There is a remarkable difference between the
facets on the front and the back of these great eyes. We have three genera
and about a dozen species of Pipunculidae in Britain but apparently they
are far from common Insects. What is known about the life-history is almost
confined to an imperfect observation by Boheman, who found the larva of _P.
fuscipes_ living after the manner of a Hymenopterous parasite in the body
of a small Homopterous Insect.[421] The pupa seems to be of the type of
that of Syrphidae.
FAM. 31. CONOPIDAE.—_Elegant flies of moderate size, of varied colours,
with abdomen slender at the base, at the tip strongly incurved and thicker;
antennae inserted close together on a prominence, three-jointed, first
joint sometimes very short. The upper surface of the body without bristles
or with but few. There is a slender, elongate proboscis, which is
retractile and usually invisible._ This rather small family of flies
includes some of the most remarkable forms of Diptera; it includes two
divisions, the Conopinae with long antennae terminated by a very minute
pointed process, and Myopinae with shorter antennae bearing a hair that is
not placed at the end of the third joint. The former are the more wasp-like
and elegant; the Myopinae being much more like ordinary flies, though they
frequently have curious, inflated heads, with a white face. The mode of
life of the larva of _Conops_ is peculiar, it being parasitic in the
interior of _Bombus_, or other Hymenoptera. They have been found to attack
_Bombus_, _Chalicodoma_, _Osmia_, _Vespa_, _Pompilus_, and other Aculeates.
Williston says that Orthoptera are also attacked. _Conops_ has been seen to
follow Bumble-bees and alight on them, and Williston says this act is
accompanied by oviposition, the larva that is hatched boring its way into
the body of the bee. Others have supposed that the flies enter the bees'
nests and place their eggs in the larvae or pupae; but this is uncertain,
for _Conops_ has never been reared from a bee-larva or pupa, though it has
frequently been procured from the imago: cases indeed having been recorded
in which _Conops_ has emerged from the body {498}of a _Bombus_ several
months after the latter had been killed and placed in an entomologist's
collection. The larva is broad, and when full grown apparently occupies
nearly all the space of the interior of the abdomen of the bee; it has very
peculiar terminal stigmata. The pupa is formed in the larval skin, which is
greatly shortened and indurated for the purpose; this instar bears, in
addition to the posterior stigmata, a pair of slightly projecting, anterior
stigmata. We have several species of Conopidae in Britain; those belonging
to the division Conopinae are all rare Insects, but the Myopinae are not so
scarce; these latter are believed to be of similar habits with the
Conopinae, though remarkably little is known about them. This is another of
the numerous families, the relations of which are still a subject for
elucidation. Brauer places the Conopidae in his section Schizophora away
from Syrphidae, but we do not comprehend on what grounds; an inspection of
the head shows that there is no frontal lunule as there is in Eumyiidae;
both _Myopa_ and _Conops_ agreeing fairly well with _Syrphus_ as to this.
We therefore place the family in its old position near _Syrphus_ till the
relations with Acalypterate Muscidae shall be better established.
FAM. 32. SYRPHIDAE (_Hover-flies_).—_Of moderate or rather large size,
frequently spotted or banded with yellow, with a thick fleshy proboscis
capable of being withdrawn into a cleft on the under side of the head;
antennae not placed in definite cavities, three-jointed (usually very
short), and leaving a seta that is not terminal in position, and may be
feathered. Squama variable, never entirely covering the halteres; the chief
(third to fifth) longitudinal veins of the wings connected near their
termination by cross-veins and usually thus forming a sort of short margin
parallel with the hind edge of the wing; a more or less imperfect false
nervure running between the third and fourth longitudinal nervures; no
empodium and generally no distinct system of bristles on the back of the
body._ The Syrphidae (Fig. 212) form one of the largest and best known of
all the families of flies; they abound in our gardens where, in sunny
weather, some species may be nearly always seen hovering over flowers, or
beneath trees in places where the rays of the sun penetrate amidst the
shade. There are two or three thousand species known, so that of course
much variety exists; some are densely covered with hair (certain
_Volucella_ and others), many are of elegant form, and some bear a
{499}considerable resemblance to Hymenoptera of various groups. The
peculiar veining of the wings permits of their easy identification, the
line of two nervules, approximately parallel with the margin of the distal
part of the wing (Fig. 212, D), and followed by a deep bay, being eminently
characteristic, though there are some exceptions; there are a few forms in
which the antennae are exceptional in having a terminal pointed process.
The proboscis, besides the membranous and fleshy lips, consists of a series
of pointed slender lancets, the use of which it is difficult to comprehend,
as the Insects are not known to pierce either animals or vegetables, their
food being chiefly pollen; honey is also doubtless taken by some species,
but the lancet-like organs appear equally ill-adapted for dealing with it.
The larvae are singularly diversified; first, there are the eaters of
Aphidae, or green-fly; some of these may be generally found on our
rose-bushes or on thistles, when they are much covered with Aphids; they
are soft, maggot-like creatures with a great capacity for changing their
shape and with much power of movement, especially of the anterior part of
the body, which is stretched out and moved about to obtain and spear their
prey: some of them are very transparent, so that the movements of the
internal organs and their vivid colours can readily be seen: like so many
other carnivorous Insects, their voracity appears to be insatiable. The
larvae of many of the ordinary Hover-flies are of this kind. _Eristalis_
and its allies are totally different, they live in water saturated with
filth, or with decaying vegetable matter (the writer has found many
hundreds of the larvae of _Myiatropa florea_ in a pool of water standing in
a hollow beech-tree). These rat-tailed maggots are of great interest, but
as they have been described in almost every work on entomology, and as
Professor Miall[422] has recently given an excellent account of their
peculiarities, we need not now discuss them. Some of the flies of the genus
_Eristalis_ are very like honey-bees, and appear in old times to have been
confounded with them; indeed, Osten Sacken thinks this resemblance gave
rise to the "Bugonia myth," a fable of very ancient origin to the effect
that Honey-bees could be procured from filth, or even putrefying carcases,
by the aid of certain proceedings that savoured slightly of witchcraft, and
may therefore have increased the belief of the operator in the
{500}possibility of a favourable result. It was certainly not bees that
were produced from the carcases, but Osten Sacken suggests that
_Eristalis_-flies may have been bred therein.
In the genus _Volucella_ we meet with a third kind of Syrphid larva. These
larvae are pallid, broad and fleshy, surrounded by numerous angular,
somewhat spinose, outgrowths of the body; and have behind a pair of
combined stigmata, in the neighbourhood of which the outgrowths are
somewhat larger; these larvae live in the nests of Bees and Wasps, in which
they are abundant. Some of the _Volucella_, like many other Syrphidae, bear
a considerable resemblance to Bees or Wasps, and this has given rise to a
modern fable about them that appears to have no more legitimate basis of
fact than the ancient Bees-born-of-carcases myth. It was formerly assumed
that the _Volucella_-larvae lived on the larvae of the Bees, and that the
parent flies were providentially endowed with a bee-like appearance that
they might obtain entrance into the Bees' nests without being detected, and
then carry out their nefarious intention of laying eggs that would hatch
into larvae and subsequently destroy the larvae of the Bees. Some
hard-hearted critic remarked that it was easy to understand that providence
should display so great a solicitude for the welfare of the _Volucella_,
but that it was difficult to comprehend how it could be, at the same time,
so totally indifferent to the welfare of the Bees. More recently the tale
has been revived and cited as an instance of the value of deceptive
resemblance resulting from the action of natural selection, without
reference to providence. There are, however, no facts to support any theory
on the subject. Very little indeed is actually known as to the habits of
_Volucella_ in either the larval or imaginal instars; but the little that
is known tends to the view that the presence of the _Volucella_ in the
nests is advantageous to both Fly and Bee. Nicolas has seen _Volucella
zonaria_ enter the nest of a Wasp; it settled at a little distance and
walked in without any fuss being made. Erné has watched the
_Volucella_-larvae in the nests, and he thinks that they eat the waste or
dejections of the larvae. The writer kept under observation
_Volucella_-larvae and portions of the cells of _Bombus_, containing some
larvae and pupae of the Bees and some honey, but the fly-larvae did not
during some weeks touch any of the Bees or honey, and ultimately died,
presumably of starvation. Subsequently, he experimented with
_Volucella_-larvae and a portion {501}of the comb of wasps containing
pupae, and again found that the flies did not attack the Hymenoptera; but
on breaking a pupa of the Wasp in two, the fly-larvae attacked it
immediately and eagerly; so that the evidence goes to show that the
_Volucella_-larvae act as scavengers in the nests of the Hymenoptera.
Künckel d'Herculais has published an elaborate work on the European
_Volucella_; it is remarkable for the beauty of the plates illustrating the
structure, anatomy and development, but throws little direct light on the
natural history of the Insects. _V. bombylans_, one of the most abundant of
our British species, appears in two forms, each of which has a considerable
resemblance to a _Bombus_, and it has been supposed that each of the two
forms is specially connected with the Bee it resembles, but there is no
evidence to support this idea; indeed, there is some little evidence to the
contrary. The genus _Merodon_ has larvae somewhat similar to those of
_Volucella_, but they live in bulbs of _Narcissus_; _M. equestris_ has been
the cause of much loss to the growers of Dutch bulbs; this Fly is
interesting on account of its great variation in colour; it has been
described as a whole series of distinct species.
The most remarkable of the numerous forms of Syrphid larvae are those of
the genus _Microdon_ (Fig. 239), which live in ants' nests. They have no
resemblance to Insect-larvae, and when first discovered were not only
supposed to be little Molluscs, but were actually described as such under
the generic names of _Parmula_ and _Scutelligera_. There is no appearance
of segmentation of the body; the upper surface is covered by a sort of
network formed by curved setae, which help to retain a coating of dirt;
there is no trace externally of any head, but on the under surface there is
a minute fold in which such mouth-organs as may be present are probably
concealed; the sides of the body project so as to form a complex fringing
arrangement; the terminal stigmata are very distinct, the lateral processes
connected with them (the "Knospen" of Dr. Meijere), are, however, very
irregular and placed at some distance from the stigmatic scar. Pupation
occurs by the induration of the external covering and the growth from it,
or rather through it, of two short horns in front. Inside this skin there
is formed a soft pupa, of the kind usual in Cyclorrhaphous flies; the
dehiscence of the external covering is, however, of unusual nature, three
little pieces being {502}separated from the anterior part of the upper
surface, while the lower face remains intact. The account of the pupation
given by Elditt[423] is not complete: the two horns that project are, it
would appear, not portions of the larval skin, but belong to the head of
the pupa, and according to Elditt are used to effect the dehiscence of the
case for the escape of the fly; there does not appear to be any
head-vesicle. Nothing is known as to the details of the life of these
anomalous larvae. M. Poujade has described two species found in France in
the nests of the ant _Lasius niger_.[424] The larva we figure was found by
Colonel Yerbury in nests of an _Atta_ in Portugal, and an almost identical
larva was recently found by Mr. Budgett in Paraguay. The flies themselves
are scarce, _Microdon mutabilis_ (formerly called _M. apiformis_) being one
of the rarest of British flies. They have the antennae longer than is usual
in Syrphidae, and the cross-veins at the outside of the wing are
irregularly placed, so that the contour is very irregular: the resemblance
to bees is very marked, and in some of the South American forms the hind
legs are flattened and hairy like those of bees. The oviposition of
_Microdon_ has been observed by Verhoeff;[425] he noticed that the fly was
frequently driven away by the ants—in this case, _Formica sanguinea_—but
returned undiscouraged to its task.
[Illustration: Fig. 239—Larva of _Microdon_ sp. Portugal. A, Dorsal view of
the larva, × 4; 1, the stigmatic structure; B, posterior view of stigmatic
structure; C, a portion of the marginal fringe of the body.]
A brief résumé of the diverse modes of life of Syrphid larvae has been
given by Perris,[426] and he also gives some information as to the curious
horns of the pupae, but this latter point much {503}wants elucidation.
Whether the Syrphidae, or some of them, possess a ptilinum that helps them
to emerge from the pupa is more than doubtful, though its existence has
been affirmed by several authors of good repute.[427]
[Illustration: Fig. 240.—_Diopsis apicalis._ Natal. A, The fly; B,
extremity of cephalic protuberance, more magnified. _a_, The eye; _b_, the
antenna; C, middle of head, front view; _c_, ocelli.]
SERIES 4. CYCLORRHAPHA SCHIZOPHORA
FAM. 33. MUSCIDAE ACALYPTRATAE.—This group of flies has been the least
studied of all the Diptera; it is generally treated as composed of twenty
or thirty different families distinguished by very slight characters. It
is, however, generally admitted by systematists that these assemblages have
not the value of the families of the other divisions of Diptera, and some
even go so far as to say that they are altogether only equivalent to a
single family. We do not therefore think it necessary to define each one
_seriatim_; we shall merely mention their names, and allude to certain
points of interest connected with them. Taken collectively they may be
defined as very _small flies, with three-jointed antennae (frequently
looking as if only two-jointed), bearing a bristle that is not terminally
placed; frequently either destitute of squamae or having these imperfectly
developed so as not to cover the halteres; and possessing a comparatively
simple system of nervuration, the chief nervures being nearly straight, so
that consequently few cells are formed_. These characters will distinguish
the group {504}from all the other Diptera except from forms of Aschiza, and
from certain Anthomyiidae, with both of which the Acalyptratae are really
intimately connected. Considerable difference of opinion prevails as to the
number of these divisions, but the families usually recognised are:—
1. Doryceridae.
2. Tetanoceridae.
3. Sciomyzidae.
4. Diopsidae.
5. Celyphidae.
6. Sepsidae incl. Piophilidae.
7. Chloropidae (= Oscinidae).
8. Ulidiidae.
9. Platystomidae.
10. Ephydridae.
11. Helomyzidae.
12. Dryomyzidae.
13. Borboridae.
14. Phycodromidae.
15. Thyreophoridae.
16. Scatophagidae. (= Scatomyzidae).
17. Geomyzidae incl. Opomyzidae.
18. Drosophilidae; incl. Asteidae.
19. Psilidae.
20. Tanypezidae (= Micropezidae).
21. Trypetidae.
22. Sapromyzidae incl. Lonchaeidae.
23. Rhopalomeridae.
24. Ortalidae.
25. Agromyzidae incl. Phytomyzidae.
26. Milichiidae.
27. Octhiphilidae.
28. Heteroneuridae.
29. Cordyluridae.
Brauer associates Conopidae with Acalyptrate Muscids, and calls the Group
Holometopa; applying the term Schizometopa to the Calyptrate Muscidae.
No generalisation can yet be made as to the larvae of these divisions,
neither can any characters be pointed out by which they can be
distinguished from the larvae of the following families. In their habits
they have nothing specially distinctive, and may be said to resemble the
Anthomyiidae, vegetable matter being more used as food than animal; many of
them mine in the leaves or stems of plants; in the genus _Dorycera_ the
larva is aquatic, mining in the leaves of water-plants, and in Ephydridae
several kinds of aquatic larvae are found, some of which are said to
resemble the rat-tailed larvae of Syrphidae; certain of these larvae occur
in prodigious quantities in lakes, and the Insects in some of their early
stages serve the Mexicans as food, the eggs being called Ahuatle, the
larvae Pusci, the pupae Koo-chah-bee. Some of the larvae of the Sciomyzidae
are also aquatic: that of _Tetanocera ferruginea_ is said by Dufour to
consist only of eight segments, and to be metapneustic; Brauer considers
the Acalyptrate larvae to be, however, in general, amphipneustic, like
those of Calyptratae. The Chloropidae are a very important family owing to
their occasional excessive multiplication, and to their living on cereals
and other grasses, various parts of which they attack, sometimes causing
great losses to the agriculturist. The species of the genus _Chlorops_ are
{505}famous for the curious habit of entering human habitations in great
swarms: frequently many millions being found in a single apartment.
Instances of this habit have been recorded both in France and England,
Cambridge being perhaps the place where the phenomenon is most persistently
exhibited. In the year 1831 an enormous swarm of _C. lineata_ was found in
the Provost's Lodge at King's College and was recorded by Leonard Jenyns;
in 1870 another swarm occurred in the same house if not in the same
room.[428] Of late years such swarms have occurred in certain apartments in
the Museums (which are not far from King's College), and always in the same
apartments. No clue whatever can be obtained as to their origin; and the
manner in which these flies are guided to a small area in numbers that must
be seen to be believed, is most mysterious. These swarms always occur in
the autumn, and it has been suggested that the individuals are seeking
winter quarters.
[Illustration: Fig. 241—_Celyphus_ (_Paracelyphus_) sp. West Africa. A, The
fly seen from above; _a_, scutellum; _b_, base of wing: B, profile, with
tip of abdomen bent downwards; _a_, scutellum; _b_, _b_, wing; _c_, part of
abdomen.]
Several members of the Acalyptratae have small wings or are wingless, as in
some of our species of _Borborus_. The Diopsidae—none of which are
European—have the sides of the head produced into long horns, at the
extremity of which are placed the eyes and antennae; these curiosities
(Fig. 240) are apparently common in both Hindostan and Africa. In the
horned flies of the genus _Elaphomyia_, parts of the head are prolonged
into horns of very diverse forms according to the species, but bearing on
the whole a great resemblance to miniature stag-horns. A genus
(_Giraffomyia_) with a long neck, and with partially segmented appendages,
instead of horns on the head, has been recently discovered by Dr. Arthur
Willey in New Britain. Equally remarkable are the species of _Celyphus_;
they do not look like flies at all, owing to the scutellum being inflated
and enlarged so as to cover all the posterior parts {506}of the body as in
the Scutellerid Hemiptera: the wings are entirely concealed, and the
abdomen is reduced to a plate, with its orifice beneath, not terminal; the
surface of the body is highly polished and destitute of bristles. Whether
this is a mimetic form, occurring in association with similar-looking Bugs
is not known. The North American genus _Toxotrypana_ is furnished with a
long ovipositor; and in this and in the shape of the body resembles the
parasitic Hymenoptera. This genus was placed by Gerstaecker in Ortalidae,
but is considered by later writers to be a member of the Trypetidae. This
latter family is of considerable extent, and is remarkable amongst the
Diptera for the way in which the wings of many of its members are
ornamented by an elaborate system of spots or marks, varying according to
the species.
FAM. 34. ANTHOMYIIDAE.—_Flies similar in appearance to the House-fly; the
main vein posterior to the middle of the wing (4th longitudinal) continued
straight to the margin, not turned upwards. Eyes of the male frequently
large and contiguous, bristle of antenna either feathery or bare._ This
very large family of flies is one of the most difficult and unattractive of
the Order. Many of its members come close to the Acalyptrate Muscidae from
which they are distinguished by the fact that a well-developed squama
covers the halteres; others come quite as close to the Tachinidae, Muscidae
and Sarcophagidae, but may readily be separated by the simple, not
angulate, main vein of the wing. The larval habits are varied. Many attack
vegetables, produce disintegration in them, thus facilitating
decomposition. _Anthomyia brassicae_ is renowned amongst market gardeners
on account of its destructive habits. _A. cana_, on the contrary, is
beneficial by destroying the migratory Locust _Schistocerca peregrina_; and
in North America, _A. angustifrons_ performs a similar office with
_Caloptenus spretus_. One or two species have been found living in birds;
in one case on the head of a species of _Spermophila_, in another case on a
tumour of the wing of a Woodpecker. _Hylemyia strigosa_, a dung-frequenting
species, has the peculiar habit of producing living larvae, one at a time;
these larvae are so large that it would be supposed they are full grown,
but this is not the case, they are really only in the first stage, an
unusual amount of growth being accomplished in this stadium. _Spilogaster
angelicae_, on the other hand, according to {507}Portschinsky, lays a small
number of very large eggs, and the resulting larvae pass from the first to
the third stage of development, omitting the second stage that is usual in
Eumyiid Muscidae.[429]
[Illustration: Fig. 242—_Ugimyia sericariae._ A, The perfect fly, × 3/2; B,
tracheal chamber of a silkworm, with body of a larva of _Ugimyia_
projecting; _a_, front part of the maggot; _b_, stigmatic orifice of the
maggot; _c_, stigma of the silkworm. (After Sasaki.)]
FAM. 35. TACHINIDAE.—_First posterior cell of wing nearly or quite closed.
Squamae large, covering the halteres: antennal arista bare: upper surface
of body usually bristly._ This is an enormous family of flies, the larvae
of which live parasitically in other living Insects, Lepidopterous larvae
being especially haunted. Many have been reared from the Insects in which
they live, but beyond this little is known of the life-histories, and still
less of the structure of the larvae of the Tachinidae, although these
Insects are of the very first importance in the economy of Nature. The eggs
are usually deposited by the parent-flies near or on the head of the
victim; Riley supposed that the fly buzzes about the victim and deposits an
egg with rapidity, but a circumstantial account given by Weeks[430]
discloses a very different process: the fly he watched sat on a leaf
quietly facing a caterpillar of _Datana_ engaged in feeding at a distance
of rather less than a quarter of an inch. "Seizing a moment when the head
of the larva was likely to remain stationary, the fly stealthily and
rapidly bent her abdomen downward and extended from the last segment what
proved to be an ovipositor. This passed forward beneath her body and
between the legs until it projected beyond and nearly on a level with the
head of the fly and came in contact with the eye of the larva upon which an
egg was deposited," making an addition to five already there. _Ugimyia
sericariae_ does great {508}harm in Japan by attacking the silkworm, and in
the case of this fly the eggs are believed to be introduced into the victim
by being laid on mulberry leaves and swallowed with the food; several
observers agree as to the eggs being laid on the leaves, but the fact that
they are swallowed by the silkworm is not so certain. Sasaki has given an
extremely interesting account of the development of this larva.[431]
According to him, the young larva, after hatching in the alimentary canal,
bores through it, and enters a nerve-ganglion, feeding there for about a
week, after which the necessity for air becoming greater, as usual with
larvae, the maggot leaves the nervous system and enters the tracheal
system, boring into a tube near a stigmatic orifice of the silkworm, where
it forms a chamber for itself by biting portions of the tissues and
fastening them together with saliva. In this it completes its growth,
feeding on the interior of the silkworm with its anterior part, and
breathing through the stigmatic orifice of its host; after this it makes
its exit and buries itself deeply in the ground, where it pupates. The work
of rupturing the puparium by the use of the ptilinum is fully described by
Sasaki, and also the fact that the fly mounts to the surface of the earth
by the aid of this same peculiar air-bladder, which is alternately
contracted and distended. Five, or more, of the _Ugimyia_-maggots may be
found in one caterpillar, but only one of them reaches maturity, and
emerges from the body. The Tachinid flies appear to waste a large
proportion of their eggs by injudicious oviposition; but they make up for
this by the wide circle of their victims, for a single species has been
known to infest Insects of two or three different Orders.
[Illustration: Fig. 243—Diagrammatic section of silkworm to show the habits
of _Ugimyia_. _a_, Young larva; _b_, egg of _Ugimyia_ in stomach of the
silkworm; _c_, larva in a nerve-ganglion; _d_, larva entering a ganglion;
_e_, larva embedded in tracheal chamber, as shown in Fig. 242, B. (After
Sasaki.)]
The species of _Miltogramma_—of which there are many in Europe and two in
England—live at the expense of Fossorial {509}Hymenoptera by a curious sort
of indirect parasitism. They are obscure little flies, somewhat resembling
the common House-fly, but they are adepts on the wing and have the art of
ovipositing with extreme rapidity; they follow a Hymenopteron as it is
carrying the prey to the nest for its young. When the wasp alights on the
ground at the entrance to the nest, the _Miltogramma_ swoops down and
rapidly deposits one or more eggs on the prey the wasp designs as food for
its own young. Afterwards the larvae of the fly eat up the food, and in
consequence of the greater rapidity of their growth, the young of the
Hymenopteron perishes. Some of them are said to deposit living larvae, not
eggs. Fabre has drawn a very interesting picture of the relations that
exist between a species of _Miltogramma_ and a Fossorial Wasp of the genus
_Bembex_[432]. We may remind the reader that this Hymenopteron has not the
art of stinging its victims so as to keep them alive, and that it
accordingly feeds its young by returning to the nest at proper intervals
with a fresh supply of food, instead of provisioning the nest once and for
all and then closing it. This Hymenopteron has a habit of catching the
largest and most active flies—especially Tabanidae—for the benefit of its
young, and it would therefore be supposed that it would be safe from the
parasitism of a small and feeble fly. On the contrary, the _Miltogramma_
adapts its tactics to the special case, and is in fact aided in doing so by
the wasp itself. As if knowing that the wasp will return to the
carefully-closed nest, the _Miltogramma_ waits near it, and quietly selects
the favourable moment, when the wasp is turning round to enter the nest
backwards, and deposits eggs on the prey. It appears from Fabre's account
that the _Bembex_ is well aware of the presence of the fly, and would seem
to entertain a great dread of it, as if conscious that it is a formidable
enemy; nevertheless the wasp never attacks the little fly, but allows it
sooner or later to accomplish its purpose, and will, it appears, even
continue to feed the fly-larvae, though they are the certain destroyers of
its own young, thus repeating the relations between cuckoo and sparrow.
Most of us think the wasp stupid, and find its relations to the fly
incredible or contemptible. Fabre takes a contrary view, and looks on it as
a superior Uncle Toby. We sympathise with the charming French naturalist,
without forming an opinion.
{510}Doubtless there are many other interesting features to be found in the
life-histories of Tachinidae, for in numbers they are legion. It is
probable that we may have 200 species in Britain, and in other parts of the
world they are even more abundant, about 1000 species being known in North
America.[433] The family Actiidae is at present somewhat doubtful.
According to Karsch,[434] it is a sub-family of Tachinidae; but the fourth
longitudinal vein, it appears, is straight.
FAM. 36. DEXIIDAE.—_These Insects are distinguished from Tachinidae by the
bristle of the antennae being pubescent, and the legs usually longer._ The
larvae, so far as known, are found in various Insects, especially in
Coleoptera, and have also been found in snails. There are eleven British
genera, and about a score of species.
FAM. 37. SARCOPHAGIDAE.—_Distinguished from Muscidae and Tachinidae by
little more than that the bristle of the antennae is feathery at the base
but hair-like and very fine at the tip._—_Sarcophaga carnaria_ is one of
the commonest British Insects; it is like the Blow-fly, though rather
longer, conspicuously grey and black, with the thorax distinctly striped,
and the pulvilli very conspicuous in the live fly. _Cynomyia mortuorum_ is
a bright blue fly rather larger than the Blow-fly, of which it is a
competitor; but in this country an unsuccessful one. The larvae of the two
Insects are found together, and are said to be quite indistinguishable.
_Cynomyia_ is said to lay only about half the number of eggs that the
Blow-fly does, but it appears earlier in the year, and to this is
attributed the fact that it is not altogether crowded out of existence by
the more prolific _Calliphora_. The species of Sarcophagidae are usually
viviparous, and one of them, _Sarcophila magnifica_ (_wohlfahrti_), has the
habit of occasionally depositing its progeny in the nostrils of mammals,
and even of human beings, causing horrible sufferings and occasionally
death: it is said to be not uncommon in Europe but does not occur in
Britain. The genus _Sarcophaga_ is numerous in species, and many of them
are beneficial. Sir Sidney Saunders found in the Troad that Locusts were
destroyed by the larvae of a _Sarcophaga_ living in their bodies; and
{511}Künckel has recently observed that in Algeria several species of this
genus attack Locusts and destroy large quantities by depositing living
larvae in the Orthoptera. In North America the Army-worm is decimated by
species of _Sarcophaga_.
Many of these Insects, when food is scarce, eat their own species with
eagerness, and it seems probable that this habit is beneficial to the
species. The parent-fly in such cases usually deposits more eggs than there
is food for, thus ensuring that every portion of the food will be rapidly
consumed, after which the partially-grown larvae complete their development
by the aid of cannibalism. It is thus ensured that the food will raise up
as many individuals as possible.
FAM. 38. MUSCIDAE.—_Bristle of antennae feathered._ This family contains
many of the most abundant flies, including the House-fly, Blue-bottles or
Blow-flies, Green-bottles, and other forms which, though very common, are
perhaps not discriminated from one another by those who are not
entomologists. The larvae live on carrion and decaying or excrementitious
matters. The common House-fly, _Musca domestica_, runs through its
life-history in a very short time. It lays about 150 very small eggs on
dung or any kind of soft damp filth; the larvae hatch in a day or two and
feed on the refuse; they may be full-grown in five or six days, and, then
pupating, may in another week emerge as perfect flies. Hence it is no
wonder that they increase to enormous numbers in favourable climates. They
are thought to pass the winter chiefly in the pupal state. The House-fly is
now very widely distributed over the world; it sometimes occurs in large
numbers away from the dwellings of man. Of Blow-flies there are two common
species in this country, _Calliphora erythrocephala_ and _C. vomitoria_.
The Green-bottle flies, of which there are several species, belonging to
the genus _Lucilia_, have the same habits as Blow-flies, though they do not
commonly enter houses. The larvae are said to be indistinguishable from
those of _Calliphora_.
The larvae of Eumyiid Muscidae are, when first hatched, metapneustic, but
subsequently an anterior pair of stigmata appears, so that the larva
becomes amphipneustic. They usually go through three stages, distinguished
by the condition of the posterior stigmata. In the early instar these have
a single heart-shaped fissure, in the second stage two fissures exist,
{512}while in the third instar there is a greater diversity in the
condition of the breathing apertures.
The various forms of Muscidae show considerable distinctions in the details
of their natural history, and these in certain species vary according to
the locality. This subject has been chiefly studied by Portschinsky, a
Russian naturalist, and a very interesting summary of his results has been
given by Osten Sacken,[435] to which the student interested in the subject
will do well to refer.
A few years ago a great deal of damage was caused in the Netherlands by
_Lucilia sericata_, a Green-bottle-fly, extremely similar to our common _L.
caesar_, which deposited its eggs in great quantities on sheep amongst
their wool. This epidemic was attributed to the importation of sheep from
England; but, according to Karsch, there is reason to suppose that the fly
was really introduced from Southern Europe or Asia Minor.[436]
The larvae of species of the genus _Lucilia_ sometimes attack man and
animals in South America, but fortunately not in this country. The larva of
_Lucilia_ (_Compsomyia_) _macellaria_ is called the screw-worm, and is the
best known of the forms that infest man, the larvae living in the nasal
fossae and frontal sinuses, and causing great suffering. The fly is common
in North America, but is said never to attack man farther north than in
Kansas. A little fly (_Stomoxys calcitrans_), very like the common
house-fly though rather more distinctly spotted with grey and black, and
with a fine, hard, exserted proboscis, frequently enters our houses and
inflicts a bite or prick on us. It is commonly mistaken for an ill-natured
house-fly that has taken to biting. It is frequently a source of irritation
to cattle. A closely allied fly, _Haematobia serrata_, is very injurious to
cattle in North America, but the same species causes no serious annoyance
in England. We may mention that the various attacks of Dipterous larvae on
man have received the general name "myiasis."
The Tse-tse fly (_Glossina morsitans_), another ally of _Stomoxys_, is not
very dissimilar in size and shape to the blow-fly.[437] {513}It bites man
and animals in South Africa, and if it have previously bitten an animal
whose blood was charged with the Haematozoa that really constitute the
disease called Nagana (fly-disease), it inoculates the healthy animal with
the disease; fortunately only some species are susceptible, and man is not
amongst them. It has recently been shown by Surgeon Bruce[438] that this
fly multiplies by producing, one at a time, a full-grown larva, which
immediately changes to a pupa, as do the members of the series Pupipara.
There are already known other Muscid flies with peculiarities in their
modes of reproduction, so that it is far from impossible that the various
conditions between ordinary egg-laying and full-grown larva- or
pupa-production may be found to exist. Although it has been supposed that
the Tse-tse fly is a formidable obstacle to the occupation of Africa by
civilised men, there is reason to suppose that this will not ultimately
prove to be the case. It only produces disease when this pre-exists in
animals in the neighbourhood; only certain species are liable to it; and
there is some evidence to the effect that even these may in the course of a
succession of generations become capable of resisting the disease
inoculated by the fly. As long ago as 1878 Dr. Drysdale suggested[439] that
this fly only produces disease by inoculating a blood-parasite, and all the
evidence that has since been received tends to show that his idea is
correct.
[Illustration: Fig. 244—The Tse-tse fly (_Glossina morsitans_). A, The fly
with three divisions of the proboscis projecting; B, adult larva; C, pupa.]
Although the facts we have mentioned above would lead to the supposition
that Muscidae are unmitigated nuisances, yet it is probable that such an
idea is the reverse of the truth, and that on the whole their operations
are beneficial. It would be difficult to overestimate their value as
scavengers. And in addition to this they destroy injurious creatures. Thus
in Algeria _Idia fasciata_, a fly like the House-fly, destroys the
{514}dreaded migratory Locust _Schistocerca peregrina_ in great quantities,
by the larvae eating the eggs of the Locust. The female of this fly, in
order to reach the desired food, penetrates from one to three inches below
the surface of the ground.
FAM. 39. OESTRIDAE (_Bot-flies_).—_Rather large or very large flies, with
extremely short antennae, bearing a segmented arista, the front of the head
prominent, the posterior part of the wings frequently rough, and with but
few veins: the mouth usually atrophied, the trophi being represented only
by tubercles; larvae living in Vertebrates, usually Mammals, though it is
possible that a few occur in Birds and even in Reptiles._ This is a family
of small extent, less than 100 species being known from all the world, yet
it is of much interest on account of the habits of its members, which,
though of large size, live entirely at the expense of living Vertebrates,
to the viscera or other structures of which they have definite relations,
varying according to the species. Some (_Gastrophilus_, etc.) live in the
alimentary canal; others (_Hypoderma_, etc.) are encysted in or under the
skin; while others (_Oestrus_, etc.) occupy the respiratory passages. As
many of them attack the animals used by man, and some of them do not spare
man himself, they have attracted much attention, and there is an extensive
literature connected with them; nevertheless the life-histories are still
very incompletely known. Indeed, the group is from all points of view a
most difficult one, it being almost impossible to define the family owing
to the great differences that exist in important points. Some think the
family will ultimately be dismembered; and Girschner has recently proposed
to treat it as a division of Tachinidae. The chief authority is Brauer, in
whose writings the student will find nearly all that is known about
Oestridae.[440] Some of them exist in considerable numbers (it is believed
that they are now not so common as formerly), and yet the flies are but
rarely met with, their habits being in many respects peculiar. Some of
them, for purposes of repose, frequent the summits of mountains, or towers,
or lofty trees. Some have great powers of humming; none of them are known
to bite their victims, indeed the atrophied mouth of most of the Oestridae
forbids such a proceeding.
{515}[Illustration: Fig. 245—_Cephalomyia maculata_, a Bot-fly of the
camel. Arabia. A, The fly with extended wings; B, under aspect of the head:
_a_, antenna; _b_, the obsolete mouth-parts.]
Some deposit their eggs on the hairs of the beasts from which the larvae
are to draw their nutriment, but others place their larvae, already
hatched, in the entrances of the nasal passages. They do not feed on the
blood or tissues of their victims, but on the secretions, and these are
generally altered or increased by the irritation induced by the presence of
the unwelcome guests. It would appear, on the whole, that their presence is
less injurious than would be expected, and as they always quit the bodies
of their hosts for the purposes of pupation, a natural end is put to their
attacks. We have ten species in Britain, the animals attacked being the ox,
the horse, the ass, the sheep, and the red deer; others occasionally occur
in connexion with animals in menageries. The eggs of _Gastrophilus equi_
are placed by the fly, when on the wing, on the hair of horses near the
front parts of the body, frequently near the knee, and, after hatching, the
young larvae pass into the stomach of the horse either by being licked off,
or by their own locomotion; in the stomach they become hooked to the walls,
and after being full grown pass out with the excreta: the Bots—as these
larvae are called—are sometimes very numerous in the stomach, for a fly
will lay as many as four or five hundred eggs on a single horse: in the
case of weakly animals, perforation of the stomach has been known to occur
in consequence of the habit of the Bot of burying itself to a greater or
less extent in the walls of the stomach. _Hypoderma bovis_ and _H. lineata_
attack the ox, and the larvae cause tumours in the skin along the middle
part of the back. It was formerly {516}inferred from this that the fly
places its eggs in this situation, and as the cattle are known to dread and
flee from the fly, it was supposed to be on account of the pain inflicted
when the egg was thrust through the skin. Recent observations have shown
that these views are erroneous, but much still remains to be ascertained.
The details of oviposition are not yet fully known, but it appears that the
eggs are laid on the lower parts of the body, especially near the heels,
and that they hatch very speedily.[441] As the imago of _Hypoderma_ appears
for only a very short period in the summer, the time of the oviposition is
certain. The newly-disclosed larva is considerably different from the more
advanced instar found in the skin of the back; moreover, a long period of
many months intervenes between the hatching of the larva and its appearance
in the part mentioned. Brauer has shown that when the grub is first found
in that situation it is entirely subcutaneous. Hence it would be inferred
that the newly-hatched larva penetrated the skin probably near the spot it
was deposited on, and passed a period in subcutaneous wandering, on the
whole going upwards till it arrived at the uppermost part: that after
moulting, and in consequence of greater need for air, it then pierced the
skin, and brought its breathing organs into contact with the external air;
that the irritation caused by the admission of air induced a purulent
secretion, and caused the larva to be enclosed in a capsule. Dr. Cooper
Curtice has however found, in the oesophagus of cattle, larvae that he
considers to be quite the same as those known to be the young of
_Hypoderma_; and if this prove to be correct, his inference that the young
larvae are licked up by the cattle and taken into the mouth becomes
probable. The larva, according to this view, subsequently pierces the
oesophagus and becomes subcutaneous by passing through the intervening
tissues. The later history of the grub is briefly, that when full grown it
somewhat enlarges the external orifice of its cyst, and by contractions and
expansions of the body, passes to the surface, falls to the ground, buries
itself and becomes a pupa. If Dr. Curtice be correct, there should, of
course, be as many, if not more, larvae found in the oesophagus as in the
back of the animal; but, so far as is known, this is not the case, and we
shall not be surprised if the normal course of development be found
different from what Dr. Curtice supposes it to be. His {517}observations
relate to _Hypoderma lineata_. Our common British species is usually
supposed to be _H. bovis_; but from recent observations it seems probable
that most of the "Ox-warbles" of this country are really due to the larvae
of _H. lineata_.
The history of _Oestrus ovis_, which attacks the sheep, is also
incompletely known, but appears to be much simpler. This fly is viviparous,
and deposits its young larvae at the entrance of the nasal passages of the
sheep, thereby causing extreme annoyance to the animal. The larvae
penetrate to the frontal sinuses to complete their growth. The duration of
their lives is unknown, for it is commonly the case that larvae of various
sizes are found together. _Cephenomyia rufibarbis_ has recently been found
in Scotland. It attacks the Red deer, and its life-history is similar to
that of _Oestrus ovis_, though the larvae apparently prefer to attain their
full growth in the pharynx of the deer.
In reference to the Oestridae that attack man, we may merely mention that
the larva of the _Hypoderma_ of the ox is occasionally found in Europe
infesting human beings, but only as an extremely rare and exceptional
event; and that only those engaged in attending on cattle are attacked;
from which it is inferred that the flies are deceived by an odour emanating
from the garments. In America numerous cases are known of Oestrid larvae
being taken from the body of man, but information about them is very
scanty. It appears, however, that there are at least four species, one of
which, _Dermatobia noxialis_, is known as a fly as well as a larva. Whether
any of these are peculiar to man is uncertain.[442] There are several
larvae of Muscidae that have similar habits to the Oestridae; hence the
statements that exist as to larvae being found in birds and reptiles cannot
be considered to apply to members of the latter family until the larvae
have been studied by an expert.
The family Ctenostylidae has been established by Bigot for a South American
Insect, of which only a single individual exists in collections. It is
doubtful whether it can be referred to Oestridae.[443]
SERIES V. PUPIPARA
The four families included in this Series are, with the exception of the
Hippoboscidae, very little known. Most of {518}them live by sucking blood
from Mammals and Birds, and sometimes they are wingless parasites. The
single member of the family Braulidae lives on bees. The term Pupipara is
erroneous, and it would be better to revert to Réaumur's prior appellation
Nymphipara. Müggenburg has suggested that the division is not a natural
one, the points of resemblance that exist between its members being
probably the results of convergence. Recent discoveries as to the modes of
bringing forth of Muscidae give additional force to this suggestion. A
satisfactory definition of the group in its present extent seems
impossible.
FAM. 40. HIPPOBOSCIDAE.—_Wings very variable, sometimes present and large,
then with waved surface and thick nervures confined to the anterior and
basal part; sometimes mere strips, sometimes entirely absent._ Certain
members of this family are well known, the Forest-fly, or Horse-fly, and
the Sheep-tick belonging to it. The proboscis is of peculiar formation, and
not like that of other flies. Seen externally it consists of two elongate,
closely adapted, hard flaps; these are capable of diverging laterally to
allow an inner tube to be exserted from the head. The details and
morphology of the structure have recently been discussed by
Müggenburg.[444] _Melophagus ovinus_, commonly called the Sheep-tick, is
formed for creeping about on the skin of the sheep beneath the wool, and
may consequently be procured with ease at the period of sheep-shearing: it
has no resemblance to a fly, and it is difficult to persuade the
uninitiated that it is such. _Hippobosca equina_ (called in this country
the Forest-fly, perhaps because it is better known in the New Forest than
elsewhere), looks like a fly, but will be readily recognised by the two
little cavities on the head, one close to each eye, in which the antennae
are concealed, only the fine bristle projecting. Very little seems to be
known as to the Natural History of this fly. _Lipoptena cervi_ lives on the
Red deer; the perfect Insect has apparently a long life, and both sexes may
be found in a wingless state on the deer all through the winter. When first
disclosed in the summer they are however provided with wings, but when they
have found a suitable host they bite off, or cast, the wings. The female,
it appears, does this more promptly than the male, so that it is difficult
to get winged individuals of the former sex.[445]
{519}[Illustration: Fig. 246.—Diagrammatic section of the larva of
_Melophagus ovinus_. (After Pratt.) _a_, mouth; _b_, suctorial pouch; _c_,
imaginal disc for adult head; _d_, meso- and meta-notal discs; _e_,
anterior tracheal anastomosis; _f_, first muscular belt; _g_, transverse
tracheal branch; _h_, the dorsal tracheal tube; _i_, sex-organ; _k_,
Malpighian tube; _l_, terminal part of intestine; _m_, terminal chamber of
tracheal tube; _n_, stigmatic fossa; _o_, terminal part of intestine; _p_,
anus; _q_, anal disc; _r_, ventral tracheal tube; _s_, stomach; _t_,
nervous system; _u_, discs for the three pairs of legs of the imago; _v_,
ventral pouch; _w_, pharynx; _x_, suctorial lip.]
Most of the known Hippoboscidae live on birds, and are apparently specially
fond of the Swallow tribe. They are all winged, though in some species the
wings are very small. The bird-infesting Hippoboscidae have been very
little studied, and will probably form a distinct family; the antennae of
_Stenopteryx hirundinis_ are quite different from those of _Hippobosca_.
The development is remarkable, and has been studied by Leuckart[446] and by
Pratt[447] in the case of _Melophagus ovinus_. The ovaries are peculiarly
formed, and produce one large egg at a time; this passes into the dilated
oviduct, and there goes through its full growth and a certain amount of
development; it is then extruded, and undergoing little or no change of
form becomes externally hardened by the excretion of chitin, passing thus
into the condition of the Eumyiid pupa. Dufour thought that there is no
larval stage in this Insect, but it is quite clear from later researches
that he was wrong, and that a larval stage of a peculiar kind, but in some
respects resembling that of the Eumyiid Muscidae, occurs. The larva has no
true head, but the anterior part of the body is invaginated, and the most
anterior part again protrudes in the invagination, so that two little
passages appear on section (Fig. 246); the upper one leads to the stomach,
which is of very large size. The tracheal system is peculiar; it is
metapneustic, there being neither anterior nor lateral spiracles. Pratt
says that there is at first a single pair of terminal spiracles, and
subsequently three pairs, hence he considers that the terminal part of the
body corresponds to three segments. This is however probably a mistaken
view; it appears more probable that the so-called three pairs of stigmata
really correspond with the complex {520}condition of the stigmata in the
later instars of certain other Dipterous larvae. The _Melophagus_-larva is
nourished by secretion from certain glands of the mother-fly; this is
swallowed and the stomach is greatly distended by this milky fluid.
Probably it was this condition that induced Dufour to suppose the larva to
be only an embryo.
