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Title: Directions for Collecting and Preserving Insects
Author: Riley, C. V.
Language: English
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SMITHSONIAN INSTITUTION.
UNITED STATES NATIONAL MUSEUM.
DIRECTIONS FOR COLLECTING AND PRESERVING INSECTS.
BY
C. V. RILEY, M. A., PH. D.,
_Honorary Curator of the Department of Insects, U. S. National Museum._
Part F of Bulletin of the United States National Museum, No. 39
(with one plate).
WASHINGTON:
GOVERNMENT PRINTING OFFICE.
1892.
=CONTENTS.=
Page.
INTRODUCTORY 3
MANUAL OF INSTRUCTIONS FOR COLLECTING AND PRESERVING INSECTS 5
CHARACTERISTICS OF INSECTS 5
SCOPE AND IMPORTANCE OF ENTOMOLOGY 6
CLASSIFICATION OF HEXAPODS 8
Order Hymenoptera 12
Order Coleoptera 14
Order Lepidoptera 16
Order Hemiptera 17
Suborder Thysanoptera 18
Order Diptera 19
Suborder Aphaniptera 20
Order Orthoptera 21
Suborder Dermaptera 22
Order Neuroptera 22
Suborder Trichoptera 23
Suborder Mecoptera 23
Suborder Neuroptera 23
Suborder Platyptera 24
Suborder Plecoptera 25
Suborder Odonata 25
Suborder Ephemeroptera 25
Suborder Thysanura 26
COLLECTING 26
General considerations 26
Collecting apparatus 29
The sweeping net 29
The water net 31
Water dip-net 32
The umbrella 32
The beating cloth 33
The umbrella net 34
The sieve 35
The chisel 36
The trowel 36
The collecting tweezers 36
The brush 37
The fumigator 38
The haversack 38
The lens and microscope 39
Collecting Hymenoptera 39
Collecting Coleoptera 42
General directions 42
Winter collecting 43
Spring collecting 44
Myrmecophilous and Termetophilous species 44
Spring flights of Coleoptera 44
Beach collecting 45
Attracting by lights 45
Traps 45
Freshet 45
Summer collecting 46
Collecting under stones 46
Collecting in rotten stumps and logs 46
Collecting in dying or dead trees 47
Beating living trees, shrubs, and vines 47
Sweeping 47
Collecting on mud and gravel banks 48
Collecting aquatic beetles 49
Collecting at the seashore and on sandy places 49
Collecting dung beetles 49
Night collecting 50
Fall collecting 50
Collecting Lepidoptera 50
Collecting the adults 50
Collecting the early states 53
Collecting Hemiptera 54
Collecting Diptera 55
Collecting Orthoptera 57
Collecting Neuroptera 58
Pseudoneuroptera 58
Neuroptera 59
KILLING AND PRESERVING INSECTS 60
First preservation of living