Some of the Hippoboscidae that live on birds take to the wing with great
readiness, and it is probable that these bird-parasites will prove more
numerous than is at present suspected.
We may here notice an animal recently described by Dr. Adensamer and called
_Ascodipteron_.[448] He treats it as the female imago of a Pupiparous
Dipteron. It was found buried in the skin of the wing of a bat of the genus
_Phyllorhina_, in the Dutch East Indies, only one individual being known.
It is entirely unsegmented, and externally without head. If Dr. Adensamer
should prove to be correct in his surmise the creature can scarcely be
inferior in interest to the Strepsiptera.
[Illustration: Fig. 247.—_Braula coeca._ × 18/1. (After Meinert.)]
FAM. 41. BRAULIDAE.—This consists only of a minute Insect that lives on
bees. The antennae are somewhat like those of the sheep-tick, though they
are not so completely concealed in the cavities in which they are inserted.
According to Müggenburg[449] a ptilinum exists, and he is also of opinion
that although the parts of the mouth differ very much from those of
Hippoboscidae they are essentially similar. Lucas says that _Braula_
specially affects the thorax of the bee: Müggenburg, that it is fond of the
queen-bee because of the exposed membranes between the body-segments that
exist in that sex. Whether this Insect is truly Pupiparous is unknown,
though Boise states that a pupa is deposited in the cell of the bee by the
side of the young larva of {521}the bee, and appears as the perfect Insect
in about twenty-one days. Müggenburg suggests that _Braula_ may be
oviparous, as he has never found a larva in the abdomen. Packard says that
on the day the larva hatches from the egg it sheds its skin and turns to an
oval puparium of a dark brown colour. The Insect is frequently though
inappropriately called bee-louse; notwithstanding its name it is not quite
blind, though the eyes are very imperfect.
FAM. 42. STREBLIDAE.— _Winged; possessing halteres; the head small, narrow
and free._ These very rare Diptera are altogether problematic. According to
Kolenati the larvae live in bats' excrement and the perfect Insects on the
bats.[450] If the former statement be correct the Insects can scarcely
prove to be Pupipara. The wing-nervuration is, in the figures of the
Russian author, quite different from that of Hippoboscidae. The Streblidae
have been associated by some entomologists with Nycteribiidae, and by
Williston with Hippoboscidae.
[Illustration: Fig. 248.—_Nycteribia_ sp., from _Xantharpyia straminea_.
Aden. A, Upper surface of female, with head in the position of repose; B,
under surface of male. x 12/1.]
FAMILY 43. NYCTERIBIIDAE.—The species of this family are found on bats;
they are apparently rare, and we have been able to examine only one
species. The form is very peculiar, the {522}Insects looking as if the
upper were the under surface. They are wingless, with a narrow head, which
reposes on the back of the thorax. The prothorax appears to be seated on
the dorsum of the mesothorax. According to Müggenburg there is no trace of
a ptilinum. A brief note on the metamorphosis[451] by Baron Osten Sacken
indicates that the mature larva differs from that of _Melophagus_ in the
arrangement of the stigmata; they appear to be dorsal instead of terminal.
There are apparently no characters of sufficient importance to justify the
association of these Insects with the other divisions of Pupipara; the sole
ground for this connection being the supposed nature of the life-history of
the larva.
[Illustration: Fig. 249—Anterior part of the body of _Nycteribia_ sp.,
found on _Xantharpyia straminea_ by Colonel Yerbury at Aden. A, Upper
surface of female, with head extended; B, under surface of male, with head
extended; C, claws of a foot.]
SUB-ORDER APHANIPTERA or SIPHONAPTERA (_Fleas_)
FAM. PULICIDAE.—_Wingless, with the body laterally compressed, so that the
transverse diameter is small, the vertical one great. The head indistinctly
separated from the body, small, with short thick antennae placed in
depressions somewhat behind and above the unfaceted eyes. These are always
minute, and sometimes wanting._
{523}[Illustration: Fig. 250—_Hystrichopsylla talpae._ Britain. (After
Ritsema.)]
[Illustration: Fig. 251.—Mouth-parts of a flea, _Vermipsylla alakurt_ ♂.
_H._ Unpaired pricking organ; _Lp._ labial palp; _Md._ mandible; _Mx._
maxilla; _Mxp._ maxillary palp. (After Wagner.)]
We all know that the Flea is so flat, or compressed sideways, that it does
not mind the most severe squeeze. This condition is almost peculiar to it;
a great flattening of the body is common in Insects—as is seen in another
annoying Insect, the bed-bug—but the compression, in the flea, is in the
reverse direction. In other respects the external anatomy of the flea shows
several peculiarities, the morphological import of which has not yet been
elucidated. The head is of very peculiar shape, small, with the antennae
placed in an unusual position; the clypeus is said to be entirely absent,
the front legs are articulated in such a manner that they have a large
additional basal piece—called by some anatomists the ischium—and in
consequence appear to be placed far forwards, looking as if they were
attached to the head; the meso- and meta-thorax have certain flaps that
have been considered to be homologues of wings; and the maxillary palpi are
attached to the head in such a way that they appear to play the part of the
antennae of other Insects (Fig. 250), and were actually considered to be
the antennae by Linnaeus, as well as others; the mouth-parts themselves are
differently constructed from those of any other Insects.[452] The maxillae
and labium are considered to be not only present, but well developed, the
former possessing palpi moderately well developed, while the labial palps
are very large and of highly peculiar form, being imperfectly transversely
jointed and acting as sheaths; the mandibles are present in the form of a
pair of elongate, slender organs, with serrated edges; and there is an
unpaired, elongate pricking-organ, thought by some to be a hypopharynx, and
by others a labrum.
{524}[Illustration: Fig. 252—Larva of _Pulex serraticeps_, the dog- and
cat-flea. (After Künckel.)]
The antennae are of unusual form, consisting of two basal joints, and,
loosely connected therewith, a terminal mass of diverse form and more or
less distinctly, though irregularly, segmented. The full number of ten
stigmata exists, Wagner giving three thoracic, with seven abdominal, placed
on segments 2-8 of the abdomen; but Packard thinks the supposed
metathoracic stigma is really the first abdominal. Fleas undergo a very
complete metamorphosis; the larvae are wormlike, resembling those of
Mycetophilid Diptera (Fig. 252). The egg of the cat's flea is deposited
among the fur of the animal, but (unlike the eggs of other parasites)
apparently is not fastened to the hair, for the eggs fall freely to the
ground from infested animals; the young larva when hatched bears on the
head a curious structure for breaking the egg-shell. It has the mouth-parts
of a mandibulate Insect and is peripneustic, having ten pairs of stigmata.
It subsequently becomes of less elongate form. Flea-larvae are able to
nourish themselves on almost any kind of refuse animal matter, Laboulbène
having reared them on the sweepings of apartments; they may perhaps
sometimes feed on blood; at any rate the contents of the alimentary canal
appear red through the transparent integuments. When full grown the larva
makes a cocoon, and frequently covers it with pieces of dust. The perfect
flea appears in a week or two thereafter; the pupa has the members free.
The food of the larvae of fleas has been much discussed and a variety of
statements made on the subject. It has been stated that the mother-flea
after being gorged with blood carries some of it to the young, but Künckel
has shown that there is very little foundation for this tale. Enormous
numbers of fleas are sometimes found in uninhabited apartments to which
animals have previously had access, and these fleas will attack in numbers
and with great eagerness any unfortunate person who may enter {525}the
apartment. The cat-flea can pass through its growth and metamorphosis with
excessive rapidity, the entire development of a generation in favourable
conditions extending but little beyond a fortnight.[453]
About a hundred kinds of fleas are known, all of which live on mammals or
birds. _Hystrichopsylla talpae_ (Fig. 250) is one of the largest, it occurs
on the Mole. It was found by Ritsema in the nests of _Bombus subterraneus_
(and was described under the name of _Pulex obtusiceps_). As these nests
are known to be harried by Voles, and as this flea has also been found on
Field-mice, it is probable that the parasites are carried to the nests by
the Voles. The species that chiefly infests man is _Pulex irritans_, an
Insect that is nearly cosmopolitan, though arid desert regions are
apparently unsuitable to it. _Pulex avium_ occurs on a great variety of
birds. _P. serraticeps_ infests the dog and the cat, as well as a variety
of other Mammals. It is a common opinion that each species of Mammal has
its own peculiar flea, but this is far from correct. Fleas pass readily
from one species of animal to another; the writer formerly possessed a cat
that was a most determined and successful hunter of rabbits, and she
frequently returned from her excursions swarming with fleas that she had
become infested with when in the rabbits' burrows; her ears were on some
occasions very sore from the flea-bites. Some of the fleas of other animals
undoubtedly bite man. There appears, however, to be much difference in the
liability of different individuals of our own species to the bites of
fleas. _Sarcopsylla penetrans_ differs in habits from other fleas, as the
female buries the anterior parts of her body in the flesh of man or other
Vertebrates, and the abdomen then becomes enormously enlarged and distended
and undergoes a series of changes that are of much interest.[454] While in
this position the Insect discharges a number of eggs. This species
multiplies sufficiently to become a serious pest in certain regions, the
body of one man having been known to be affording hospitality to 300 of
these fleas. _Sarcopsylla penetrans_ is known as the Sand-flea, or chigger,
and by numerous other names. Originally a native of tropical America it has
been carried to other parts of the world. Another _Sarcopsylla_, _S.
gallinacea_, attaches itself to the eyelids {526}of the domestic fowl in
Ceylon, and an allied form, _Rhynchopsylla pulex_, fastens itself to the
eyelids and other parts of the body of birds and bats in South America. In
Turkestan _Vermipsylla alakurt_ attacks cattle—ox, horse, camel,
sheep—fastening itself to the body of the animal after the fashion of a
tick. Retaining this position all through the winter, it becomes distended
somewhat after the manner of the Sand-flea, though it never forms a
spherical body. The parts of the mouth in this Insect (Fig. 251) are
unusually long, correlative with the thickness of the skins of the animals
on which it lives. Grassi considers that the dog's flea, _Pulex
serraticeps_, acts as the intermediate host of Taenia.
Great difference of opinion has for long prevailed as to whether fleas
should be treated as a Sub-Order of Diptera or as a separate Order of
Insects. Wagner and Künckel, who have recently discussed the question,
think they may pass as aberrant Diptera, while Packard,[455] the last
writer on the subject, prefers to consider them a separate Order more
closely allied to Diptera than to any other Insects. Although widely known
as Aphaniptera, several writers call them Siphonaptera, because Latreille
proposed that name for them some years before Kirby called them
Aphaniptera. Meinert considers them a separate Order and calls it Suctoria,
a most unfortunate name.
ORDER VIII. THYSANOPTERA.
_Small Insects, with a palpigerous mouth placed on the under side of the
head and apposed to the sternum so as to be concealed. With four slender
wings, fringed with long hairs on one or both margins, or with rudiments
of wings, or entirely apterous. Tarsi of one or two joints, terminated by
a vesicular structure. The young resemble the adult in general form, but
there is a pupal stadium in which the Insect is quiescent and takes no
food._
The tiny Insects called Thrips are extremely abundant and may often be
found in profusion in flowers. Their size is only from 1/50 to ⅓ of an inch
in length; those of the latter magnitude are in fact giant species, and so
far as we know at present are found only in Australia (Fig. 253). As
regards the extent {527}of the Order it would appear that Thysanoptera are
insignificant, as less than 150 species are known. Thrips have been,
however, very much neglected by entomologists, so it will not be a matter
for surprise if there should prove to be several thousand species. These
Insects present several points of interest; their mouth-organs are unique
in structure; besides this, they exhibit so many points of dissimilarity
from other Insects that it is impossible to treat them as subdivisions of
any other Order. They have, however, been considered by some to be aberrant
Pseudoneuroptera (cf. Vol. V.), while others have associated them with
Hemiptera. Both Brauer and Packard have treated Thysanoptera as a separate
Order, and there can be no doubt that this is correct. Thysanoptera have
recently been monographed by Uzel in a work that is, unfortunately for most
of us, in the Bohemian language.[456]
[Illustration: Fig. 253—_Idolothrips spectrum._ Australia.]
The antennae are never very long, and are 6 to 9-jointed. The head varies
much, being sometimes elongate and tubular, but sometimes short; it has,
however, always the peculiarity that the antennae are placed quite on its
front part, and that the mouth appears to be absent, owing to its parts
being thrust against the under side of the thorax and concealed. Their most
remarkable peculiarity is that some of them are asymmetrical: Uzel looks on
the peculiar structure, the "Mundstachel," _m_, _m_ {528}(Fig. 254) found
on the left side of the body, as probably an enormous development of the
epipharynx. Previous to the appearance of Uzel's work, Garman had, however,
correctly described the structure of the mouth;[457] he puts a different
interpretation on the parts; he points out that the mandibles (_j_),
so-called by Uzel, are attached to the maxillae, and he considers that they
are really jointed, and that they are lobes thereof; while the Mundstachel
or piercer is, he considers, the left mandible; the corresponding structure
of the other side being nearly entirely absent. He points out that the
labrum and endocranium are also asymmetrical. We think Garman's view a
reasonable one, and may remark that dissimilarity of the mandibles of the
two sides is usual in Insects, and that the mandibles may be hollow for
sucking, as is shown by the larvae of Hemerobiides. There are usually three
ocelli, but they are absent in the entirely apterous forms.
[Illustration: Fig. 254—Face (with base of the antennae) of _Aeolothrips
fasciata_. (After Uzel.) _a_, Labrum; _b_, maxilla with its palp (_c_);
_bl_, terminal part of vertex near attachment of month-parts; _d_, membrane
between maxilla and mentum; _e_, mentum ending in a point near _f_; _g_,
membrane of attachment of the labial palp _h_; _i_, ligula; _j_, _j_ the
bristle-like mandibles; _k_, the thicker base of mandible; _l_, chitinous
lever; _m_, mouth-spine, with its thick basal part _n_, and _o_, its
connection with the forehead, _r_, _r_; _p_, foramen of muscle; _s_ and
_t_, points of infolding of vertex; _u_, a prolongation of the gena.]
The wings appear to spring from the dorsal surface of the body, not from
the sides; the anterior pair is always quite separated from the posterior;
the wings are always slender, sometimes very slender; in other respects
they exhibit considerable variety; sometimes the front pair are different
in colour and consistence from the other pair. The abdomen has ten
segments, the last of which is often tubular in form. The peculiar
vesicular structures by which the feet are terminated are, during movement,
alternately distended and emptied, and have two hooks or claws on the
sides. The stigmata are extremely peculiar, there being four pairs, the
first being the mesothoracic, 2nd {529}metathoracic, 3rd on the second
abdominal segment, 4th on the eighth abdominal segment.[458] There are four
Malpighian tubes, and two or three pairs of salivary glands. The dorsal
vessel is said to be a short sack placed in the 7th and 8th abdominal
segments. The abdominal ganglia of the ventral chain are concentrated in a
single mass, placed in, or close to, the thorax; the thorax has two other
approximated ganglia, as well as an anterior one that appears to be the
infra-oesophageal.
The metamorphosis is also peculiar; the larva does not differ greatly in
appearance from the adult, and has similar mouth-organs and food-habits.
The wings are developed outside the body at the sides, and appear first,
according to Heeger, after the third moult. The nymph-condition is like
that of a pupa inasmuch as no nourishment is taken, and the parts of the
body are enclosed in a skin: in some species there is power of movement to
a slight degree, but other species are quite motionless. In some cases the
body is entirely bright red, though subsequently there is no trace of this
colour. Jordan distinguishes two nymphal periods, the first of which he
calls the pronymphal; in it the Insect appears to be in a condition
intermediate between that of the larva and that of the true nymph; the old
cuticle being retained, though the hypodermis is detached from it and forms
a fresh cuticle beneath it. This condition, as Jordan remarks, seems
parallel to that of the male Coccid, and approaches closely to complete
metamorphosis; indeed the only characters by which the two can be
distinguished appear to be (1) that the young has not a special form; (2)
that the wings are developed outside the body.
Thrips take their food, it is believed, in the same manner as Aphidae, by
suction; but the details of the process are not by any means certain, and
examination of the stomach is said to have resulted in finding pollen
therein. Walsh thought that Thysanoptera pierce and suck Aphidae. An
elaborate inquiry by Osborn[459] failed to elicit satisfactory confirmation
of Walsh's idea, though Riley and Pergande support it to some extent;
Osborn concludes that the ordinary food is not drawn directly from sap, but
consists of exudation or pollen, the tissues {530}of the plant being
pierced only when a supply of food from the usual sources falls short.
Members of this family have been reputed as being very injurious to
cultivated plants, especially to cereals, and it is said that as a result
the harvests in Europe have been seriously diminished. Several species may
take part in the attacks. These appear to be directed chiefly against the
inflorescence. Lindeman thought that _Limothrips denticornis_ (= _Thrips
secalina_), and _Anthothrips aculeata_ (= _Phloeothrips frumentarius_),
were the most destructive species in an attack of Thrips on corn that he
investigated in Russia. Uzel suggests that injuries due to other causes are
sometimes ascribed to Thrips.[460] In hot-houses these Insects are well
known, and sometimes occasion considerable damage to foliage. The German
horticulturalists call them black-fly, in distinction from Aphidae or
green-fly. Some Thysanoptera live under bark, and even in fungi, and in
Australia they form galls on the leaves of trees. This observation is due
to Mr Froggatt, and is confirmed by specimens he sent to the writer.
Vesicular bodies in the leaves of _Acacia saligna_ were traversed on one
side by a longitudinal slit, and on a section being made, nothing but
Thrips, in various stages of growth, was found inside them. A second kind
of gall, forming masses of considerable size on the twigs of _Callistemon_,
is said by Mr Froggatt to be also due to Thrips, as is a third kind on
_Bursaria spinosa_. It is curious that Thrips' galls have not been observed
in other parts of the world.
Thysanoptera are devoured by small bugs of the genus _Triphleps_, as well
as by beetles; a small Acarid attacks them by fixing itself to the body of
the Thrips. Nematode worms and their eggs were found by Uzel in the
body-cavity. He found no less than 200 Nematodes in one Thrips, and noticed
that they had entirely destroyed the ovaries. Woodpeckers, according to
him, tear off the bark of trees and eat the Thysanoptera that are concealed
thereunder, though one would have surmised that these minute Insects are
too small to be game for such birds. They have, it appears, no special
protection, except that one species (a larva of _Phloeothrips_ sp.) is said
to emit a protective fluid.
Parthenogenesis seems to be frequent amongst Thysanoptera, {531}and is
found in concurrence with diversity as to winged and wingless females of
the same species, so as to have given rise to the idea that the phenomena
in this respect are parallel with those that are more widely known as
occurring in Aphidae. Under certain circumstances few or no males are
produced (one of the circumstances, according to Jordan, being season of
the year), and the females continue the species parthenogenetically. In
other cases, though males are produced they are in very small numbers. Some
species of Thysanoptera are never winged; in others the individuals are
winged or wingless according to sex. But there are other cases in which the
female is usually wingless, and is exceptionally winged. The winged
specimens in this case are, it is thought, of special use in disseminating
the species. Jordan has suggested that these phenomena may be of a regular
nature, but Uzel does not take this view. Another condition may be
mentioned, in which the species is usually wingless, but winged individuals
of the male as well as of the female sex occasionally appear. _Thrips lini_
apparently makes regular migrations, feeding at one time underground on the
roots of flax, and then changing to a life in the open air on other plants.
Numerous forms of Thysanoptera, belonging to both of the great divisions of
the Order, have been found fossil in Europe and North America, but all are
confined to deposits of the Tertiary epoch.
Of the 135 species known to Uzel, 117 are European; they are divided into
two Sub-Orders. 1, Terebrantia, in which the females are provided with an
external toothed ovipositor, of two valves; 2, Tubulifera, in which there
is no ovipositor, and the extremity of the body is tubular in both sexes.
The British species are about 50 in number, and were described by Haliday
about 60 years ago;[461] of late they have been very little studied.
The name Physopoda or Physapoda is used for this Order, instead of
Thysanoptera, by several naturalists.
{532}CHAPTER VIII
HEMIPTERA—OR BUGS
ORDER IX. HEMIPTERA.
_Mouth consisting of a proboscis or mobile beak (usually concealed by
being bent under the body), appearing as a transversly-jointed rod or
grooved sheath, in which are enclosed long slender setae (like
horse-hairs). Wings (nearly always) four; the anterior frequently more
horny than the posterior pair, and folding flat on the back, their apical
portions usually more membranous than the base_ (Heteroptera); _or the
four wings may cover the abdomen in a roof-like manner, and those of the
anterior pair may not have the basal and apical parts of different
consistences_ (Homoptera); _sometimes all four of the wings are
transparent. The young resembles the adult in general form; the wings are
developed outside the body, by growth, at the moults, of the sides of the
hinder portions of the meso- and meta-notum; the metanotal prolongations
being more or less concealed by the mesonotal._
The Hemiptera or Bugs are perhaps more widely known as Rhynchota. In
deciding whether an Insect belongs to this Order the student will do well
to examine in the first place the beak, treating the wings as subordinate
in importance, their condition being much more variable than that of the
beak. The above definition includes no reference to the degraded Anoplura
or Lice. These are separately dealt with on p. 599; they are absolutely
wingless, and have an unjointed proboscis not placed beneath the body, the
greater part of it being usually withdrawn inside the body of the Insect.
The Hemiptera are without exception sucking Insects, and {533}the
mouth-organs of the individual are of one form throughout its life. In this
latter fact, coupled with another, that the young are not definitely
different in form from the adult, Bugs differ widely from all other Insects
with sucking-mouth. They agree with the Orthoptera in the facts that the
mouth does not change its structure during the individual life, and that
the development of the individual is gradual, its form, as a rule, changing
but little. In respect of the structure of the mouth, Orthoptera and
Hemiptera are the most different of all the Orders. Hence, Hemiptera is
really the most isolated of all the Orders of Insects. We shall
subsequently see that, like Orthoptera, the Order appeared in the
Palaeozoic epoch. Although a very extensive Order, Hemiptera have for some
incomprehensible reason never been favourite objects of study. Sixty years
ago Dufour pointed out that they were the most neglected of all the great
Orders of Insects, and this is still true; our acquaintance with their
life-histories and morphology especially being very limited.
[Illustration: Fig. 255—_Eusthenes pratti_ (Pentatomidae). China. A, Nymph:
_a_, case of anterior, _b_, of posterior wing; _c_, orifices of
stink-glands; B, the adult Insect.]
There is probably no Order of Insects that is so directly connected with
the welfare of the human race as the Hemiptera; indeed, if anything were to
exterminate the enemies of Hemiptera, we ourselves should probably be
starved in the course of a few months. The operations of Hemiptera,
however, to a large extent escape observation, as their mouth-setae make
merely pricks that do not attract notice in plants; hence, it is probable
that {534}injuries really due to Hemiptera are frequently attributed to
other causes.
In the course of the following brief sketch of the anatomy and development
of Hemiptera, we shall frequently have to use the terms Heteroptera and
Homoptera; we may therefore here mention that there are two great divisions
of Hemiptera having but little connection, and known by the above names:
the members of these two Sub-Orders may in most cases be distinguished by
the condition of the wings, as mentioned in the definition at the
commencement of this chapter.
EXTERNAL STRUCTURE.—The mouth-parts consist of an anterior or upper and a
posterior or lower enwrapping part, and of the organs proper, which are
four hair-like bodies, dilated at their bases and resting on a complex
chitinous framework. The lower part forms by far the larger portion of the
sheath and is of very diverse lengths, and from one to four-jointed: it is
as it were an enwrapping organ, and a groove may be seen running along it,
in addition to the evident cross-segmentation. The upper covering part is
much smaller, and only fills a gap at the base of the sheath; it can
readily be lifted so as to disclose the setae; these latter organs are
fine, flexible, closely connected, rods, four in number, though often
seeming to be only three, owing to the intimate union of the components of
one of the two pairs; at their base the setae become broader, and are
closely connected with some of the loops of the chitinous framework that is
contained within the head. Sometimes the setae are much longer than the
sheath; they are capable of protrusion. Although varying considerably in
minor points, such as the lengths of the sheath and setae, and the number
of cross-joints of the sheath, these structures are so far as is known
constant throughout the Order. There are no palpi, and the only additions
exceptionally present are a pair of small plates that in certain forms
(aquatic family Belostomidae) lie on the front of the proboscis near the
tip, overlapping, in fact, the last of the cross-articulations.
Simple as is this system of trophi its morphology is uncertain, and has
given rise to much difference of interpretation. It may be granted that the
two portions of the sheath are respectively upper lip, and labium; but as
to the other parts wide difference of opinion still prevails. On the whole
the view most generally accepted, to the effect that the inner pair of the
setae correspond {535}in a broad sense with maxillae of mandibulate
Insects, and the outer pair with mandibles, is probably correct. Mecznikow,
who studied the embryology,[462] supports this view for Heteroptera, but he
says (_t.c._ p. 462), that in Homoptera the parts of the embryo
corresponding with rudimentary maxillae and mandibles disappear, and that
the setae are subsequently produced from peculiar special bodies that are
at first of a retort-shaped form; the neck of the retort becoming
afterwards more elongate to form the seta; also that in the Heteropterous
genus _Gerris_ the embryology in general resembles that of Homoptera, but
the development of the setae is like that of other Heteroptera (_t.c._ p.
478). This discontinuity in the development of the Homopterous mouth has
since been refuted by Witlaczil,[463] who found that the retort-shaped
bodies really arise from the primary segmental appendages after they have
sunk into the head. We are therefore justified in concluding that the
mouth-parts are at first similarly developed in all Hemiptera, and that
this development is of a very peculiar nature.
[Illustration: Fig. 256—Mouth-parts of Hemiptera. (After Wedde.) A, Section
of the head and proboscis of _Pyrrhocoris apterus_: _dr_, gland; _i.g_,
infra-oesophageal ganglion; _lb_, labium; _lr_, labrum; _m_, muscles; _m_^1
muscle (depressor of labium); _m_^2, muscle of syringe; _ph_, pharynx; _s_,
setae; _s.g_, supra-oesophageal ganglion; _sp. dr_, salivary gland; _spr_,
syringe: B, transverse section of proboscis of _Pentatoma rufipes_, at
third joint of sheath: _m_, _m_, muscles; _md_, mandibular seta; _mx_,
maxillary setae; _n_, nerve; _p_, the sheath or labium; _tr_, trachea.]
Smith is convinced that there are no traces of mandibular structure in any
Hemiptera.[464] On the other hand, numerous entomologists have supposed
they could homologise satisfactorily various parts of the Hemipterous
trophi with special parts of the {536}maxillae and labium of mandibulate
Insects. This point has recently been discussed by Marlatt[465] and by
Heymons.[466] From the latter we gather that the mode of growth is peculiar
by the extension backwards of some of the sclerites, and their becoming
confounded with parts of the wall of the head. From all this it appears
that at present we cannot correctly go farther than saying that the trophi
of Hemiptera are the appendages of three head-segments, like those of other
Insects. The views of Savigny, Léon,[467] and others to the effect that
labial palpi, and even other parts of the labium of Mandibulata can be
satisfactorily identified are not confirmed by Heymons.
Underneath the pharynx, in the head, there is a peculiar structure for
which we have as yet no English term. It was apparently discovered by
Landois and Paul Mayer,[468] and has been called "Wanzenspritze," which we
translate as syringe. It may be briefly described as a chamber, into which
the salivary ducts open, prolonged in front to the neighbourhood of the
grooves of the setae in the rostrum; behind, it is connected with muscles;
it has no direct connection with the pharynx, and though it was formerly
supposed to be an organ of suction, it seems more probable that it is of
the nature of a force-pump, to propel the products of some of the bug's
glands towards the tips of the setae.
The rostrum being extended from its position of repose, the tip of the
sheath is brought into contact with the object to be pierced, the surface
of which is probably examined by means of sensitive hairs at the extremity
of the sheath; these therefore functionally replace to some extent the
palpi of other Insects. As a rule the sheath does not penetrate (though
there is reason for believing that in various of the animal-feeding bugs it
does so), but the setae are brought into action for piercing the skin of
the plant; they are extremely sharp, and the outer pair are usually barbed,
so that when once introduced a hold is easily maintained. This being
established it is thought that the salivary pump comes into play, and that
a fluid is injected into the object pierced so as to give rise to
irritation or congestion, and thus keep up a supply of fluid at the point
operated on: this fluid extends along the grooved setae by capillary
attraction, and the {537}rapidity of the current is increased by a pumping
action of the pharynx, and possibly by movements of the setae themselves.
Though the setae are often extremely elongate—sometimes several times the
length of the body—they are nearly always slender, and there is no reason
to suppose that a perfect, or air-tight, tube is formed; hence it is
probable that capillary attraction is really the chief agent in the
ingestion of the fluid. The slight diversity of structure of the
Hemipterous trophi is in very striking contrast with what we find in
mandibulate Insects, and in the less purely suctorial Insects, such as
Diptera and some divisions of Hymenoptera. Schiödte in commenting on this
has suggested that it is probably due to the small variety of actions the
rostrum is put to.[469]
[Illustration: Fig. 257—_Saccoderes tuberculatus_ Gray. Brazil. (Fam.
Reduviidae.) (Antennae absent in the specimen represented.)]
The head exhibits great variety of form; in the Homoptera the front part is
deflexed and inflexed, so that it is placed on the under surface, and its
anterior margin is directed backwards; it is often peculiarly inflated; in
the Lantern-flies or Fulgoridae (Fig. 282) to an incomprehensible extent.
In the great Water-bugs, Belostomidae, there is on the under surface a deep
pocket for each antenna, beautifully adapted to the shape of the
curiously-formed appendage (Fig. 279). The prothorax is always very
distinct, frequently large, and in many of the Heteroptera (Fig. 257), as
well as in the Homopterous family, Membracidae (Fig. 283), assumes the most
extraordinary shapes. Both meso- and meta-thorax are well developed. The
former is remarkable for the great size of the scutellum; in some cases
(Plataspides, Scutellerides) this forms a large process, {538}that entirely
covers and conceals the alar organs, so that the Insect has all the
appearance of being apterous. The exact composition of the abdomen has not
been satisfactorily determined, opinions varying as to whether the segments
are nine, ten, or eleven in number. The difficulty of determining the point
is due to two facts: viz. the extreme modification of the terminal segments
in connection with the genital appendages, and the prominence of the
extremity of the alimentary canal. If this terminal projection is to be
treated as a segment, it would appear that eleven segments exist, at any
rate in some cases; as the writer has counted ten distinct segments in a
young Coreid bug, in addition to the terminal tube. This tube in some of
the male Heteroptera is very subject to curious modifications, and has been
called the rectal cauda. Verhoeff considers that ten segments were
invariably present in the females examined by him in various families of
Heteroptera and Homoptera.[470] In Aphidae (a division of Homoptera),
Balbiani considers there are eleven abdominal segments present; but he
treats as a segment a projection, called the cauda, situate over the anus;
this structure does not appear to be homologous with the rectal cauda we
have just mentioned. In Coccidae the number of abdominal segments is
apparently reduced. Schiödte states[471] that the older authorities are
correct in respect of the stigmata; there are, he says, in Heteroptera
invariably ten pairs; one for each thoracic segment; and seven abdominal,
placed on the ventral face of the pleural fold of the abdomen. In some
cases there are additional orifices on the external surface that have been
taken for stigmata, though they are really orifices of odoriferous glands;
these openings may exist on the metasterna or on the dorsal surface of the
abdomen. The lateral margins of the abdomen are frequently greatly
developed in Heteroptera, and are called "connexivum;" the upper and lower
surfaces of the body meeting together far within the marginal outline. Dr
Anton Dohrn many years ago[472] called attention to the extremely
remarkable structure of the terminal segments in many male Hemiptera; and
the subject has been subsequently very imperfectly treated by the present
writer and other entomologists, but it has never received the attention it
deserves.
{539}In the females of numerous Heteroptera and Homoptera (Capsidae,
Cicadidae, etc.) there is a well-developed ovipositor, that serves both as
a cutting instrument to make slits in the stems of plants, and as a
director to introduce the eggs therein. Verhoeff considers that it always
consists of two pairs of processes (though one pair may be very small), one
from the eighth abdominal segment, the other from the ninth.[473]
The antennae usually have very few joints, often as few as four or five,
their maximum number of about twenty-five being attained in the males of
some Coccidae, this condition being, however, present in but few of even
this family. In _Belostoma_ (Fig. 279) they assume extremely curious forms,
analogous to what we find in the Coleopterous genus _Hydrophilus_. In
addition to the compound eyes, there are usually ocelli, either two or
three in number, but wanting in many cases. The usual number of joints of
the tarsi is three, but in Coccidae there is only one joint.
[Illustration: Fig. 258.—Alar organs of a Capsid bug (_Capsus laniarius_).
A, Elytron: A, clavus; B, corium; C, cuneus; D, membrane; E, E, cell of the
membrane; B, hind-wing.]
The wings (Fig. 258) exhibit much diversity. The anterior pair usually
differ greatly from the posterior; they are called elytra, hemi-elytra or
tegmina. This difference in the two pairs is the rule in the first of the
great divisions of the Order, and the name Heteroptera is derived from the
fact. In this Sub-Order the front wings close over the back, and are more
or less horny, the apical part being, however, membranous. Systematists
make use of the wings for the purpose of classification in Heteroptera, and
distinguish the following parts, "clavus," "corium," "membrane," the corium
being the larger horny division, the clavus the part lying next the
scutellum and frequently very sharply distinguished from the corium; the
membrane is the apical part. The outer or costal part of the wing is also
often sharply delimited, and is called the "embolium;" in the great family
Capsidae and a few others, the outer apical part of the {540}corium is
differentiated from the rest of the surface, and is termed the "cuneus." In
Plataspides, one of the divisions in which the alar organs are entirely
covered by the scutellum, they are modified in a very remarkable manner. In
the Homoptera the divisions named above do not exist, and the wings in
repose are placed in a different position, as stated in our definition of
the Order. It is said to be very difficult to homologise the wing-nervures
of Hemiptera, and nothing appears to be known as to the mode of their
development.
The alar organs in Hemiptera exhibit a very frequent form of variation
within the limits of the same species; this has not yet been
elucidated.[474] In some cases in the Heteroptera nearly all the
individuals of a generation may have the wings aborted; sometimes this
occurs as a local variation. In Aphidae the occurrence of winged and
wingless individuals is very common, and has even become an important
factor in their extraordinary life cycles. (See _Chermes_, etc.,
subsequently.)
INTERNAL ANATOMY.—The alimentary canal presents considerable diversity and
some remarkable features. There is a slender tube-like oesophagus and a
large crop. It is difficult to assign any of the parts posterior to this to
the divisions usual in other Insects, and it is said that the distinction
of parts histologically is as vague as it is anatomically. In the
Heteroptera the Malpighian tubes open into two (or one) vesicular
dilatations seated immediately in front of the short rectum: between this
point and the crop there may be a very elongate, slender portion with one
or more dilatations, these parts apparently replacing the true or chylific
stomach. There is no gizzard. In the Homoptera the relations of the
divisions of the alimentary canal are even more puzzling; the canal is
elongated and forms coils, and these are connected with tissues and tunics
so as to make their dissection extremely difficult. List says that there
are great differences in the alimentary canal among the members of the one
family Coccidae. There are usually four Malpighian tubes, but in Coccidae
there is only one pair, and in Aphidae none. The excretory cells of these
tubes are in Hemiptera of remarkably large size. There is a large
development of salivary glands, at least two pairs existing. There can be
little doubt that some of their products are used for purposes of
injection, as {541}already described, though Künckel came to the conclusion
that the saliva when placed in living plants is totally innocuous.[475]
The ganglia of the nervous system are all concentrated in the thorax and
head. In some cases (in various Homoptera) the infra-oesophageal ganglion
is placed at a distance from the supra-oesophageal ganglion, and may even
be united with the thoracic mass of ganglia (_Orthezia_, etc.); in this
case the chitinous framework of the mouth-parts is interposed between the
supra- and the infra-oesophageal ganglia. In _Pentatoma_ all the three
ganglionic masses are brought into close proximity, but in _Nepa_ the
thoracic mass of ganglia and the infra-oesophageal ganglion are widely
separated.
The ovarian tubes vary greatly in number: according to List in _Orthezia
cataphracta_ the number differs considerably in different individuals, and
even in the two ovaries of the same individual, the number being usually
two. The testes are not placed in a common tunic, though they are
frequently approximated or even contiguous.[476]
The smell of bugs is notorious. In many species it is not unpleasant,
though as a rule it is decidedly offensive. It is a remarkable fact that
the structures connected with the production of this odour are different in
many cases in the young and in the adult. The odour emitted by the latter
proceeds from a sac seated at the base of the abdomen, and opening
exteriorly by means of an orifice on each side of the metasternum; while in
the young there are two glands situated more dorsally and a little more
backwards, and opening on two of the dorsal plates of the abdomen (Fig.
255, A).[477] In the young the dorsum of the abdomen, where the
stink-glands open, is exposed, but this part in the adult is covered by the
wings. The odorific apparatus is specially characteristic of Heteroptera,
and Künckel states that there is so much variety that generic and even
specific characters might be drawn from conditions of the stink-glands. As
a rule they are most constantly present in the plant-feeding forms; in some
essentially carnivorous forms (Reduviidae, Nepidae, {542}Notonectidae) they
are entirely absent. The offensive matter emitted by _Notonecta_ is of a
different nature, and is probably anal in origin.
METAMORPHOSIS OR POSTEMBRYONIC DEVELOPMENT.—In the language of the
systematists of metamorphosis, Hemiptera are said to be Homomorpha
Paurometabola—that is, the young differ but little from the adult.
According to Brauer's generalisations they are Menorhynchous,
Oligonephrous, Pterygogenea, _i.e._ they have a sucking mouth that does not
change during life, few Malpighian tubes, and are winged in the adult
state. It is generally admitted that the Homoptera do not completely agree
with Heteroptera in respect of the metamorphosis, it being more marked in
the former, and in Coccidae attaining (as we shall mention when discussing
that family) nearly if not quite the condition of complete metamorphosis of
a peculiar kind. Unfortunately we are in almost complete ignorance as to
the details of the life-histories and development of Heteroptera, so that
we can form no generalised opinion as to what the post-embryonic
development really is in them, but there are grounds for supposing that
considerable changes take place, and that these are chiefly concentrated on
the last ecdysis. The young of some bugs bear but little resemblance to the
adult; the magnificently-coloured species of _Eusthenes_ (Fig. 255), before
they attain the adult condition are flat, colourless objects, almost as
thin as a playing-card; it is well known that the extraordinary structures
that cover and conceal the body in Plataspides, Scutellerides, Membracides,
etc., are developed almost entirely at the last moult: it is not so well
known that some of these changes occur with much rapidity. A very
interesting account of the processes of colour-change, as occurring in
_Poecilocapsus lineatus_ at the last ecdysis, has been given by
Lintner,[478] and from this it appears that the characteristic coloration
of the imago is entirely developed in the course of about two hours,
forming a parallel in this respect with Odonata. When we come to deal with
Aphidae we shall describe the most complex examples of cycles of
generations that exist in the whole of the animal kingdom.
FOSSIL HEMIPTERA.—Hemiptera are believed to have existed in the Palaeozoic
epoch, but the fossils are not numerous, and opinions differ concerning
them. _Eugereon hockingi_, a {543}Permian fossil, was formerly supposed to
be a Homopterous Insect, but it is very anomalous, and its claim to a
position in Hemiptera is denied by Brauer,[479] who considers it to be
Orthopterous. It is now generally recognised that this fossil requires
complete reconsideration. Another Permian fossil, _Fulgorina_, is admitted
to be Homopterous by Scudder, Brauer and Brongniart. Scudder thinks the
Carboniferous _Phthanocoris_ was an Archaic Heteropterous Insect, and if
correct this would demonstrate that both of the two great Sub-Orders of
Hemiptera existed in Palaeozoic times. Brauer, however, is inclined to
refer this fossil to Homoptera, and Brongniart[480] speaks of it as being
without doubt a Fulgorid. _Dictyocicada_, _Rhipidioptera_ and
_Meganostoma_, from the Carboniferous shales of Commentry, have also been
referred to Fulgoridae by Brongniart, but the evidence of their alliance
with this group is far from satisfactory. In the Secondary epoch numerous
Hemiptera existed, and are referred to several of the existing families.
They come chiefly from the Oolite. In the Eocene of the Isle of Wight a
fossil has been discovered that is referred to the existing Homopterous
genus _Triecphora_.
We are not entitled to conclude more from these facts than that Homoptera
probably appeared before Heteroptera, and date back as far as the
Carboniferous epoch.
CLASSIFICATION AND FAMILIES.—No complete catalogue of Hemiptera exists, but
one by M. Severin is in course of publication. It is probable that there
are about 18,000 species at present described, two-thirds of this number
being Heteroptera. In Britain we have about 430 species of Heteroptera and
600 of Homoptera. The classification of the Order is not in a very advanced
condition. The following table exhibits the views of Schiödte[481] in a
modified form:—
Front of head not touching the coxae. I. Heteroptera.
Front of head much inflexed so as to be in contact with the coxae.
II. Homoptera.
Sub-Order I. Heteroptera.
Posterior coxae nearly globose, partly embedded in cavities, and having
a rotatory movement. Mostly terrestrial forms. 1. Trochalopoda.
Posterior coxae not globose, larger, and not embedded; their articulation
with sternum almost hinge-like. Posterior aspect of hind femur usually
more or less modified for the reception of the tibia when closed on{544}
it: mostly aquatic forms. 2. Pagiopoda.
Division 1. Trochalopoda.
This division includes the majority of the families of Heteroptera—viz.
the whole of the terrestrial families except Saldidae, and it also
includes Nepidae, a family of water-bugs.
Division 2. Pagiopoda.
This includes the six purely aquatic families of Heteroptera, except
Nepidae, which appear to have very little connection with the other
aquatic bugs. The only terrestrial Insects included in the family are the
Saldidae; in these the femora are not modified as they are in the aquatic
forms. Hemiptera that live on the surface of water, not in the water, are
classed with the terrestrial species. With these exceptions this
arrangement agrees with that of GYMNOCERATA and CRYPTOCERATA as usually
adopted,[482] and therefore followed in the following pages. Schiödte's
characters, moreover, do not divide his two divisions at all sharply.
Sub-Order II. Homoptera.
Tarsi usually three-jointed Series Trimera.
" " two-jointed " Dimera.
" " of one joint " Monomera.
The classification of Homoptera is in a most unsatisfactory state;[483]
no two authors are agreed as to the families to be adopted in the series
Trimera. We have recognised only five—viz. Cicadidae, Fulgoridae,
Membracidae, Cercopidae, and Jassidae. The Dimera consists of Psyllidae,
Aphidae, Aleurodidae; and the Monomera of Coccidae only. It is usual to
associate the Dimera and Monomera together under the name of either
Phytophthires or Sternorhyncha, but no satisfactory definition can be
given of these larger groups, though it seems probable that the families
of which they are composed are natural and distinct.
Sub-Order I. HETEROPTERA.
SERIES 1. GYMNOCERATA.
The majority of the terrestrial families of Heteroptera form the series
Gymnocerata, in which the antennae are conspicuous, and can be moved about
freely in front of the head, while in {545}Cryptocerata they are hidden.
The series Gymnocerata includes all the terrestrial Heteroptera, and the
two families, Hebridae and Hydrometridae, which live on the surface of the
water or in very damp places; while Cryptocerata includes all the forms
that live under water.
[Illustration: Fig. 259—_Phloea corticata._ South America.]
FAM. 1. PENTATOMIDAE.—_Scutellum very large, at least half as long as the
abdomen, often covering the whole of the after-body and alar appendages.
Antennae often five-jointed. Proboscis-sheath four-jointed. Ocelli two.
Each tarsal claw with an appendage._—This, the largest and most important
family of the Heteroptera, includes upwards of 4000 species, and an immense
variety of forms. It is divided into no less than fourteen sub-families.
The species of one of these, Plataspides, are remarkable for their short,
broad forms, and the peculiar condition of the alar organs, which are so
completely concealed by the great scutellum that it is difficult to believe
the Insects are not entirely apterous. The head is usually inconspicuous
though broad, but in a few forms it is armed with horns. Though this
sub-family includes upwards of 200 species, and is very widely distributed
in the Old World, it has no representatives in America. The Scutellerides
also have the body covered by the scutellum, but their organs of flight are
less peculiar than they are in the Plataspides; the Insects of this
sub-family are highly remarkable on account of their varied and frequently
vivid coloration; some of them are metallic, and the colour of their
integuments differs greatly in some cases, according to whether the
specimen is wet or dry; hence the appearance after death is often very
different from that of the living specimen. These Insects are extremely
numerous in species. The sub-family Phloeides (Fig. 259), on the contrary,
includes only three or four South American species: they have no
resemblance at all to other Pentatomidae; they are flat, about an inch
long, and look like scales of bark, in this respect agreeing with _Ledra_
and some other Homoptera. The South American sub-family Cyrtocorides (Fig.
260) is of {546}equally small extent; the species are of strange irregular
shapes, for which we can find no reason. The Tessaratomides includes many
of the largest Hemiptera-Heteroptera, some of its members attaining two
inches in length.
The great family Pentatomidae, containing about 400 species, is represented
in Britain by about 36 native species, the most interesting of which are
perhaps those of the genus _Acanthosoma_. De Geer noticed long ago that the
female of _A. griseum_ exhibits great solicitude for its young, and his
statement has since been confirmed by Mr. Parfitt and the Rev. J. Hellins,
who found that the mother not only protects the eggs but also the young,
and that for a considerable time after hatching.[484]
[Illustration: Fig. 260—_Cyrtocoris monstrosus._ South America, × 3.]
Very little is known as to the life-histories of Pentatomidae. In some
cases the young are very different in appearance from the adults. The
peculiar great scutellum is not developed till the mature condition is
reached. But little attention has been given to the habits of Pentatomidae;
it is generally considered that they draw their nutriment from plants; the
American _Euthyrhynchus floridanus_ has, however, been noticed to suck the
honey-bee, and we think it probable that a good many Pentatomids will be
found to attack Insects.
The term Pentatomidae as applied to this family is of modern origin: in
most books the equivalent group is called Scutata, or Scutati, and the term
Pentatomidae is restricted in these works to the sub-family called
Pentatomides in the system we adopt.
FAM. 2. COREIDAE.—_Scutellum not reaching to the middle of the body;
proboscis-sheath four-jointed; ocelli present; antennae generally elongate
and four-jointed, inserted on the upper parts of the sides of the head;
femora not knobbed at the tip._—The members of this great family are easily
recognised by the above characters; formerly it was called Supericornia in
connection with the characteristic position of the antennae. About 1500
species are known, and they are arranged in no less than twenty-nine
sub-families. Many of them are Insects of large size, and they frequently
have a conspicuous disc, or dilatation, on one of the joints of the
antennae.
{547}[Illustration: Fig. 261.—_Diactor bilineatus._ South America. × 3/2.
Fig. 262—_Phyllomorpha laciniata_, carrying some of its eggs. Spain.]
Another very curious and, as yet, inexplicable peculiarity very commonly
met with among them, is that the hind legs may be of great size and
deformed; either the femora or the tibiae, or both, being very much
distorted or armed with projections. Brilliant colour is here comparatively
rare, the general tone being indefinite tints of browns, greys, or smoky
colours. The South American genus _Holymenia_ (_Copius_ of older authors)
consists of slender forms, having the elytra transparent even on the basal
part like Homoptera; this and some other peculiarities give the species of
this genus a certain resemblance to Insects of other Orders; Westwood says
that _Diateina holymenoides_ (Diptera) greatly resembles a bug of the genus
_Holymenia_. The tropical American genus _Diactor_ consists of a few
species of elegant colour having the hind legs very peculiarly shaped, the
tibiae being flattened and expanded in a sail-like manner, and ornamented
with agreeable colours different {548}from those on the rest of the body;
they are made more conspicuous by the femora being remarkably long and
thin; it is probable that they are used as ornaments. The subfamily
Phyllomorphides consists of about a dozen species, and is found in several
of the western parts of the Eastern hemisphere, one species, _P.
laciniata_, occurring in Southern Europe. This Insect is of very delicate
texture, and the sides of the body are directed upwards and deeply divided
so that a sort of basin is formed, of which the dorsum of the body is the
floor; the Insect is very spinose, and is thus enabled to carry its eggs,
the spines helping to retain them in position on the back. It is said to be
the male that thus carries the eggs. This species is able to stridulate,
and when doing so vibrates its antennae with excessive rapidity. We have
only about a score of species of Coreidae in Britain, and none of the
remarkable forms of the family are among them.
FAM. 3. BERYTIDAE.—_Very slender Insects with the first joint of the
antennae and the femora thickened at the tips._—This small family was not
distinguished from Coreidae by the older authors. It consists of about
fifty species, eight of which are found in Britain.
FAM. 4. LYGAEIDAE.—_The characters are the same as those mentioned for
Coreidae, except as regards the insertion of the antennae; the upper
surface or face of the head is not so flat, but is transversely convex, so
that seen in profile the antennae appear to be inserted well down on the
sides of the head._—The name Infericornia was formerly applied to these
Insects. They are on the average of smaller size than the members of the
Coreidae or Pentatomidae, and are much less conspicuous in colour and form;
a good many of the larger Lygaeids are, however, variegate with black,
yellow, and red. The family is very numerous in species, about 1400 being
known; they are arranged in thirteen sub-families; we have about sixty
species in Britain, nearly all small. _Eremocoris_ lives, when immature, in
the nests of the wood-ant, according to Wasmann. The family includes some
notorious Insect-pests. The Chinch-bug, _Blissus leucopterus_, commits very
serious ravages on corn and grasses in North America. The Cotton-stainer,
_Dysdercus suturellus_ is also very injurious to cotton in certain parts of
the New World: its growth has been described by Riley,[485] who thinks a
dye valuable for {549}commercial purposes might be procured from the
Insect. This bug has recently developed the habit of sucking oranges, and
has thus become injurious in Florida, as the fruit readily decays after it
has been punctured by these Insects. The phenomenon of "micropterism" is
exhibited by numerous Lygaeids, as well as by Pyrrhocoridae.
FAM. 5. PYRRHOCORIDAE.—_Distinguished from Lygaeidae only by the absence of
ocelli_, and not recognised as a distinct family by all Hemipterists. About
300 species are included. Our only British member is the notorious
_Pyrrhocoris apterus_; it is, however, very rare in this country, though it
abounds on the Continent, and has been the object of investigation by
embryologists and others. It displays in a most marked manner the curious
dimorphism as to the alar organs that is so common in certain divisions of
Hemiptera; the elytra and wings being sometimes normally developed, while
in other cases the wings are entirely absent, and the horny, basal part of
the elytra only is present. In some localities, and in some years, only the
micropterous form is found, while on other occasions there may be a large
percentage of the macropterous form. The abundance of this Insect has
enabled the French chemist Physalix to obtain an amount of its colouring
matter sufficient for analysis; as the result he procured a substance,
insoluble in water, very closely allied to carotine.[486] The Oriental
Insect _Lohita grandis_ is one of the most remarkable of Bugs, the male of
the Sumatran variety being over two inches in length, having enormously
long antennae, and the abdomen extended to about twice the normal length,
while the other sex is in the usual condition in these respects. The
species is said to be injurious to the cotton-plant in India.
FAM. 6. TINGIDAE.—_Tarsi two-jointed. Elytra more or less reticulate,
consisting of strong, irregular, thick lines forming a framework of cells,
the enclosed part of the cell being of different texture and frequently
transparent; antennae with terminal joint more or less knob-like, the
preceding joint very long; ocelli wanting; pronotum prolonged behind,
covering the scutellum; front coxae placed at the lack of the thorax._—This
is the first of a series of families with only two joints to the feet.
These little bugs are very remarkable objects, and exhibit much variety in
their peculiar {550}sculpture, which in numerous forms attains a condition
of elegance well worthy of attention. There are nearly 300 species known,
and in Britain we have about a score. The characters we have given above do
not apply to the genus _Piesma_, though it is usually placed in this
family; its scutellum is not covered, and ocelli are present. Although but
little is known as to the nature of the lives of Tingidae, yet it was
pointed out long ago by Réaumur that a species of the family (probably _C.
clavicorne_, Fig. 263), lives in deformations of the flowers of the Labiate
plant now called _Teucrium chamaedrys_; Frauenfeld has more recently
confirmed this observation, and shown that the closely allied _C. teucrii_
affects the flowers of _T. montanum_ in a similar manner.[487]
[Illustration: Fig. 263—_Copium clavicorne._ Europe. (After Rübsaamen.)]
[Illustration: Fig. 264—_Aradus orientalis._ Siam.]
FAM. 7. ARADIDAE.—_Very flat, broad; scutellum exposed, large or moderate;
abdomen broader than the alar organs, which it frequently encases like a
broad frame. Front coxae placed in the middle of the prosternum._—These
very flat Insects, of obscure colour, have frequently very peculiar
sculpture. They live under bark, or on fungi growing from bark, and are
supposed to draw their nutriment from the fungi, though but little is
actually known as to their natural history. The family is almost
cosmopolitan, and includes about 300 species, of which five occur in
England. The small sub-family Isoderminae consists of a few species that
are placed only provisionally in Aradidae; they differ from the normal
members by there being no groove on the {551}breast, so that the rostrum is
free. Of the five species, three occur in Chili and Patagonia, two in
Tasmania, and one in Australia.
FAM. 8. HEBRIDAE.—_Minute bugs, of semiaquatic habits, clothed beneath with
a dense, minute, silvery pubescence; antennae five-jointed; legs of not
more than average length; elytra in larger part membranous._—This small
family consists altogether of only about a dozen species; we have two
species of the genus _Hebrus_ in Britain; they are usually found in very
wet moss.
[Illustration: Fig. 265.—_Halobates sobrinus._ Under surface of a female
carrying eggs. Pacific Ocean (Marquesas).]
FAM. 9. HYDROMETRIDAE.—_Form very diverse; antennae four-jointed, tarsi
two-jointed. Coxae usually widely separated. Either wingless or with elytra
of one texture throughout, having no membranous part. Under surface with a
minute velvet-like pubescence. In many forms the legs are of great
length._—Although of comparatively small extent—scarcely 200 species being
at present known—this family is of great interest from the habit possessed
by its members of living on the surface of water. In the case of the
notorious genus _Halobates_ (Fig. 265) the Insects can even successfully
defy the terrors of Neptune and live on the ocean many hundreds of miles
from land. There is great variety of form among Hydrometridae. The European
and British genus _Mesovelia_ is of short form, and but little dissimilar
from ordinary land-bugs, with which, indeed, it is connected by means of
the genus _Hebrus_, already noticed. _Mesovelia_ represents the sub-family
Mesoveliides, which, though consisting of only four species, occurs in both
hemispheres, and in the tropics as well as in the temperate regions. Our
species, _M. furcata_, walks on the surface of the water, the movements of
its legs and the position of its coxae being those of land-bugs. Another
British Insect—the highly remarkable _Hydrometra stagnorum_—is of
excessively slender form, with long thin legs, by aid of which it
{552}walks on the surface-film of water, above which its body is held well
separated. It is easily drowned, and if submerged it has great difficulty
in escaping from the water. This genus represents the sub-family
Hydrometrides, and is apparently almost cosmopolitan. _Velia currens_ is
another common British Insect; it loves the eddies and currents of
backwaters on burns and streams, and is very abundant in Scotland. An
American ally, _Rhagovelia plumbea_, appears to be not uncommon on the
surface of the ocean in the Gulf of Mexico, near the shores. The great
majority of the family belong to the division Gerrides, of which the
curious, long Insects that float so lazily and skim so easily on the
surface of quiet streams are typical. The species of the genus now called
_Gerris_, but formerly known as _Hydrometra_ are apparently distributed all
over the world; we have ten in Britain. They have very long legs, and on
being alarmed move away with the greatest ease.
The genus _Halobates_ includes at present fifteen species. They are found
on the ocean, where the surface-water is warm, in various parts of the
world. They are destitute of any trace of alar organs, the meso- and
meta-thorax are closely united and large, while the abdomen is very small,
so that the body is of oval form; the middle legs are thrown so far back
that they are placed immediately over the posterior pair. When the sea is
calm these Insects skim over the surface with rapidity, but disappear as
soon as it becomes agitated. They are believed to feed on small animals
recently deceased; Witlaczil says on the juices of jelly-fish. The young
are frequently met with, and there can be no doubt that the whole
life-cycle may be passed through by the Insect far away from land. The
Italian ship _Vettor Pisani_ met with a bird's feather floating on the
ocean off the Galapagos Islands, covered with eggs which proved to be those
of _Halobates_ in an advanced stage of development. It was formerly
believed that the female carries the eggs for some time after their
exclusion, and although this has since been denied, it is nevertheless an
undoubted fact, for it was observed by Mr. J. J. Walker,[488] to whom we
are indebted for a specimen having the eggs still attached to the body, as
shown in Fig. 265. Mr. Walker believes the bugs shelter themselves when the
sea is at all rough by keeping at a sufficient distance {553}below the
surface; they can dive with facility, and are gregarious. They are
frequently found close to the shore, and Mr. Walker has even met with them
on land. The stink-glands of other Hemiptera are said by Nassonoff to be
replaced in _Halobates_ by peculiar ventral glands. An allied genus,
_Halobatodes_, was supposed to be oceanic, but this is not the case, some
of the species having been found recently in fresh water in India, and
others in estuaries at Port Darwin. A remarkable allied form, _Hermatobates
haddoni_, was recently discovered by Professor Haddon in Torres Straits.
Apart from the oceanic life, _Halobates_ is by no means the most
extraordinary of the Hydrometridae. The Javanese _Ptilomera laticaudata_
repeats some of its peculiarities, and is of larger size, with the sexes
very different. The most remarkable of the family is perhaps the
fresh-water genus _Rheumatobates_ (Fig. 266), in which the males have
peculiar prehensile antennae that look like legs. These curious Insects
inhabit North America and the West Indies.
[Illustration: Fig. 266—_Rheumatobates bergrothi._ × 10. West Indies.
(After Meinert.)]
We may here notice an enigmatic Insect called _Hemidiptera haeckeli_ by
Léon. From the single specimen known it is concluded that the Insect has
only one pair of wings, and that they are attached to the metathorax. It
is, however, possible, as {554}suggested by Bergroth,[489] that the
anterior pair have been detached by some accident.
FAM. 10. HENICOCEPHALIDAE.—_Head swollen behind the eyes so as to form a
sort of globe, on the anterior part of which the ocelli are placed. Rostrum
extremely short. Elytra rather large, of one consistence throughout;
conspicuously veined._—There is only one genus; it is very widely
distributed, about a dozen species being known; one of these occurs in the
south of Europe. These curious little bugs appear to be most nearly allied
to the Reduviidae. According to Westwood and others they are somewhat
gregarious; a Tasmanian species dances in the air after the fashion of
midges or May-flies, and dispenses an agreeable, musk-like odour.
[Illustration: Fig. 267—_Carcinocoris binghami_ (Phymatidae). Burma.]
FAM. 11. PHYMATIDAE.—_Front legs of peculiar structure, short and stout,
with long coxae, short thick femora, and tibiae curvate, pointed;
frequently without tarsi._—The Insects of this family are believed to be
predaceous, the structure of the legs being such as is called raptorial,
and one species, _Phymata erosa_, being known to capture and suck
honey-bees in North America. There are only about seventy species of
Phymatidae known. We have {555}none in Britain, though there are a few in
Southern Europe; one of these, _P. crassipes_, extends as far north as
Paris. The distinction of the family from Reduviidae is doubtful.[490]
There are a few very rare forms (Fig. 267) in which the front tibia is
articulated to the femur in such a way that a pair of pincers is formed:
the tarsus is in this form, as well as in some other Phymatidae, absent.
[Illustration: Fig. 268—_Ghilianella filiventris._ Brazil. A, the female
Insect. B, extremity of the body of the male.]
FAM. 12. REDUVIIDAE.—_Head more or less elongate, very movable, eyes placed
much in front of the thorax, ocelli, when present, behind the eyes.
Proboscis short, or moderately short, not extending on to the breast, in
repose curved under the head so as to form a loop therewith. Elytra, when
present, consisting of three divisions. Tarsi three-jointed._—This is one
of the largest and most important families of Hemiptera. Upwards of 2000
species are already known; the habits seem to be chiefly of a predaceous
nature, the creatures drawing their nutriment from the animal rather than
from the vegetable kingdom, and their chief prey being in all probability
other kinds of Insects. There is, perhaps, no family of Insects exhibiting
a greater variety of form and colour. The Emesids are amongst the most
delicate of Insects, equalling in this respect the {556}daddy-long-leg
flies; they are, however, highly predaceous; their front legs are
peculiarly formed for capturing and holding their prey, and have long
coxae, like _Mantis_, so that these Insects are commonly mistaken for small
or young Mantises, from which their sucking proboscis at once distinguishes
them. This curious starved-looking form of bug reaches its maximum of
peculiarity in the South American genus _Ghilianella_ (Fig. 268). According
to Pascoe the linear form enables the young larva to be carried about by
the mother, the long slender abdomen of the larva being curled around the
thorax of the parent. _Ploiaria pallida_, from Woodlark Island, is an
Insect of excessive fragility and elegance, with the long thin legs
coloured with alternate patches of black on a white ground, giving rise to
a very curious appearance remarkably analogous to what we find in some of
the equally delicate daddy-long-leg flies.
[Illustration: Fig. 269—_Nabis lativentris_, young. Cambridge. A, Insect
seen from above; B, profile.]
We have three species of Emesides in Britain, but most of our Reduviidae
belong to the sub-family Nabides. These approximate to ordinary bugs in
appearance and characters more than do any other of the Reduviidae. One of
our indigenous Nabides is of great interest from the curious resemblance it
has to an ant (Fig. 269). The likeness is brought about by the sides of the
base of the abdomen being very pallid in colour, except a dark mark in the
middle; this mark is in shape like the pedicel of an ant. Viewed in profile
it is found that on the base of the abdomen there is an elevation like the
"scale" in this position in {557}ants, and that the abdomen is extremely
ant-like in form. This resemblance is quite parallel with that of an
Orthopteron to an ant (see Vol. V. p. 323); the Insect is by no means
uncommon, and it is strange that this curious case of resemblance should
hitherto have escaped notice. The bug runs about on plants and flowers, and
is frequently in company with ants, but we do not know whether it preys on
them. Not the least remarkable of the facts connected with this Insect is
that the resemblance is confined to the earlier instars; the adult bug not
being like an ant. We may here mention that there are numerous bugs that
closely resemble ants, and that on the whole there is reason to believe
that the resembling forms are actually associated during life, though we
really know very little as to this last point.
[Illustration: Fig. 270—_Ptilocnemus sidnicus._ Australia. (After Mayr.)]
[Illustration: Fig. 271—_Myiodocha tipulina._ China.]
The little sub-family Holoptilides, with twenty-five species, but widely
distributed in the Eastern hemisphere, is remarkable on account of the
feathered {558}antennae and legs of its members (Fig. 270). Altogether
fourteen sub-families are recognised, the most extensive one being
Harpactorides, including a great variety of remarkable forms; in the South
American genus _Notocyrtus_ (better known as _Saccoderes_, Fig. 257), the
prothorax is swollen and covers the body to a greater or less extent in the
fashion of a hood. In _Yolinus_ and _Eulyes_ the coloration is the most
conspicuous system that could be devised, the sides of the abdomen
(connexivum) being expanded into bright-red lobes on which are placed
patches of polished-black. The most remarkable form of Reduviid is,
perhaps, one from China (Fig. 271) of considerable size, of great
fragility, and greatly resembling, like some Emesides, a daddy-long-legs
fly, though it does not belong to the Emesides. It is an altogether
anomalous form. According to Seitz there is found on the Corcovado in
Brazil a Reduviid that exactly resembles one of the dark stinging-wasps of
the genus _Pepsis_, and the bug makes the same sort of movements as the
wasp does, though these are of a kind quite different from those of
ordinary bugs.[491]
[Illustration: Fig. 272—Eggs of _Endochus cingalensis_. "The eggs are
attached to a leaf and to each other by a viscid substance; eggs red, the
cover pale yellow, with the club white at the tip."—MS. note of E. E.
Green.]
Although the attacks of Reduviidae on animals are usually confined to the
smaller and more defenceless kinds, yet this is by no means invariably the
case; there are in fact numerous species that do not hesitate to attack man
himself. Several species of _Reduvius_ do this in Southern Europe, and are
frequently met with in houses. _R. personatus_ is the only species of the
genus in England; though far from common anywhere, it is sometimes found in
houses, and is said to destroy the common bed-bug; it is able to pass its
whole existence in our habitations, for the young are found as frequently
as the adult, and are usually concealed by a quantity of dusty matter, or
refuse, adhering to the body. This habit of covering the body with some
foreign substance is natural to the Insect, the young that are found on
trees being covered with matter derived therefrom. Darwin has given us an
account of {559}the Benchucha,[492] a bug an inch long, which in South
America attacks human beings after the fashion of the common bed-bug. In
this case no ill-effects follow the attack, but in the case of _Conorhinus
sanguisuga_ in Arizona, great pain and inflammation ensue and may end in
the gathering and discharge of pus.
Not the least remarkable of characters of _Reduviidae_ is the form of the
eggs of some of the species (Fig. 272, and Vol. V. Fig. 78, C); the egg
bearing a peculiar operculum, the purpose of which is at present quite
mysterious.
FAM. 13. AËPOPHILIDAE.—A single species forms this family. It is of
considerable interest, as it is incapable of flight, passing a large part
of its life covered by the sea. _Aëpophilus bonnairei is a small Insect
with quite short head, without ocelli, and with the organs of flight
represented by a pair of very short elytra, with rounded hind-margins._ It
is found on the shores of Western France, and, as a great rarity, on our
own south coast. It no doubt sucks small soft animals. In the Channel
Islands it occurs in spots where it is nearly always covered by a
considerable depth of water.
FAM. 14. CERATOCOMBIDAE.—_Minute bugs with ocelli and elytra. Rostrum free.
Head not broad, somewhat prolonged in front; eyes close to the thorax.
Elytra usually without a distinctly separated membrane. Tarsi
three-jointed._—This family includes at present only a few, minute, fragile
bugs, that have often been classified with Cimicidae or Anthocoridae. We
have only two British species, one of which, _Dipsocoris alienus_, is
common amongst the damp shingle at the margins of the burns and waters of
Scotland.
FAM. 15. CIMICIDAE.—_Ocelli absent; elytra very short and broad, so that
the broad abdomen is left uncovered. Head short and broad. Rostrum received
in a groove beneath the head. Tarsi three-jointed._—Although this family
consists of only a dozen species, it is the most notorious of all the
Order, as it includes the detestable _Cimex lectularius_ or common Bed-bug.
This Insect is now peculiar to the habitations of man, and is said not to
trouble savage races; or rather it is supposed to be present only when the
habitations have a certain degree of comfort and permanence. It has no
fixed period of the year for its development, but the generations succeed
one another so long as the temperature {560}is sufficiently elevated;
during too cold weather the Insects merely become stupefied, their lives
being as it were interrupted till warmth returns. It is a favourite food
with other Insects, and is destroyed by cockroaches and ants as well as by
_Reduvius_; the small black ant _Monomorium_ will, it is said, clear a
house of the bed-bug in a few days. Nothing is really known as to the
origin of this Insect; it is now very widely distributed. The other species
of the family frequent birds and bats, and are very similar to the common
bug. The genus to which the bed-bug belongs is in many works called
_Acanthia_ instead of _Cimex_. Other authors apply the term _Acanthia_ to
_Salda_, but it is better to allow the name _Acanthia_ to fall into disuse.
FAM. 16. ANTHOCORIDAE.—_Minute bugs, usually with ocelli and with elytra;
the latter occasionally abbreviated, but usually fully developed, with
membranous tip. Head prolonged in the middle in front much beyond the
insertion of the antennae; eyes not far from the thorax. Rostrum
free._—These small and obscure Insects appear to be rather numerous in
species, and to be chiefly connected with woods and forests. Some of the
species live in ants' nests. We have 27 British species belonging to 11
genera. About 200 species of the family are known. The members of the
sub-family Microphysides are remarkable from the great dissimilarity of the
sexes, for which it is not possible to assign any reason.
[Illustration: Fig. 273—_Polyctenes fumarius._ (After Westwood.)]
FAM. 17. POLYCTENIDAE.—_Proboscis-sheath three-jointed, tarsi four-jointed,
antennae four-jointed. Tegmina quite short, of one consistence._—The four
or five anomalous species forming this family are parasites on bats of the
genus _Molossus_, and have been found in both the Eastern and Western
hemispheres. Westwood, who first described {561}them,[493] treated them as
aberrant Anoplura or Lice, but there do not appear to be any sufficient
grounds for removing these parasites from Hemiptera-Heteroptera. The
condition of their alar organs reminds one of what exists in _Cimex_ and
_Aëpophilus_, and the mouth is not known to possess any very peculiar
structure. We have had no opportunity of making a thorough examination of
_Polyctenes_, and therefore speak with some diffidence.
[Illustration: Fig. 274—_Helopeltis_ sp. East India.]
[Illustration: Fig. 275—Section of a stem with egg of a Capsid bug allied
to _Helopeltis_ (Moesa-blight). × 58. (After Dudgeon.)]
FAM. 18. CAPSIDAE.—_Moderate-sized or small bugs, of delicate consistence,
without ocelli; the elytra and wings usually large in proportion to the
body, the former with two cells (occasionally only one) in the membrane.
Antennae four-jointed, the second joint usually very long, the terminal two
more slender than the others. The proboscis not received in a groove.
Scutellum exposed, moderately large. Tarsi three-jointed. Female with an
ovipositor capable of exsertion._—This family is one of the most extensive
of the Hemiptera; we have about 170 species in Britain, where they are most
abundant in the south. The exotic species have been but little collected.
Their colours are usually delicate rather than vivid, and are never
metallic. They frequent plants of all kinds, and many of them skip by the
aid of their wings with great agility in the sunshine. The majority
probably suck the juices of the plants, but some are known to prey on other
Insects. The species of the Indian genus _Helopeltis_ (Fig. 274) are
remarkable by possessing a knobbed spine projecting straight up from the
scutellum, making the individual look as if it were a specimen with a pin
through {562}it: they attack the tea-plant and do considerable damage. They
are known as Mosquito-blight. The egg is of comparatively large size, and
is placed by the bug in the stems of the tea-plant, but attached to one end
of the egg are two long slender threads that project externally. A similar
egg (Fig. 275) and method of oviposition have been described by Mr. Dudgeon
as occurring in another species of Capsidae, called Moesa-blight, in
India.[494]
FAM. 19. SALDIDAE.—_Head short and broad, with large, prominent eyes.
Ocelli present. Proboscis not applied to under surface of head or breast in
repose. Scutellum large, not covered. Elytra covering the upper surface of
the abdomen, formed of three distinct parts. Tarsi three-jointed._—These
little bugs run with velocity over mud in damp places, or live in wet moss;
some of them can jump; they are all of dark or obscure colour. There are
only three genera: _Salda_, of which we have numerous British species,
being the principal one.
SERIES 2. CRYPTOCERATA.
The remaining families of Heteroptera are of aquatic habits, and form in
nearly all works a separate division called Hemiptera Cryptocerata (or
Hydrocorisae, or Hydrocores), distinguished by the antennae being
apparently absent; they are, however, really present, being situate on the
under side of the head, to which they are closely pressed, or in some cases
placed in a pocket in front of each eye. There are six of these families.
Schiödte is doubtless correct in treating this division as an unnatural
one; it is, however, generally adopted, and is convenient for the purposes
of nomenclature and arrangement.
FAM. 20. GALGULIDAE or PELOGONIDAE.—_Form short and broad; head very broad,
with prominent eyes, ocelli present. Hind legs thin, formed for
running._—The Insects of this family are but little known; they are only
sub-aquatic in habits, frequenting damp places at the margins of streams
and waters. The presence of ocelli distinguishes them from other
water-bugs, with which indeed the Galgulidae appear to be but little
related. There are only about twenty species of the family known. We
possess none in Britain; but one, _Pelogonus marginatus_, occurs {563}in
South Europe. The other members of the family are very widely scattered
over the surface of the earth.
FAM. 21. NEPIDAE.—_Abdomen furnished behind with a long slender siphon;
front legs more or less elongate for capturing prey, placed quite at the
front edge of the prothorax._—This family consists of two interesting but
very dissimilar genera, _Nepa_ and _Ranatra_. Both are widely distributed
over the earth, and are rather numerous in species.[495] We have one
species of each genus in Britain. _Nepa cinerea_, the common
"water-scorpion," is one of the commonest of Insects in Southern Britain,
living concealed in shallow waters when nearly or quite stagnant. _Ranatra
linearis_ (Fig. 276) is much less common, and appears to be getting rarer;
it is not recorded from farther north than Cambridge.
[Illustration: Fig. 276.—_Ranatra linearis_, with the two portions, _a_, of
the respiratory siphon separated. Cambridge.]
The nature of the respiratory arrangements in these Insects is of
considerable interest; the long tube at the extremity of the body consists
of two parts (as shown in Fig. 276) brought together in the middle, one
from each side. Lacaze-Duthiers states that the processes are elongated
pleurae, but in the young it is far from clear that this is the case.
However that may be, they seem to convey air to the true breathing organs,
situate inside the cleft on the apical part of the abdomen itself; but
details as to the way in which transfer of air is effected along this
{564}very protracted passage are not forthcoming. The development in _Nepa_
has been studied to a certain extent. The apical stigmata are the only pair
of the abdominal stigmata that exist in the imago of _Nepa_, the other six
pairs being obliterated; the third, fourth, and fifth, according to
Schiödte, in a very peculiar manner: hence, as Martin says,[496] the
respiratory system is metapneustic. In an earlier stage of the life,
however, these six pairs of stigmata exist in functional activity placed in
a groove on the under surface of the body; so that the condition is that
termed peripneustic, and remains so till the final moult, when the long
siphon appears. In the early life there is a short prolongation from the
end of the body in connection with the pair of grooves alluded to, but it
is a single unpaired organ, and does little therefore to explain the
appearance of the siphon, which must, at present, be considered as being
suddenly developed at the last moult.
[Illustration: Fig. 277—Egg of _Nepa cinerea_. (After Korschelt.)]
The eggs of Nepidae are remarkable objects; that of the common
water-scorpion bears seven filaments at one end (Fig. 277); while that of
_Ranatra_ is more elongate, and bears only two, very elongate, threads.
These eggs are deposited in the stems of water-plants, being introduced
therein, so that the body of the egg is concealed while the threads
project: those of _Ranatra_ are placed in stems floating on the water, and
in consequence of the threads the stems look as if they were infested by
some fungus. The structure and formation of the eggs have been investigated
with considerable detail by Korschelt.[497] He looks on the filaments as
pneumatic, and considers that they supply a coating of air to the body of
the egg; they consist of a spongy mass encircled by two layers of
egg-shell, both of these latter being peculiar in structure; the spongy
mass is continuous with a layer of the same kind of substance placed on the
interior of the shell of the body {565}of the egg. It will be recollected
that we have described (p. 562) an egg, apparently of the same nature,
deposited by Capsids in the stems of land plants, so that it is very
doubtful whether the threads are really connected with the aquatic
development of the embryo in Nepidae. But the most interesting feature
connected with these eggs is, according to Korschelt, the mode of
development of the filaments, which is _sui generis_; the shell of the egg
is developed in the ordinary manner as an exudation or excretion from
epithelial cells; but the shell of the filament is formed as an
intracellular product; a mode of chitin-formation that appears to be
peculiar to this structure. Korschelt remarks that "it is in the highest
degree worthy of attention how by any process of development through a
large number of successive generations so complex a condition could be
established as the result of adaptation to external conditions; and this
becomes even more interesting when we remember that highly peculiar special
processes and departures from the usual modes of tissue-formation are
necessary to permit the development of this apparatus."[498]
FAM. 22. NAUCORIDAE.—_No ocelli, and no terminal process to the body; front
legs inserted on or near the front of the prosternum. Anterior femora
usually broad and flat._—The members of this family are truly aquatic, and
swim readily in the water. The family is small, including about nine genera
and thirty species, but, like many water-Insects, the genera are widely
distributed. We have two in Britain—one of them, _Naucoris_, common; the
other, _Aphelocheirus_, rare.
FAM. 23. BELOSTOMIDAE.—_No ocelli, and no long terminal tube to the body;
front legs inserted near the front of the prosternum. Posterior tibiae not
spiny; flattened and provided with swimming hairs._—Although these Insects
have been classified with Nepidae they have but little relation therewith;
on the other hand, the distinctions from Naucoridae are far less important.
The family includes some of the largest Insects. The South American
_Belostoma grande_ attains a length of four or four and a half inches.
Notwithstanding their considerable size Belostomidae exist in very large
numbers in some localities, and frequently destroy young fish by aid of the
powerful though short rostrum.
{566}[Illustration: Fig. 278—_Zaitha anura_, carrying eggs on its back.
West Indies.]
[Illustration: Fig. 279—Antenna of _Belostoma_ sp. A, One side of the under
surface of the head, with antenna, _b_, extended; B, with the antenna
retracted, _a_, Side of head; _c_, pocket for antenna; _d_, position of the
eyes. The corresponding joints of the antenna are numbered 1, 2, 3, 4 in
each figure.]
They appear to be unable to resist the attraction of artificial light, and
are consequently sometimes destroyed in large numbers. It has long been
known that species of the genera _Diplonychus_ and _Zaitha_ carry their
eggs on their backs. There is no special receptacle for the purpose, but
the eggs are kept in their peculiar position by means of a cement insoluble
in water. It has been stated by Dimmock that they are placed in position by
means of a long, flexible ovipositor. Schmidt, however, found that a
specimen of _Diplonychus_, bearing eggs and examined by him, was a male,
and he subsequently found that this was the case with other egg-bearing
individuals of other species, so that the mode in which the eggs are placed
in this position and the object of so curious a habit, remain uncertain.
The species of _Belostoma_ are highly remarkable on account of the curious
and complex structure of their antennae, in respect of which the nearest
analogy is to be found in the large Coleoptera of the genus _Hydrophilus_.
A very deep, ear-like pocket, exactly suited to the form of the antennae,
exists on the under side of the head; hence in repose no sign of the
peculiar shape of the antennae exists. When the antennae are placed in this
ear-like pocket only the one side of the basal joints is exposed, the long
processes being received into the deep pocket. In _Hydrophilus_ the antenna
is used as an accessory organ of respiration, and it will be interesting to
learn whether this is also the case in _Belostoma_. Belostomidae have
patches of air-carrying pubescence, analogous with those of _Hydrophilus_,
on the under sides of the body, elytra and wings, but we do not {567}know
how they are charged. Another extremely interesting analogy is found in the
manner in which the elytra are locked to the body; a projection from the
thoracic side-pieces, forming a long pouch, into which a fold on the inner
side of the elytra fits, the two being subsequently locked by the action of
some special projections. This arrangement is similar to that which exists
in the anomalous family of water-beetles Pelobiidae. In order to make this
mechanism more perfect the side-pieces in _Belostoma_ form free processes.
Martin has informed us that the young have the metasternal episternum
prolonged to form a lamella that he thinks may be for respiratory
purposes.[499] About twelve genera and upwards of fifty species of
Belostomidae are known. None exist in our isles, but several species extend
their range to Southern Europe. In the waters of the warm regions of the
continents of both the Old and New Worlds they are common Insects, but as
yet they have not been found in Australia.
FAM. 24. NOTONECTIDAE.—_Prosternum short, so that the legs are placed near
the back part of it as well as near the front; back of the head overlapped
by the front of the pronotum._—The water-boatmen are extremely common in
our ponds, where they may be seen rising to the surface and raising the
posterior extremity of the body for breathing. They swim on their backs
instead of in the usual position, and have an elaborate arrangement of long
hairs on the body to assist them to carry about an air-supply. They are
said to be lighter than the water, and to have some difficulty in keeping
away from the surface. _Notonecta glauca_ is the only British species, but
we have a second minute Insect, _Plea minutissima_, belonging to the
family. It lies in the mud at the bottom of shallow waters, and may
sometimes be fished up in great numbers. It is considered by some authors
to form a distinct family. The oviposition of _Notonecta_ has been observed
by Regimbart; the eggs are inserted into the stems of aquatic plants.
FAM. 25. CORIXIDAE.—_Prosternum short, as in Notonectidae; summit of the
head free from the thorax._—We have numerous species of the genus Corixa in
Britain; and others extremely similar in appearance occur in various parts
of the world. The head is remarkably free, and capable of great rotation.
On dissection it is found to be attached to the thorax only by a
{568}narrow area; in this respect it differs widely from _Notonecta_, which
possesses an extremely large occipital foramen, and the head of which
possesses but little freedom of movement. The extremely short proboscis is
more or less retractile, and therefore frequently appears absent. A second
British genus consists of a single species, _Sigara minutissima_. These
Insects, unlike _Notonecta_, are quite at home beneath the water, where
they scurry about with extreme rapidity, and occur sometimes in enormous
numbers. In Mexico the eggs of _Corixa americana_ and of _C. femorata_ are
used as food, and are said to be very nice. The Insects themselves are used
as food in both Mexico and Egypt. The species of this family can make a
noise beneath the water by rubbing the front feet against the
proboscis.[500] The males have a very complex asymmetry of the terminal
segments, and in some species possess on one side of the dorsal surface a
curious asymmetrical organ consisting of rows of very closely-packed,
intensely black, comb-like plates, called by Buchanan White a strigil. This
organ seems to be similar to the peculiar structures found on the terminal
segments of certain species of Scutellerides.
Sub-Order II. HOMOPTERA.[501]
FAM. 1. CICADIDAE.—_Head with three ocelli, placed triangularly on the
summit between the compound eyes; antennae consisting of a short basal
joint, surmounted by a hair-like process divided into about five segments.
Front femora more or less thick, armed with teeth. Peduncle (or basal
joints) of antennae without sensitive organs._—This important family
consists chiefly of large Insects, few being as small as one inch across
the expanded wings, while in some the expanse is as much as seven inches.
As a rule the four wings are transparent and shining, with the nervures
remarkably distinct and dark coloured; but there are numerous forms where
the whole creature, including the wings, is highly pigmented in a showy
manner; frequently in black and yellow. Cicadas are said to be without any
special protection, and to be destroyed in considerable numbers by birds
and other animals. The body is broad and robust, and is never shaped into
the extravagant forms we meet with in some of the other families of
Homoptera.
{569}[Illustration: Fig. 280—_Cicada septendecim._ North America. (After
Riley.) A, Larva; B, nymph; C, nymph skin after emergence of the imago, D;
E, section of twig with series of eggs; F, two eggs magnified.]
Cicadidae are almost confined to the warmer regions of the earth, but we
have one species, a great rarity, in the extreme south of England;
altogether there are about 800 species known. These Insects are seen above
ground—so far as the life-histories are at present known—only in the
perfect condition, the creatures in their earlier stages being subterranean
and living on roots. As soon as the individual comes out of the ground it
splits open the nymph-skin, and the perfect Cicada emerges. One species—the
North American _Cicada septendecim_—is a most notorious Insect owing to its
life-cycle of seventeen years. It is considered that the individual, after
nearly seventeen years of underground existence, comes to the surface and
lives for a brief period the life of a noisy Insect. This is the only
Insect at present known having so considerable a longevity. This fact, and
several other peculiarities, have attracted much attention, so that there
is an extensive literature connected with the seventeen-year Cicada. It has
a wide distribution over the United States, but does not confine its
appearance to every seventeenth year, being found somewhere or
other—frequently in numerous localities—almost every year. The evidence as
to its periodicity has been obtained by taking the locality and other
points into consideration as well as the year of appearance. {570}By so
doing it has been found possible to establish the existence of twenty-two
broods which are distinguished by consecutive numeration. This being done,
the evidence as to the years during which Cicadas have appeared in any
given locality is examined, and the result is believed to bear out the view
that the life-cycle of the individual Insect is really one of seventeen
years. According to this view there are, underground, in certain localities
individuals of different ages that will appear on the surface as mature
individuals in different years. Thus in 1885 it was understood that there
were underground in Alabama two broods, viz. brood xviii. that would appear
on the surface in 1894, and brood iv. that would appear on the surface in
1896. The predictions made as to the years in which Cicadas would appear in
some given locality are considered to have proved correct. Moreover,
particular entomologists have in certain localities verified by personal
examination the appearance of the Insects for several consecutive periods
of seventeen years. These facts appear fairly conclusive, but they are much
complicated by another point, viz. that in certain localities the period is
one of thirteen, not of seventeen, years. This is to some extent a question
of climate, the thirteen-year interval being chiefly characteristic of the
Southern States. It is not, however, entirely so, for there are localities
in which the broods have an interval of either thirteen years or seventeen
years. Another fact should be remembered, viz. that it is admitted that not
quite all the individuals of a particular brood are true to their proper
time of appearance; in other words, a few specimens may appear precociously
a year or two before their comrades, while some may lag behind to a
considerable extent. It is therefore a matter for great surprise that,
under these circumstances, the broods should keep distinct at all, for one
would suppose that time-variation of this kind would lead to completely
obscuring the distinctness of the broods. We must also call attention to
the fact that both the seventeen-year and the thirteen-year broods have a
dimorphic form, or sub-species, called _C. cassinii_ which accompanies the
ordinary form, with which it is apparently as a rule not connected by
intermediates.[502]
{571}Cicadidae are provided with powerful ovipositors. The eggs of _C.
septendecim_ are deposited in the woody stems of bushes; after remaining
there a few weeks the young hatch out, drop to the ground, and, as
previously stated, disappear for nearly seventeen years, nearly the whole
of which time is passed in the larval state, the nymph-condition existing
for only a few days. They feed on the roots of various trees; it has been
said that they are injurious in this way, but other authorities maintain
that they suck only a moist exudation from the roots. It is very difficult
to obtain information as to their strange, prolonged, subterranean life; it
said that the Insects sometimes penetrate to a great depth—ten feet, even
twenty feet are mentioned;—and as great changes may take place on the
surface during their long lives, these Insect Rip Van Winkles sometimes
emerge in very strange conditions, and may appear even in deep cellars.
When the pupa comes to the surface it hooks itself on to the stem of some
plant or other object, the skin of the back splits, and the Cicada emerges.
Among the inexplicable peculiarities of this Insect must be mentioned the
fact that when emerging it sometimes constructs chimneys, or flues,
extending several inches above the surface of the ground. The reason for
this is much disputed; it was said that they are for refuge against
inundations, but this appears to be very doubtful. Certain of the broods
consist of an almost incalculable number of individuals, and it is very
strange to hear woods, or other localities, that have been for many years
free from these Insects, all at once resounding with their noisy song. The
seventeen-year Cicada is considered to be doomed to a speedy extinction;
the extension of cultivation and building, and the introduction to America
of the English sparrow, are likely to prove too much for the Insect.
Although Hemiptera are classified by many among the Ametabola or Insects
without metamorphosis, it is impossible to deny that the Cicadidae exhibit
a considerable amount of metamorphosis, and they are usually mentioned as
exceptional. The young (Fig. 280, A) is totally unlike the adult in form
and colour, and maintains, to a certain extent, its existence by the aid of
a different set of implements. The larva of the Cicada is colourless, with
an integument of very feeble consistence, rather large antennae, and a
remarkable pair of fossorial legs; {572}the wings are totally wanting. The
mode of passage from the larval to the pupal state has not been recorded.
The pupa, or nymph, differs from the larva by its much shorter, compressed
form; by being encased in a remarkably hard shell; and by the antennae
approximating in form to those of the adult. It has short wing-pads at the
sides of the body; the front legs are remarkably powerful, and the creature
is capable of moving about; the imago escapes from the pupa by the
splitting dorsally of the middle of the thoracic segments. The empty
pupa-skin does not shrivel, but retains its form, and in countries where
Cicadas occur, frequently attracts attention by the strange form it
presents, being often placed in a conspicuous position.
SONG.—Cicadas are the most noisy of the Insect world; the shrilling of
grasshoppers and even of crickets being insignificant in comparison with
the voice of Cicada. Darwin heard them in South America when the _Beagle_
was anchored a quarter of a mile from the shore; and _Tympanoterpes gigas_,
from the same region, is said to make a noise equal to the whistle of a
locomotive.[503] A curious difference of opinion prevails as to whether
their song is agreeable or not; in some countries they are kept in cages,
while in others they are considered a nuisance. The Greeks are said to have
decided in favour of their performances, the Latins against them. Only the
males sing, the females being completely dumb; this has given rise to a
saying by a Greek poet (so often repeated that it bids fair to become
immortal) "Happy the Cicadas' lives, for they all have voiceless
wives."[504] The writer considers the songs of the European species he has
heard far from unpleasant, but he is an entomologist, and therefore
favourably prepossessed; and he admits that Riley's description of the
performances of the seventeen-year Cicada is far from a satisfactory
testimonial to the good taste of that Insect; Riley says, "The general
noise, on approaching the infested woods, is a combination of that of a
distant threshing-machine and a distant frog-pond. That which they make
when disturbed, mimics a nest of young snakes or young birds under similar
circumstances—a sort of scream. They can also produce {573}a chirp somewhat
like that of a cricket and a very loud, shrill screech prolonged for
fifteen or twenty seconds, and gradually increasing in force and then
decreasing." The object, or use of the noise is very doubtful; it is said
that it attracts the females to the males. "De gustibus non est
disputandum!" perhaps, however, there may be some tender notes that we fail
to perceive; and it may be that the absence of any definite organs of
hearing reduces the result of a steam-engine whistle to the equivalent of
an agreeable whisper. No special auditory organs have been detected[505] as
we have already intimated; and certain naturalists, amongst whom we may
mention Giard, think that the Insects do not hear in our sense of the word,
but feel rhythmical vibrations; it is also recorded that though very shy
the Insects may be induced to approach any one who will stand still and
clap his hands—in good measure—within the range of their sensibilities.
There is a good deal of support to the idea that the males sing in rivalry.
VOCAL STRUCTURES.—Although we may not be able to pronounce a final opinion
as to the value to the Insect of the sounds, yet we cannot withhold our
admiration from the structures from which they proceed. These are indeed so
complex that they must be ranked as amongst the most remarkable
voice-organs in the animal kingdom. They are totally different from the
stridulating organs that are found in many other Insects, and are indeed
quite peculiar to the Cicadidae. Some difference of opinion has existed as
to the manner in which the structures act, but the account given by Carlet,
some of whose figures we reproduce, will, we believe, be found to be
essentially correct. The structures are partly thoracic and partly
abdominal. On examining a male _Cicada_ there will be seen on the under
surface two plates—the opercula—usually meeting in the middle line of the
body and overlapping the base of the abdomen to a greater or less extent
according to the species, sometimes nearly covering this part of the body;
these are enlargements of the metathoracic epimera; they can be slightly
moved away from the abdomen, and, as the latter part is capable of a still
greater extent of movement, a wide fissure may be produced, displaying the
complex {574}structures. In order to see the parts it is better to cut away
an operculum; underneath it three membranes can be seen, an external, the
timbal; an anterior, the folded or soft membrane; and a posterior, the
mirror. This last is a most beautiful object, tensely stretched and
pellucid, yet reflecting light so as to be of varied colours; there are
also three stigmata, and some chambers connected with the apparatus. The
sound is primarily produced by the vibrations of the timbal, to which a
muscle is attached; the other membranes are probably also thrown into a
condition of vibration, and the whole skeleton of the Insect helps to
increase or modify the sound, which is probably also influenced by the
position of the opercula. The stigmata probably play an important part by
regulating the tension of the air in the chambers. In the female some of
the structures are present in a rudimentary form, but there are no muscles,
and this sex appears to be really quite voiceless.
[Illustration: Fig. 281.—Musical apparatus of _Cicada plebeia_. (After
Carlet.) A, Ventral view (Operculum on right side is removed); _ap_,
apophysis; C, cavern; _c_, trochantin (cheville of Réaumur); _ent_, part of
internal skeleton of abdomen; _mi_, specular membrane; _m.pl_, soft or
folded membrane; P, base of leg; _st_, _st′_, _st″_, stigmata; _t_, drum
"timbale"; _v_, operculum; _1a_, first, _2a_, second abdominal segment: B,
same seen laterally, portion of abdominal wall as well as operculum
removed; A, point of insertion of hind wing; _Mes_, mesothorax; _sc_,
scutum of metathorax; _3a_, third abdominal segment; rest as in A.]
FAM. 2. FULGORIDAE.—_Ocelli two (rarely three, or entirely obsolete),
placed beneath the eyes or near the eyes, usually in cavities of the
cheeks, antennae placed beneath the eyes, very variable in form; usually of
two joints terminated by a very fine hair, the second joint with a peculiar
texture of the surface, owing to the existence of sensitive structures_
(Hansen). _Form of head very diverse; vertex and face forming either a
continuous curve, or the planes of the vertex and face forming an acute
angle, or both {575}prolonged so as to form a projection or growth that may
be monstrous. Prothorax neither armed nor unusually developed._
[Illustration: Fig. 282—_Fulgora candelaria._ × 1. China.]
This family is of large extent, and includes at present so great a variety
of forms that it is really almost impossible to frame a definition that
will apply to all. The unusual situation of the ocelli and the peculiar
second joint of the antennae must at present be taken as the best
diagnostic characters: occasionally a third ocellus is present. Some of the
Fulgoridae are amongst the largest Insects, others are quite small. The
family includes the so-called Lantern-flies, in which the front of the head
forms a huge misshapen proboscis that was formerly believed to be luminous.
Many of the species are of brilliant or beautiful coloration. A great
many—and of very different kinds—have the curious power of excreting large
quantities of a white, flocculent wax. This is exhibited by our little
British Insects of the genus _Cixius_, and in some of the exotic forms is
carried to an extent that becomes a biological puzzle. The Tropical
American genus _Phenax_ may be cited as an example; being about an inch
long it flies about with a large mass of this waxy substance twice as long
as itself; indeed, in the Mexican _P. auricoma_, the waxy processes are
four or five inches long. This wax forms a favourite food of certain kinds
of Lepidoptera, and two or three larvae of a maggot-like nature may
frequently be found concealed in the wax of the live Fulgorids; this has
been recorded by Westwood as occurring in India; and Champion has observed
it in the New World.[506] {576}The wax of Fulgorids is used by the Chinese
for candles and other purposes; and this white Insect-wax is said to be
much esteemed in India. Very curious chemical substances have been obtained
from it, but its importance in the economy of the Insects that produce it
is quite obscure. We have about seventy species of Fulgoridae in Britain.
They belong to the subfamilies Tettigometrides, Issides, Cixiides, and
Delphacides, which by many authors are treated as separate families. The
exotic subfamily Flatides is highly peculiar. In some of its members the
head is very different from that of the ordinary forms, being narrow, and
the vertex and front forming a continuous curve. Some of these Insects are
remarkably like butterflies or moths (_e.g._ the African _Ityraea
nigrocincta_ and the species of the genus _Pochazia_), but the young are
totally unlike the old, the posterior part of the body bearing a large bush
of curled, waxy projections, several times the size of the rest of the
body.
[Illustration: Fig. 283—A, B, _Heteronotus trinodosus_. A, Male seen from
above; B, profile of female; _a_, terminal part of pronotum; _b_, terminal
part of abdomen: C, front view of head and pronotum of _Cyphonia clavata_.
Both species from Central America. (From _Biol. Centr. Amer. Rhynch.
Homopt._ II.)]
FAM. 3. MEMBRACIDAE.—_Prothorax prolonged backwards into a hood or
processes of diverse forms; antennae inserted in front of the eyes; ocelli
two, placed between the two eyes._—This family is of large extent but its
members are chiefly tropical, and are specially abundant in America.
Although not of large size the Membracidae are unsurpassed for the variety
and grotesqueness of their shapes, due to the unusual development of the
pronotum. We figure two of these forms (Fig. 283).[507] Very little is
known about their {577}habits and life-histories. We have only two species
of the family in Britain, and these do not afford any ground for supposing
that there are any peculiarities in their lives at all commensurate with
the oddness of the Insect's structures. Belt has recorded the fact that in
Nicaragua the larvae of certain Homoptera were assiduously attended by ants
for the sake of a sweet juice excreted by the bugs, but it is by no means
clear that these larvae were really those of Membracidae. In North America
_Ceresa bubalus_ and _C. taurina_ place their eggs in an extremely neat
manner in the woody twigs of trees. The young have but little resemblance
to the adults, the great thoracic hood being absent, while on the back
there is on each segment a pair of long, sub-erect processes having
fringed, or minutely spiny, margins.[508]
FAM. 4. CERCOPIDAE.—_Ocelli two (occasionally absent) placed on the vertex;
antennae placed between the eyes. Thorax not peculiarly formed._—In the
characteristic forms of this family the front of the vertex bears a suture,
touched on each side by one at right angles to it, or converging to it so
as to form a triangle or a sort of embrasure; the hind tibiae have only one
to three strong spines. The Cercopidae are much less extraordinary than
many of the previously considered families. But some of them have the habit
of secreting a large quantity of fluid; and when in the immature stages,
certain of them have the art of emitting the liquid in the form of bubbles
which accumulate round the Insect and conceal it. These accumulations of
fluid are called cuckoo-spits or frog-spits; and the perfect Insects are
known as frog-hoppers, their power of leaping being very great. The most
abundant of the frog-hoppers in our gardens is _Philaenus spumarius_, a
little Insect of about a quarter of an inch long, obscurely coloured, with
more or less definite pale spots; it is so variable in colour that it has
received scores of names. Some of the Insects do not use their fluid in
this manner, but eject it in the form of drops, and sometimes cast them to
a considerable distance. The phenomena known as weeping-trees are due to
Cercopidae; some of the species make such copious exudations of this kind
that the drops have been compared to a shower of rain. In Madagascar it is
said that _Ptyelus goudoti_ exudes so much fluid that five or six dozen
larvae would about fill a {578}quart vessel in an hour and a half. The
frog-spit is considered by some naturalists to be a protective device; the
larvae are, however, a favourite food with certain Hymenoptera, which pick
out the larvae from the spits and carry them off to be used as stores of
provision for their larvae. In Ceylon the larva of _Machaerota guttigera_
constructs tubes fixed to the twigs of the tulip-tree, and from the tube
water is exuded drop by drop. According to Westwood, this Insect is
intermediate between Cercopidae and Membracidae.[509]
FAM. 5. JASSIDAE.—_Ocelli two, placed just on the front margin of the head
(almost in a line with the front of the eyes or more to the front) or on
the deflexed frons. Hind tibiae usually with many spines._ This vaguely
limited family includes a very large number of small or minute Insects,
usually of narrow, parallel form, and frequently excessively delicate and
fragile. They are often mentioned under the name of Cicadellinae. Ashmead
distinguishes two families, Bythoscopidae, in which the ocelli are clearly
on the frons or front, and Jassidae, in which they are on the upper edge
thereof. _Ulopa_, _Ledra_, and a few other exceptional forms, are also by
many distinguished as representatives of distinct families. Very little is
actually known as to the life-histories of these small and fragile Insects,
but it is believed that the eggs are usually deposited in the leaves or
stems of plants, and more particularly of grasses. In North America the
development of _Deltocephalus inimicus_, from hatching to assumption of the
adult form, has been observed by Webster to occupy about six weeks. As
Jassidae are numerous both in species and individuals it is believed that
they consume a considerable part of the vegetation of pastures. Osborn has
calculated that on an acre of pasture there exist, as a rule, about one
million of these hoppers, and he considers they obtain quite as large a
share of the food as the Vertebrates feeding with them.
FAM. 6. PSYLLIDAE.—_Minute Insects with wings usually transparent, placed
in a roof-like manner over the body; with three ocelli, and rather long,
thin antennae of eight to ten joints. Tarsi two-jointed._—These small
Insects have been studied chiefly in Europe and North America, very little
information having yet been obtained as to the exotic forms. They are about
the {579}size of Aphidae, but in form and general appearance remind one
rather of Cicadidae. The wings are in many cases even more perfectly
transparent than they are in many Cicadidae. They are sometimes called
springing plant-lice, as their habit of jumping distinguishes them from the
Aphidae. Löw has called attention to the remarkable variation in colour
they present in conformity with either the age of the individual, the
food-plant, the climate, and, more particularly, the season of the
year.[510] Réaumur long since pointed out that at their ecdyses these
Insects go through a remarkable series of changes of colour, and Löw found
that this did not take place in the normal manner in the winter generation
that hibernates. This has been confirmed by Slingerland in North America in
the case of _Psylla pyricola_,[511] which has been introduced there. He
finds that there are several generations in the year, and that the
hibernating adults differ from the summer adults in size, being nearly
one-third larger; in their much darker colouring; and especially in the
coloration of the front wings.
[Illustration: Fig. 284—_Psylla succincta._ x 15. Europe. (After Heeger.)
A, larva before first moult. B, larva after third moult. C, adult.]
In the earlier stages, Psyllidae differ greatly in appearance from the
adult forms; the legs and antennae in the newly hatched larvae are short,
and have a less number of joints. In the nymph the shape is very peculiar,
the large wing-pads standing out horizontally {580}from the sides of the
body, so that the width of the creature is about as great as the length.
The period occupied by the development apparently varies according to
season. Witlaczil, who has given an account of many details of the anatomy
and histology of various Psyllidae,[512] considers that there are four
larval stages; Heeger's account of _Psylla succincta_ is not quite clear on
this point, and Slingerland indicates a stage more than this, the perfect
Insect being disclosed as the result of a fifth moult; it is probable that
he is correct. In these earlier stages the body bears long hairs called
wax-hairs; according to Witlaczil in the young larvae of certain
species—_Trioza rhamni_, e.g.—these are broad and flat, so as to make the
body appear studded with oval processes; he states that these hairs change
their form during the growth of the individual. Nothing is more remarkable
in Psyllidae than the amount of matter they secrete or exude from their
bodies; in some species the substance is a "honey-dew," and the nymph may
keep itself covered with a drop of it: in other cases it is solid, as shown
in Réaumur's figures of _P. buxi_, where this exudation forms a string
several times longer than the body, and attached to it. Another form of
exudation is a light downy or waxy matter. Slingerland says that honey-dew
was exuded by _P. pyricola_ in such quantities that it "literally rained
from the trees upon the vegetation beneath; in cultivating the orchard the
back of the horse and the harness often became covered with the sticky
substance dropping from the trees. It attracts thousands of ants, bees, and
wasps, which feed upon it." The writer last year observed in the New Forest
a stunted sloe-bush, about which a large number of Bombi were busily
occupied; and examination showed that they were thrusting their proboscides
into the curled and deformed leaves, in which were secreted nymphs of a
_Psylla_ exuding honey-dew. It must not be assumed that this honey-dew is
the excrement of the Insect; this also is known, and is a different
substance. Those who have tasted it say that the honey-dew has a clean,
good flavour. The source of the honey-dew is not quite certain, but it
seems probable that it comes, like the solid matter figured by Réaumur,
directly from the alimentary canal, and not from hairs or pores on the
body. Psyllidae give rise to definite formations or galls on certain
plants; sometimes these Psyllid galls are mere changes in form of a limited
part, or {581}parts, of a leaf, giving rise either to crumpling or to
growth of a portion in one direction only, so that on one surface of the
leaf a swelling is formed, and on the opposite side a more or less deep
cavity in which the Insect dwells. A formation of this kind on the leaves
of _Aegopodium podagraria_ is described by Thomas[513] who states that the
growth is due to the deposition of an egg of the _Psylla_, and is
independent of the after life of the Insect; a fungus—_Puccinia
aegopodii_—forms similar structures on the leaves. Structures much more
definite than this may be the result of the attacks of Psyllidae; for an
example the reader may refer to Réaumur's account of _Psylla buxi_.[514] In
Australia and Tasmania there are Psyllidae known as Laap or Lerp Insects,
the products of which are called leaf-manna or Lerp, and are used as food.
This manna is a scale produced by the young Insect on the leaves of
_Eucalyptus_ as a covering or protection. The scale is fastened to the leaf
by a hinge, and is somewhat like the shell of a cockle. Although the scales
are said to be in some cases objects of great beauty, very little is known
about these Australian Psyllidae, one of which has, however, been referred
by Schwarz to the genus _Spondyliaspis_, Signoret.[515] About 160 species
of Psyllidae are known to occur in the Palaearctic region, and about fifty
of them have been found in Britain.[516]
FAM. 7. APHIDAE (_Plant-lice or Green-fly._)—_Minute Insects; as usually
met with destitute of wings, though many individuals have two pairs of
transparent wings. Antennae long, or moderately long, three- to
seven-jointed; abdomen frequently with a pair of tubes (siphons), or short
processes on the upper side of the fifth abdominal segment. Tarsi
two-jointed, first joint sometimes excessively short._—These soft-skinned
Insects are frequently called blight, and are so abundant in temperate
climates that a garden, however small, is sure to afford abundance of
specimens during the warm months of the year. This great abundance is due
to peculiarities in the physiological processes that render these obscure
little animals highly important creatures; the individual life for several
generations is restricted to constant, or at any rate copious, imbibition
of food, accompanied by an almost uninterrupted {582}production of young by
parthenogenetic females, the young so produced becoming rapidly (sometimes
in the course of eight or ten days, but more usually in about twenty days)
themselves devoted to a similar process; so that in the comparatively short
period of a few months the progeny resulting from a single individual is
almost innumerable. This remarkable state of affairs is accompanied by
other peculiarities of physiology, with the result that the life-histories
of successive generations become very diverse, and complex cycles of series
of generations differing more or less from one another are passed through,
the species finally returning to bi-sexual reproduction, and thus
inaugurating another cycle of generations. The surprising nature of these
facts has in the last 150 years caused an immense amount of discussion, but
no satisfactory light has yet been thrown on the conditions that really
give rise to the exceptional phenomena. These phenomena are (1)
parthenogenesis; (2) oviparous and viviparous reproduction; (3) the
production of generations of individuals in which the sexes are very
unequally represented, males being frequently entirely absent; (4) the
production of individuals differing as to the acquirement of wings, some
remaining entirely apterous, while others go on to the winged form; (5) the
production of individuals of the same sex with different sexual organs, and
distinctions in the very early (but not the earliest) stages of the
formation of the individual; (6) differences in the life-habits of
successive generations; (7) differences in the habits of individuals of one
generation, giving rise to the phenomenon of parallel series. All these
phenomena may occur in the case of a single species, though in a very
variable extent.
The simple form of Aphid life may be described as follows:—eggs are laid in
the autumn, and hatch in the spring, giving rise to females of an imperfect
character having no wings; these produce living young parthenogenetically,
and this process may be repeated for a few or for many generations, and
there may be in these generations a greater or less number of winged
individuals, and perhaps a few males.[517] After a time when temperature
falls, {583}or when the supply of food is less in quantity, or after a
period of deliberate abstention from food, sexual individuals are produced
and fertilised eggs are laid which hatch in the spring, and the phenomena
are repeated. In other cases these phenomena are added to or rendered more
complicated by the intercalated parthenogenetic generations exhibiting
well-marked metamorphosis, of kinds such as occur in apterous or in winged
Insects; while again the habits of successive generations may differ
greatly, the individuals of some generations dwelling in galls, while those
of other generations live underground on roots.
PARTHENOGENESIS.—Returning to the various kinds of peculiarities we have
enumerated on the preceding page, we may remark that the phenomena of
parthenogenesis have been thoroughly established as occurring in Aphidae
since Bonnet discovered the fact 150 years ago; and though they have not
been investigated in much detail it is known that the parthenogenesis is
usually accompanied by the production of young all of the female sex. In
other cases males are parthenogenetically produced; but whether these males
come from a female that produces only that sex is not yet, so far as the
writer knows, established. A note by Lichtenstein[518] suggests that
usually only one sex is produced by a parthenogenetic female, but that both
sexes are sometimes so produced. There is not at present any species of
Aphid known to be perpetuated by an uninterrupted series of parthenogenetic
generations. It was formerly supposed that there are no males at all in
_Chermes_, but, as we shall subsequently show, this was erroneous. It has,
however, been observed that a series of such generations may be continued
without interruption for a period of four years, and we have no reason to
suppose that even this could not be much exceeded under favourable
conditions. The parthenogenetic young may be produced either viviparously
or oviparously, according to species.
OVIPAROUS AND VIVIPAROUS REPRODUCTION.—The distinction between these two
processes has been extensively discussed, some naturalists maintaining that
they are thoroughly distinct _ab initio_. This view, however, cannot be
sustained. The best {584}authorities are agreed that in the earliest
processes of individualisation the ovum, and the pseudovum[519] giving rise
to a viviparous individual, are indistinguishable. Leydig, Huxley,
Balbiani, and Lemoine are agreed as to this. Nevertheless, differences in
the development occur extremely early. The nature of these differences may
be briefly described by saying that in the viviparous forms the embryonic
development sets in before the formation of the egg is properly completed.
Balbiani says, "In fact at this moment [when the viviparous development is
commencing] the germ [pseudovum] is far from having obtained the
development it is capable of, and from having accumulated all the matter
necessary for the increase of the embryo, so that the evolution of the
former coincides, so to speak, with that of the latter. On the other hand,
in the true ovum the two processes are chronologically separate, for the
rudiment of the new individual never appears before the egg has completed
the growth of its constituent parts."[520] As regards the difference in
structure of the organs of viviparously and oviparously producing
individuals, it is sufficient to remark that they are not of great
importance, being apparently confined to certain parts remaining
rudimentary in the former. Leydig, indeed, found an _Aphis_ in which
certain of the egg-tubes contained eggs in various stages of development,
and others embryos in all stages.[521]
As regards the physiology of production of winged and wingless individuals
there has been but little exact inquiry. Vast numbers of individuals may be
produced without any winged forms occurring, while on the other hand these
latter are occasionally so abundant as to float about in swarms that darken
the air; the two forms are probably, however, determined by the supply of
food. The winged forms are less prolific than the apterous forms; and
Forbes has noticed in _Aphis maidi-radicis_, where the generations consist
partly of apterous and partly of winged individuals, that when the corn
begins to flag in consequence of the attacks of the _Aphis_, then the
proportion of {585}winged individuals becomes large.[522] The appearance of
winged individuals is frequently accompanied by a peculiar change of habit;
the winged individuals migrating to another plant, which in many cases is
of a totally different botanical nature from that on which the apterous
broods were reared: for instance _Aphis mali_, after producing several
apterous generations on apple, gives rise to winged individuals that
migrate to the stems of corn or grass, and feeding thereon commence another
cycle of generations. The study of this sort of Aphis-migration is chiefly
modern, but many very curious facts have already been brought to light;
thus _Drepanosiphum platanoides_, after producing a certain number of
viviparous generations on maple (_Acer_), quits this food-plant for
another, but after two or three months returns again to the maple, and
produces sexual young that lay eggs.[523] Histories such as this are rather
common. Even more interesting are the cases of those species that, after
some weeks of physiological activity on a plant, pass into a state of
repose on the same plant, and then after some weeks produce sexual young.
On the whole, it would appear that the appearance of winged forms is a
concomitant of decreasing nutrition. It is a very remarkable fact that the
sexually perfect females are invariably apterous, and this is frequently
also the case with the males. It is also highly remarkable that the
sexually perfect individuals are of comparatively small size. There are at
least three kinds of males in Aphidae—1, winged males; 2, wingless males
with mouth well developed; 3, wingless small males with mouth absent. As
regards some of these points the conditions usual in Insect life are
reversed.[524] Huxley inclined to treat all these products of a fertilised
egg, that are antecedent to another process of gamogenesis (_i.e._
production with fertilisation), as one zoological individual: in that case
the Aphis zoological individual is winged before attaining the mature
state, and is wingless and smaller when mature. Some species may have as a
rule two, others three, winged generations in a year.
{586}[Illustration: Fig. 285—_Chermes abietis_; hibernating female or
"winter-mother." Europe. Much magnified. (After Cholodkovsky.)]
PARALLEL SERIES.—In certain cases individuals of one generation assume
different habits, and so set up the phenomenon known as parallel series.
This has been recently investigated in the genus _Chermes_ by Blochmann,
Dreyfus, and Cholodkovsky. This latter savant informs us[525] that a
wingless parthenogenetic female of _Chermes_ hibernates on a
fir-tree—_Picea excelsa_—and in the spring lays numerous eggs; these hatch,
and by the effects of suction of the _Chermes_ on the young shoots, galls
are formed (Fig. 286), in which the Insects are found in large numbers;
when they have grown the galls open, and allowing the Insects to escape
these moult and become winged females. They now take on different habits;
some of them remain on the _Picea_, lay their eggs thereon, and out of
these there are produced young that grow into hibernating females, which
next spring produce galls as their grandmothers did; but another portion
migrates to the Larch (_Larix_); here eggs are laid, from which proceed
wingless parthenogenetic females, that hibernate on their new or secondary
plant, and in the following spring lay their eggs and give rise to a
dimorphic generation, part of them becoming nymphs and going on to the
winged condition, while the other part remain wingless and lay eggs, that
give rise to yet another wingless generation; in fact, a second pair of
parallel series is formed on the new plant, of which one is wingless, and
exclusively parthenogenetic, and continues to live in this fashion for an
indefinite period on the secondary plant, while the other part becomes
winged; these latter are called sexuparous, and go back to the _Picea_, and
there lay eggs, that give rise to the sexual forms. If we would summarise
these facts with a view to remembering them, we may say that a migration of
a part of a generation from the _Picea_ was made with a view of producing a
sexual generation, but that only a portion of the migrants succeeded in
effecting the object of the migration, and this only in their third
generation. Thus portions remained on the _Picea_, {587}producing unisexual
(female) individuals, and a portion of those that emigrated to the _Larix_
remained thereon, producing also unisexual (female) individuals, while the
others returned to the _Picea_ and produced a sexual generation. How long
the production of the unisexual generations may continue has not been
determined.
_Phylloxera._—The _Phylloxera_, that has caused such an enormous amount of
damage in the Old World during the last thirty years, is a small Aphid that
was introduced from North America into Europe. In North America it is not
so injurious as it is in Europe, owing, no doubt, to slight distinctions in
the conditions of life in the two hemispheres, as one of which may be
mentioned that in Europe a larger proportion of the individuals produced
appear to confine themselves to feeding on the roots, _P. vastatrix_ being
one of the species that lives both in galls on leaves, and underground on
the roots. The species is one that exhibits in their most complex form the
peculiar phenomena of Aphid life we have already mentioned. It has probably
only one congener, _Phylloxera quercus_, and of this Lichtenstein says that
in its cycle, from the starting-point of the winter-egg to the assumption
of the sexual condition, it exhibits a series of no less than twenty-one
forms.[526] The life of _Phylloxera vastatrix_ apparently differs
essentially from what we have described in _Chermes_, inasmuch as the
migrations are only between leaf and root of the same plant—the vine—and
not from one species of plant to another. Some authorities treat
_Phylloxera_ and _Chermes_ as a separate family under the name of
Phylloxeridae.
[Illustration: Fig. 286—Gall, or false cone of _Chermes abietis_.
Cambridge. The small figure, to the left, is a section made at the level
indicated by the pointing line _a_, and shows the chambers containing
young.]
_Galls._—Like _Phylloxera_, many species of Aphidae live partially, others
wholly, in galls that are produced by plants as the result of one or more
Aphids interfering with a delicate part of the plant when it is in a young
and growing state. The usual position of Aphid galls is on a leaf or
leaf-stalk. But in the case of the genus _Chermes_, {588}a bud or some
growing part of the spruce-fir is affected in such a way that it gives rise
to an object having externally the appearance of a little fir-cone, while
inside it consists of chambers in which the Aphids reside. The forms of
Aphid-galls are very diverse, but this is probably due to the plant rather
than to the Insect, for the same species of Aphis may give rise to
different forms of galls. Réaumur thought that each Aphid-gall was due to a
single individual that irritated the tissue of the plant, so that the
latter grew up at the point of irritation and enclosed the Insect.
A few points as to the anatomy of Aphids should be noticed. It is doubtful
whether the antennae have ever really more than six joints, the apparent
seventh joint being actually a sort of appendage of the sixth. The rostrum
is externally three-jointed, and is remarkable for the great diversity in
its length, sometimes it is quite short, at others several times longer
than the body (Fig. 285); the setae are often very much longer than the
sheath; in cases where this great length of rostrum exists, the individual
may often be found with the tip firmly fixed in the bark, and, as it were,
tethered by means of the rostrum, the length of which allows, nevertheless,
considerable locomotion. Suction is performed by contractions of the
pharynx. There has been much difference of opinion as to whether there is a
salivary syringe, and Witlaczil failed to find it. Krassilstschik is,
however, positive that it exists,[527] and that it is analogous to that
described by Mayer in _Pyrrhocoris_, but there are great differences of
structure between the two. It is very difficult to determine the number of
segments at the extremity of the body; this is terminated dorsally by a
median organ placed above the anus, and known as the cauda. Balbiani
apparently considers that there are ten abdominal segments and the cauda.
The alimentary canal has a small stomach, and an elongate intestine, the
terminal division of which is capacious and remarkably long. There are no
Malpighian tubes; according to Kowalevsky, their function is discharged by
the posterior part of the alimentary canal. There exists, however, a
peculiar structure, the pseudovitellus, a sort of cellular, double string;
and Witlaczil, in his valuable paper[528] on the anatomy of Aphidae,
suggests that this {589}organ may in some way replace the missing
Malpighian tubes. Another highly peculiar structure is the siphons,
frequently called nectaries, honey-tubes, or siphuncles. They are situated
on the dorsal aspect of the fifth abdominal segment, but exist only in
certain of the sub-families; they are of very different lengths according
to the species, and are capable of movement; they open directly into the
body cavity, though exceptional openings into the body cavity are extremely
rare in Insects. They excrete a waxy matter, which first appears as
oil-like globules. It was formerly supposed that they were the means of
secreting the sugary matter, called honey-dew, so much prized by ants and
some other Insects; but this is now ascertained to be erroneous. This
matter comes from the alimentary canal, and is secreted in large quantities
by some species, Büsgen having observed that forty-eight drops, each about
1 mm. in diameter, were emitted by a single individual in twenty-four
hours.[529] Certain gall-dwelling Aphidae—_Pemphigus_, _Chermes_ (Fig.
285), _Schizoneura_—possess numerous wax glands; these seem to replace the
siphons, and excrete the peculiar, whitish flocculent matter that is so
conspicuous in some of these Aphids.
Earlier anatomists failed to find any dorsal vessel, and it is consequently
reported in books to be absent. It has been, however, recently detected by
Witlaczil, and Mordwilko states that it does not differ from that of other
Insects.
We have already alluded to the fact that the mode of reproduction of Aphids
leads to an unrivalled increase. This, however, is not due to the
prolificness of the individual, which, in point of fact, appears to be
considerably below the average in Insects, but rather to the rapidity with
which the young begin to reproduce. This has been discussed by Huxley,
Buckton, and others. The first-named naturalist calculated that the produce
of a single _Aphis_ would, in the course of ten generations, supposing all
the individuals to survive, "contain more ponderable substance than five
hundred millions of stout men; that is, more than the whole population of
China."[530] It has since been contended that Professor Huxley's
calculation was much below the mark. Although it is somewhat difficult to
make a calculation dealing adequately with the actual facts, yet it is
clear that the increase {590}of Aphids is such that, drawing as they do
their nutriment directly from the plant in its growing state, in the course
of two or three years there would be no nutriment available for other
animals, except such as might be derived from plants not attacked by
Aphids. The numbers of Aphidae would be so great that they could not be
expressed by ordinary numerical methods, and their increase would be
actually limited only by the relations existing between different kinds of
plants, and between plants and Aphids. This result is avoided by the fact
that Aphids are themselves the victims of a whole army of Insect enemies.
They have the numerous members of a special group (Braconidae, Aphidiides)
of minute Hymenoptera to live inside their bodies, and many Aculeate
Hymenoptera depend entirely on the Aphidae as the source of food for their
own progeny. The Lady-birds—Coccinellidae—live on Aphids and Coccids, and
themselves increase to such an extent as to be in many years a conspicuous
part of the Insect world. Crowds of the larvae of Hemerobiids and Syrphids
are constantly engaged in spearing and sucking the Aphides. Hence the old
naturalist Bonnet said that, just as we sow grain for our benefit, Nature
has sown Aphids for the benefit of multitudes of different Insects. He
might have added that these different Insects are for the benefit of man,
it being clear that without them the population of the world must rapidly
decrease.
Ants treat Aphidae more intelligently than most other Insects do, for they
do not destroy the helpless creatures, but utilise their products in the
way man does those of the cows he keeps. The relations between ants and
Aphids is itself an extensive chapter in Natural History; many facts have
been brought to light showing that the ants manage the Aphids in a prudent
or intelligent manner, distributing them when too numerous in one place,
keeping guard over them, even building shelters for them, and in some cases
keeping them in direct association, by retaining the Aphids in their own
dwellings. The further investigation of these points goes, the more it
tends to raise the actions of the ants to the level we call in ourselves
intelligent. It would even appear that the ants are acquainted with the
migrations of the Aphids from one species of plant to another, Webster
informing us that as the Aphis-population on an apple tree multiplied the
ants in attendance anticipated their migration to wheat and grass {591}by
carrying them to those plants.[531] We have nearly 200 species of Aphidae
in Britain,[532] and there may perhaps be 800 known altogether. To what
extent they may occur in the tropics is undetermined. There are said to be
no native species in New Zealand.
[Illustration: Fig. 287—Instars of _Aleurodes immaculate_. Europe. (After
Heeger.) A, Nymph, from above; B, nymph, under surface; C, imago.]
FAM. 8. ALEURODIDAE.—_Minute Insects, with four mealy wings, seven-jointed
antennae, two-jointed feet, terminated by two claws and a third process._
These minute Insects are at present a source of considerable perplexity,
owing to the curious nature of their metamorphosis, and the contradictory
accounts given of them. In the earlier stages they are scale-like and
quiescent, being fixed to the under side of a leaf. The French authors
Signoret and Girard state that the young are hatched having visible
appendages and segmentation, but that after they are attached to the leaf
the organs gradually suffer atrophy. Maskell states the opposite, saying
that the organs in the earliest stages are not usually recognisable, but
become faintly visible with the growth of the Insect. Heeger states that
the larva undergoes three ecdyses, and he gives the figures we reproduce;
if he be correct it would appear that the nymph undergoes a great
development. Réaumur, on account apparently of their great metamorphosis,
treated the species {592}known to him as being Lepidopterous, though he
correctly pointed out their distinctions. At present we can only conclude
that the Aleurodidae undergo a metamorphosis of a kind peculiar to
themselves, and requiring renewed investigation. The family has been
monographed by Signoret, and more recently by Maskell, who has increased
the number of species to about sixty.[533] We have three or four in
Britain, one of which, _A. brassicae_, is extremely abundant on various
kinds of cabbage in certain years.
[Illustration: Fig. 288—Scale-Insect. A, _Aspidiotus camelliae_, on the
stem of a plant; B, a female scale magnified. (After Green.)]
FAM. 9. COCCIDAE (_Scale-Insects_, _Mealy-bugs_).—_Insects, usually minute,
with only a single claw to the foot; the male with one pair of wings, but
without mouth-parts; the female wingless and usually so degraded in form
that most of the external organs and appendages cannot be distinguished._
The form in which these Insects are most generally known is that of a small
scale or shell-like body closely adhering to leaves, fruits, or bark. The
scales are of the most varied form, so that no general description can be
given of them. The scale may be defined as an accumulation of excreted
matter, combined with the cast skin or skins of the Insect, covering the
body either totally or partially, and thus acting as a shield under which
the subsequent development takes place. All Coccidae do not form scales;
but the habit of excreting a large quantity of peculiar matters to the
outside of the body is universal; this excreted substance is frequently
white, and of a powdery nature, and Coccids of this kind are known as
mealy-bugs. In other cases the exudation is like shell or glass, and the
creature may become quite encysted therein. In this way the forms of
Cocidae known as "ground-pearls" are formed. When first hatched from the
egg Coccidae are mite-like creatures, and it is only subsequently that the
females lose the power of locomotion. The females of numerous forms of
Coccidae—more particularly the mealy-bugs—do not lose the antennae and
legs. There is also a group (Brachyscelides) of Coccids that live in
{593}galls. This highly aberrant group is, however, peculiar to Australia;
elsewhere very few gall-making Coccids have been discovered.
[Illustration: Fig. 289—_Dactylopius longispinus._ Female on portion of a
fig-leaf. (After Berlese.)]
There are upwards of 800 species of Coccidae at present known.[534] The
family was monographed by Signoret about twenty-five years ago, and since
then there has been very much matter concerning them published in a
scattered manner.[535] No general work has been published on the British
species, but Mr. Newstead is preparing one. The classification of Insects
so minute as Coccidae, and with such extreme difference in the sexes, is,
of course, a matter of great difficulty; the best divisions are those given
by Green in his _Coccidae of Ceylon_.[536]
The fact that there is only one pair of wings in the perfect male Coccid
would appear to ally these Insects with the Diptera; these Coccidae have,
too, like the Diptera, a small appendage on each side of the metathorax.
Witlaczil shows that these little processes may really represent a pair of
wings, inasmuch as they are developed from imperfect folds of hypodermis,
_i.e._ imaginal discs. Beyond these facts and the occurrence in certain
females (Margarodes) of a great histolysis during the post-embryonic
development, there is nothing to indicate any relationship between Coccidae
and Diptera. It has been shown by Riley that these little processes, in
some forms, serve as hooks to attach or control the true wings, and this
function is never assumed by the halteres of Diptera. Although Coccidae are
placed next Aphidae, yet the two families appear to be really very
different. The modes of reproduction so peculiar in Aphidae reappear to a
certain extent in Coccidae, but are associated with profound
{594}distinctions. Though the viviparous method of reproduction and
parthenogenesis occur in Coccidae, yet they are only exceptional, and they
are not put to the same uses by the species that exhibit the phenomena.
Thus we have seen that in Aphidae generations of imperfect individuals are
produced with rapidity, while the individual is not directly very prolific.
In Coccidae the reverse is the case—the generations are usually similar to
one another; they do not, as a rule, follow with rapidity, and the female
is usually very prolific, thousands of young being sometimes produced by a
single individual. The extraordinary polymorphism of the species of Aphidae
is not exhibited by Coccidae, though, contrary to what we find in Aphidae,
the males and females are usually excessively different. The two families
apparently also differ in that Coccidae are specially characteristic of
warm climates, Aphidae of the temperate regions.
PARTHENOGENESIS.—Owing to the fact that the males are very minute
creatures, totally different from the females, and living but a very short
time, they were but little known to the earlier observers. It was therefore
only natural to suppose that parthenogenesis was very common. Of late years
the males of a great many species have become known, so that ordinary
sexual reproduction must be considered as the normal method in Coccidae,
although, in the great majority of cases, the male is still unknown. It
has, however, been shown in numerous cases that parthenogenesis may occur
even when males exist; and there are some abundant species of which it has
not been possible to find a male. In 1887 Moniez[537] announced that he had
discovered the male of _Lecanium hesperidum_ (one of the notoriously
parthenogenetic species) in an ovarian cul-de-sac in the body of the
female, and he therefore considers that sexual reproduction occurs. He does
not say how pairing takes place, and we are not aware that his observation
has been confirmed. If correct it will be necessary to reconsider the whole
question as to parthenogenesis in Coccidae. Apterous males are known in two
or three species.
The post-embryonic development of Coccidae is of the most unusual
character. It is quite different in the two sexes, and in each of them it
presents features not found elsewhere. It has, however, as yet been studied
in only a few forms, and even in them is incompletely known.
{595}[Illustration: Fig. 290—Instars of _Dactylopius citri_. (After
Berlese.) A, Egg; B, young larva; C, first male nymph; D, second male
nymph; E, adult male; F, adult female. All equally magnified. x 20.]
When hatched from the egg the young Coccids are all similar, male and
female being indistinguishable. A difference soon appears, with the result
that the male, after passing through more than one pupal condition, appears
as a winged Insect. The female never becomes winged, but, if we may judge
from the incomplete accounts we at present possess, her development varies
much according to species. In some she retains the legs, antennae, and
mouth-organs; in others she loses these parts, though retaining the
original form in a general manner; while in a third (_Margarodes_) she
becomes encysted, and apparently suffers an almost complete histolysis,
reappearing after a very long period (it is said it may be as much as seven
years) in a considerably altered form. The post-embryonic development of
_Aspidiotus nerii_ has been studied by Schmidt[538] and Witlaczil,[539]
whose accounts agree except as to some points, such as the number of
ecdyses. The young, or larva, is hatched with fairly well-developed legs,
antennae, and rostrum; there is no external difference between the sexes.
The larva selects some spot on the plant and drives its rostrum therein,
thus becoming fixed; moults occur, and the body excretes waxy matter from
its sides in processes that fell together and form the shield; the female
becomes much larger than the male. The legs and antennae of both sexes
disappear, so that the power of movement is completely lost. The
mouth-parts also atrophy. The female after this undergoes no further
change, except that of growth in connection with ovarian development.
{596}[Illustration: Fig. 291—Development of male of _Aspidiotus nerii_. A,
Newly hatched larva; B, prae-pupal instar; C, pupa before ecdysis; D, pupa
shortly before the emergence of the imago: _a_, antenna; _e_, eye; _f_,
wing-rudiment; _l_, leg; _o_, basal part of mouth-organs. (After Schmidt.)
Magnification not definitely stated.]
The male, however, continues development; notwithstanding the impossibility
of taking food, owing to the absence of a mouth, it increases much in size,
and the organs of the future perfect Insect commence to develop from
imaginal discs in a manner similar to that which occurs in the Dipterous
genus _Corethra_; no mouth-parts are however developed, these being merely
represented by spots of pigment, or rudimentary additional eyes. The wings
are developed outside the body. Difference of opinion prevails as to the
nature of the instars between the young larva and the imago. It is clear,
however, that Fig. 291, D, corresponds fairly with the pupa of Insects with
complete metamorphosis, and the instars shown in Fig. 291, B, C, may
therefore be looked on as equivalents of the resting-larva stage of
ordinary Insects with complete metamorphosis. Witlaczil considers this
development to be a condition of incomplete, approaching very nearly to
complete, metamorphosis. The condition is perhaps more precisely estimated
if we recollect that winged Insects are divided into two series, in one of
which the wings are developed outside the body; in the other, inside the
body. The Insects with very complete metamorphosis all belong to the second
of these two series, while in the male Coccid we have the highest form of
metamorphosis attained by any of the first series. As regards the
development of the female encysted nymph or pupa, previously alluded to as
being found in the "ground-pearls" of {597}the genus _Margarodes_, we can
at present offer the reader no satisfactory account.[540]
PRODUCTS OF COCCIDAE.—Honey-dew is secreted by Coccidae, but as a rule not
so extensively as by Aphidae and some other Homoptera; nevertheless, it is
often sufficient to make the plants frequented by Coccids very sticky and
unclean. Some species make a really extensive exudation of such matter.
Réaumur records that a Coccid, which is doubtless _Lecanium persicae_,
excretes a supply of honey-dew that drips to the ground; he says it tastes
sweet and nice. The manna mentioned in the book of Exodus is pretty
certainly the honey-dew secreted by _Coccus_ (now _Gossyparia_)
_mannifera_, which lives on _Tamarix_ in many places in the Mediterranean
basin. This substance is still called by the Arabs "Man," and is used as
food; in its natural state it is a substance very like honey; it is
doubtless excreted by the _Coccus_, and is not produced directly by the
_Tamarix_ as some have supposed. Waxy matters are produced by several
Coccidae. _Ceroplastes ceriferus_, a Lecaniid, produces white wax in India.
_Ceroplastes_ is a widely distributed genus, and various species of it have
been used for the purpose of producing wax in other parts of the world. The
white wax of China is understood to be produced by another Lecaniid,
_Ericerus pela_; but little is known as to this Insect; it is said that the
wax is produced by the winged males. The substance was formerly greatly
prized in China, but is falling into disuse on account of the introduction
of Kerosene. Lac is produced by _Carteria lacca_, a Lecaniid living in
India on _Anona squamosa_, as well as on species of _Ficus_, _Rhamnus_ and
other trees; the lac is the shelly scale produced by the Insect as a
covering; it is composed in larger part of resinous matter, with which
there is mixed a comparatively small quantity of wax and other substances.
The body of this Insect also affords the red substance called lake. Various
species of _Kermes_ formerly afforded a red dye well known to the Greeks
and Romans. These Insects live on _Quercus coccifera_ in the Mediterranean
region. A medicinal syrup is also obtained from them. _Porphyrophora
polonica_ was used in North and Central Europe for the same purposes as
_Kermes_; it is a Coccid living on the roots of _Polygonum cocciferum_.
These European Insects were replaced commercially {598}after the discovery
of America by the cochineal Insect, _Coccus cacti_, a Mexican Coccid
feeding on a Cactus called Nopal (_Opuntia coccinellifera_). This Insect
was subsequently introduced to the Eastern hemisphere, and was established
with more or less success in a few spots on the borders of the
Mediterranean. In the Canary Islands it flourished on other species of
_Cactus_, became acclimatised, and was the object of an extensive commerce.
The colour in the case of all these Coccid dyes was obtained from the
bodies of the Insects, in the tissues of which it is contained. The dyes
have now been largely displaced in commerce by the derivatives of Aniline.
Axin is produced by the Mexican Coccid _Llaveia axinus_; this substance
appears to be of a very peculiar nature; it is apparently chiefly fatty,
and contains a peculiar acid, axinic acid. Axin is used as an external
medicinal application in various affections; and it is also employed as a
varnish; it dries and hardens on exposure to the air, and is said to be of
considerable value.[541] In our British genus _Orthezia_ the body of the
female is completely covered with a symmetrical snow-white armour, from
which project the pink legs and antennae. This is one of the forms in which
the female preserves the legs to the end of her life. The objects called
ground-pearls, already alluded to, have long been known in various parts of
the world, and in the island of St. Vincent they are sufficiently large to
be collected and strung for necklaces. These bodies are the encysted pupae
of Coccids of the genus _Margarodes_; the cyst is said to be of chitin. _M.
vitis_ commits serious ravages on the vines in Chili by sucking their
roots, and it is probable that all the species are of subterranean habits;
this would partially explain the fact that very little is known about the
history of these pearls, though naturalists have been acquainted with them
for many years.
The gall-making Coccids of the group Brachyscelides have only recently been
at all investigated; the galls they give rise to are sometimes about a foot
in length, and there appear to be numerous species and several genera in
Australia; they are especially abundant on _Eucalyptus_ and Acacias. The
females are highly remarkable from the variable conditions the legs assume,
so that in some cases they may be described as biped Insects, the {599}hind
legs remaining, though the others have atrophied.[542] Very little indeed
is known as to these Insects. One of the most peculiar points of their
economy appears to be that the galls giving rise to males are different
from those producing females.
ANOPLURA or LICE.
[Illustration: Fig. 292.—_Pediculus capitis_, ♀. Human head. (After
Piaget.)]
_Small Insects with thin integument; entirely wingless, the three thoracic
segments indistinctly separated; the head bearing in front a short tube
furnished with hooks; from which tube there can be protruded another very
delicate sucking-tube. Feet terminated by a single long claw._ The
Anoplura, Pediculidae, or lice are disgusting Insects about which but
little is known. The most contrary opinions have been expressed as to their
mode of taking their nourishment, which is, without exception, the blood of
Mammals; on the bodies of which they pass the whole of their life. It is a
most difficult matter to examine their mouth; the best information on this
point is given by Schiödte and Graber, but though these two authorities
agree, their results are very incomplete, and do not warrant us in
expressing a confident opinion as to the nature of the relationship between
Hemiptera and Anoplura—a question that has been for long a moot one. The
short tube furnished with hooks in front (Fig. 293, _d_) is considered to
be the lower lip, and the tube inside is, it is suggested, a combination of
the homologues of maxillae and mandibles; there is also what may be a
labrum (_g_); and inside the head a framework, at any rate analogous to if
not homologous with, the parts of this kind we have described as existing
in Hemiptera. All the parts, with the exception of the basal tube or head
of the beak, are of the most minute and delicate nature, so that it is
difficult to see their form or comprehend their relations. It is evident
that they are very different anatomically from the mouth-parts of
Hemiptera; still there is {600}sufficient general resemblance to warrant
the belief that the parts in the two may ultimately be shown to be also
morphologically similar. If Meinert be correct, this view will, however,
not prove to have any foundation. He considers that morphologically the
mouth of the louse has no similarity to that of the bug; the protrusible
parts in the former he considers to be modifications of epipharynx and
hypopharynx; and the rod-like structures to be hypopharyngeal lamellae; and
that they are thus totally different from the setae of bugs.[543] He
considers Lice to be a distinct Order of Insects for which he proposes the
name Siphunculata.
The alimentary canal and nervous system resemble those of Mallophaga more
than they do those of Hemiptera. The oesophagus leads into a large stomach
bilobed in front; at the posterior extremity of this there open the four
Malpighian tubes, and behind these there is a well-marked small intestine.
The nervous system consists of a cephalic ganglion and of three other
closely approximated ganglia, the posterior one the larger. It remains
doubtful whether or not the first of these three ganglia is the
infra-oesophageal one.[544]
[Illustration: Fig. 293.—Mouth-organs of louse. (After Graber.) _b_, _c_,
Chitinous envelope into which the beak can be withdrawn; _d_, head of the
beak, with crown of spines; _g_, labrum; _h_, delicate tube protruded (very
rarely seen in this state); _m′_, unpaired muscle.]
The species of lice, so far as known, are not numerous, some six genera and
about forty species being all that are recorded; they occur on various
kinds of mammals, including some that live in water. Seals have a genus,
_Echinophthirius_, peculiar to them. Monkeys are specially liable to be
affected by lice; the genus that chiefly occurs on them is _Pedicinus_, a
very distinct one, in which there are only three instead of five joints to
the antennae. Perhaps the most remarkable louse is _Haematomyzus
elephantis_, that of the elephant; it has a long proboscis in front of the
head. As a rule each species of louse is confined to one species of
Mammalia, or to very closely allied forms. Man is said to be infested
{601}by three species, _Pediculus capitis_, _P. vestimenti_ and _Phthirius
inguinalis_; Meinert is of opinion that _P. capitis_ and _P. vestimenti_
are only one species, and Schiödte appears also to have thought this
probable. Andrew Murray was of opinion that the heads of different
varieties of men are infested by distinct varieties of _P. capitis_. His
conclusion was chiefly based on examination of specimens preserved by
Charles Darwin; it requires confirmation. Very little is known as to the
life-history of the louse. Leeuwenhoek made himself the _corpus vile_ for
an experiment, from which he concluded that the _Pediculus vestimenti_ is
very prolific. That scientific men did not know whether the louse bites or
sucks was formerly made the ground for a taunt. Schiödte has given an
almost pleasing account of the way in which he settled this,[545] showing
that the sucking action is beyond all doubt. Accounts of disease called
Phthiriasis, attributed to lice, are to be found in many old books, but the
evidence does not warrant us in believing anything more than that persons
suffering from some disease, and in a neglected and filthy condition, were
horribly infested with these disgusting Insects.
It is usual to say that Pediculidae are Hemiptera degraded by a long
exclusive persistence in parasitic habits. At present, however, this must
be looked on as a pious opinion, rather than as an induction from our
knowledge of their morphology and embryology; for this is at present too
imperfect to warrant any final conclusion.
{602}NOTES AND CORRIGENDA
VOL. VI.
Note to P. 4: _Classification of Hymenoptera._ Mr. W. Ashmead has
published[546] a sketch of a new classification of Hymenoptera, in which
the points we have suggested are given effect to; the first division of the
Petiolata being carried out with reference to the position of the
ovipositor, while part of the Proctotrypidae is brought into the Aculeate
division. We cannot, however, commend this arrangement as final, for
several points have not received sufficient consideration.
Note to P. 172, line 22. For the words "We shall subsequently see,"
substitute "We have previously said" (p. 161).
Note to P. 350, line 10 from bottom: _instead of_ "only one genus," _read_
"only one Old World genus."
Note to P. 541, line 16: _instead of_ "two" _read_ "ten."
VOL. V.
P. 217, line 4. _For_ sterna _read_ nota.
P. 271. The lettering of Fig. 158 is erroneous; under the lower pointing
line the letter d should be inserted, and the left hand upper pointing line
should bear the letter c _instead of_ d.
P. 277, line 7. _Instead of_ Fig. 162, _read_ Fig. 163; and line 9,
_instead of_ Fig. 163 _read_ Fig. 164.
P. 378. The species figured has since been described by Mr. Haviland as
_Termes malayanus_.
P. 380. The species figured has since been described by Mr. Haviland as
_Termes mirabilis_.
P. 383. _Hodotermes japonicus._ It has been recorded (_P. Boston Soc._ xii.
1869, p. 139) that this is not a Termite, but an immature form of the
earwig _Brachylabis maritima_.
Pp. 480 and 481. It is not made clear that the distinction in the number of
joints of the palpi of Phryganeides and Limnophilides applies to the males
only; in both groups the number of joints in the females is five. The
remark as to Phryganeides occurring in the Southern Hemisphere is
erroneous. It is Limnophilides that reappear in Chili, not Phryganeides.
P. 490. Fig. 333 A, _f_ and its line point to a division of the mesonotum,
not of the metanotum.
P. 564. Habits of _Pelecinus_. Mr. S. A Forbes has recorded an observation
suggesting that _P. polyturator_ may be a parasite of Lamellicorn beetles
of the genus _Lachnosterna_. See _Rep. Ins. Illinois_, xix. 1896, p. 79.
{603}INDEX
Every reference is to the page: words in italics are names of genera or
species; figures in italics indicate that the reference relates to
systematic position; figures in thick type refer to an illustration; f. =
and in following page or pages; n. = note.
Abdomen, of _Chrysis_, 2;
of Coleoptera, 185;
of Diptera, 446;
of Hemiptera, 538;
of Lepidoptera, 313;
of Thysanoptera, 528
Abdominal legs, 9
Abeille-perce-bois, 33
Abeille tapissière, 51
_Abispa_, 77
_Acacia fistulosa_, beetles in, 213
Acalyptrate Muscidae, _494_
_Acanthia_, _560_
Acanthomeridae, 483
_Acanthosoma griseum_, 546
Acari, relations to Insects, 220, 223, 238, 530
_Acentropus_, 425
Acephalous larvae, 449
Achreioptera, _219_
Acraeides, 350
_Acridium maroccanum_, 254
_Acrocera globulus_, 490
Acroceridae, 489
_Acronycta_, 418
_Actias luna_, 374
Actiidae, _510_
Acutilingues, _20_
Adapted excrement, 284, 284, 380
_Adelops_, 221
Adensamer, on _Ascodipteron_, 520
Adephaga, _190_, 200 f., _216_, _234_
Adimeridae, 240
_Adimerus setosus_, 241
Adlerz, on _Formicoxenus_, 160;
on _Tomognathus_, 161
Adminicula, 327
_Aëdes_, 455 n.
_Aegeria_, 387
Aegeriidae, 386
Aegialitidae, 265
_Aegocera tripartita_, 411
_Aenictus_, 159, _179_, _180_
_Aenigmatias blattoides_, 495
_Aeolothrips fasciata_, 528
Aëpophilidae, 559
_Aëpus_, 206
Aërostatic setae, 408
Aërostats, 449
Aganaidae, 408
Agaristidae, _370_, _371_, 410
_Agdistes_, 426
Agdistinae, _426_
_Agenia carbonaria_, _A. hyalipennis_, 105
_Ageronia_, 354
_Aglycyderes setifer_, 298
Aglycyderidae, 297
Agromyzidae, _504_
_Agrotis_, 415;
_A. spina_, 417
Ahuatle, 504
_Alaena_, _350_
_Alaopone_, 179, 180
Alar organs—see Wings, Elytra, Tegmina
_Aletia xylinae_, 416
_Aleurodes brassicae_, 592;
_A. immaculata_, 591
Aleurodidae, 591
_Alucita_, _426_;
_A. polydactyla_, 426
Alucitidae, 371, 426.
Alula, 447
_Amara_, 205
Amber, Insects in, 144, 269, 458
_Amblyopone_, 180
Amblyoponides, 132, 180
Ambrosia, 295
_Ambryllis_, 409
_Amicta quadrangularis_, 394
_Ammophila_, 111;
_A. affinis_, 111;
_A. hirsuta_, 111;
_A. holosericea_, 111
Amphicyrtides, _242_
_Amphidasis betularia_, 412, 414
Amphiodont, 193
Amphipneustic, 450
_Amphizoa lecontei_, 207
Amphizoidae, 207 {604}
_Ampulex compressa_, 114, 115;
_A. ruficornis_, 115;
_A. sibirica_, 114
Ampulicides, 114 f., 169
Amycterides, 291
Anal armature, 328, 416
Anal nervures, 318
_Anaphe_, 376
Anaspini, 267
_Anaspis_, 268
Anatomy—see External Structure and Internal Anatomy
Anchor-process, 459
Ancient, Lepidopteron, 435—see also Primitive
Ancylolominae, _425_
_Andrena_, _23_, 25, 30, 301, 303;
hair of, 11;
_A. labialis_, 488;
_A. nigroaenea_, 23;
_A. ovina_, 30
Andrenidae, _20_
Andrenides, 23
_Andrenimorpha_, 388
Andrenoides, _20_
Androconia, 331 f.
_Anergates atratulus_, 160 f.
Angelitos, 63
_Anisopteryx aescularia_, 411
_Anisotoma cinnamomea_, 222
Anisotomidae, _223_
Anisotomides, 222
Anlagen, 143
Anobiides, 247
_Anobium_, 254;
_A. paniceum_, 247;
_A. striatum_, 248;
_A. tessellatum_, 248
_Anochetus ghiliani_, 174
_Anomma_, 178
_Anophthalmus_, 205
Anoplura, 599 f.
_Anosia erippus_, _A. menippe_, 345;
_A. plexippus_, 307;
larva, 324;
pupa, 327
Antennae;
of _Belostoma_, 566;
of flies, 441;
of Lamellicornia, 191;
of Lepidoptera, 307;
of butterflies, 340, 341;
of Sphingidae, 380
_Antherophagus_, 235
Anthicidae, 266
_Anthidium_, 45;
_A. bellicosum_, 47;
_A. diadema_, 45;
_A. manicatum_, 45;
_A. septemdentatum_, 47;
_A. strigatum_, 30
_Anthocopa_, 51
Anthocoridae, _560_
_Anthomyia angustifrons_, _A. brassicae_, _A. cana_, 506
Anthomyiidae, 506
Anthophila, 10 f.
_Anthophora_, 32, 33;
destroyer of, 272, 274;
_A. personata_, 33;
_A. pilipes_, 33;
proboscis of, 17
_Anthothrips aculeata_, 530
Anthracides, 486
_Anthrax_, 486 f.;
_A. fenestralis_, 489;
_A. trifasciata_, 44
_Anthrenus fasciatus_, 241
Anthribidae, 278, 290
Antisquama, 448
Antitegula, 447
Ant-plant, 138, 139, 168
Ants, 131 f.;
and Aphidae, 590;
and caterpillars, 356
Ants'-nest, Insects, 200, 213, 221, 223, 224, 225, 231, 236, 240, 548;
larva, 501, 502
Anus, 314, 320
Aorta, 320
Aortal chamber, 320
_Apate capucina_, 246
_Apatela_, 418
_Apathus_ = _Psithyrus_, q.v.
Apatidae, 246
_Apatura_;
larvae, 354;
_A. iris_, 344
Apaturides, 352
_Aphaenogaster_, 164, 165, 221;
_A. arenarius_, 164;
_A. barbarus_, 131, 164;
_A. structor_ 164, 240
Aphaniptera, 522 f.
_Aphanocephalus_, 228
_Aphelocheirus_, 565
Aphidae, 581 f.;
and ants, 181
Aphidiides, 590
_Aphis maidi-radicis_, 584
_Aphomia sociella_, 424
Apidae, 10 f., 20, _32_
Apioceridae, 492
_Apis_, _53_;
_A. adansonii_, 69;
_A. domestica_, 68;
_A. dorsata_, 69;
_A. fasciata_, _A. ligustica_, 68;
_A. mellifica_, 65 f.;
feet of queens and workers, 69;
ligula of, 16;
worker and hairs, 12
_Apoda_, 402;
_A. testudo_, etc., 401, 402
Apodidae, 402
_Apoica pallida_, nest, 83
_Aporia crataegi_, 322
Appetite, 491
_Apterogyna_, 96
_Apterona_, 393, 394;
_A. crenulella_, var. _helix_, 395
Apterous, beetles, 187, 263;
females, 95, 96, 140, 171, 174, 315, 392, 393, 407, 413, 430, 592—see
also Workers;
Insects, 95, 96, 474, 495, 496, 505, 518, 531, 581;
males, 140, 160, 161, 172, 585, 594
Aquatic;
caterpillar, 377;
cocoons, 280;
larva, 421 f., 425, 504;
pupa, 423
Aradidae, 550
_Aradus orientalis_, 550
_Araeocerus_, 290
_Araschnia levana_, _A. prorsa_, 353
Arbelidae, _369_, 396
_Arceina_, 373
Archiapidae, _21_, _22_
Archiapides, _21_ f.
_Arctia caja_, 308;
_A. villica_, 410
Arctiidae, _370_, _404_, 408, _410
Argiva_, 414 {605}
_Argynnis_, larvae, 354;
_A. paphia_, androconia, 332
_Argyromoeba sinuata_, 76;
_A. trifasciata_, 486
Arista, 442
Army-worm, 416
_Aromia moschata_, 188
_Arthropterus_, 214
_Asclera caerulea_, 267
_Ascodipteron_, 520
_Asemorhoptrum lippulum_, _160_
Asilidae, 491
_Asilus_, 492;
_A. crabroniformis_, 441
Asparagus-beetle, 281
_Aspidiotus camelliae_, 592;
_A. nerii_, 595, development of, 596
_Aspidiphorus_, 246
_Aspidomorpha_, pupa, 283, 284
Association, of _Anergates_ and _Tetramorium_, 160;
of ants and other Insects etc., 180 f.;
of _Formica_ and _Formicoxenus_, 159;
of _Strongylognathus_ and _Tetramorium_, 162;
of _Tomognathus_ and _Leptothorax_, 161
_Astata boops_, 119
_Astatides_, 119
Asteidae, _504_
_Astomella lindeni_, 490
_Astynomus_, 285
_Atemeles_, 225;
and ant, 182
Athericerous, 441
_Atherix_, 481;
_A. ibis_, 480
_Athous rhombeus_, 257
_Atractocerus_, 254
Atrophy of mouth and stomach, 310
_Atta_, 137, 164 n., 165, 502
_Attacus_, 373;
_A. atlas_, 373
Attelabides, 291
Attini, 158, 159, 165
Attitude, 381, 384, 385, 388, 412, 413, 425, 429
_Atylotus fulvus_, 483
_Autocrates aenea_, 275
_Automeris_, 373
Axin, 598
_Azteca_, 158
Azygos oviduct, 321
_Badamia exclamationis_, 365
Barrett, on increase of melanism, 414
Basket-worms, 393
Bat-parasites, 521, 560
Bataillon, on metamorphosis, 306
Bates, H. W., on classification of butterflies, 344;
on homoeochromatism, 351;
on _Megacephala_, 201
Batesian mimicry, 337, 339
_Bathyscia_, 221
Beak, 532
Beauregard, on vesicating Insects, 275
Beaver, Insect on, 219, 221
Becher, on mouth of Diptera, 444 n.
Bed-bug, 559;
enemy of, 558
Beddard, on animal coloration, 339 n.
Bee (_i.e._ honey-bee)—see _Apis mellifica_
Bee-louse or -tick, 520
Bees, 10 f.
Bees born of carcases, myth, 499
Bees' nest beetle, 235
Bees, stylopised, 300, 303
Beetles, 184 f.
Bellesme, on buzzing, 19
Belostomidae, 534, 565
Bembecidae, 482
Bembecides, 119 f.
_Bembex_, 509;
_B. rostrata_, 4, 120, 120 f.;
_B. spinolae_, 130 n.
Benchucha bug, 559
_Berosus_, 218
Berytidae, 548
_Bibio_, 475, 476, 477;
_B. marci_, 477
Bibionidae, 475
Birds and butterflies, 338
Biscuit-weevil, 247
_Bitoma crenata_, 233
_Bittacomorpha_, 473
Black-fly, 530
Blanchard, on flies attacking man, 517 n.
Blepharoceridae, 464
Blind beetles, 205, 221, 233
_Blissus leucopterus_, 548
Blister-beetles, 269
Blochmann, on founding new nests, 145
Blood-sucking, Diptera, 457;
Mosquitoes, 467
Blood-worms, 468
Blow-flies, 511
Blue-bottles, 511
Bogus Yucca-moth, 433
_Boletophila luminosa_, 463
Boll-worm, 416
Bombardier-beetles, 201
_Bombus_, 53 f.;
insect in nest of, 221;
fleas in nests of, 525;
parasite of, 94, 497;
proboscis of, 13 f., 14;
_B. agrorum_, 54;
_B. lapidarius_, 54;
_B. muscorum_, 57;
_B. variabilis_, 60
Bombyces, _367_
Bombycidae, _368_, 375, 406
Bombyliidae, 485
_Bombylius major_, 488
_Bombyx mori_, 375;
_B. yamamai_, 325
Book-worm, 247
Borboridae, _504_
_Borborus_, 505
_Borocera madagascariensis_, 405
Bostrichidae, 246
Bot-flies, 514
Brachelytra, _224_
Brachycera, 441, 454
Brachycerides, 291
Brachyscelides, 592, 598
_Brachytarsus_, 290
Braconidae, 590 {606}
_Bradypus cuculliger_, Tineid on, 430
Brahmaeidae, _368_, 374
Brain, 320;
cephalic and thoracic, 449
Branchiae, 208, 244
Brands, 332
Brassolides, 349
_Brathinus_, 223
Brauer, on Dipterous larvae, 451;
on Oestridae, 514
_Braula coeca_, 520
Braulidae, 520
Breastbone, 459
Breeze-flies, 443, 481
Breitenbach, on proboscis of Lepidoptera, 311 n.
Breithaupt, on proboscis of bee, 15;
on deglutition of bees, 18
Brenthidae, 295
_Brenthus anchorago_, 297
_Brephos notha_, 415, 416
Brimstones, 357
_Brontes planatus_, 234
Brown-tail moths, 407
Bruchidae, 276
_Bruchus fabae_ and _B. lentis_, 277, _B. pisi_, 277
_Bryophila_, 418
Buckell, on development of pattern, 335
Buffalo-gnats, 477
Bugong-moth, 417
Bugonia-myth, 499
Bull-dog ants, _171_, 173
Bull's-horn thorn and ants, 168
Bumble bee—see _Bombus_
Buprestidae, 261
_Buprestis attenuate_, supposed larvae of, 262 n.
Burgess, on suction, 311
Burnet-moths, 390
Burrows, of _Dasypoda_, 27;
of _Halictus_, 24, 25;
of _Odynerus_, 74
Bursa copulatrix, 321
Burying-beetles, 221
Butterflies, _341_ f.
Buzzing, 19
Byrrhidae, 242, _255_
_Byrrhus pilula_, 242
Bythoscopidae, 578
_Byturus_, _241_
_Cadphises moorei_, 391
Calandrides, 289
Calcium oxalate, 406
_Calicurgus_, 101;
_C. hyalinatus_, 102, 106
_Caligo eurylochus_, 350
_Callidea baro_, 303 n.
Callidulidae, _370_, 400
_Calliphora_; 448;
_C. erythrocephala_, _C. vomitoria_, 511
_Callirhipis dejeani_, 256
_Callomyia_, 496
_Callostoma fascipennis_, 489
_Caloptenus_, 270;
_C. italicus_, 489, _C. spretus_, 488, 506, enemies of
Calypter, calypterate, 448
Calyptrate Muscidae, 448, _504_
Camberwell Beauty, _352_
Camel bot-fly, 515
Camponotides, 144
_Camponotus_, 145;
_C. ligniperdus_, 138, 145, 147;
_C. pennsylvanicus_, 138, 146;
_C. rubripes_, 131;
_C. rufipes_, 137
Camptosomes, _279_, 281
Canephorinae, 394, 395
Cantharidae, 269 f.
Cantharides, _270_
Capsidae, 561
_Capsus laniarius_, 539
Carabidae, 204 f.
Carabides, _206_
Caraboidea, _190_, 200 f.
_Carcinocoris_, 554
Carder-bees, 45 f., 45
_Cardiocondyla_, 161
_Cardiophorus_, 258
Carlet, on sting, 6;
on sound-organs of _Cicada_, 574
Carnivora, _200_
Carotine, 549
Carpenter-bees, 33
Carpenter-worms, 395
Carpets, 411
_Carpocapsa juliana_, _C. pomonella_, _C. splendana_, _C. saltitans_, 428
_Carpophagus_, 278
_Carteria lacca_, 597
Carus, on paedogenesis, 461
_Caryoborus_, 278
Case, 281, 392, 393, 394, 417, 422, 423, 430, 431
Cassidides, _279_, 283
Caste-production, 142
_Castnia_, 307, 309, 316, 319;
_C. eudesmia_, _C. therapon_, 372
Castniidae, _369_, 371
_Castor canadensis_, parasite of, 219
_Cataclysta lemnata_, 423
Caterpillar, 322, 324, 325;
of Diptera, 474
_Catopomorphus_, 221
Cauda, 538, 588
Cave-beetles, 205, 221
Cebrionides, _260_
_Cecidipta excoecaria_, 424
_Cecidomyia buxi_, 459;
_C. destructor_, 460;
_C. tritici_, 460
Cecidomyiidae, 455 n., 458
_Cecropia_, plant and ants, 158
_Cedeocera_, 297 n.
Cell, of wing, 317, 318;
complete and incomplete, 116 n.
Cells, formation of, by bees, 21, 22, 24, 25, 28, 33, 34, 35, 46, 48, 51,
52, 54, 56, 60;
earthen, 72, 106;
of _Coelonites_, 89
Celyphidae, _504_ {607}
_Celyphus_, 505
_Cemonus unicolor_, 128
Cephaloidae, 275
_Cephalomyia maculata_, 515
_Cephaloon_, 275
Cephalothorax, 465;
of _Stylops_-larva, 302
_Cephenomyia rufibarbis_, 517
Cerambycidae, _278_, 285
Cerambycides, _287_
_Ceramius_, _89_;
_C. lusitanicus_, 89
_Ceranchia_, 374
_Cerapachys_, _175_ n.
_Ceratina_, 11, _32_
Ceratocampidae, _368_, 375
Ceratocombidae, 559
Ceratognathini, 194, _195_
_Ceratonema_, 401
_Ceratopogon_, 469;
_C. bipunctatus_, _C. pulicaris_, _C. varius_, 470
_Cerceris_, 125;
_C. arenaria_, 125;
_C. bupresticida_, 125;
_C. labiata_, 125;
_C. tuberculata_, 126
Cercopidae, 577
_Ceresa bubalus_, _C. taurina_, 577
_Cerocoma schaefferi_, 275
Cerophytides, _260_
_Ceroplastes ceriferus_, 597
_Ceroplatus mastersi_, 463
_Cerura vinula_, 383
Cervical sclerites, 472
_Cetonia_, in ants'-nests, 149;
_C. floricola_, 200
Cetoniides, _195_, 199
_Chaerocampa_, 380; recte _Choerocampa_
Chaetophorous, 446
Chaetotaxy, 446
Chafers, 194 f.
Chalcosiidae, 391, _420_
_Chalia hockingi_, 394
_Chalicodoma_, 32, 35;
_C. muraria_, 30, 35 f., 36, 254, 486;
_C. parietina_, _C. pyrenaica_, 39
Change of habit in larva, 301, 431
Chapman, Dr. T. A., on _Chrysis_, 3;
on classification of pupae of Lepidoptera, 367;
on _Hepialus_, 398;
on _Metoecus paradoxus_, 268;
on pupa of Lepidoptera, 327 n.
_Charagia_, 396
_Chartergus chartarius_, nest of, 82, 83
_Cheilosia chrysocoma_, 439
_Cheimatobia brumata_, 414
_Cheliomyrmex_, _180_
Chelonariides, 242
_Chelonia_, 410
_Chelostoma_, _35_
_Chennium bituberculatum_, 224
_Chermes_, 583, 586, 587;
_C. abietis_, 586, 587, 589
Cheshire, on proboscis of bee, 15
Chigger, 525
Child, on sense-organ, 442
China-marks, 421
Chinch-bug, 548
_Chionea araneoides_, 474
Chiromyzidae, 479
Chironomidae, 468, _474_
_Chironomus_, 440, 468
Chlamydes, _279_
_Chlorion_, 110ü
Chloropidae, _504_
_Chlorops_, 504
_Choerocampa elpenor_, 380
Choerocampini, 381
Cholodkovsky on _Chermes_, 586
_Choragus sheppardi_, 290
Chorion, 322
Chrysalis, 326, 344
Chrysauginae, 423
Chrysididae, 1 f.
_Chrysiridia madagascariensis_, 419
_Chrysis bidentata_, 3;
_C. ignita_, 3;
_C. shanghaiensis_, 4
_Chrysochus pretiosus_, 279
_Chrysocoris grandis_, 303 n.
Chrysomelidae, _276_, 278 f.
Chrysomelides, _279_
Chrysopolomidae, 396
_Chrysops_, 482
_Cicada_, 123;
_C. plebeia_, 574;
_C. septendecim_, 569
Cicadellinae, 578
Cicadidae, 568 f.
_Cicindela hybrida_, 202
Cicindelidae, 201 f.
_Cicinnus_, _378_ n.
_Cilix glaucata_ = _spinula_, 401
_Cimex_, _560_;
_C. lectularius_, 559
Cimicidae, 559
Cioidae, 245
_Cis melliei_, 245
Cistelidae, 264
_Cistus salvifolius_, beetle-larvae in, 282
_Cithaerias_, 348
_Citheronia_, 375
Cixiides, _576_
_Cixius_, 575
Clambidae, _223_
Clasper, 314
Classification, of ants, 144;
of bees, 20;
of butterflies, 341;
of Coleoptera, 189;
of Diptera, 454 f.;
of Hemiptera, 543;
of Hymenoptera Aculeata, _10_;
of Lepidoptera, 339 f.;
of moths, 366 f.
Clavicornia, _189_, _213_, 265
_Claviger testaceus_, 224
Clavigerides, 224
Clavus, 539
Clear-wings, 386
Cleggs, 481
_Cleosiris_, 400
_Cleptes_, 2, 4
Cleridae, 253
Click-beetles, 256 {608}
Clicking butterfly, 354
_Clidicus_, 223
_Clisiocampa neustria_, 322
Clothes-moths, 430
Clouded-yellows, 357
Clypeus, 307
_Clythra_ in ants'-nests, 149
Clythrides, _279_
_Cnemidotus caesus_, 209
_Cnethocampa processionea_, 376
Coarctate larva, 271
Coccidae, 592 f.;
destroyer of, 290
_Coccidula_, _239_
Coccinellidae, 237
_Coccus cacti_, 598;
_C. mannifera_, 597
Cochineal Insect, 598
Cochliopodidae, 402 n.
_Cochlophora_, 394
Cockchafer, 198
Cockroach, parasite of, 269
Cock-tail, 225
Cocoon, 46, 55, 66, 109, 122, 328, 347, 373, 376, 384, 385, 391, 403,
404, 405, 407, 419, 424, 436, 460, 462, 494;
flax-seed, 460;
of ants, 134;
aquatic, 280, 377
_Cocytia durvillii_, 382
Cocytiidae, 382
Codling-moth, 428
_Coelioxys_, 31
_Coelonites_, _89_;
_C. abbreviatus_, cells of, 89
_Coenomyia ferruginea_, 480
Coenomyiidae, 479
_Coenonympha_, 348
_Colaenis_, _351_
_Coleophora_, 431
Coleoptera, 184 f.
_Colletes_, 22;
_C. daviesanus_, 30
_Colobopsis_, 138
Colon, 320
Colorado beetle, 278
Colour, corresponding with locale, 201;
and surroundings, 337;
of larva and habits, 336;
of Sphingidae larvae, 381;
physiology of larval, 413;
of caterpillars and sex, 325;
development of, in Hemiptera, 542;
of eyes, 440
_Coluocera formicaria_, 240
Colydiidae, 233, 234
_Colydium_, 233
Comb, 63, 64, 65, 78, 79
Combs and brushes, 134
Compound pupa, 452
_Composmyia_, 512
Comstock, on nervures, 317 n.
Conchylidae, _427_
Connexivum, 538
Conopidae, 497, _504_
_Conorhinus sanguisuga_, 559
_Copiopteryx_, 373
_Copium clavicorne_, 550
_Copius_, 547
Copper butterflies, 356
Coprides, 195 f.
Coprini, _195_ n.
_Copris hispanus_, 197
Copulatory pouch, 320, 321
Cordyluridae, _504_
Coreidae, 546
_Corethra_, 467
Corium, 539
_Corixa_, 567
Corixidae, 567
Corn-leaves, larva on, 281
_Coronidia_, 419
_Corotoca_, 227
_Corticaria_, 240
Corylophidae, 228
Corynetides, 253
_Coscinocera hercules_, 372
Cossidae, _369_, 395
Cossonides, 294
_Cossus_, 309;
_C. ligniperda_, 319
Costal nervure, 318
Cotton-stainer bug, 548
Cotton-worm, 416
Courtship, 494;
of _Hepialus_, 398 f.
Coxa, 307
_Crabro_, 129;
_C. cephalotes_, 129;
_C. stirpicola_, 130 n.
Crabronides, 128 f.
Crambidae, 425
Crane-flies, 471
_Cratoparis_, 290
Cremaster, 327, 328, 344, 426
Cremastochilini, 200
_Cremastochilus_, 200
_Cremastogaster_, 165, 213;
_C. tricolor_, 165
Crepitation, 213, 214
Criocerides, _279_, 280
_Crioceris asparagi_, 281;
_C. merdigera_, 281
_Crossocerus_, 130;
_C. wesmaeli_, 130
Cryptocephalides, _279_
_Cryptocephalus_, _282_
Cryptocerata, _544_, 562 f.
Cryptocerini, 132, 134, 158, 159, 169
_Cryptocerus_, 138;
_C. atratus_, 170
Cryptophagidae, 235, _237_
_Cryptophagus dentatus_, 235
Cryptostomes, _279_, 282
_Cteniza ariana_, destroyer of, 490
_Ctenophora_, 475
Ctenostylidae, 517
Ctenuchinae, _409_
Cuckoo-bees, 22
Cuckoo-spit, 577
Cucujidae, _232_, 234
Cucujos, 258
Cuculinae, _20_
_Culex pipiens_, 466
Culicidae, 466 f.
Cultelli, 443
Cuneus, 539, 540 {609}
Cupesidae, 234
Curculionidae, 290
Curtice, on _Hypoderma_, 516
_Curupira_, 465
Cut-worms, 415
Cyathoceridae, 243
_Cybister laterimarginalis_ or _roeseli_, 210;
_C. tripunctatus_, 211
_Cybocephalus_, 232
Cyclica, _279_, 282
Cyclorrhapha, 454;
_C. Aschiza_, 455, 494 f.;
_C. Schizophora_, 456, 503 f.
_Cylidrus_, 253
Cylindrotomina, 474
Cymatophoridae, _368_, 386
Cymbidae, 410
_Cynomyia mortuorum_, 510
_Cyphagogus segnipes_, 296
_Cyphanta_, _368_ n.
_Cyphonia clavata_, 576
Cyphonidae, 255
Cyrtidae, 489
Cyrtocorides, 545
_Cyrtocoris monstrosus_, 546
Dacnides, 237
_Dactylopius citri_, 595
Daddy-long-legs, 471
_Dakruma coccidivora_, 424
Dalla Torre, Catalogue of Hymenoptera, 21
Danaides, 344, _347_
Danaioid Heliconiidae, 346
_Danais archippus_, or _plexippus_, 345
Dances, 351, 464, 493, 554
Darwin, C., on _Pelobius_, 208
Darwin, F., on proboscis of Lepidoptera, 311 n.
Dascillidae, _243_, 255
_Dascillus cervinus_, 255
_Dasychira pudibunda_, 408;
_D. rossii_, 407
Dasygastres, _20_, 35 f.
_Dasypoda hirtipes_, 27
Dead-leaf butterfly, 353
Death-watches, 248, 254
December-moth, 406
Deer bot-fly, 517
Deer-fly, 518
Delphacides, _576_
_Deltocephalus inimicus_, 578
Deltoidae, 418, _423_
Denudatae, _20_, 29
_Deporaus_, 291
_Dermatobia noxialis_, 517
Dermestidae, 241
_Deroca_, 400
Derodontidae, 244, _253_
_Derodontus maculatus_, 245
De Saussure, on wasps' nests, 81
Devil's coach-horse, 225
Dewitz, on development, of sting, 8;
of thoracic appendages, 9
Dexiidae, 510
_Diactor bilineatus_, 547
_Dianeura_, 392
_Diateina holymenoides_, 547
Dichoptic, 440
_Dicthadia_, 178, 180
_Dictyocicada_, 543
_Dilophus febrilis_, 477;
_D. vulgaris_, 476
Dimera, _544_
Dimorphic, generations, 586;
males, 161, 172
Dimorphism, 139;
of wings, 549
_Dinapate wrightii_, 246
Dingar, 70
_Dinoponera grandis_, 132, 134, 171
_Dionychopus niveus_, 410
Diopsidae, 503, _504_, 505
_Diopsis apicalis_, 503
Dioptinae, 409
_Dioptoma adamsi_, 251
_Dioscorea batatas_, beetle-larvae in, 280
_Dioxys cincta_, 32, 43
Diphyllides, _237_
_Diplocotes_, _248_
_Diplonychus_, 566
_Diploplectron_, 119
Diploptera, _10_, 71 f.
_Diplosara lignivora_, 429
_Diplosis_, 459;
_D. resinicola_, 459
_Dipsocoris alienus_, 559
Diptera, 438 f.
Dipterous parasitic larva, 26
_Dirphia tarquinia_, 377
Discocellular nervures, 318
_Dismorphia_, 346, 357
Dissociation of embryo, 70 n.
_Dixa_, 471
Dixidae, 471
Dohrn, Anton, on Hemiptera, 538
_Dolichoderides_, _157_
Dolichopidae, 493
_Dolichopus undulatus_, 441
_Dolichurus haemorrhous_, 116
_Donacia_, 280
Donaciides, 279
Dorsal vessel, 320;
529—see also Internal Anatomy
_Dorycera_, 504
Doryceridae, _504_
Dorylides, 174 f.
Dorylini, _175_, _177_
_Dorylus_, 133, 177, 179;
_D. helvolus_, 178
_Doryphora decemlineata_, 278
Dragon, 383, 385
Drepanidae, _370_, 400
_Drepanosiphum platanoides_, 585
Drepanulidae, 400
Drilides, _248_
Driver ants, 178
Drones, 63, 67, 69 {610}
Drosophilidae, _504_
_Drurya_, 362
Dryomyzidae, _504_
_Dryophthorus_, _289_
Dubois, on luminescence, 259
Dudgeon, on _Badamia_, 365
Dufour, on host helping parasite, 26
Duke of Burgundy fritillary, 355
Duration, of ant-colonies, 154;
of wasp-colonies, 70 n., 80;
of life—see Longevity
Durrant, on moth-cases, 431
Dutch bulbs, larva in, 501
Dyar, classification of larvae of moths, 367
_Dycladia_, 389
_Dynastes_, 199
Dynastides, _195_, 199
_Dysdercus suturellus_, 548
Dytiscidae, 210 f.
_Dytiscus_, 211
_Earias_, 410
Eau de Javelle, 368 n.
_Echinophthirius_, 600
_Eciton_, 159, 175, f;
_E. hamatum_, 175, 177
Ecitonini, _174_, 175 f.
_Ecpantheria_, 409
_Ectatomma auratum_, 131
_Ectrephes kingi_, 248
Edible larvae, 287
Egg, 305, 435, 468;
as food, 504, 568;
of bot-fly, 514, 515;
of Capsidae, 561;
carried, 547, 551, 566;
of _Endochus_, 558;
of Reduviidae, 559;
of flea, 524;
laid by pupa, 469;
of Lepidoptera, 321, 322;
of _Nepa_, 564;
numerous, 397, few, 197;
standing out string of, 378;
swallowed, 508
Egg-tubes, 321
Eggers, 322, 405
_Elaphidion villosum_, 286
_Elaphomyia_, 505
Elateridae, 256
Elaterides, _260_
_Eleodes_, 263
_Elephantomyia_, 472
Elmides, 244
_Elymnias_, 348
Elymniidae, 348
Elytra, 184, 186, 539
Embolium, 539
Embryonic dissociation, 70 n.
_Emenadia flabellata_, 269
Emery on classification of ants, 144;
on polymorphism in ants, 143
Emesiides, 555
Emperor-moth, 374
Empidae, 492, _494_
Empodium, 446
_Empretia stimulans_, 403
_Encyrtus_, 34;
_Encyrtus fuscicollis_, embryology of, 70
Endomychidae, _237_, 239
Endotrichiinae, _423_
Endromidae, _369_, 406
Energopoda, _457_, _491_
_Enhydrus_, 216
Entomophila, _10_
Enzyme, 259
_Epeolus variegatus_, 30
_Ephestia kuhniella_, 306, 424
Ephydridae, _504_
_Ephyra pendularia_, 412
Epiblemidae, _427_
_Epicausis smithi_, 409
_Epichnopteryx_, _395_
Epicopeiidae, _368_, 418
Epicranium, 307
_Epicypta scatophora_, 463
_Epidapus scabiei_, 462
Epilachnides, 238
Epimeron, 307
_Epinotia funebrana_, 428;
_E. hypericana_, parasite of, 476
Epipaschiinae, _423_
Epipharyngeal sclerites, 14
Epipharynx, 14, 308, 443, 600
Epiplemidae, _368_, 420
_Epipyrops_, 404
Episternum, 307
_Epitritus_, 170
_Epuraea_, 232
_Erastria scitula_, 417
_Erebia_, _347_;
_E. aethiops_, 347
Erebides, 418
Eremochaeta, _457_
Eremochaetous, 446
_Eremocoris_, 548
Ergatandrous, 140 n.
Ergatogynous, 140 n., 142
Ergatoid, 140
_Ericerus pela_, 597
_Eriocephala_, 308;
_E. calthella_, 434
Eriocephalidae, 433
_Eriocera_, 472
_Eristalis_, 499
Ermine-moths, 409
Erotylidae, _235_, 236
Erucaeformia, 475
_Erycides_, _364_
Erycinidae, _341_, 354, _358_
Erycinides, _355_
_Ethon_, 262
Eucephalous larvae, 450
_Eucera_, _32_
_Eucharis myrmeciae_, 173
_Euchloe cardamines_, egg, 322;
larva, 358, 359;
pupa, 358;
_E. genutia_, 358
_Euchroma goliath_, 261
_Eucinetus_, 256
Eucleidae, 401
_Euclidia mi_, 415
Eucnemides, 260 {611}
_Eudaemonia_, 373
_Eudamus proteus_, 340
_Eueides_, 351
_Eugereon hockingi_, 542
_Euglossa_, 34;
_E. cordata_, 35
_Eugnoristus monachus_, 289
_Eulema_, 35
Eulen, 414
_Eulyes_, 558
_Eumaeus_, 355
_Eumenes arbustorum_, 73;
_E. coarctata_, 73, 74;
_E. conica_, 74;
_E. flavopicta_, 72;
_E. pomiformis_, 72;
_E. unguiculata_, 73
Eumenidae, 72 f.
Eumolpides, _279_
Eumyiid flies, _456_
_Euparagia_, 89
_Euphoria_, 200
_Euplocia_, 408
_Euploea_, 345
Eupoda, _279_, 280
_Eupsalis minuta_, 296
Eupterotidae, _368_, 376
_Eurygona_, larva, 355
_Euschemon rafflesiae_, 371
_Eusemia vitticoides_, 410
_Eusthenes pratti_, 533
_Euthyrhynchus floridanus_, 546
_Excoecaria biglandulosa_, 424
Excrement as covering, 281, 283, 463—see also Adapted excrement.
Excremental dwellings, 284, 379
External structure, of Aphidae, 588;
of Chrysididae, 2;
of Coleoptera, 185;
of Diptera, 439 f.;
of fleas, 523;
of Hemiptera, 534;
of _Hepialus_, 400;
of Hymenoptera Aculeata, 5;
of Lepidoptera, 307 f.;
of Thrips, 527
Exudation of fluid, 238
Eye-collar, 387
Eyes, four in number, 215, 251, 476
Fabre, J. H., on _Ammophila_, 111;
on _Anthrax_, 486;
on _Bembex_, 120 f.;
on _Calicurgus_, 101;
on _Chalicodoma_, 37 f.;
on _Eumenes_, 72;
on _Halictus_, 24;
on _Miltogramma_, 509;
on _Osmia_, 48 f.;
on _Scarabaeus_, 196;
on _Scolia_, 97 f.;
on _Sitaris_, 272;
on _Sphex_, 108;
on _Stelis nasuta_, 30
False cones of _Chermes_, 587
Families of moths, key to, 368 f.
Feeding young, 147
_Fertonius luteicollis_, 130
Fever-fly, 477
_Filaria_, and Mosquitos, 468
Filicornia, _200_
Finding nest, 38 f., 126
Finn, on protected butterflies, 345 n.
Flagella, 384, 442
Flatides, 576
Flax-seed cocoon, 460
Fleas, 522 f.
Fly-disease, 513
Food, abstinence from, 254;
of bee-larvae, 19;
small in amount, 277
Food-reservoir, 320
Footmen, 409
Forbes, on ant sounds, 155
Forel, Aug., on tropical American Ants, 138;
on classification of Ants, 144
Forest-fly, 518
_Formica exsectoides_, 149;
_F. fusca_, 137, 150, 151;
_F. rufa_, 148, 154;
_F. sanguinea_, 149;
_F. schavfussi_, 152
Formicidae, 131 f.
_Formicoxenus nitidulus_, 148, 159
_Fornax_, 260
Fossil, Ants, 143;
Beetles, 261;
Diptera, 458;
Hemiptera, 542;
Thrips, 531;
Wasps, 88—see also Palaeozoic
Fossores, 7, _10_, 90 f., 346;
classification, 93
Fossorial solitary wasps—see Fossores
Founding new nests, Ants, 145 f.
Frenulum, 316, 318, 319, 400
Friederich, on Parnid larvae, 244
Friese, on habits and classification of bees, 21;
on hosts and parasites, 30 f.
Fritillaries, _352_, 354
Froghoppers, 577
Frog-spit, 577
Frontal ganglion, 320
_Fulgora candelaria_, 575
Fulgoridae, 543, 574;
larva living on, 404
Fulgorina, 543
_Fumea_, 393, 395
Fungus cultivated by ants, 167
Fungus-gnats, 462
Funnel-twister, 292
Gad-flies, 481
Gahan, J. C., on _Praogena_, 264
Galea, 309
Galerucides, _279_
Galgulidae, 562
_Galleria mettonella_, 306, 331
Galleriidae, 423
Gall-midge-flies, 461
Galls, 262, 430, 424;
of Coccidae, 598;
of Aphids and _Phylloxera_, 587;
of Psyllidae, 580;
of Thrips, 530
Ganglbauer, on Staphylinidae, 224
Garden-whites, 357
Garman, on mouth-parts of Thysanoptera, 528
_Gastropacha quercifolia_, 405
_Gastrophilus equi_, 515
_Gavara_, 401
Gelechiides, 429
Gena, 185
Generations, 306
Geometers, 411 {612}
Geometridae, _368_, 411, _416_, _420_
Geomyzidae, _504_
Georyssidae, 243
_Georyssus pygmaeus_, 243
_Geotrupes_, stridulation of, 195
Gerrides, 552
_Gerris_, 535, 552
_Ghilianella filiventris_, 555
Ghost-moths, 396
_Giraffomyia_, 505
Girdlers, 286
Glands, 321, 323, 331, 363, 399, 538, 553;
accessory, 320;
of Filippi, 324;
mandibular, 216;
salivary, 326;
silk-, 325;
stink-, 257;
wax-, 589
Glaphyrini, _195_ n.
_Glaphyroptera picta_, 441
Glaucopides, 339
Glossa, 309
_Glossina morsitans_, 512, 513
Glow-worms, 248;
New Zealand, 363
_Glyptus_, 206
Gnats, 466, 468
_Gnophaela_, 409
Gnostidae, 223
Goat-moths, 395—see also _Cossus_
Godart on trumpeter-bee, 58
Godman and Salvin, on spermathecal bodies, 321
Gold-tail moths, 407
Gonapophyses, 9, 305
Gonin, on development of wing, 328, 329
Goossens, on legs of Lepidoptera larvae, 323
_Gossyparia_, 597
Graber, on mouth of louse, 599
_Grapholitha sebastianiae_, 428
Grapholithidae, _427_
Grass-moths, 425
Grayling, 347
Green, E. E., on classification of Coccidae, 593
Green-bottles, 511
Green-fly, 581 f.
Ground-beetles, 204 f.
Ground-pearls, 592, 598—see also _Margarodes_
Grypocera, _341_
Guest-ant, 159
Gula, 185
Gymnocerata, _544_, 544 f.
Gymnodomes, 82
Gyrinidae, _201_, 215
_Gyrinus_, 215
Haase, on mimicry, 339 n.
_Hadrus lepidotus_, 482
_Haematobia serrata_, 512
_Haematomyzus elephantis_, 600
_Haematopota_, 482;
_H. pluvialis_, 483, 443
Haemoglobin, 468
_Haemonia_, 280;
_H. curtisi_, 280
_Haetera_, 348
Hag-moth, 403
Hairs, plumose or feathered, 11, 12;
of Dermestid larvae, 241—see also Setae
Half-loopers, 415
_Halias_, 410
_Halictus_, _23_;
_H. lineolatus_, 24;
_H. malachurus_, 23;
_H. maculatus_, 25;
_H. morio_, 24;
_H. quadricinctus_, 22, 25;
_H. rubicundus_, 26;
_H. sexcinctus_, 24, 269
Haliplidae, 209
_Halirytus amphibius_, 474
_Halobates_, 552;
_H. sobrinus_, 551
_Halobatodes_, 553
Halteres, 438, 448, 593
Halticides, _278_, _279_
_Hamadryas_, 347
Hammock-moth, 379
Hampson, on classification of moths, 367 f.;
on clicking butterfly, 354;
on frenulum, 316
_Hampsonia pulcherrima_, 391
Handlirsch, on _Bombus_, 58
Harpactorides, 558
Harpalides, _206_
_Harpalus_, 205;
_H. caliginosus_, 185
Harpes, 314
Hart, C. A., on larvae of Diptera, 473
Hart, J. H., on the parasol-ant, 142
Harvesting ants, 164
Hatchett Jackson, on colour of larvae, 325
Haustellata, _366_
Haustellum, 308
Hawk-moths, 380 f.
Head-vesicle, 442
Hearing, organs of, 191, 313
Heath-butterfly, _347_
Hebridae, 551
_Hebrus_, 551
_Hecatesia_, 371
Heerwurm, 464
Heliconiidae, _346_
Heliconiides, 351
_Heliconius_, 346;
_H. erato_, _H. melpomene_, _H. rhea_, 351
_Heliothis armigera_, 416
_Helluodes taprobanae_, 206
_Helochares_, 218
_Helodes_, 255
Helomyzidae, _504_
_Helopeltis_, 561
Helotidae, 235
_Hemaris_, 383
_Hemerodromia_, 493
_Hemidiptera haeckeli_, 553
Hemi-elytra, 539
Hemileucidae, 374
Hemiptera, 532 f.
Henicocephalidae, 554 {613}
Hepialidae, 306, _369_, 396 f.
_Hepialus_, 309, 310, 311, 317, 319, 322;
_H. humuli_ and others, 396 f.;
_H. lupulinus_, 397
Heredity, 454
_Heriades_, _35_
_Hermatobates haddoni_, 553
_Hermetia_, 479
Hesperiidae, _341_, _342_, 363
Hessian fly, 452, 460
_Hestia idea_, 340
Heterocera, _340_, 366, f.
Heteroceridae, _219_, 243
_Heterogenea_, 402
Heterogeneidae, 402
Heterogyna, _10_, 131 f.
Heterogynidae, _369_, 392
_Heterogynis_, 369 n., 392
Heteromera, _190_, 262 f.
Heteroneuridae, _504_
_Heteronotus trinodosus_, 576
Heteroptera, 532, 534, 535, 539, 543
Heterotarsini, _264_
_Hexatoma pellucens_, 441
Heylaerts, on Psychidae, 392
Hibernation, of _Vanessa_, 352
_Hilara_, 493
_Hilbrides_, 405
Hill-ant, see _Formica rufa_
Hill-grub, 417
Himantopteridae, 392
_Himera pennaria_, 411
_Hippobosca equina_, 518
Hippoboscidae, 518
Hippopsini, 288
_Hirmoneura obscura_, 485
_Hispa_,282
Hispides, _279_, 282
Histeridae, 230
_Histia_, 391
Histoblasts, 453
Histolysis, 452, 595
Hockings, on stingless bees, 63
Hoffer, on _Bombus_, 54
Hollandiidae, 396
_Hololepta_, 230
Holometopa, _504_
Holoptic, 440
Holoptilides, 557
_Holymenia_, 547
Homoeochromatism, 337, 351
_Homoeoderus mellyi_, 193
Homomorpha, 542
Homophysinae, 421
Homoptera, 532, 534, 535, 543, 544;
parasite of, 303, 497
Honey, 18, 80
Honey-ant, 152
Honey-bee—see _Apis mellifica_
Honey-dew, 580, 589, 597
Hook-tips, 400
_Hoplopus_, 74
Horn, G. H., on classification of Carabidae, 206;
of Silphidae, 223
Horn, W., on classification of Cicindelidae, 202 n.
Hornet, 81, 87
Hornet's-nest beetle, 227
Horns as food, 430
Horse bot-fly, 515
Horse-flies, 481, 518
Hot springs, Insects in, 479
House-fly, 511
Hover-flies, 498
Hubbard, on ambrosia-beetles, 295;
on _Phobetron_, 403;
on _Xenos_, 303
Huxley, on Aphids, 585, 589;
on sclerites of oesophagus, 15
_Hybocampa milhauseri_, 385
Hybotinae, 492
_Hydnophytum_, 139;
_H. montanum_, 138
_Hydrocampa nymphaeata_, 421
Hydrocampidae, _42l_
Hydrocampinae, 421
Hydrocores, 562
Hydrocorisae, 562
_Hydrocyphon deflexicollis_, 255
_Hydrometra_, _552_;
_H. stagnorum_, 551
Hydrometridae, 551
Hydrophilidae, 216 f.
Hydrophilides, _219_
_Hydrophilus piceus_, 217
Hydroporides, 201
_Hydroporus_, 211, 212
Hydroscaphidae, 228
_Hydrous caraboides_, 218
_Hygrobia_, 208
_Hylecoetus dermestoides_, 255
_Hylemyia strigosa_, 506
_Hymenitis_, 346
Hymenoptera Aculeate, 4 f.;
H. Tubulifera, 1 f.
Hyper-metamorphosis, 270, 488
Hypertely, in _Kallima_, 354
_Hyphydrus_, 212
Hypnody, 489
_Hypocephalus armatus_, 288
Hypochlorite of potash, 368 n.
_Hypoderma bovis_, _H. lineata_, 515
_Hyponomeuta_, parasite of, 70 n.
Hypopharyngeal sclerites, 14, 17
Hypopharynx, 15 n., 324, 443, 524, 600
Hypopygium, 446
Hypsidae, _370_, 408
_Hypsoides radama_, 376
_Hystrichopsylla talpae_, 523
_Idia fasciata_, 513
_Idolothrips spectrum_, 527
Imaginal discs or folds, 596
Imbauba ant, 158
Individual, 585
Inedible associations, 338, 339
Infericornia, 548 {614}
Infra-oesophageal ganglion, 541
Inquilines, 30, 81
Insects as food, 417, 504, 568
Instars, of _Aspidiotus_, 596;
of Coccidae, 595;
of _Epicauta_, 271
Instinct, 235, 274, 373, 403, 424, 487, 546;
of Ants, 590;
of _Bembex_, 121;
of _Chalicodoma_, 37;
of _Dasypoda_, 28;
of _Melipona_, 64;
of _Miltogramma_ and _Bembex_, 509;
of _Odynerus_, 76;
of _Osmia_, 48 f.;
of _Pompilus_, 102;
of _Rhynchites_, 292;
of _Trigona_, 64
Internal anatomy, of Diptera, 449;
of _Hepialus_, 400;
of Hemiptera, 540;
of Lepidoptera, 319 f.;
of larva of Lepidoptera, 324;
of Lice, 600
Internal nervures, 318
Iodine, 213
Ipides, 232
Ischium, 523
_Ischnogaster_, 82, 88;
_I. mellyi_, 87
Isoderminae, 550
Isomera, _190_
Issides, _576_
_Ithomia_, 346;
_I. pusio_, 346
Ithomiides, 346, 351
_Ituna_, _346_
_Ityraea nigrocincta_, 576
Jassidae, 578
Jiga, or "mimic me," 92
Johnston's organ, 442
Jordan, on antennae of butterflies, 341 n.;
on Thysanoptera, 529 f.
Jugatae, _366_
Jugum, 316, 400
_Jugurthia_, _89_
_Julodis_, 262
Jumping-beans, 428
_Kallima_, 353
Karbi, 63
Kellogg, on Lepidopterous structure, 307 f.
Kentish glory, 406
_Kermes_, 597
Knot-horns, 424
_Komarovia victoriosa_, 99
Koo-chah-bee, 504
Kootchar, 63
_Koptorthosoma_, 70 n.
Korschelt, on formation of eggs of _Nepa_, 564
Künckel d'Herculais, on _Volucella_, 501
Kungu cake, 467
Laap Insects, 581
Labella, 443
_Labidus_, _175_, 176, 180
Labium of Lepidoptera, 310
Laboulbène, on sound-production by Arctiidae, 410
Lac, 597
Lacinia, 309
Laciniata, _366_, 434
_Lacon murinus_, 257
_Lacosoma chiridota_, 378
Lady-birds, 237
_Lagoa opercularis_, 404
Lagoidae, 404
_Lagria hirta_, 264
Lagriidae, 264
Lake, colour, 597
Lamellicornia, _190_ f.;
enemies of, 97
Lamiides, _287_, 288
Lamprosomides, _279_
Lampyrides, 248
_Lampyris noctiluca_, 250
_Langelandia anophthalma_, 233
Languriides, 237
Lantern-flies, 575
Laparosticti, _195_ n.
_Laphria_, 492
Lapidicolous beetles, 205
Lappet-moth, 405
_Laricobius_, 253
_Larra anathema_, 117;
_L. pompiliformis_, 117
_Larrada_, 117;
_L. modesta_, 118
Larrides, 116 f.
Larvae, of beetles, 188 f., 188;
of _Chrysis_, 3;
of _Dasypoda_, 28;
of Hymenoptera, 7;
of Lepidoptera, 323;
of _Sphex_, 109
Lasiocampidae, _369_, 375, 405
_Lasiorhynchus barbicornis_, 297
_Lasius alienus_, 140;
founding nest, 146;
_L. fuliginosus_, 138, 153;
_L. niger_, 153
Latridiidae, 240
_Latridius minutus_, 240
Latter, O., on Puss-moth, 384
Leaf-cutting ants, 165 f.
Leaf-nests (ants), 155
_Lecanium hesperidum_, 594;
_L. oleae_, 417;
_L. persicae_, 597
_Ledra_, 545, _578_
Legs, abdominal, 9
_Leistus spinibarbis_, 204
_Lema melanopa_, 281
Lemoniidae, 354
Léon, on _Hemidiptera_, 553
Lepidoptera, 304 f.;
L. Haustellata, L. Laciniata, _366_
_Leptalis_, 346, 357
Leptidae, 479
Leptinidae, 220
_Leptinillus_, 221
_Leptinus testaceus_, 220
_Leptis scolopacea_, 441, 481
_Leptocircus_, 362
Leptoderini, 221
_Leptogenys_, 171;
_L. falcigera_, 171
_Leptomastax_, 223
_Leptothorax acervorum_, 161
Lerp Insects, 581
_Leto_, 397; {615}
_L. venus_, 396
_Leucania unipunctata_, 416
Leuckart, on _Melophagus_, 519
_Leucospis_, 46;
_L. gigas_, 44
Leuthner, on _Odontolabis_, 193
_Libythea_, _342_
Libytheides, 355
Lice, 599 f.
Ligula, 16
_Limacodes_, 489
Limacodidae _370_, 401;
parasite of, 4
_Limnas chrysippus_, 345
Limnichides, 242
_Limnobia intermedia_, 472
Limnobiinae, 472
_Limochores taumas_, 340
_Limothrips denticornis_, 530
Lindeman, on injuries from Thrips, 530
Lingua, 16
Lingula, 15
_Liometopum microcephalum_, 158
_Lipara lucens_, 128, 451
Liparidae, 406
_Liponeura brevirostris_, 465
Liponeuridae, 464
_Lipoptena cervi_, 518
_Liptena_, 356
Lipteninae, 356
_Lita solanella_, 430
_Lithophilus_, 239
Lithosiidae, 408
Lithosiinae, 409
_Llaveia axinus_, 598
Lobster, 383;
Lobster-moth, 385
_Loepa newara_, 374
_Lohita grandis_, 549
_Lomaptera_, 200
_Lomechusa_, 142, 225
Lonchaeidae, _504_
Lonchopteridae, 490
Longevity, 33, 135, 286, 306;
of _Cicada_, 569;
of _Melolontha_, 198;
of _Scarabaeus_, 197
Longicorns, 285
Loopers, 411, 415
Lorum, 14, 14, 16
Lowne, on blow-fly, 449;
on foot of _Dytiscus_, 211
Lucanidae, 193
_Lucanus cervus_, 194;
antenna of, 191
Luciferase, Luciferine, 259
_Lucilia_, 511, 512;
_L. caesar_, _L. macellaria_, _L. sericata_, 512
_Luciola_, 249;
_L. italica_, 249
_Ludia delegorguei_, 373
Luminescence, 250, 258 f., 463, 469
Lunula, 442
Lutz, on exudation of Coccinellidae, 238
_Lycaena baetica_, 356
Lycaenidae, _341_, _355_, 356
Lycides, _248_
_Lycorea_, 346
Lyctides, _246_
Lygaeidae, 548
Lymantriidae, _370_, 406
_Lymexylon navale_, 254
Lymexylonidae, 254
Lyonnet, on anatomy of caterpillar, 324 n.
_Machaerota guttigera_, 578
M‘Cook, on honey-tub ants, 152
_Macrocneme_, 389
Macroglossini, 380
Macrolepidoptera, 340
_Macronychus quadrituberculatus_, 244
_Macrotoma heros_, 287
Maggot, 449
Malachiidae, 252
_Malachius aeneus_, 252
Malacodermidae, 248, _252_, 266
Malaxation, 110, 126
Malpighian tubes, 320, 334, 429, 449, 460, 466, 473, 529, 540, 588
_Mamillo curtisea_, 378
Man—see Manna
Mandibles, of Lepidoptera, 308;
of pupa, 436, 437
Mandibulata, 434, 536
Manna, 597
Manson, on Mosquitoes, 468
_Manticora maxillosa_, 203;
_M. tuberculata_, 202
_Marane_, 377
Marbled-white, _347_
Marchal, on embryonic dissociation, 70 n.;
on _Ammophila_, 111;
on pigments, 334
_Margarodes_, 595, 597, 598;
_M. vitis_, 598
Marimbouda da casa, 118
_Maruina_, 471
Masaridae, 88 f.
_Masaris_, 89;
_M. vespiformis_, 88, 89
Mason-bee, 35 f.—see _Chalicodoma_;
of New Zealand, 107
_Mastigus_, 223
Matthews, on Hydroscaphidae and Corylophidae, 228;
on Sphaeriidae, 227
Maxillae, of Lepidoptera, 309
Mayer, Paul, on Hemiptera, 536
Meadow-brown, _347_
Meal-worm, 263, 264
Mealy-bugs, 592
Mechanitidae, _346_
_Medeterus ambiguus_, 493
Median nervure, 318
_Megacephala_, 201
_Megachile_, _35_, 51;
_M. albocincta_, 52, 53;
_M. anthracina_, 52;
_M. fasciculata_, 52;
_M. lanata_, 53;
_M. proxima_, 53
Megalopides, _279_, 282
Megalopygidae, 404
_Megalybus gracilis_, 490
_Meganostoma_, 543
_Megarrhina_, 445, 467
Megascelides, _279
Megasoma_, 199 {616}
_Megathymus_, 371
_Megistorhynchus longirostris_, 485
Meijere, on stigmata, 450
Meinert, on Anoplura, 600;
on mouth of Diptera, 444;
on paedogenesis, 461;
on _Stylops_, 302
Melandryidae, 265
Melanism, 414
_Melanitis_, 351
_Melanophila decostigma_, 261
_Melecta_, 31, 33;
_M. luctuosa_, 31
_Meliboeus_, larva, 355
_Meligethes_, 232
_Melinaea_, 351
_Melipona_, _53_, 62;
_M. scutellaris_, 64
_Melitaea_, larvae, 354
Mellifera, 10
_Mellinus_, 123;
_M. arvenis_, 123, 124;
_M. sabulosus_, 124
_Meloe_, 33, 274
Meloidae, 269
Meloides, _270_
_Melolontha vulgaris_, 194, 198
Melolonthides, _195_, 198
_Melophagus ovinus_, 518, 519
_Melophorus inflatus_, 153
Melyridae, 252
Membracidae, 576, _578_
_Membracis foliata_, 577 n.
Membrane, of Hemiptera, 539
Menorhynchous, 542
_Merodon equestris_, 501
Merrifield, temperature experiments, 337
Mesodont, 193
Mesophragma, 312, 445
Mesoscutellum, 312
Mesoscutum, 311
Mesosternum, 307
_Mesovelia_, 551
Mesozoic beetles, 261
_Messor_, 164
_Metamorpha_, _351_
Metamorphosis, 529;
of Aleurodidae, 591;
of _Cicada_, 571;
of Coccidae, 594 f.;
of Diptera, 452;
of Hemiptera, 542
Metapneustic, 450
Metascutellum, 313
_Methoca ichneumonides_, 96
Metochy, 183
_Metoecus paradoxus_, 268
Meyrick, classification of Lepidoptera, 367
_Miastor_, 461
Mice, insects in nests of, 221
_Microdon_, 501, 502
Microlepidoptera, _340_, 427;
trophi, 309
Micropezidae, 504
Microphysides, 560
Microptera, _224_
Micropterism, 549
Micropterygidae, _369_, 435
_Micropteryx_, 307 f., 317, 319, 327, _433_, 435, 436
Midge, 461, 470
Migration, Aphis-, 585
Mik, on _Hilara_, 493
Milichiidae, _504_
_Miltogramma_, 121, 508
_Mimacraea_, 356
_Mimesa bicolor_, 128
Mimesides, 127
Mimicry, 337 f.—see also Resemblance
Mines, Dipteron in, 474
_Miscophus_, 116
Models, 346
Moesa-blight, 561, 562
Mollusca, eaten by beetle-larvae, 252;
larvae mistaken for, 501—see also Snails
_Molossus_, parasite of, 560
Monarch-butterfly, 345
_Monda rhabdophora_, 393
_Monema flavescens_, 4
Moniez, on fertilisation of Coccidae, 594
_Monodontomerus nitidus_, 44
_Monohammus confusus_, 286
Monomera, _544_
Monommidae, 265
_Monomorium_, 560;
_M. pharaonis_, 163
Monotomides, 240
_Montezumia dimidiata_, nest of, 83
_Mordella_, 268
Mordellidae, 267
_Mordellistena floridensis_, 268
_Mormolyce_, 205
Mormolycides, _206_
Morphides, 348
_Morpho_, 315, 331, 349;
_M. menelaus_, 318;
_M. achilles_, _M. epistrophis_, larvae of, 349
Mosquito, 466 f.
Mosquito-bees, 61
Mosquito-blight, 562
Moth-flies, 470
Moths, 366 f.
Motuca fly, 122, 482
Mouth, absence of, 310, 443, 489, 514, 515, 585, 596
Mouth-parts, of Diptera, 442 f.;
of fleas, 523;
of Hemiptera, 534, 535;
of Hymenoptera Aculeata, 13;
of Lepidoptera, 307 f.;
of Lice, 599, 600
Mud-dauber, 113
Müggenburg, on _Melophagus_, 518
Müller, Fritz, on Imbauba-ant, 158;
on _Trigona_, 64
Müller, H., on _Dasypoda hirtipes_, 27
Müller, W., on South American larvae, 344 n.
Müllerian mimicry, 339
Mundstachel, 527, 528
Murray, A., on Lice, 601
_Musca domestica_, 511
Muscidae, 511 f., 517;
M. Acalyptratae, 503 f.;
M. Calyptratae, 448, 504
Musotimidae, 423 {617}
Mustiliidae, _376_
_Mutilla_, 94, 95;
_M. europaea_, 94
Mutillides, 94 f.
_Mycetaea hirta_, _239_, 240
Mycetaeidae, 239
_Mycetobia pallipes_, 462, 463
Mycetophagidae, 237
Mycetophilidae, 462
Mydaidae, 491
_Mygnimia_, 105
Myiasis, 512
_Myiatropa florea_, 499
_Myiodocha tipulina_, 557
Myoditini, 267
Myopinae, 497, 498
_Myrapetra_, 82
_Myrmecia_, _171_, 172, 173
_Myrmecocystus hortideorum_, 152;
_M. melliger_, 152;
_M. mexicanus_, 152
_Myrmecodia_, 139
Myrmecophilous Insects, 181 f.
_Myrmedonia_, 226
_Myrmica laevinodis_, 148;
_M. rubra_, 133;
_M. rubra_, races _ruginodis_, _scabrinodis_, 163
_Myrmicides_, 158
Myrmicini, 159
Nabides, 556
_Nabis lativentris_, 556
_Nacerdes melanura_, 266
_Naclia ancilla_, 390
Nagana, 513
Nagel, on digestion by injection, 212
_Nagoda nigricans_, 401
_Nanosella fungi_, 228
Nassonoff, on Strepsiptera, 301 n., 302
Naucoridae, 565
_Necrobia ruficollis_, 253
_Necrophorus_, 221
Nectar, 18
_Neleus interruptus_, antenna, 191
_Nematobola orthotricha_, 431
Nematodes, in Thysanoptera, 530
_Nematois metallicus_, 321
Nemeobiides, 355
_Nemeobius lucina_, 335, 355
_Nemestrina_, 455 n.
Nemestrinidae, 484
Nemocera, 440;
N. Anomala, N. Vera, 456
_Nemognatha_, 304
Nemosomides, _233_
Neocastniidae, 372
Neolepidoptera, 366
Neotropidae, _346_
_Nepa_, 541;
_N. cinerea_, 563
Nepidae, _544_, 563
_Nepticula_, 431
Nervous system, Coleoptera, 191
Nervules, 319, 429
Nervuration, of Diptera, 447;
of Lepidoptera, 317 f.
Nervures, 318, 319;
development of, 329 f.;
swollen, 347, 348;
of _Eumenes_, 73
Nests, of ants, 136 f., 155;
of _Formica fusca_ and _Solenopsis fugax_, 137;
of _Porphyraspis_, 284;
of wasps, 79 f., 79, 81, 83, 87
Netrocera, _341_ n.
Neuroblasts, 453
Newbigin, Miss, on pigments, 334
Newport, on _Meloe_, 270
Nicagini, _195_
Nicolas, on _Halictus_, 24
Nilionidae, 265
_Nitidula_, 232
Nitidulidae, 231, _235_
Noctuidae, 311, _370_, _410_, 411, 414 f.
Node, 131, 134
Nolidae, 410
Nolinae, 409
_Nomada_, 30;
_N. lathburiana_, 30;
_N. sexfasciata_, 30
Nonne, 407
Nopal cactus, 598
Nosodendrides, _242_
_Notocyrtus_, 558
Notodontidae, 305, _368_, 383
Notodontina, _411_
Notonectidae, 567
Number of species: of Apidae, 10;
of Butterflies, 343;
of Coccidae, 593;
of Coleoptera, 184;
of Diptera, 438;
of Fleas, 525;
of Hemiptera, 543;
of Lepidoptera, 306;
of Lice, 600;
of Thrips, 527
Nun, 407
Nurses, 66, 134
_Nyctalemon_, 419
Nyctemeridae, 409
Nycteolinae, 410
_Nycteribia_, 521, 522
Nycteribiidae, 521
Nymph, of _Cicada_, 569;
of Thrips, 529
Nympha inclusa, 452
Nymphalidae, 341, 343 f.
Nymphalides, 351
Nymphipara, 518
_Nymphula stagnata_, _N. stratiotata_, 423
_Nyssonides_, 123
Oak-Pruner, 286
Obtusilingues, _20_
Oceanic bugs, 552
Ocelli, 325;
O. compositi, 325
Ochthiphilidae, _504_
_Ocneria_, 407 n.;
_O. dispar_, 408
_Ocnerodes_, 489
_Ocnogyna_, 409
_Ocypus olens_, 225
_Odontolabis sinensis_, 193
Odontomachi, _171_, 173
Odour, of bugs, 541
_Odynerus_, 74 f., 269; {618}
_O. antilope_, 75;
_O. callosus_, 76;
_O. parietum_, 3;
_O. punctum_, 77;
_O. reniformis_, 73, 75;
_O. spinipes_, 3, 76
_Oecocecis guyonella_, 430
_Oecodoma_, 137, 164, 165;
_Oe. cephalotes_, 133
_Oecophylla smaragdina_, 147
Oecophoridae, 429
Oedeagus, 314 [recte aedeagus]
_Oedematopoda princeps_, 387
Oedemeridae, 266
Oestridae, 514
_Oestrus ovis_, 517
_Ogcodes_, 489, 490
Oil-beetles, 269
_Oinophila v-flavum_, 430
Olethreutidae, _427_
_Olibrus bicolor_, 231
_Oligarces_, 461
Oligonephrous, 542
Oligoneura, 461
Ommatophorinae, 414
_Oncideres_, 286
_Opetia_, 496
_Ophideres fullonica_, 311
Opomyzidae, _504_
_Opostega_, 429
Orange-tip, 357—see also _Euchloe_
_Orectochilus_, 216
_Oreta hyalodisca_, 400
Origin of parasitic bees, 32
Orneodidae, _340_, _371_, 426
_Ornithoptera_, 360;
_O. brookiana_, 362;
_O. paradisea_, 360, 361, 362
Orphnephilidae, 470
Ortalidae, _504_, _506_
_Ortalis_, 447
_Orthezia_, 541, 598
Orthogenya, _494_
_Orthogonius_, 206
_Orthoperus atomarius_, _O. brunnipes_, 228
Orthoptera, _533_;
parasite of, 497
Orthorrhapha, 454;
O. Brachycera, 478 f.;
O. Nemocera, 455, 458 f.
_Oryctes nasicornis_, 199
Oscinidae, _504_
Osmeterium, 363
_Osmia_, 47, 48 f;
enemy of, 100;
hair of, 11;
_O. cyanoxantha_, 32;
_O. leucomelana_, 29;
_O. tricornis_, 48;
_O. tridentata_, 48 f.
Osten Sacken on Bugonia, 499;
on Chaetotaxy, 446;
on classification of Diptera, 456;
summary of Portschinsky, 512
Othniidae, 265
Otiorhynchides, 437
_Ourocnemis_, 355, _356_
Ovaries, 541, 602;
in larva, 325
Oviduct, 320, 321
Oviposition, of _Cicada_, 571;
of _Notonecta_, 567;
of _Tachina_, 507
Ovipositor, 436, 506, 531, 539
Owlet-moths, 414
Ox-warbles, 517
_Oxybelus_, 129
Oxychirotinae, 425
Ozaenides, 214
_Pachypus_, 187
Packard, on Hymenopterous metamorphosis, 7
Pad, of Lepidoptera, 314
Paedogenesis, 303, 461
Pagiopoda, _544_
Palaeolepidoptera, _366_
_Palaeomicra_, 435
Palaeotropinae, _347_
Palaeozoic Insects, 311, 542
Palmer-worm, 323
Palpicornia, _219_
_Paltostoma_, 465
_Palustra_, 377
_Pangonia longirostris_, 482
_Panomoea_, 237
Panurgides, _20_
_Papilio_, 359;
_P. ajax_, forms of, 335;
_P. antimachus_, 362;
_P. zalmoxis_, 362
Papilionidae, _342_, _357_, 359
_Paracelyphus_, 505
_Paragia_, _89_
Parallel series in Aphidae, 585
_Parandra_, 288
_Parapompilus gravesii_, 105
_Paraponera clavata_, 172
_Paraponyx_, 423
Paraptera, 312
Parasites, among ants, 183;
of mason-bee, 43;
of larva of _Andrena_, 26;
of _Odynerus_, 76
Parasitic, bees, 23, 29 f.;
_Prosopis_, 32;
Diptera, 507
_Parasyscia_, _175_ n.
_Parmula_, 501
_Parnassius_, _342_, 362
Parnidae, _219_, 243, _255_
_Parnopes carnea_, 4
_Parnus_, 244
Parthenogenesis, 24, 85, 86, 395, 430, 469, 530, 583, 594
Parthenogenetic young, 139 n.
Passalidae, 192;
larva, 192, _262_
_Passaloecus_, 128
Patagia, 311, 312
Pattern, formation of, 335
_Patula_, 414
Paurometabola, 542
Paussidae, _201_, 213
_Paussus cephalotes_, etc., 214
_Pavonia_, 350
Pea-weevil, 277
Peacock butterfly, _352_
Peal, on sound-producing ant, 156
Peckham, on Fossores, 130 n.;
on instinct, 70, 99
_Pectinicornia_, _194_ {619}
_Pedicinus_, 600
Pediculidae, 599
_Pediculus capitis_, 599, 601;
_P. melittae_, 274;
_P. vestimenti_, 601
Pedilidae, _266_
Peduncle, 133, 134
_Pegomyia inanis_, 79
Pelobiidae, 207
_Pelobius tardus_, 208
Pelogonidae, 562
_Pelopaeus_, 110, 112 n.;
_P. bilineatus_, 114;
_P. laetus_, 113, 117;
_P. madraspatanus_, 113;
_P. spirifex_, 112
_Peltasticta_, 245
Peltides, 233
_Pemphigus_, 589
_Pemphredon lugubris_, 128
Pemphredonides, 127
Penis, 314
Pentamera, _190_
Pentanephria, 466
_Pentatoma_, 541;
_P. rufipes_, 535
Pentatomidae, 533, 545, _546_
_Pepsis_, 104, 389;
_P. formosus_, 105
Pérez, on bee-parasitism, 32;
on _Halictus_, 24
_Pericoma canescens_, 470
Pericopinae, 409
_Peridrepana_, 401
_Perilitus_, 282
Peripneustic, 450
Peritracheal spaces, 332, 333
Perkins, R. C. L., on bee and acarid symbiosis, 70;
on _Odynerus_, 76;
on _Prosopis_, 21
_Perophora batesi_, _P. melsheimeri_, 377;
_P. sanguinolenta_, 379
Perophoridae, 377
Perothopides, 260
Peytoureau, on morphology of abdomen, 313, 314
Phaeism, 337
Phalacridae, 231
_Phalacrocera replicata_, 474
Phaloniadae, _427_
_Phanaeus splendidulus_, antenna of, 191
Pharynx, 320
Phaudinae, 392
_Pheidole_, 165
_Pheidologeton laboriosus_, 159;
_P. diversus_, 167
_Phenax_, 575
_Phengodes hieronymi_, 249
Phengodini, 251
_Philaenus spumarius_, 577
Philanthides, 124 f.
_Philanthus apivorus_, 127;
_P. triangulum_, 125
_Phileurus didymus_, antenna, 191
_Philonthus nitidus_, 225
_Phlebotomus_, 470
_Phloea corticata_, 545
Phloeides, 545
_Phloeothrips frumentarius_, 530
_Phobetron pithecium_, 403
_Phonapate_, 246
Phoridae, 494
_Phosphaenus hemipterus_, 249
Phosphorescence, 250—see also Luminescence
Phragma, 307, 313
Phragmocyttares, 81
_Phthanocoris_, 543
Phthiriasis, 601
_Phthirius inguinalis_, 601
Phycitidae, 424
Phycodromidae, _504_
_Phyllocnistis_, 431
_Phyllomorpha laciniata_, 547, 548
_Phyllorhina_, parasite of, 520
_Phylloxera_, 587
Phylogeny of butterflies, 343 n.
Phymatidae, 554
_Phymatopus_, 399
Physapoda or Physopoda, 531
Phytomyzidae, _504_
Phytophaga, _190_, _237_, 276 f.
_Phytophthires_, _544_
Phytoscopic effects, 336
_Pierella_, 348
Pieridae, _341_, 357
_Pieris brassicae_, 340;
development of wing, 328, 329, 333
_Piesma_, 550
Pigments, 330, 334, 357
Pilifer, 308
Pill-beetles, 242
Pinaridae, 405
Piophilidae, _504_
Pipunculidae, 496
_Pipunculus_, 496
_Pison_, 118
Pit-falls, 481
_Plagiolepis trimeni_, 153
_Plagithmysus_, 287
Plant-lice, 581 f.
Plants and ants, 183
Plataspides, 545
_Platycnema_, 496
Platypezidae, 496
_Platyphora lubbocki_, 495
Platypides, 289, 295
Platypsyllidae, 219
_Platypsyllus castoris_, 219
_Platysoma depressum_, 230
Platystomidae, _504_
_Plea minutissima_, 567
Pliny, on Mason-bee, 44
_Ploiaria pallida_, 556
Plume-moths, 426
Plumules, 331
_Plusia_, 415
_Pochazia_, 576
Podilegidae, _32
Poecilocampa populi_, 406 {620}
_Poecilocapsus lineatus_, 542
Poecilocyttares, 81
_Pogonomyrmex barbatus_, 164
_Pogonostoma_, 203
Poison, of Hymenoptera, 7 f.
Poison-glands, 2
Poisonous caterpillars, 376, 403, 404, 405
_Polistes_, 86;
_P._ and _Stylops_, 301, _303_
Pollen-gathering and -carrying, 11, 12
_Polybia_, nests of, 81, 82, 83
_Polyctenes fumarius_, 560
Polyctenidae, 560
_Polyergus lucidus_, 151;
_P. rufescens_, 150 f.
Polymorpha (Coleoptera), _189_, _190_, 213 f.
Polymorphism, 139 f., 143
_Polyphylla fullo_, antenna, 191
_Polyploca_, 386
Polyplocidae, 386
_Polyplocotes_, _248_
_Polyrhachis_, 155;
_P. pandurus_, 156;
_P. spinigera_, 138
Pompilidae, 93, 101 f.
_Pompilus_, 103;
_P. polistoides_, 104;
_P. sericeus_, 106
_Ponera contracta_, _P. ergatandria_, _P. punctatissima_, 172
Ponerides, 132, 170 f.
_Porphyraspis tristis_, 284
_Porphyrophora polonica_, 597
_Porrorhynchus_, 216
Portschinsky, on habits and development of Muscidae, 507, 512
Post-metamorphic growth, 141
Post-scutellum, 307, 312
_Potamogeton pectinatus_, beetle on, 280
_Potamophilus acuminatus_, 244
Potassium hydroxide, 328, 384
Potato-beetle, 278
Pouch, abdominal, 350, 362
Poulton, on colours, 336, 339
Praecostal nervures, 319
Praescutum, 312
Pratt, on imaginal discs, 453 n.;
on _Melophagus_, 519
_Prepona_, larva, 354
Prey, of Fossores, table, 92
_Pria dulcamarae_, 232
Primitive, beetles, 251, 252;
Diptera, 475
_Priocnemis affinis_, 5;
_P. bicolor_, 107
Priodont, 193
Prionides, 287
Proboscis, 13, 14, 16, 17, 304, 307, 309, 311, 443, 482, 485, 532
Processional maggots, 464
Processionary caterpillars, 376, 408
Prodoxidae, 432;
mouth, 309
_Prodoxus_, 433
Pro-legs, 323
Prolific, Aphids, 589;
Coccids, 594;
_Hepialus_, 397;
Lice, 601;
_Meloe_, 274;
_Stylops_, 301
Prominents, 383
_Pronuba_, 321;
_P. yuccasella_, 432;
_P. synthetica_, 432
Pronymph, 453
Propodeum, 131, 133
Propolis, 63
Propygidium, 187
_Prosopis_, _21_, 22;
hair of, 11;
proboscis of, 17;
_P. signata_, 21
Protection, 43, 413;
of trees by ants, 158;
of plant by ants, 168
Proterhinidae, 298
_Proterhinus lecontei_, 298
Protolepidoptera, _336_
_Protoparce carolina_, 309
_Protopaussus_, 214
_Psammorycter vermileo_, 481
Pselaphidae, 223;
and ants, 182
_Psen atratus_, _P. concolor_, 127
_Psephenus_, 244
Pseudholoptic, 440 n.
Pseudocorylophidae, 228
_Pseudodicthadia_, 180;
_P. incerta_, 177
_Pseudodoxia limulus_, 431
_Pseudomeria graeca_, 99
Pseudomorphides, 205, _206_
_Pseudomyrma bicolor_, 168
Pseudomyrmini, 168
Pseudoneuroptera, _527_
Pseudopaedogenesis, 303
Pseudopod, 188, 264, 267, 290, 449, 492
_Pseudopontia paradoxa_, 357
Pseudo-pupa, 271, 273
Pseudotetramera, _190_
Pseudotrimera, _239_
_Pseudovespa_, 88
Pseudovarium and Pseudovum, 584
Pseudovitellus, 588
Psilidae, _504_
_Psiliglossa_, larva, 8
_Psilocephala_, 484
_Psilura monacha_, 407
_Psithyrus_, _53_, 57, 59 f.;
_P. campestris_, 60;
_P. vestalis_, 60
Psocidae, 248
_Psyche helix_, 394
Psychidae, _369_, 392
Psychina, _394_, _395_, 404
_Psychoda_, 466
Psychodidae, 470
_Psylla pyricola_, 579, 580;
_P. succincta_, 579;
_P. buxi_, 580
Psyllidae, 578
_Pterocheilus_, 76
_Pterodecta_, 400
Pterophoridae, _340_, _371_, _425_, 426
Pterophorinae, 426
_Pterostichus_, 205
Pterothysanidae, _369_, 406
Pterygodes, 312
Pterygogenea, 542
Ptilinum, 442, 503, 520
_Ptilinus pectinicornis_, 253 {621}
_Ptilocnemus sidnicus_, 557
_Ptilomacra_, 395
_Ptilomera laticaudata_, 553
Ptinidae, 246
_Ptomaphila lacrymosa_, 222
_Ptychoptera_, 466
Ptychopterinae, 472
_Ptyelus goudoti_, 577
Pugs, 411
_Pulex avium_, _P. irritans_, _P. serraticeps_, 525;
_P. obtusiceps_, 525
Pulicidae, 522 f.
_Puliciphora lucifera_, 495
Pulvillus, 446
Pupa, of beetles, 188 f.;
coarctata, 452;
obtecta, 227, 327, 451;
depositing eggs, 469;
hairy, 407, 426;
of Lepidoptera, 326 f.;
with mandibles, 436
Puparium, 452
Pupation, of _Badamia_, 365;
of _Parnassius_ and _Thais_, 363
Pupipara, 456, 513, 517
Purple emperor, 344
Pusci, 504
Puss-moth, 328, 383, 406
Pygidium, 187
Pyralidae, _340_, _370_, 420
_Pyralidina_, _420_, _426_
_Pyrameis atalanta_, 353;
_P. cardui_, 353;
_P. tameamea_, 353
Pyraustidae, 421
_Pyrochroa rubens_, 266
Pyrochroidae, 266
_Pyrophorus_, 258;
_P. noctilucus_, 259
Pyrrhocoridae, 549
_Pyrrhocoris apterus_, 535, 549
_Pyrrhopyge_, 364
Pythidae, 265
_Pytho depressus_, 266
_Quartenia_, _89_
Queen, 66, 67, 69, 140
Races, of _Apis_, 68
Radial nervures, 319
Raffray, on _Pogonostoma_, 204;
on classification of Paussidae, 214;
on classification of Pselaphidae, 224
Railway-beetle, 251
_Ranatra linearis_, 563
Raptorial legs, 493, 554, 556
Réaumur, on _Xylocopa_, 33
Receptaculum seminis, 140
Rectal cauda, 538
Red admiral, _352_
Red ant—see _Formica rufa_
Reduviidae, 555 f. 537
_Reduvius personatus_, 558
Régimbart, on Gyrinidae, 216
Resemblance, between ant, wasp, and spider, 169;
between _Anthophora_ and _Bombus_, 33;
between _Arctia villica_ and _Eusemia villicoides_, 410;
between beetle-larva and Termite, 206;
between _Bombus_ and _Eulema_, 35;
between Bombyliidae and Hymenoptera, 489;
between bug and ant, 556, 557;
bug and Tipulid, 556, 558;
bug and fly, 547;
in butterflies, 348;
between Callidulidae and Lycaenidae, 400;
between _Celyphus_ and Hemiptera, 505;
between Cleridae and insects they destroy, 254;
between Dioptinae and Ithomiides, 409;
between Diptera and Hymenoptera, 499, 500;
between _Epicopeia_ and _Papilio_, 418;
between Flatides and Lepidoptera, 576;
of flies and bees, 502;
to galls, 403;
between host and parasite-bees, 30;
between Insects of different Orders, 339;
of Ithomiides to other butterflies, 346;
between lady-bird and Endomychid, 237;
of larva to a colony of larvae, 418;
of larva of _Odynerus_ and of _Chrysis_, 4;
between larvae, 162;
in Limacodidae, 401;
of Lobster caterpillar, 385;
between Longicorns and Hymenoptera, 287;
of moth to bird-excrement, 401;
of parasite and prey, 95;
of Pericopinae and Heliconiides, 409;
between protected butterflies, 345;
between _Psithyrus_ and _Bombus_, 59;
of Reduviid and _Pepsis_, 558;
between _Rhyphus_- and _Mycetobia_-larvae, 463;
of Syntomids to other Insects, 388 f.;
of Tipulids and Hymenoptera, 475;
between two kinds of ants, 162
Resting-larva, 306
Retinaculum, 316, 319, 420
Retort-shaped bodies, in mouth of Hemiptera, 535
Reuter, E., on classification of butterflies, 343 n.
_Rhachicerus_, 480
_Rhagovelia plumbea_, 552
_Rhaphiorhynchus_, 483
_Rhegmatophila alpina_, 305, 386
_Rheumatobates bergrothi_, 553
Rhinomacerides, 291
_Rhinopsis_, 115;
_R. ruficornis_, 169
_Rhinosimus_, 266
_Rhipicera mystacina_, 256
Rhipiceridae, 256
Rhipidiini, 267
_Rhipidioptera_, 543
Rhipiphoridae, 267
Rhipiphorides, 268
Rhipiptera, 298 [in error for Rhiphiptera]
_Rhizophagus_, _232_
_Rhizotrogus_, 191
_Rhodoneura_, _405_
_Rhogmus_, 179, _180_
Rhopalocera, 340, 341 f.
_Rhopalomelus angusticollis_, 206
Rhopalomeridae, 504 {622}
_Rhopalosoma poeyi_, 100
Rhopalosomides, _100_
_Rhygchium brunneum_, _R. carnaticum_, _R. nitidulum_, _R. oculatum_, 77
_Rhynchites betulae_, 291, 292
Rhynchitides, 291
Rhynchophora, _190_, 277, 288 f.
Rhynchophorous series, _240_
_Rhynchopsylla pulex_, 526
Rhynchota, 532
Rhyphidae, 478
_Rhyphus_, 463
Rhysodidae, _201_, 234
Riley, on _Epicauta_, 270, 271;
on spermathecal bodies, 321;
on Yucca-moth, 432
_Ripidius pectinicornis_, 269
Rippe, of Schäffer, 334
Robber-flies, 491
Rose-chafers, 200
_Rosema_, 401
Rostrum, 291, 472
Rothney, on _Ampulex_, 115;
on _Sima_, 169;
on _Sphex_, 110
Rothschild, N. C., on morphology of fleas, 523 n.
Royal jelly, 66
_Rozites gongylophora_, 167
Ruby-wasps, 1 f.
Rurales, _342_
Rutelides, _195_, 198
_Saccoderes_, 558;
_S. tuberculatus_, 537
Saccus, 314
_Sagra splendida_, 279
Sagrides, _279_
_Salda_, _560_
Saldidae, _544_, 562
Salivary, duct, 320;
gland, 320
Sand-flea, 525;
-flies, 477
_Saperda populnea_, 285, 286
Sapromyzidae, _504_
_Sapyga quinquepunctata_, 100
Sapygides, 99
_Sarcophaga_, 510;
_S. carnaria_, 510
Sarcophagidae, 510
_Sarcophila magnifica_, _S. wohlfahrti_, 510
_Sarcopsylla gallinacea_, _S. penetrans_, 525
Sarginae, 479
_Saropoda_, _32_
_Sarrothripus_, 410
Sasaki, on parasite of silkworm, 508
_Saturnia_, 307, 310;
_S. pavonia_, 313, 374
Saturniidae, _368_, 372
Satyrides, 347
Sauba, or Sauva, ant, 137
Saunders, E., on feathered hairs, 11;
on proboscis of bees, 16
Saunders, Sir S., on Hymenopterous larvae, 8
Scale, 131, 133, 315, 467;
development of, 329 f.;
-formation, 333;
-holder, 331
Scale-Insects, 592 f.;
enemy of, 356, 357, 417, 425, 430
Scalpella, 443
Scape, 441
Scaphidiidae, 229
_Scaphisoma agaricinum_, 229
Scaphium, 314
Scapulae, 312
Scarabaeidae, 194 f.
Scarabaeini, 196
_Scarabaeus sacer_, 196, 197
Scatomyzidae, _504_
Scatophagidae, _504_
_Scatopse_, 477
_Sceliphron_, 112;
_S. nigripes_, 91
Scenopinidae, 484
Schäffer, on structure of wings and nervures, 330
Schiödte, on Anoplura, 599 f.;
on Hemiptera, 543
_Schistocerca peregrina_, enemy of, 506, 514
_Schizocarpus mingaudi_, 220
Schizometopa, _504_
_Schizoneura_, 589
Schizophora, 455
Schmidt-Schwedt, on _Donacia_, 280
_Schoenbergia_, 360, 361
Schoenobiinae, _425_
_Sciapteron_, 387
_Sciara militaris_, 464
Sciomyzidae, _504_
_Sciophila unimaculata_, 462
_Scolia bifasciata_, _S. haemorrhoidalis_, 97
Scoliidae, 93, 94 f.
Scoliides, 97 f.
Scolytidae, 294
Scopariidae, _421_
Scopariinae, _421_
_Scopelodes_, 401
Scopulipedes, _20_, 32 f.
Screw-worm, 512
Scudder, on butterflies, 543
Scutata or Scutati, _546_
Scutellerides, 545
_Scutelligera_, 501
Scutellum, 307, 312, 537
Scutum, 307;
S. proboscidis, 443
Scydmaenidae, 223
Scymnites, 238
_Scymnus minimus_, 238
Seasonal dimorphism or variation, 335
Seitz, on Syntomid resemblances, 388, 389
Semi-loopers, 415
Seminal duct, 321
Semi-pupa, 271
Semper, on development of wing, 333
Sense-organ, 442, 448;
thoracico-abdominal, 414;
in Uraniidae, 419
Sepsidae, _504_
_Sericaria mori_, 375
Sericteria, 325 {623}
Seroot-fly, 482
Serricornia, _189_, _213_, _255_
_Sesia_, 387;
_S. scoliaeformis_, 321
Sesiidae, 386, _388_, 370 (for Syntomidae), 389
Setae, 534 f.;
aërostatic, 408
_Setina_, 410
Seventeen-year _Cicada_, 569
Sex, differences, 92, 95;
production of, 32, 67;
in larva, 325
Sexuparous, 586
Sharp, on classification of Dytiscidae, 213 n.
Sheep, bot-fly, 517;
-tick, 518
Shield, 592
Shoulder, -lappets, 312;
-tufts, 312;
of wing, 316, 319
_Siagona_, 206
Siculodidae, 423
Siebold, von, on Strepsiptera, 301
_Sigara minutissima_, 568
Sight, of _Pompilus_, 104
Silk-glands, 325
Silkworm, 375;
affected by parasitic fly, 507, 508;
Madagascar-, 405
_Silpha_, 221;
_Silpha atrata_, _S. laevigata_, _S. lapponica_, 222;
_S. obscura_, 222;
_S. opaca_, _S. thoracica_, 222
Silphidae, 221 f., _252_, _256_
_Sima_, _168_;
_S. leviceps_, stridulating organ, _169_;
_S. rufonigra_, 169
Simuliidae, 477
_Simulium columbaczense_, 477
_Sinodendron cylindricum_, 194
Siphon, 563, 581, 589
Siphonaptera, 522 f.
Siphonophora, 239
Siphunculata, 600
_Sitaris_, 33;
_S. humeralis_, 272
_Sitodrepa_, 247
Skippers, 363
Slave-making ant, 149, 150, 163
Sloth, 430
Slug-worms, 402
Smallest Insect, 228
Smerinthini, 380
_Smerinthus populi_, 309, 381
Smith, F., on _Mellinus arvensis_, 123
Snails, enemies of, 205, 222, 510;
parasite of, 495
Social, bees, 35;
wasps, 78, 84
Sociales, _20_, 53 f.
_Solanum dulcamara_, beetle on, 232
Soldiers, 132
Soldier-ant, 150
_Solenobia_, 395, 430
_Solenopsis fugax_, 137
Solitary wasps—see Fossores and Eumenidae
Song, of _Cicada_, 572
_Soronia_, 232
Sound-organs, 448;
of _Ageronia_, 354;
of _Hecatesia_, 371;
of _Cicada_, 573, 574—see also stridulating organs
Sound-production, 155, 156;
by _Aegocera_, 411;
by Arctiidae, 410;
by Sphingidae, 382—see also Stridulation
Spalacopsini, 288
Spatula, 459
Spencer, Herbert, on Weismann, 143
_Spercheus emarginatus_, 218, 219
Spermatheca, 320, 321
_Spermophila_, 506
Sphaeridiides, _219_
Sphaeriidae, 227
_Sphaerites_, _223_
Sphaeritides, 229
_Sphaerius acaroides_, 227
Sphaerocarides, 279
_Sphecia_, 387
_Sphecius speciosus_, 123
_Sphecodes_, _21_, 22;
_S. gibbus_, 23, 23;
_S. rubicundus_, 22;
_S. subquadratus_, 23
Sphegidae, 93, 107 f.
Sphegides, 107 f.
_Sphex coeruleus_, 110;
_S. flavipennis_, 108;
_S. lobatus_, 110;
_S. maxillosus_, 108
Sphindidae, 245
Sphingidae, 309, 315, 316, _368_, 380 f.
_Sphinx ligustri_, 380
Spider parasite, 490
_Spilosoma_, 408
Spinneret, 324, 325, 403, 417
_Spirachtha_, 227
Spiracles, 188, 191;
of Diptera, 449 f.;
of Hippoboscidae, 519;
of Lepidoptera, 313, 314;
of _Lipara_, 451;
of _Nepa_, 564;
of Thrips, 528
_Spondyliaspis_, 581
Spondylidae, 288
Springing plant-lice, 579
Spuler, on nervures, 317 n.
Squama, 448
Squeakers, 209
_Staetherinia_, 401
Stag-beetles, 193
Stalk, 317, 319
Staphylinidae, _223_, 224 f.
Staudinger, Schatz and Röber, on butterflies, 343 n.
_Stauronotus maroccanus_, 489
_Stauropus fagi_, 385
_Stelis minuta_, 29;
_S. nasuta_, 30, 43;
_S. signata_, 30
Stelocyttares, 81
_Stenamma westwoodi_, _159_
_Stenopteryx hirundinis_, 519
_Stephostethus_, 240
Sternorhyncha, _544_
_Sterrhopteryx_, 394
Stethopathidae, 496
Stigmata—see Spiracles
_Stigmatomma_, _180_
_Stigmus pendulus_, 128
Sting, 4, 5, 6, 58, 144; {624}
development of, 8, 9
Stinging, 98;
by _Calicurgus_, 102;
by Pompilidae, 104;
by _Sphex_, 109
Stingless bees, 61
Stink-gland, 257, 533;
-vessel, 225
Stipes, 309
Stizinae, 123
Stomach, 320
_Stomoxys calcitrans_, 512
Stratiomyidae, 478
_Stratiomys_, 452
Straus-Durckheim, on _Melolontha_, 198
Strawberries, eaten by beetles, 205
Streblidae, 521
Strepsiptera, _189_, 298 f.
_Streptoperas_, 401
Stridulating organ, of _Myrmica_, 133;
of _Heterocerus_, 243;
of _Passalus_-larva, 192;
of _Sima leviceps_, 169
Stridulation, of ants, 134;
of _Corixa_, 568;
of Criocerides, 281;
of Dynastides, 199;
of _Geotrupes_, 195;
of Ipides, 232;
of _Lomaptera_, 200;
of Longicorns, 287;
of larva of _Lucanus cervus_, 194;
of Megalopides, 282;
of _Melolontha_-larva, 198;
of _Mutilla_, 94;
of _Pelobius_, 208;
of _Phonapate_, 246;
of _Phyllomorpha_, 548;
of _Praogena_, 264;
of _Siagona_, 206;
of _Trox_, 195
Strigil, 568
Striphnopterygidae, _376_
_Strongylognathus huberi_, _S. testaceus_, 162
_Strumigenys_, 170
Style, 442
Stylopidae, 298
Stylopised bees, 26
_Stylops dalii_, 299
_Styx infernalis_, 340, 358
_Suana_, 405
Subcostal nervure, 318
Submedian nervure, 318
Suboesophageal ganglion, 320
Sucking-stomach, 311, 449
Suction by Lepidoptera, 311
Suctoria, 526
Supericornia, 546
Swallow-flies, 519
Swarming of wasps, 70 n.
Swarms, 62, 65, 67, 80, 135, 467, 505, 584
Swift-moths, 396
Symbiosis, of ants and plants, 139;
of bee and Acarid, 70.
See also Ants'-nest Insects, and Association
_Symbius blattarum_, 269
Symphily, 183
Synecthry, 183
_Synemon_, 371
_Synoeca cyanea_, nest, 82
_Syntelia westwoodi_, 229
Synteliidae, 229
Syntomidae, 339 n., _369_, 388
_Syntomis phegea_, 390
Syringe, 535, 536
Syrphidae, 439, 498 f.
_Systoechus oreas_, 489
_Systropus crudelis_, 489
Tabanidae, 481, 492
_Tabanus_, 482
Tachinidae, 507, _514_
_Tachysphex panzeri_, 117
_Tachytes_, 116;
destroyer of, 275;
_T. australis_, 113, 117;
_T. pectinipes_, 117
Tachytides, 116
_Taenia_, fleas as hosts of, 526
_Tajuria diaeus_, pupa, 357
_Taleporia_, 395
Taleporiidae, 430
Tanypezidae, _504_
Taphroderides, 296
_Tapinoma erraticum_, 157
Tarantula-killer, 105
_Tarphius_, 233
_Tarsolepis_, 383
Taschenberg, on anatomy of flea, 523 n.
_Tascina_, _372_
Tea-plant bug, 562
_Teara melanosticta_, 408
Tegula, 71, 187, 307, 311, 312, 447
Tegmina, 539
Teleodont, 193
Telephorides, _248_
_Telmatophilus_, 235
_Temnochila coerulea_, 232
Temnochilides, _233_
_Tenebrio molitor_, 263
Tenebrionidae, 263
_Tenebroides mauritanica_, 232
Tentacle, maxillary, 309, 432
Tenthredinidae, parasite of, 4
Terebrantia, 531
Termites, 203, 206, 227, 231
Terrifying attitude, 384
Tesseratomides, 546
Testes, 321, 324, 400, 429;
in larva, 325
_Tetanocera ferruginea_, 504
Tetanoceridae, _504_
_Tetragona_, _53_, _61_
Tetramera, _190_
_Tetramorium caespitum_, 160, 163
Tettigometrides, _567_
_Teucrium_, bug and galls on, 550
_Thais_, pupation of, 363
_Thanaos_, _342_;
_T. tages_, androconia, 332
Therevidae, 484
_Thiridopteryx_, 420
Thomas, on androconia, 331
Thorictidae, 236
_Thorictus_, 236
Thrips, 526 f.;
_Thrips lini_, 531;
_T. secalina_, 530
Throscides, _260
Thyatira batis_, _T. derasa_, 386 {625}
Thymaridae, 392
Thynnides, 96
Thyreophoridae, _504_
Thyrididae, _370_, 404
_Thyridopteryx ephemeraeformis_, 394
Thysanoptera, 526 f.
Tiger-beetles, 201 f.
Tiger-moths, 409
_Tillus elongatus_, 253, 254
Tinaegeriidae, _370_, 387
_Tinea_, 305;
_T. pellionella_, 429, 430;
_T. vastella_, 430;
_T. vivipara_, 430
Tineidae, _340_, _370_, _394_, _427_, 428
Tineodidae, 423
_Tineola biselliella_, 430
Tingidae, 549
_Tipula brobdignagia_, 475
Tipulidae, 471 f.;
T. Brevipalpi, 472, 473;
T. Longipalpi, 472, 475
Tipulinae, 475
_Tiresias serra_, 241
_Titanus giganteus_, 287
_Tithorea_, 346
Tomicides, 295
_Tomognathus sublaevis_, 161
Tongue, 309
Tortoise-shell butterflies, 352
Tortricidae, _340_, _395_, 427, _432_
Tortricina, _395_
_Toxorrhina_, 472
_Toxotrypana_, 506
_Trechus_, 205
Trichiini, 200
_Trichocera_, 473
_Trichodes alvearius_, _T. ammios_, _T. apiarius_, 254
_Trichophaga tapetzella_, 430
Trichoptera, 306, _425_
Trichopterygidae, 227
_Trichopteryx fascicularis_, 227
Trichroism, 351
Trichterwickler, 294
_Trichura_, 389, 390
Trictenotomidae, 275
_Triecphora_, 543
_Trigona_, _53_, _61_;
_T. carbonaria_, 63;
_T. crassipes_, 65;
_T. mosquito_, 62
Trimera, _238_, 544
_Trimeria_, _89_
_Trineura aterrima_, 494
_Triodites mus_, 489
_Trioza rhamni_, 580
_Triphaena_, 415
_Triphleps_, 530
_Tritoma bipustulata_, 236
Triungulin, 262, 268, 270, 271, 272, 299, 300
Trochalopoda, _543_, _544_
Trochanter, 307;
divided, 123
_Trochilium_, 387
Trogini, _195_
Trogositidae, 232, 235
_Trogosita mauritanica_, 232
Tromoptera, 457
Trophi—see Mouth-parts
_Trox_, stridulation, 195
Truffle-beetle, 222
Trumpeter bumble-bee, 58
_Trypanaeus_, 230
Trypanidae, 395
Trypetidae, _504_, 506
Trypoxylonides, 118
_Trypoxylon_, 118;
_T. albitarse_, 118;
_T. figulus_, 119
Tse-tse fly, 512, 513
Tubulifera, _1_ f.
Tubulifera (Thrips), 531
Tulip-tree, tubes on, 578
Turkey-gnats, 477
Turnip-flea, 278
Tusser, or Tussore, silk, 374
_Tympanoterpes gigas_, 572
_Typhlatta_, _179_, _180_
_Typhlopone_, 178, 179, 180
_Ugimyia sericariae_, 507
Ulidiidae, _504_
_Ulopa_, _578_
Uncus, 314
_Urania rhipheus_, 419
Uraniidae, _368_, 419
Uric acid pigments, 357
_Urodon_, _278_
Uzel, on Thysanoptera, 527
_Vanessa_, 352;
larva, 354—see also _Pyrameis_ and _Araschnia_
_Vanessula_, 356
Vapourer-moths, 407
Variation, of _Anomma burmeisteri_, 179;
of _Bombus_, 58;
of larvae, 336;
of _Sphecodes_, 23;
of male and worker ants, 160;
of workers and females, 162;
due to parasites, 26;
of larva and imago, 408;
generic, 401;
local, 398;
in nervuration, 414;
and dimorphism in Geometrid-larvae, 412;
of mandibles of Lucanidae, 193;
in colour of Psyllidae, 579;
trichroism of hind wings, 351;
in size of Brenthidae, 297;
of time and form in _Cicada_, 570;
in wings, 540;
as to winged or wingless, 531;
change in, 414;
seasonal, 335
Vasa deferentia, 321
Veils, 493
Veins—see nervures
_Velia currens_, 552
_Velleius dilatatus_, 227
Verhoeff, on _Agenia_, 106;
on _Halictus_, 25;
on Siphonophora, 239;
on _Stelis minuta_, 29;
on terminal segments of beetles, 186
_Vermileo degeeri_, 481
_Vermipsylla alakurt_, 523, 526 {626}
Verson, on rudiments of wings, 328
Vertebrates, larvae of Diptera, attacking, 506, 510, 512, 514, 517, 520;
tick-fleas on, 526
_Vespa_, nests of, 79, 83;
_V. austriaca_, 81, 88;
_V. crabro_, 81;
_V. germanica_, 79
Vespidae, 78
Viviparous, Aphids, 583;
fly, 506, 511, 513, 518 f.;
moths, 430;
Staphylinidae, 227
Voice—see Song, Sound-organs, Stridulation
_Volucella_, 500;
_V. bombylans_, 441
Wagner, on morphology of fleas, 523 n.;
on paedogenesis, 460
Walker, J. J., on _Halobates_, 552
Wallace, on flight of Hesperiidae, 364
Walsingham, Lord, on Tortricidae, 427
Walter, on mouth of Lepidoptera, 308, 310
Wandering ants, 175 f.
Wanzenspritze, 536
Wasmann, on Ants'-nest Insects, 181 n., 183;
on _Lomechusa_, 142, 226;
on Weismann, 143
Wasps, 71 f.
Wasps'-nest, beetle, 235;
Insect, 268
Water-scorpion, 563
Wax, 65, 575, 576, 597
Wax-glands, 589
Wax-hairs, 580
Wedde, on mouth of Hemiptera, 535
Weeping-trees, 577
Weevil, biscuit-, 247;
pea-, 277
Weinland, on halteres, 448
Wet- and dry-season forms, 336
Whirligig-beetle, 215
White wax, 576, 597
Whittell, on _Pelopaeus_ and _Larrada_, 117
Wielowiejski, on luminous organs, 250
Wing-cases, of beetles, 186, 270
Wing, of bugs, 539;
of Diptera, 447;
of Lepidoptera, 315 f.;
development of, 328;
structure of, 329
Wingless—see Apterous
Wingless and winged Aphids, 584
Wing-nervures—see Nervures
Wing-rib, 330, 333
Wing-veins—see Nervures
Winter-gnats, 473
Winter-moth, 414
Winter-mother, 586
Wire-worm, 258
Wood-ant—see _Formica rufa_
Wood-leopard moth, 309, 395
Woodpecker, Diptera in, 506
Workers, 54, 66, 67, 79, 85, 132, 140
Worm-eaten furniture, 248
_Xantharpyia straminea_, parasite of, 521, 522
_Xenos_, 303;
_X. rossii_, 299, 301
_Xestobium_, _248_
_Xylocopa_, 32, 34, 70;
submentum of, 14;
_X. chloroptera_, 34;
_X. violacea_, 33
_Xylodiplosis_, 458, 459
Xylophagidae, 479
Xylophaginae, 480
Xylophilidae, 266
_Xylotrupes gideon_, 199
Yellow-fever-fly, 464
_Yolinus_, 558
Young carried, 556
Yucca-moth, 432
_Zabrus_, 205
_Zaitha anura_, 566
_Zelotypia staceyi_, 396
_Zemioses celtis_, 296
_Zeuzera aesculi_, 309, 395
Zeuzeridae, 395
Zygaenidae, _369_, 388, 390, _392_, _394_
_Zygia_, 253
END OF VOL. VI
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NOTES
[1] Systematic monograph, Mocsáry, Budapest, 1889. Account of the
European Chrysididae, R. du Buysson in André, _Spec. gen. Hym._ vol.
vi. 1896.
[2] _Ent. Mag._ vi. 1869, p. 153.
[3] _Ann. Sci. Nat._ (7) ix. 1890, p. 1.
[4] _C. R. Ac. Paris_, cxviii. 1894, p. 873.
[5] _Trans. ent. Soc. London_, 1873, p. 408.
[6] _Zeitschr. wiss. Zool._ xxv. 1875, p. 184.
[7] _Morph. Jahrb._ xxiv. 1896, p. 192.
[8] _Zeitschr. wiss. Zool._ xxx. 1878, p. 78.
[9] _Proc. ent. Soc. Washington_, iii. 1896, p. 334.
[10] _Trans. ent. Soc._ 1878, p. 169.
[11] The mode of wetting the pollen is not clear. Wolff says it is done by
an exudation from the tibia; H. Müller by admixture of nectar from
the bee's mouth. The latter view is more probably correct.
[12] In studying the proboscis the student will do well to take a _Bombus_
as an example; its anatomy being more easily deciphered than that of
the honey-bee.
[13] Leuckart proposed the term lingula; but the word gives rise to the
impression that it is a mistake for either lingua or ligula. Packard
calls the part "hypopharynx."
[14] For figures and descriptions of the proboscides of British bees,
refer to E. Saunders, _Jour. Linn. Soc._ xxiii. 1890, pp. 410-432,
plates III.-X.: and for details of the minute structure and function
to Cheshire, _Bees and Bee-keeping_, vol. i.
[15] Breithaupt, _Arch. Naturges._ lii. Bd. i. 1886, p. 47.
[16] See Fig. 26, p. 71.
[17] _Bull. Mus. Paris_, i. 1895, p. 38.
[18] _C.R. Ac. Paris_, lxxxvii. 1878, pp. 378 and 535.
[19] _Catalogus Hymenopterorum_, Leipzig, 10 vols. 1892-96; _Bees_, vol.
x.
[20] _Zool. Jahrb. Syst._ iv. 1891, p. 779. This paper is a most valuable
summary of what is known as to the habits of European solitary bees,
but is less satisfactory from a systematic point of view.
[21] _Bull. Soc. ent. France_, 1894, p. cxv.
[22] Marchal, _Rev. Sci._ 15th February 1890, and Ferton, _t.c._ 19th
April.
[23] _C.R. Ac. Paris_, lxxxix. 1879, p. 1079, and _Ann. Sci. Nat._ (6),
ix. 1879, No. 4.
[24] _Act. Soc. Bordeaux_, xlviii. 1895, p. 145.
[25] _Verh. Ver. Rheinland_, xli. 1884, p. 1.
[26] It is impossible for us here to deal with the question of the origin
of the parasitic habit in bees. The reader wishing for information as
to this may refer to Prof. Pérez's paper, _Act. Soc. Bordeaux_,
xlvii. 1895. p. 300.
[27] Refer to p. 70 _postea_, note, as to a recent discovery about
_Xylocopa_.
[28] _Souvenirs entomologiques_. 4 vols. Paris, 1879 to 1891.
[29] The "_Chalicodome des galets_" or _C_. "_des murailles_" of the
French writer; in some places he speaks of the species as being _C.
muraria_, in others as _C. parietina_.
[30] _Trans. Zool. Soc. London_, vii. 1870, p. 178.
[31] _Mt. Ver. Steiermark_, xxxi. 1882, p. 69.
[32] _Zool. Anz._ vii. 1884, p. 312.
[33] _SB. Ges. Wien._ xxxviii. 1888, p. 34.
[34] _Ent. Nachr._ xii. 1886, p. 177.
[35] _Tr. ent. Soc. London_, 1868, p. 133.
[36] _Tr. ent. Soc. London_, 1884, p. 149.
[37] _Ann. Soc. ent. France_ (5), iv. 1874, p. 567.
[38] See Pérez, _Act. Soc. Bordeaux_, xxxiii. 1880, p. lxv.; and Cameron,
_Tr. Soc. Glasgow_, n. s. ii. 1889, p. 194.
[39] _Ann. Nat. Hist._ (6), xix. 1897, p. 136.
[40] Janet has suggested that the folding is done to keep the delicate
hind-margins of the wings from being frayed.
[41] _Zool. Anz._ xix. 1896, p. 449. See also note, _antea_, p. 70.
[42] _Monographie des guêpes sociales_, Geneva, 1853-1858, pp. cc. and
356, plates i.-xxxvii.
[43] Hence probably the great difference in the abundance of wasps in
different years: if a period of cold weather occur during the early
stages of formation of a wasp family, operations are suspended and
growth delayed; or death may even put an end to the nascent colony.
[44] _CR. Ac. Paris_, cxvii. 1893, p. 584; _op. cit._ cxxi. 1895, p. 731;
_Arch. Zool. exper._ (3) iv. 1896, pp. 1-100.
[45] Kumagusu Minakata, in _Nature_, l. 1894, p. 30.
[46] As this work is passing through the press we receive a book by Mr.
and Mrs. Peckham on _The Instincts and Habits of the Solitary Wasps_,
Madison, 1898. They are of opinion that, in the case of some species,
it does not matter much whether the victim is or is not killed by the
stinging.
[47] _P. ent. Soc. Washington_, iii. 1896, p. 303.
[48] Monograph by Lucas, _Berlin ent. Zeitschr._ xxxix. 1894.
[49] "Die Gattungen der Sphegiden," _Ann. Hofmus. Wien._ xi. 1896, pp.
233-596. Seven plates.
[50] We will take this opportunity of correcting an error in the
explanation of Fig. 333 of the preceding volume, showing the
propodeum, etc. of _Sphex chrysis_. _f_ points to a division of the
mesonotum, not of the metanotum, as there stated.
[51] _Pelopaeus_ disappears from the new catalogue of Hymenoptera as the
name of a valid genus; its species being assigned to _Sceliphron_ and
various other genera. We have endeavoured, as regards this name, to
reconcile the nomenclature of previous authors with that used in the
new catalogue by placing the generic name adopted in the latter in
brackets.
[52] When a second cell is more or less perfectly marked out, the cell
with which it is connected is said to be appendiculate. The nervures
frequently extend beyond the complete cells towards the outer margin,
forming "incomplete" cells; only complete cells are counted, except
when "incomplete" is mentioned.
[53] See on this point the note on p. 130.
[54] The pupae and cocoons of ants are usually called by the uninstructed,
"ants' eggs." In this country they are used as food for pheasants.
[55] The parthenogenetic young produced by worker females are invariably
of the male sex.
[56] The student must recollect that the winged female ants cast their
wings previously to assuming the social life. The winglessness of
these females is a totally different phenomenon from that we here
allude to.
[57] See Forel, _Verh. Ges. deutsch. Naturf._ lxvi. 1894, 2, pp. 142-147;
and Emery _Biol. Centralbl._ xiv. 1894, p. 53. The term ergatoid
applies to both sexes; a species with worker-like female is
ergatogynous; with a worker-like male ergatandrous.
[58] _Nature_ li. 1894, p. 125.
[59] _Biol. Centralbl._ xv. 1895, p. 640.
[60] Prof. Forel has favoured the writer by informing him of several cases
of these rare intermediate forms he has himself detected.
[61] _Biol. Centralbl._ xiv. 1894, p. 53.
[62] Forel's latest views on this subject will be found in the _Ann. Soc.
ent. Belgique_ xxxvii. 1893, p. 161; the very valuable paper by
Emery, in _Zool. Jahrb. Syst._ viii. 1896, p. 760.
[63] _Ann. Soct. ent. France_, 1893, p. 467.
[64] _Ann. Soc. ent. France_, 1893, _Bull._ p. cclxiv.
[65] Forel, _J. Bombay Soc._ viii. 1893, p. 36.
[66] See von Ihering, _Berlin. ent. Zeitschr._ xxxix. 1894, p. 364; and
Forel, _Ann. Soc. ent. Belgique_, xl. 1896, p. 170.
[67] _Ann. Soc. ent. Belgique_, xxxvii. 1893, p. 163.
[68] _Bih. Svenska Ak._ xxi. 1896, Afd. iv. No. 4.
[69] Until recently this genus was generally known as _Atta_, but this
name is now applied to the leaf-cutting ants, that were formerly
called _Oecodoma_.
[70] Forel, _Bull. Soc. Vaudoise_, xxx. pp. 29-30, 1894.
[71] _Tr. ent. Soc. London_, 1893, pp. 365-467.
[72] For a valuable revision of _Dorylus_ and its allies see Emery, _Zool.
Jahrb. Syst._ viii. 1895, pp. 685, etc. We, however, doubt the wisdom
of extending the sub-family so as to include _Cerapachys_,
_Parasyscia_, etc.
[73] A Catalogue of Myrmecophilous and Termitophilous Arthropods was
published by Wasmann, Berlin 1894.
[74] For a summary of this subject see Wasmann, _Congr. internat. Zool._
iii. 1896, pp. 411-440.
[75] For explanation of this term see vol. v. p. 524.
[76] An interesting exception occurs in the Malacodermidae, where this
coadaptation is wanting, or is imperfect; they are frequently
considered to be the most primitive of existing beetles.
[77] In a series of memoirs in various German periodicals during the last
five or six years (see especially _Deutsche ent. Zeit._ 1893 and
1894, also subsequent years of _Arch. Naturges._). It should be
noticed that in the course of his studies Verhoeff has modified some
of his earlier views.
[78] We consider this term inferior to Tetramera for nomenclatorial
purposes.
[79] _Danske Selsk. Skr._ (6), viii. No. 1, 1895.
[80] _Horae Soc. ent. Ross._ xiv. 1879, p. 15.
[81] In this sub-family there are numerous forms in which the elytra cover
the pygidium, and in which the number of conspicuous ventral segments
is reduced to five or even four. We use the term Coprides as
equivalent to the "Laparosticti" of Lacordaire (_Gen. Col._ iii.
1856); it thus includes the "Coprini" and "Glaphyrini" of the
_Catalogus Coleopterorum_, vol. iv. Munich, 1869.
[82] _Considérations genérales sur l'anatomic comparée des animaux
articulés_, etc., Paris 1828, 4to. xix. and 435 pp., and Atlas of ten
(xx.) plates, and 36 pp.
[83] Raspail, _Mém. soc. zool. France_, vi. 1893, pp. 202-213.
[84] _Ann. soc. ent. France_, (v.) iv. 1874, p. 39.
[85] In Theratides this outer lobe is in a rudimentary state, like a seta.
[86] The first portion of a classification of Cicindelidae by Dr. Walther
Horn, _Revision der Cicindeliden_, Berlin, 1898, has appeared since
this was written.
[87] _Natural History of aquatic Insects_, 1895, p. 376.
[88] _Tr. Amer. ent. Soc._ xv. 1888, p. 18.
[89] _Op. cit._ v. 1881, p. 91; cf. Sharp, _Tr. ent. Soc. London_, 1882,
p. 61.
[90] _P. ent. Soc. Washington_, ii. 1892, p. 341.
[91] _Descent of Man_, i. 1890, p. 338; The views of Landois and Recker,
_Arch. f. Naturgesch._ lvii. 1, 1891, p. 101, are erroneous.
[92] See _J. Linn. Soc. Zool._ xiii. 1876, p. 161.
[93] For many particulars as to respiration of _Dytiscus_, and
peculiarities of the larva see Miall, _Aquatic Insects_, 1895, pp.
39, etc. (In the figure given on p. 60 the large stigma on the
terminal segment of the abdomen is omitted, though it is referred to
in the text.)
[94] For classification and structure see Sharp, "On Dytiscidae," _Sci.
Trans. R. Dublin Soc._ (2) ii. 1882.
[95] Descriptions of larvae that may possibly be those of Paussids have
been published by Xambeu, _Ann. Soc. Linn. Lyon_, xxxix. 1892, p.
137, and Erichson, _Arch. Naturgesch._ xiii. 1847, p. 275.
[96] _Arch. Mus. Paris_ (2), viii. and ix. 1887.
[97] For classification and monograph of the family, see Régimbart, _Ann.
Soc. ent. France_, 1882, 1883, and 1886. For a catalogue, Séverin,
_Ann. Soc. ent. Belgique_, xxxiii. 1889.
[98] _Ann. Soc. ent. France_, xxi. 1852, p. 619.
[99] Horn, _Tr. Amer. ent. Soc._ xv. 1888, p. 23; Riley, _Insect Life_, i.
1889, p. 300.
[100] _Insect Life_, i. 1889, pp. 200 and 306.
[101] _Tr. Amer. ent. Soc._ viii. 1880, pp. 219-321.
[102] Westwood, _Tr. ent. Soc. London_ (N.S.) iii. 1855, p. 90; Wasmann,
_Krit. Verzeichniss Myrmekoph. Arthropod._ 1894, p. 121.
[103] _Rev. ent. franc._ ix. 1890.
[104] _Die Käfer von Mitteleuropa_: II. _Familienreihe, Staphylinoidea._
Vienna, 1895 and 1899.
[105] _Vergleichende Studien über Ameisengäste_, Nijhoff, 1890; and
_Tijdschr. ent._ xxxiii. 1890, pp. 93, etc.; _Biol. Centralbl._ xv.
1895, p. 632.
[106] Schiödte, _Ann. Sci. Nat. Zool._ (4) v. 1857, p. 169.
[107] _Biol. Centr. Amer. Col._ ii. pt. i. 1888, p. 156.
[108] Monograph, _Trichopterygia illustrata_, by A. Matthews, London, 1872.
[109] For further information refer to Matthews, _An Essay on_ Hydroscapha,
London, 1876, 20 pp. 1 pl.
[110] _Ann. Nat. Hist._ (5) xix. 1887, p. 115.
[111] _Larves de Coléoptères_, 1878, p. 11, pl. i.
[112] _Biol. Centr. Amer. Col._ ii. pt. i. p. 438.
[113] The family was monographed by the Abbé de Marseul in _Ann. Soc. ent.
France_, 1853-1862, but great additions have been made since then.
[114] For characters of larvae of various genera, see Perris, _Larves,
etc._ p. 24.
[115] _SB. Ak. Wien._ xxiv. 1857, p. 330.
[116] Catalogue of Trogositidae, by Leveillé, in _Ann. Soc. ent. France_,
1888, p. 429.
[117] For classification, see Sharp, _Biol. Centr. Amer. Col._ ii. pt. i.
1894, p. 443.
[118] See Ganglbauer, _Käf. Mitteleuropas_, i. p. 530, as well as Leconte
and Horn _Classification_, etc., p. 130.
[119] Perris, _Larves, etc._, p. 75.
[120] Ritsema, _Catalogue of_ Helota, _Notes Leyden Mus._ xiii. 1891, p.
223, and xv. 1893, p. 160.
[121] _Zool. Anz._ xviii. 1895, p. 244.
[122] Gerstaecker, _Monographie der Endomychiden_, Leipzig, 858, 1433 pp.
Since this work was published, the species known have been multiplied
two or three times.
[123] _Stettin. ent. Zeit._ xlii. 1881, pp. 104-112.
[124] It is probable that we do not know more than the fiftieth part of the
existing species, most of which lead lives that render them very
difficult to find.
[125] _Bull. ent. ital._ 1886, p. 406, and _Ent. Zeit. Stettin_, xliii.
1887, pp. 201-206. Emery does not mention the name of the species,
but we presume it to be the common Italian fire-fly, _Luciola
italica_.
[126] _Zeitschr. wiss. Zool._ xxxvii. 1882, p. 354; also Emery, _op. cit._
xl. 1884, p. 338. For another theory as to the luminescence, see p.
259.
[127] _Bull. Soc. Zool. France_, xii. 1887, p. 137, _postea_.
[128] _Deutsche ent. Zeitschr._ xxxii. 1888, pp. 145-167.
[129] _Ent. Mag._ xxiv. 1887, p. 148.
[130] _Larves des Coléoptères_, 1878, p. 208.
[131] _Ann. Soc. ent. France_, 1894, p. 7.
[132] Perris, _Ann. Soc. ent. France_ (2) ix. 1851, p. 48.
[133] _Arch. Naturgesch._ xlviii. 1, 1882, p. 371.
[134] "Les Élatérides lumineux," _Bull. Soc. Zool. France_, xi. 1886; also
_Leçons de Physiologie générale_, Paris, 1898, and _C.R. Ac. Sci._
cxxiii. 1896, p. 653.
[135] It seems impossible to understand the morphology of the anterior
segments by mere inspection; the anterior spiracle being seated on
the segment behind the broad thorax. Considerable difference of
opinion has prevailed as to what is head, what thorax; the aid of
embryology is necessary to settle the point. The larva described by
Westwood (_Mod. Classif._ i. 1839, p. 229), and figured as probably
_Buprestis attenuata_ is doubtless a Passalid.
[136] Casey has examined the wings in the genus _Blapstinus_ (an "apterous"
genus), and found that the wings are extremely varied in development,
according to the species; in no case, however, did they appear to be
capable of giving more than a laboured and feeble flight.—_Ann. New
York Ac._ v. 1890, p. 416.
In _Eleodes_, though the meso- and meta-notum are formed of delicate
membrane, the wings exist as minute flaps, requiring some examination
for their detection.
[137] _Ann. Nat. Hist._ (4) vi. 1870, p. 314; and _Ent. Mag._ xxvii. 1891,
p. 18.
[138] _Mitt. Schweiz. ent. Ges._ iv. 1876, p. 556.
[139] _Ann. Soc. ent. France_, lx. 1891, p. 447.
[140] "On the Natural History, Anatomy, and Development of the Oil-Beetle,
_Meloe_," _Tr. Linn. Soc._ xx. 1851, p. 297; and xxi. 1853, p. 167.
[141] _Rep. U.S. ent. Commission_, i. 1878, p. 297.
[142] _Amer. Nat._ xvii. 1883, p. 790.
[143] For illustration of this metamorphosis, see Vol. V. p. 159 of this
work.
[144] _Les Insectes Vésicants_, Paris 1890, 554 pp. Parts of this work were
previously published in _J. de l'Anat. Phys._, xxi. xxii. xxiii. 1886
and 1887.
[145] _Genera des Coléoptères (Suites à Buffon)_, x. Paris, 1874, p. 15.
[146] _Berlin. ent. Zeit._ 1887, p. 325, and 1889, p. 299.
[147] _Ann. Soc. Liége_, x. 1855, p. 260.
[148] _Mem. Soc. Liége_, xvi. 1861, p. 387.
[149] Packard, 5th Rep. _U.S. Ent. Comm._ 1890, p. 689.
[150] Not a growing tree, but the instrument used for stretching boots.
[151] _Berlin. ent. Zeitschr._ xli. 1896, SB. p. 22.
[152] Sharp, _Ann. Soc. ent. Belgique_, xxviii. 1884, CR. p. cvii.
[153] For a more extensive account of _Rhynchites betulae_ and others refer
to Wasmann. _Der Trichterwickler_, Münster, 1884, and Debey,
_Beiträge zur Lebensund Entwickelungsgeschichte ... der Attelabiden_,
Bonn, 1846. The first includes an extensive philosophical discussion;
the second is a valuable collection of observations.
[154] _Bull. U.S. Dep. Agric. ent._ New series, No. 7, 1897.
[155] Perris, _Ann. Sci. Nat._ (2) xiv. 1840, p. 89, pl. iii.
[156] In the males of the genus _Cedeocera_ the tips of the elytra are
drawn out into processes almost as long as the elytra themselves, and
rivalling the forceps of earwigs.
[157] The stature of the individuals of the same species is, in some of
these Brenthidae, subject to extreme variation, especially in the
males, some individuals of which—in the case of _Brenthus
anchorago_—are five times as long as others.
[158] This remark applies to the Strepsiptera parasitic on Hymenoptera:
nothing whatever is known as to the life-histories of the species
that attack Hemiptera.
[159] Although not an invariable, it seems that it is a general rule that
the _Stylops_ produced from the body of one individual are all of one
sex; it has even been stated that female bees produce more especially
female _Stylops_, and male bees male _Stylops_. If any correlation as
to this latter point exist, it is far from general.
[160] Von Siebold, _Arch. Naturges._ ix. 1843, pp. 137-161. Nassonoff's
recent paper is in Russian, but so far as we can gather (cf. _Zool.
Centralbl._ i. 1894, p. 766), it does not add greatly to the data
furnished by von Siebold.
[161] _Ent. Meddel._ v. 1896. p. 148, and _Ov. Danske Selsk._ 1896, p. 67.
[162] _Horae Soc. ent. Ross._ xiv. 1879, p. 14.
[163] Named by Mr. Distant _Callidea baro_; according to the Brussels
catalogue of Hemiptera, _Chrysocoris grandis_ var. _baro_.
[164] Kellogg, _Kansas Quarterly_, ii. 1893, p. 51, plate II.
[165] _Jena. Zeitschr. Naturw._ xviii. 1885, p. 751.
[166] The writer is not quite convinced that the supposed mandibles of
these Macrolepidoptera are really entitled to be considered as such.
[167] _Tr. ent. Soc. London_, 1893, p. 263.
[168] _Amer. Natural._ xxix. 1895, p. 637. It should be recollected that
many Lepidoptera do not possess any proboscis.
[169] _Jena. Zeitschr. Naturw._ xviii. 1885, p. 168.
[170] _Amer. Natural._ xiv. 1880, p. 313.
[171] For an account of the structures at the tip of the proboscis of this
moth, and of the beautiful manner in which the lobes of the maxillae
are dovetailed together, see Francis Darwin, _Quart. J. Micr. Sci._
xv. 1875, p. 385. For details as to numerous proboscides, and as to
the difficulties that exist in comprehending the exact mode of action
of the organ, refer to Breitenbach's papers, especially _Jena.
Zeitschr. Naturw._ xv. 1882, p. 151.
[172] See Cholodkovsky, _Zool. Anz._ ix. p. 615; Haase, t.c. p. 711; also
Riley, _P. ent. Soc. Washington_, ii. 1892, p. 310.
[173] _Fourth Rep. U.S. Entom. Commission_, 1885, p. 49.
[174] _C.R. Ac. Sci. Paris_, cxviii. 1894, p. 360; and his _Thesis_,
Bordeaux, 1895.
[175] _C.R. Ac. Sci. Paris_, cxviii. 1894, p. 542.
[176] _Fauna of British India_, Moths, i. 1892, p. 6.
[177] It is impossible for us to treat of the difficulties that exist on
this point, and we must refer the student to the pamphlet, "The
Venation of the Wings of Insects," by Prof. Comstock, Ithaca, 1895,
being a reprint, with an important prefatory note, from the _Elements
of Insect Anatomy_, by J. H. Comstock and V. L. Kellogg, also to
Packard's discussion of the subject in _Mem. Ac. Sci. Washington_,
vii. 1895, pp. 84-86. The method of Spuler, alluded to in these two
memoirs, is based on development, and, when extended, will doubtless
have very valuable results. See Spuler, _Zeitschr. wiss. Zool._ liii.
1892, p. 597.
[178] The structure and development of scales and nervures is dealt with as
part of the brief study of the development of the wing, on p. 329,
etc.
[179] The internal anatomy of Lepidoptera has not been extensively studied.
For information refer to Dufour, _C.R. Ac. Paris_, xxxiv. 1852, p.
748; Scudder, _Butt. New England_, i. 1889, p. 47; Minot and Burgess,
_Fourth Rep. U. S. Entom. Comm._ 1885, p. 53.
[180] _Tr. Linn. Soc. London_ (2), v. 1890, p. 143.
[181] _P. ent. Soc. Washington_, ii. 1892, p. 305.
[182] _Acta Ac. German._ li. 1887, p. 238.
[183] _Ann. Soc. ent. France_, 1887, pp. 384-404, Pl. 7.
[184] _Isis_, 1845, p. 835.
[185] For anatomy of caterpillars refer to Lyonnet's famous work, _Traité
anatomique de la chenille qui ronge le bois de saule_, La Haye, 1762.
[186] See Plateau, _Bull. Ac. Belgique_, xv. 1888, p. 28; in reference to
structure of ocelli, Blanc, _Tête du Bombyx mori_ ... 1891, pp. 163,
etc.; and Landois in _Zeitschr. wiss. Zool._ xvi. 1866, p. 27.
[187] _Entwickelungsgeschichte der Schmetterlinge_, Cassel, 1815.
[188] _Tr. Linn. Soc. London, Zool._ 2nd Ser., v. 1890, pp. 147, 148.
[189] For information as to the structure and function of the silk-vessels,
refer to Helm, _Zeitschr. wiss. Zool._ xxvi. 1876, p. 434; and
Gilson, _La Cellule_, vi. 1890, p. 116.
[190] _Jahresber. Schlesisch. Ges._ lviii. 1881, p. 116.
[191] The student will find important information as to the varieties of
external form of pupae in Dr. T. A. Chapman's writings; see
especially _Tr. ent. Soc. London_, 1893, 1894, and 1896.
[192] Latter, _Tr. ent. Soc. London_, 1895, p. 399.
[193] _Bull. Soc. Vaudoise_, xxx. 1894, No. 115.
[194] _Zeitschr. wiss. Zool._ liii. 1892, p. 623.
[195] _Zool. Jahrb. Anat._ iii. 1889, p. 646.
[196] _Amer. Natural._, xxvii. 1893, p. 1018.
[197] _Amer. Natural._, xxxii. 1898, p. 256.
[198] _Zeitschr. wiss. Zool._ viii. 1857, p. 326.
[199] _Phil. Trans._ 186 B, 1896, No. 15.
[200] _Natural Science_, viii. 1896, p. 94.
[201] _Bull. Soc. ent. France_, 1896, p. 257.
[202] _Ent. Record_, vi. 1895, p. 258.
[203] _Trans. ent. Soc. London_, 1892, p. 293, etc.
[204] The term mimicry is sometimes used in a wider sense; but we think it
better to limit it to its original meaning. The word is a most
unfortunate one, being both inadequate and inaccurate.
[205] _Trans. Linn. Soc._ xxiii. 1862, p. 507.
[206] A summary of the chief aspects of the question is contained in
Beddard's _Animal Coloration_, London, 1892. An account of the
subject with numerous illustrations has been given by Haase,
"Untersuchungen über die Mimicry," _Bibl. Zool._ iii. 1893, Heft
viii. Those who wish to see the case as stated by an advocate may
refer to Professor Poulton's work, _The Colours of Animals_
(International Scientific Series), lxviii. London, 1890.
[207] _P. Zool. Soc. London_, 1883, p. 372.
[208] _Kosmos_, xix. 1886, p. 353. The Insects alluded to by both these
naturalists are now, we believe, placed in the Family Syntomidae (see
p. 388).
[209] _Stett. ent. Zeit._ li. 1891, p. 264; and lvi. 1895, p. 234.
[210] For an account of the antennae of butterflies, see Jordan, _Nov.
Zool._ v. 1898, pp. 374-415.
[211] Haase first proposed the name Netrocera (_Deutsche ent. Zeit. Lep._
iv. 1891, p. 1) for Hesperiidae, as a division distinct from all
other butterflies; Karsch replaced the name in the following year by
Grypocera, because _Netrocera_ is the name of a genus.
[212] The literature of butterflies has become extremely extensive. The
following works contain information as to general questions: 1,
Scudder's _Butterflies of New England_, a beautifully illustrated
work completed in 1889, and replete with interesting discussions. 2,
Staudinger, Schatz and Röber, _Exotische Tagfalter_, in three folio
volumes (Fürth, 1884-1887), with illustrations of exotic butterflies
and a detailed sketch of their characters. 3, Enzio Reuter, "Uber die
Palpen der Rhopaloceren," in _Acta Soc. Sci. Fenn._ xxii. 1896,
treating fully of classification and phylogeny.
[213] _Journal of Entomology_, i. 1862, p. 218: for early instars of South
American Nymphalidae see Müller, _Zool. Jahrb. Syst._ i. 1886, p.
417.
[214] This is the subject of Scudder's _Life of a Butterfly_, 1893.
[215] _P. Zool. Soc. London_, 1883, p. 205.
[216] Finn, _J. Asiat. Soc. Bengal_, lxvi. 1896, p. 528; lxvii. 1897, p.
213.
[217] _Trans. Linn. Soc._ xxiii, 1862, p. 495.
[218] _Kosmos_, xix. 1886, p. 355.
[219] _P. ent. Soc. London_, 1879, p. xxix.
[220] Allen's Naturalists' Library, _Butterflies_, i. 1896.
[221] A most unfortunate diversity exists in the generic names applied to
these _Vanessa_, as well as in those of many other Lepidoptera.
[222] _Ann. Nat. Hist._ (6), iv. 1889, p. 212.
[223] _P. Zool. Soc. London_, 1892, p. 191.
[224] _Bull. Soc. ent. France_, 1856, pp. c, ci.
[225] Baker, _Tr. ent. Soc. London_, 1887, p. 175, Pl. ix.
[226] _Ann. Soc. ent. France_ (4), vii. 1867, p. 665, Pl. xiii.
[227] _J. Bombay Soc._ ix. 1895, pp. 338-341.
[228] Hopkins, _Phil. Trans._ 186 B, 1895, p. 661.
[229] _Ann. Nat. Hist._ (6), iv. 1889, p. 213. We trust there will not be
many more Künstlers, as this beautiful butterfly must certainly
become extinct, if the female be really as rare as is supposed.
[230] _Mem. Ac. Washington_, vii. 1895, p. 57.
[231] _Tr. ent. Soc. London_, 1893, p. 97, with Suppl. _op. cit._ 1896, pp.
129 and 567.
[232] _Amer. Natural._ xxix. 1895, p. 1066. See also _Ann. N. York Ac._
viii. 1895, p. 194, and _Ent. Record_, 1897, pp. 136 and 196.
[233] _Handbook of British Lepidoptera_, 1895.
[234] London, 1892. Published under the authority of the Secretary of State
for India in Council.
[235] Those numbered 2, 8, 10, 17, 22, 27, 44, and 46 in our arrangement.
[236] For explanatory diagram of the wings, see Fig. 161, I. When the
nervuration is obscured by the wing-scales, it may be rendered
temporarily visible by the application, with a camel's-hair brush, of
a little benzine. The wings may be permanently denuded of their
scales by being placed for a short time in Eau de Javelle
(hypochlorite of potash).
[237] The genus _Cyphanta_ (one species from India) has nervule 5 of the
fore wing proceeding from the lower angle of the cell.
[238] This is a mistake of Sir George Hampson's. It has long been known
that the female of _Heterogynis_ does not leave the cocoon (for
references see p. 392); the larvae, however, do not live in cases, as
those of Psychidae do.
[239] See Westwood, _Tr. Linn. Soc. London_ (2), i. 1877, p. 165, etc.
[240] For habits of some Brazilian Castnia see Seitz, _Ent. Zeit. Stettin_,
li. 1890, p. 258.
[241] For pupa see Chapman, _Ent. Rec._ vi. 1895, pp. 286, 288.
[242] _Souvenirs entomologiques_, quatrième série, 1891, pp. 39-46.
[243] _Amer. Natural._ xii. 1878, p. 379.
[244] Cotes, "Wild Silk Insects of India," _Ind. Mus. Notes_, ii. No. 2,
1891, 15 plates.
[245] See on this subject Pérez, _Act. Soc. Bordeaux_, xlvii. 1894, p. 236,
etc.
[246] _Berlin. ent. Zeitschr._ xxvii. 1883, p. 9.
[247] _Tr. Linn. Soc._ ser. 2, ii. 1885, p. 421.
[248] _Psyche_, vi. 1893, p. 385.
[249] Bar and Laboulbène, _Ann. Soc. ent. France_, (v.) iii. 1873, p. 300.
[250] _Op cit._ (5), vii. 1877, p. 181; and _Ent. Zeit. Stettin_, xxxix.
1878, p. 221; and xliv. 1883, p. 402.
[251] _Ann. New York Ac._ viii. 1893, p. 48.
[252] _Tr. ent. Soc. London_, n.s. iii. 1854, p. 1.
[253] Dyar says, "We may surmise that it is to present a terrifying
appearance toward small enemies." He calls the Insect both
_Perophora_ and _Cicinnus_, _melsheimeri_, and states that it belongs
[according to the larva] to Tineidae; the appendages he considers to
be enormously developed setae. _J. N. York ent. Soc._ iv. 1896, p.
92.
[254] _Tijdsch. Ent._ xxxviii. 1895, p. 56, Pl. 4.
[255] _Ann. New York Ac._ viii. 1893, p. 48.
[256] Weyenbergh, _Tijdschr. Ent._ xvii. 1874, p. 220, Pl. xiii.
[257] Jones, _P. Liverpool Soc._ xxxiii. 1879, p. lxxvii.
[258] _Studies in the Theory of Descent_, part 2, London, 1881.
[259] _Tr. ent. Soc. London_, 1885 and 1886.
[260] _Tijdschr. Ent._ xl. 1897, pp. 27-103, 4 plates.
[261] _Tr. ent. Soc. London_, 1884, p. 351.
[262] _Tr. ent. Soc. London_, 1887, p. 297, Pl. x.
[263] See Poulton, _Tr. ent. Soc. London_, 1886, etc.
[264] _Op. cit._ 1895, p. 399.
[265] _P. ent. Soc. London_, 1880, p. iii.
[266] _Ent. Monthly Mag._ xiii. 1877, p. 231.
[267] _Entomologist_, xxiii. 1890, p. 92.
[268] _Mem. Ac. Washington_, vii. 1895, 290 pp., 49 plates.
[269] _Tr. ent. Soc. London_, 1878, p. 121, Pl. v.
[270] _Op. cit._ 1889, pp. 1-40, 6 plates.
[271] Walsingham, _Op. cit._, 1889. c. p. 21.
[272] _Ent. Zeit. Stettin_, lvi. 1895, p. 233.
[273] _Op. cit._ li. 1890, p. 261.
[274] _Ent. Zeit. Stettin_, li. 1890, p. 263.
[275] For details as to habits, etc., see Rambur, _Ann. Soc. ent. France_,
v. 1836, p. 577; and Graslin, _op. cit._ xix. 1850, p. 396.
[276] Monograph of European Psychidae, _Ann. Soc. ent. Belgique_, xxv.
1881, p. 29, etc.
[277] Heylaerts, _op. cit._ p. 55.
[278] _Zool. Anz._ xx. 1897, p. 473. This is probably _Apterona
crenulella_, or one of its varieties.
[279] _Bull. U.S. Dep. Agric. Ent._ x. 1887, p. 22.
[280] _Ann. New York Ac._ viii. 1893, p. 54.
[281] Kalender, _Ent. Zeit. Stettin_, xxxv. 1874, p. 203.
[282] _Ent. Tidskr._ xvi. 1895, p. 116.
[283] On larvae of Hepialidae, _J. New York ent. Soc._ iii. 1895, p. 69,
Plates III. IV.
[284] Olliff, _Australian Hepialidae, Entomologist_, xxviii. 1895, p. 114.
[285] _Ent. Mag._ xiii. 1876, p. 63; and xxiii. 1886, p. 164.
[286] Weir, _Entomologist_, xiii. 1880, p. 249, plate; King, _Ent. Record_,
vii. 1895, p. 111.
[287] Bertkau, _SB. Ver. Rheinland_, xxxvi. 1879, p. 288; and _Arch.
Naturg._ xlviii. i. 1882, p. 362.
[288] _Zool. Anz._ iii. 1880, p. 186.
[289] It is much to be regretted that, as in so many other Lepidoptera, no
satisfactory agreement as to names has been attained; our British _A.
testudo_ is variously styled _Limacodes testudo_ (by Chapman and most
naturalists), _Apoda limacodes_ (by Meyrick), or _Apoda avellana_
(Kirby, _Catalogue of Moths_). The family is called either
Limacodidae, Apodidae, Cochliopodidae, or Heterogeneidae.
[290] See Chapman, _Tr. ent. Soc. London_, 1894, p. 345, Plate VII., for
our British species; for North American forms, Dyar, _Life-histories
of the New York Slug-caterpillars_ (in progress, with numerous
plates), _J. New York ent. Soc._ iii. etc., 1895.
[291] See Packard, _P. Amer. Phil. Soc._ xxxi. 1893, pp. 83, 108, Plates.
(He uses the term Cochliopodidae instead of Limacodidae); also Dyar,
as above.
[292] _Insects affecting the Orange_, Washington, 1885, p. 143.
[293] _Tr. ent. Soc. London_, 1894, p. 348.
[294] _Op. cit._ 1876, p. 522; and 1877, p. 433.
[295] _P. Amer. Phil. Soc._ xxxii. 1894, p. 275.
[296] Revision of the Thyrididae; Hampson, _P. Zool. Soc. London_, 1897, p.
603.
[297] _P. ent. Soc. London_, 1891, p. xv.
[298] This moth is known under several generic names—_Psilura_, _Liparis_,
_Ocneria_, _Lymantria_; there is now a very extensive literature
connected with it. A good general account by Wachtl may be found in
_Wien. ent. Zeit._ x. 1891, pp. 149-180, 2 Plates.
[299] Wachtl and Kornauth, _Mitt. forst. Versuchswesen Österreichs_, Heft
xvi. 1893.
[300] Crahay, _Ann. Soc. ent. Belgique_, xxxvii. 1893, p. 282.
[301] _Amer. Natural._ xxix. 1895, p. 801.
[302] _Catalogue of Lepidoptera Heterocera_, i. 1892.
[303] _Ann. Soc. ent. France_ (4), iv. 1864, p. 689.
[304] _P. Zool. Soc. London_, 1892, p. 188.
[305] _Tr. ent. Soc. London_, 1892, pp. 53-140; for criticism on the
nomenclature, see Rebel, _Ent. Zeit. Stettin_, liii. 1892, p. 247.
[306] See Poulton, _Tr. ent. Soc. London_, 1884, p. 51; _op. cit._ 1892, p.
293; and Bateson, p. 213; Gould, p. 215.
[307] Giraud, _Ann. Soc. ent. France_ (4), v. 1865, p. 105; Fauvel, _l.c._
_Bull._ p. liii.
[308] For a table, see Meyrick, _l.c._
[309] Barrett, "Increasing Melanism in British Geometridae," _Ent. Monthly
Mag._ 1895, p. 198.
[310] _P. Zool. Soc. London_, 1892, p. 192.
[311] Although this term is widely used in North America, it is not in use
in England, though it may possibly have originated in Scotland. See
Slingerland, _Bull. Cornell University Exp. Stat._ 104, 1895, p, 555.
[312] _Fourth Rep. U.S. Ent. Commission_, 1885, p. 3.
[313] _Insect Life_, vi. 1894 p. 6.
[314] See Chapman, _The Genus_ Acronycta _and its Allies_, London, 1893.
[315] _Insects Injurious, etc._, Ed. 1862, Boston, p. 437.
[316] See Westwood, _Tr. Zool. Soc. London_, x. pp. 507, etc., for
discussion of this question and for figures; also E. Reuter, _Act.
Soc. Sci. Fenn._ xxii. 1896, p. 202.
[317] _Congr. Internat. Zool._ ii. 1892, pt. 2, p. 180.
[318] Ragonot, _Ann. Soc. ent. France_, 1890 and 1891; and Meyrick, _Tr.
ent. Soc. London_, 1890, p. 429.
[319] _Ent. Mag._ xii. 1876, p. 210, and xvii. 1881, p. 249.
[320] _Zool. Jahrb. Syst._ vi. 1892, p. 617.
[321] _Nat. Hist. Aquatic Insects_, London, 1895.
[322] For Bibliographic references connected with the divisions of
Pyralidae see Ragonot, _Ann. Soc. ent. France_ (6), x. 1890, pp. 458,
etc.
[323] Monograph, by Ragonot, in Romanoff, _Mem. Lep._ vii. 1893.
[324] _Ent. Zeit. Stettin_, 1878, p. 230.
[325] Howard, _Insect Life_, vii. 1895, p. 402.
[326] Monograph by Hampson, _P. Zool. Soc. London_, 1895, p. 897-974.
[327] Disqué, _Ent. Zeit. Stettin_, li. 1890, p. 59. Cf. also Rebel, _Zool.
Jahrb. Syst._ xii. 1898, p. 3.
[328] Classification; Meyrick, _Tr. ent. Soc. London_, 1886, p. 1.
[329] _P. Linn. Soc. N. S. Wales_ (2), vi. 1881, p. 410.
[330] _Handbook Brit. Lep._ 1895, p. 493.
[331] _Tr. ent. Soc. London_, 1895, p. 495.
[332] _Zool. Anz._ v. 1882. p. 262.
[333] _Ann. Soc. ent. France_ (4), x. 1870, p. 1, pl. vii.
[334] For table of the larvae, according to number of feet and other
characters, see Sorhagen, _Berlin. ent. Zeit._ xxvii. 1883, pp. 1-8.
[335] _P. Linn. Soc. N.S. Wales_ (2) vii. 1892, p. 593.
[336] Durrant, _Ent. Mag._, xxxi. 1895, p. 107.
[337] "The Yucca moth and Yucca Pollination," _Rep. Missouri Botanical
Garden_, 1892, pp. 99-158.
[338] The maxillary tentacle is considered by Prof. J. B. Smith to be a
prolongation of the stipes, cf. _antea_, p. 309; also _Insect Life_,
v. 1893, p. 161.
[339] Chapman, _Tr. ent. Soc. London_, 1894, p. 366.
[340] Walter, _Jena. Zeitschr. Naturw._ xviii. 1885. He did not distinguish
_Eriocephala_ as a genus, as we have explained on p. 308.
[341] _Amer. Natural._ xxix. 1895, pp. 636 and 803.
[342] Wood, _Ent. Mag._ xxvi. 1890, p. 148.
[343] See Chapman, _Tr. ent. Soc. London_, 1893, p. 255.
[344] Osten Sacken, _Tr. ent. Soc. London_, 1884, p. 501, and _Berlin. ent.
Zeitschr._ xxxvii. 1892, p. 423, etc.
[345] Osten Sacken has recently discussed the intermediate conditions, and
proposed the name "pseudholoptic" for some of them, _Berlin. ent.
Zeitschr._ xli. 1896, p. 367.
[346] Girschner, _Berlin. ent. Zeitschr._ xxxi. 1887, p. 155.
[347] It may be well to remark that this name was formerly applied to all
Diptera except Nemocera.
[348] _Zool. Anz._ xvii. 1894, p. 35, and _Ann. Nat. Hist._ (6) xiii. 1894,
p. 372; _Zeitschr. wiss. Zool._ lviii. 1895, p. 475.
[349] Cf. Osten Sacken, _Berlin. ent. Zeitschr._ xxxviii. 1893; and Becher,
_Wien. ent. Zeit._ i. 1882, p. 49. For an account of the condition,
with diagrammatic figures, of the fly emerging from the pupa, cf.
Sasatti, _J. Coll. Japan_, i. 1887. p. 34, pl. vi.
[350] It is frequently said that one sex of a single species may be
dimorphic in this respect, but we shall subsequently mention (in
Blepharoceridae) that this is not yet sufficiently established.
[351] _Fluernes Munddele, Copenhagen_, 1881, 91 pp. 6 plates; _Ent.
Tidskr._ i. 1879, p. 150; Becher having given (_Denk. Ak. Wien._ xlv.
1882, p. 123) an interpretation different from that of Meinert, this
author set forth his general views in _Zool. Anz._ v. 1882, pp. 570
and 599.
[352] The reader should not suppose that there are only two views as to the
Dipterous mouth, for actually there are several; our object is here
only to give a general idea of the subject.
[353] _Tr. Linn. Soc. London_ (2) v. 1892, p. 271.
[354] _Tr. ent. Soc. London_, 1884, p. 497.
[355] Osten Sacken, although making use of the terms tegula and antitegula,
suggested the propriety of using squama and antisquama, as we have
done.
[356] _Zeitschr. wiss. Zool._ li. 1891, p. 55.
[357] Brandt, _Horae Soc. ent. Ross._ xiv. 1878, p. vii.; xv. 1879, p. 20.
Brauer, _Denk. Ak. Wien_, xlvii. 1883, pp. 12-16. Künckel, _C.R. Ac.
Paris_, lxxxix. 1879, p. 491.
[358] _Blow-fly_, 1895: in two vols. For Anatomy of _Volucella_, see
Künckel d'Herculais, _Recherches sur l'org. des Volucelles, Paris_,
1875 and 1881.
[359] _Tijdschr. Ent._ xxxviii. 1895, pp. 65-100.
[360] _Denk. Ak. Wien_, xlvii. 1883, pp. 1-100, pls. i.-v.
[361] Since our brief and imperfect sketch of metamorphosis appeared in
Vol. V. of this series, Packard has treated the subject more fully in
his _Text-book of Entomology_, New York, 1898; and Pratt has
summarised the state of knowledge as to imaginal discs in _Psyche_,
viii. 1897, p. 15, etc.
[362] Monograph of Oestridae, _Verh. Ges. Wien_, 1863, and other papers
_op. cit._ 1864, 1867, 1869; also _Denk. Ak. Wien_, xlii. 1880,
xlvii. 1883.
[363] Becher, _Wien. Ent. Zeit._ i. 1882, p. 49; for observation on
connecting forms see Brauer, _Verh. Ges. Wien_, xl. 1890, p. 272.
[364] The palpi are said to be of only one segment in some genera of
Cecidomyiidae. The Cecidomyiidae are easily distinguished by the
minute size—body not more than a line long—and by there not being
more than six nervules at the periphery of the wing. _Aëdes_
(Culicidae) has also short palpi.
[365] It is said by Schiner that in the anomalous genus _Nemestrina_ the
palpi are of three segments.
[366] For tables of the families of flies the student may refer to Loew,
_Smithson-Misc. Coll._ vi. Art. i. 1862; to Brauer, _Denk. Ak. Wien_,
xlii. 1880, p. 110 (Orthorrhapha only); to Williston, _Manual of N.
American Diptera_, 1896; to Schiner, _Fauna austriaca, Diptera,
Vienna_, 1860, etc.
[367] _Berlin. ent. Zeitschr._ xxxvii. 1892, p. 365, and xli. 1897, p. 365.
[368] _Tr. Amer. ent. Soc._ iii. 1871, p. 345.
[369] _Bull. Soc. ent. France_, 1893, p. lxxx.
[370] _Naturhist. Tidskr._ (3) viii. 1874, p. 34, pl. xii.
[371] _Ann. Soc. ent. France_ (2) vii. 1849, p. 346.
[372] _Trans. New Zealand Inst._ xxiii. 1890, p. 48.
[373] Osten Sacken, _Berlin. ent. Zeitschr._ xxxvii. 1892, p. 442; and
Perris, _Ann. Soc. ent. France_ (2) vii. 1849, p. 202.
[374] See Guérin-Méneville, _Ann. Soc. ent. France_ (2) iv. 1846; _Bull._
p. 8; and Nowicki, _Verh. Ges. Wien_, xvii. 1867, _SB._ p. 23.
[375] For details as to the family cf. Osten Sacken, _Berlin. ent.
Zeitschr._ xl. 1895, p. 148; and for the larvae F. Müller, _Arch.
Mus. Rio-Jan._ iv. 1881, p. 47. The name "Liponeuridae" was formerly
applied by some authorities to this family, but it is now generally
recognised that Blepharoceridae is more legitimate.
[376] _Berlin. ent. Zeit._ xxv. 1881, p. 61; and cf. Brauer, _Wien. ent.
Zeit._ i. 1882, p. 1.
[377] _Natural History of Aquatic Insects_, London, 1895, chap. ii.
[378] _Tr. Linn. Soc. Lond._ (2) ii. 1884, p. 367.
[379] For an extremely interesting account of _Chironomus_ refer to Miall's
book, already cited, and, for the larva, to the valuable work of
Meinert on Eucephalous larvae of Diptera, _Danske Selsk. Skr._ (6)
iii. 1886, p. 436.
[380] _Ann. Nat. Hist._ (4) viii. 1871, p. 31.
[381] _Ibid._ (6) xv. 1895, p. 133.
[382] For metamorphoses of aquatic species of _Ceratopogon_, see Miall and
Meinert, already quoted: for examples of the terrestrial species, and
their illustrations, refer to Mik, _Wien. ent. Zeit._ vii. 1888, p.
183.
[383] Monograph, Eaton, _Ent. Mag._ xxix. and xxx. 1893, 1894: supplement
_op. cit._ 1896, etc.
[384] _Tr. ent. Soc. London_, 1895, p. 141.
[385] _Tr. ent. Soc. London_, 1895, p. 479.
[386] _A Naturalist's Sojourn in Jamaica_, London, 1853, p. 284.
[387] _Bull. Illinois Lab._, iv. 1895, p. 193.
[388] Miall's _Aquatic Insects_, 1895, p. 174.
[389] "Studies," etc., _Berlin. ent. Zeitschr._ xxxi. 1887.
[390] _Tr. ent. Soc. London_, 1897, p. 362.
[391] _Tr. ent. Soc. London_, 1897, pp. 343-361.
[392] _Acta Univ. Lund._ xxxiii. (2) No. 7, 1897.
[393] "Studies," etc., _Berlin. ent. Zeitschr._ xxx. 1886, p. 153.
[394] Osten Sacken, _Berlin. ent. Zeitschr._ xxxvii. 1892, p. 450.
[395] _Entomologist_, xiv. 1881, p. 287. This observation has never, we
believe, been confirmed.
[396] _Ann. Soc. ent. France_ (2) v. 1847, p. 46.
[397] Perris, in _Ann. Soc. ent. France_ (2) v. 1847, p. 37, pl. i.
[398] _Ann. Soc. ent. France_ (5) i. 1871, _Bull._ p. lxvii.
[399] _Rep. Dep. Agric. Ent. Washington_, 1886, p. 492.
[400] Cf. Réaumur, _Mem._ v. 1740, p. 21; and Perris, _Ann. Soc. ent.
France_ (4) x. 1870, p. 190.
[401] _Verh. Ges. Wien_, xxx. 1880, p. 343.
[402] _Arch. Naturges._ xli. i. 1875, p. 48.
[403] _Bull. Illinois Lab._ iv. 1895.
[404] _Ent. Mag._ xxiii. 1886, p. 51.
[405] _Ann. Soc. ent. France_, ii. 1833, p. 492.
[406] _Wien. ent. Zeit._ ii. 1883, pp. 11 and 24, pl. i.
[407] _Ent. Mag._ xiv. 1878, p. 196.
[408] For figures, etc., cf. Westwood, _Tr. ent. Soc. London_, 1876, p.
507, pls. v. vi.
[409] _Verh. Ges. Wien_, xix. 1869, p. 737, pl. xiii.
[410] _Tr. ent. Soc. London_ (3) i. 1862, p. 338, pl. xi.
[411] _Verh. Ges. Wien_, xix. 1869, p. 941.
[412] _Ann. Soc. ent. France_ (4) x. 1870, p. 221.
[413] _SB. Ak. Wien_, xci. 1885, p. 392.
[414] _Ent. Mag._ xiv. 1877, p. 226; for a discussion of the subject see
Mik, _Wien. ent. Zeit._ xiii. 1894, p. 273.
[415] _Amer. Natural._ xxviii. 1894, p. 35.
[416] Perris, _Ann. Soc. ent. France_ (4) x. 1870, p. 321, pl. 4; and
Laboulbène, _op. cit._ (5) iii. 1873, p. 50, pl. v.
[417] Perris, _Ann. Soc. ent. France_ (4) x. 1870, p. 354.
[418] _Ent. Meddelelser_, ii. 1890, p. 213.
[419] Frauenfeld, _Verh. Ges. Wien_, xx. p. 37, pl. iii.
[420] For monograph of Pipunculidae, see Becker, _Berlin. ent. Zeitschr._
xlii. 1897, pp. 25-100.
[421] _Ofv. Ak. Forh._ xi. 1854, p. 302, pl. v., since confirmed by others,
see Giard, _C.R. Ac. Sci._ cix. 1889, pp. 79 and 708.
[422] _Natural History of Aquatic Insects_, 1895, p. 198.
[423] _Ent. Zeit. Stettin_, vi. 1845, p. 384, pl. i.
[424] _Ann. Soc. ent. France_ (6) iii. 1883, p. 23, pl. i.
[425] _Ent. Nachr._ xviii. 1892, p. 13.
[426] _Ann. Soc. ent. France_ (4) x. 1870, p. 330.
[427] See on this difficult subject, Becher, _Wien. ent. Zeit._ i. 1882, p.
49.
[428] _Loudon's Magazine_, v. 1832, p. 302; _P. ent. Soc. London_, 1871, p.
x.
[429] Baron von Osten Sacken informs the writer that this statement has
since been withdrawn by Portschinsky as being erroneous.
[430] _Ent. Amer._ iii. 1887, p. 126.
[431] _J. Coll. Japan_, i. 1886, pp. 1-46, plates i.-vi.
[432] _Souvenirs entomologiques_, 1879, pp. 246-254.
[433] A list of the Insects known to be attacked by Dipterous parasites has
been given by Brauer and Bergenstamm, _Denk. Ak. Wien_, lxi. 1895.
[434] _Berlin. ent. Zeit._ xxx. 1886, p. 135.
[435] _Berlin. ent. Zeitschr._ xxxi. 1887, p. 17.
[436] _Biol. Centralbl._ vii. 1887, p. 521.
[437] For an account of the habits of this fly, see Kirk, _J. Linn. Soc._
viii. 1865, pp. 149-156; and for a bibliographic list, Wulp,
_Tijdschr. Ent._ xxvii. 1884, p. xci. and pp. 143-150.
[438] _Preliminary Report on the Tse-tse Fly Disease_, 1895.
[439] _P. Liverpool Soc._ xxxiii. 1878, p. 13, note.
[440] We may specially mention the monograph of Oestridae, published in
1863 by the _K. k. Zool.-Bot. Ges. Wien_, and supplements in _Wien.
ent. Zeit._ v. vi. 1886, 1887; these include copious bibliographic
lists.
[441] Riley, _Insect Life_, iv. 1892, p. 302.
[442] See Blanchard, _Ann. Soc. ent. France_ (7) ii. 1892, pp. 109, 154.
[443] See Bigot, _Ann. Soc. ent. France_ (6) ii. 1882, p. 21, Brauer,
_Monograph_, 1863, p. 51, and _Wien. ent. Zeit._ vi. 1887, p. 75.
[444] _Arch. Naturgesch_. lviii. i. 1892, pp. 287-322, pls. xv. xvi.
[445] Stein, _Deutsche ent. Zeit._ xxi. 1877, p. 297.
[446] _Abh. Ges. Halle_, iv. 1858, p. 145.
[447] _Arch. Naturgesch._ lix. i. 1893, p. 151.
[448] _SB. Ak. Wien._ cv. 1896, _Abtheil._ i. p. 400.
[449] _Arch. Naturges._ lviii. i. 1892, p. 287.
[450] _Horae Soc. ent. Ross._ ii. 1863, p. 90.
[451] _Tr. ent. Soc. London_, 1881, p. 360.
[452] The best general description of the external anatomy of the flea is
to be found in Taschenberg, _Die Flöhe_, 1880. The morphology is
better elucidated, though still incompletely, in Wagner's valuable
"Aphanipterologische Studien," _Horae Soc. ent. Ross._ xxiii. 1889,
pp. 199-260, 5 plates, and _op. cit._ xxxi. 1897, pp. 555-594, 3
plates. Cf. also N. C. Rothschild, _Nov. Zool._ v. 1898, pp. 533-544,
3 plates.
[453] Howard, _Bull. Dep. Agric. Ent._ N.S. No. 4, 1896.
[454] Schimkewitsch, _Zool. Anz._ vii. 1884, p. 673.
[455] _P. Boston Soc._ xxvi. 1894, pp. 312-355.
[456] _Monographie der Ordnung Thysanoptera_, Königgrätz, 4to, 1895.
[457] _Bull. Essex Inst._ xxii. 1890, p. 24; also _Amer. Natural._ xxx.
1896, p. 591.
[458] Jordan in an interesting paper, _Zeitschr. wiss. Zool._ xlvii. 1888,
p. 573, says that in the division "Terebrantia" there are only three
pairs of stigmata.
[459] _Insect Life_, i. 1888, p. 138.
[460] See Lindeman, _Bull. Soc. Moscou_, lxii. 1886, No. 2, p. 296, and
Uzel, _Mon._ 1895, pp. 397, 398.
[461] _Entomological Magazine_, iii. 1836, p. 439, and iv. 1837, p. 144.
[462] _Zeitschr. wiss. Zool._ xvi. 1866, p. 389.
[463] _Arb. Inst. Wien_. iv. 1882, p. 415.
[464] _Tr. Amer. Phil. Soc._ xix. 1896, p. 176.
[465] _P. ent. soc. Washington_, iii. 1895, p. 241.
[466] _Ent. Nachr._ xxii. 1896, p. 173.
[467] _Zool. Anz._ 1897, No. 527, p. 73.
[468] _Arch. Anat. Physiol._ 1874, p. 313, and 1875, p. 309.
[469] For the structure and development of the Hemipterous trophi, see
Mayer, _Arch. Anat. Physiol._ 1874 and 1875; Mecznikow, _Zeitschr.
wiss. Zool._ xvi. 1866, p. 389; Geise, _Arch. Naturgesch._ xlix. 1,
1883, p. 315; Wedde, _op. cit._ li. 1, 1885, p. 113; Mark, _Arch.
mikr. Anat._ xiii. 1877, p. 31: Smith, _Tr. Amer. Phil. Soc._ xix.
1896, p. 176.
[470] _Ent. Nachr._ xix. 1893, p. 369.
[471] _Naturhist. Tidskr._ (3) vi. 1896; translated in _Ann. N. Hist._ (4),
vi. 1870, p. 225.
[472] _Ent. Zeit. Stettin_, xxvii. 1866, p. 321.
[473] _Ent. Nachr_. xix. 1893, p. 375.
[474] On this subject, see Reuter, _Ann. Soc. ent. France_ (5) v. 1875, p.
225.
[475] _Ann. Soc. ent. France_ (4) vii. 1867, p. 45.
[476] The chief work on the internal anatomy of Hemiptera is still Dufour's
_Recherches anatomiques et physiologiques sur les Hémiptères, Mem.
Savans Étrangers_, Paris, iv. 1833, p. 129.
[477] Künckel, _Ann. Soc. ent. France_ (4) vii. 1867, p, 45, and _C.R. Ac.
Paris_, cxx. 1895, p. 1002.
[478] In Slingerland's _Cornell Univ. Bull._ No. 58, 1893, p. 222.
[479] _SB. Ak. Wien._ xci. 1 Abth., 1885, p. 275.
[480] _Les Insectes fossiles, etc._, 1894, p. 452.
[481] _Ann. Nat. Hist._ (4) vi. 1870, p. 225.
[482] A table of the families is given by Ashmead, but does not work out
quite satisfactorily, _Entom. Americana_, iv. 1888, p. 65; a brief
table of the characters of the British families is given by Saunders,
_Hemiptera-Heteroptera of the British Islands_, 1892, p. 12.
[483] Those who wish to see tables of the families are referred to Ashmead,
_loc. cit._; to Pascoe, _Ann. Nat. Hist._ (5) ix. 1882, p. 424; to
Stål's _Hemiptera Africana_, vol. iv. 1866; and for the families
found in Britain to Edwards, _Hemiptera-Homoptera of the British
Islands_. For a discussion in Danish on the value of the characters
used, cf. Hansen, _Ent. Tidskr._ xi. 1890, pp. 19-76.
[484] _Ent. Mag._ vii. 1870, p. 53.
[485] _Insect Life_, i. 1889, p. 234.
[486] _C.R. Ac. Sci. Paris_, cxviii. 1894, p. 1282.
[487] _Verh. Ges. Wien._ iii. 1858, p. 157.
[488] _Ent. Mag._ xxix. 1893, p. 227.
[489] _Wien. ent. Zeit._ xi. 1892, p. 169.
[490] _Monograph of Phymatidae_: Handlirsch, _Ann. Hofmus. Wien_, xii.
1897, p. 127.
[491] _Ent. Zeit. Stettin_, li. 1890, p. 281.
[492] _Naturalist's Voyage_, ed. 1884, p. 330; chap. xv.
[493] _Thesaurus ent. Oxoniensis_, 1874, p. 197.
[494] _Ind. Mus. Notes_, iii. No. 5, 1894, p. 53.
[495] Ferrari, Monograph of _Nepa, Ann. Hofmus. Wien_, iii. 1888, p. 171.
[496] _Bull. Soc. Philomat._ (8) v. 1893, p. 57. There is some diversity of
opinion as to the respiratory orifices, and some authorities say that
thoracic stigmata exist even in the imago.
[497] _Acta Ac. German._ li. 1887, p. 224, and _Zeitschr. wiss. Zool._
xliii. 1886, p. 537.
[498] Korschelt, _Acta._ _t.c._ p. 245. Compare the remarks we have made on
p. 559 as to the peculiarities of eggs of many other Hemiptera.
[499] _Bull. Mus. Paris_, 1896, p. 238.
[500] See Carpenter, _Irish Naturalist_, iv. 1895, p. 59.
[501] See remarks on pp. 543, 544.
[502] We must refer those who may wish for further information as to this
complex and difficult question to the writings of the late Professor
Riley, especially to Bulletin No. 8, 1885, U.S. Department of
Agriculture, division of entomology; and to the more recent report by
Marlatt, _Bull. Dep. Agric. Ent._, N.S. No. 14, 1898.
[503] Some entomologists consider that this "railway-whistle" note is the
result of the combined efforts of several individuals. Cf. Mathew,
_Ent. Mag._ xi. 1875, p. 175.
[504] It is unnecessary to say that the poet was not Sappho, but one of the
baser sex, named Xenarchus.
[505] Swinton claims that one of the membranes in the vocal apparatus is an
auditory organ; if so, the male would be deafened by his own noise,
while the females, not possessing the organ, should not hear the
song.
[506] _P. ent. Soc. London_, 1883, p. 20.
[507] A considerable variety of these extraordinary creatures are figured
in _Biol. Centr. Amer. Rhynch. Homopt._ ii.
[508] Riley, _P. ent. Soc. Washington_, iii. 1895, p. 88. For the younger
stages of _Membracis foliata_, see _Tijdschr. Ent._ (2) iv. 1869, pl.
viii.
[509] _Tr. ent. Soc. London_, 1886, p. 329.
[510] _Verh. z.-b. Ges. Wien_, xxvi. 1876, p. 167.
[511] _Cornell Univ. Agric. exp. station Bulletin_, 44, 1892, and _Bull._
108, 1896.
[512] _Zeitschr. wiss. Zool._ xlii. 1885, pp. 569-638.
[513] _Zeitschr. Naturw._ (2) xii. 1875, p. 438.
[514] Réaumur, Mém. iii. 1737, _Dixiéme Mémoire_.
[515] _P. ent. soc. Washington_, iv. 1897, p. 66.
[516] For list see Scott, _Ent. Mag._ xviii. 1882, p. 253.
[517] There is some doubt on this point, as the earlier observers seem to
have supposed that a winged individual appearing in a generation
chiefly apterous was _ipso facto_, a male; it seems, however, to be
certain that perfect winged males appear in some species in
generations producing no perfect sexual females. Speaking generally,
the course of events seems to be that in summer there exist only
wingless and winged parthenogenetic females, and that the sexually
perfect forms appear for the first time in autumn.
[518] _Mitt. Schweiz. ent. Ges._ iv. 1876, p. 529.
[519] The term pseudovum is applied, as a matter of convenience, to the
earlier condition of the viviparously-produced form, and the term
pseudovarium to the ovary producing it.
[520] Balbiani, _Ann. Sci. Nat. Zool._ (5) xi. 1869, p. 29. For concise
recent remarks on the early embryonic states, see Lemoine, _Bull.
Soc. ent. France_, 1893, p. lxxxix.
[521] _Acta Ac. German._ xxxiii. 1869, No. 2, p. 81.
[522] _Seventeenth Rep. Insects Illinois_, 1891, p. 66.
[523] Kessler, _Acta Ac. German._ li. 1887, pp. 152, 153.
[524] In connection with this the absence of a functional mouth in the
imago state of numerous Lepidoptera, and of Oestrid Diptera, should
not be forgotten.
[525] _Horae Soc. ent. Ross._ xxiv. 1890. p. 386.
[526] _Ent. Zeit. Stettin_, xxxvi. 1875, p. 368.
[527] _Zool. Anz._ xv. 1892, p. 220.
[528] _Arb. Inst. Wien_, iv. 1882, Heft iii. p. 397; see on this organ also
Mordwilko, _Zool. Anz._ xviii. 1895, p. 357.
[529] _Biol. Centralbl._ xi. 1891, p. 193.
[530] See, _inter alia_, Webster, _J. New York ent. Soc._ i. 1893, p. 119.
[531] _J. New York Ent. Soc._ i. 1893, p. 120. See also as to knowledge on
the part of ants, Forbes, _Eighteenth Rep. Insects Illinois_, 1894,
pp. 66, etc.
[532] Monograph by Buckton, _Ray Society_, 4 vols. 1879-1883.
[533] _Tr. New Zealand Inst._ xxviii. 1895.
[534] A catalogue of Coccidae has recently been published by Mr. T. D. A.
Cockerell in _Bull. Illinois Lab._ iv. 1896, pp. 318-339.
[535] Signoret's papers are to be found in eighteen parts in _Ann. Soc.
ent. France_, 1868 to 1876: the most considerable subsequent
systematic papers are those by Maskell in the _Transactions of the
New Zealand Institute_ from 1878 to the present time.
[536] _Coccidae of Ceylon_, pt. 1, 1896, p. 16.
[537] _C. R. Ac. Sci. Paris_, civ. 1887, p. 449.
[538] _Arch. Naturgesch._ li. i. 1885, p. 169.
[539] _Zeitschr. wiss. Zool._ xliii. 1886, p. 156.
[540] For summary as to our present knowledge of this curious condition of
Insect life, see Mayet, _Ann. Soc. ent. France_, 1896, p. 419.
[541] For additional information as to useful Coccidae, see Blanchard,
_Bull. Soc. Zool. France_, viii. 1883, p. 217.
[542] Rubsaamen's paper on these Insects gives references to most of the
previous literature, _Berlin. ent. Zeitschr._ xxxix. 1894, p. 199.
[543] _Ent. Meddel._ iii. 1891, p. 82.
[544] Cf. Graber, _Zeitschr. wiss. Zool._ xxii. 1872, p. 165, and Landois
in the same Journal, xiv. 1864, p. 24.
[545] _Ann. Nat. History_ (3), xvii. 1866, p. 213.
[546] _N. York Ent. Soc._ vii. March 1899, p. 45.
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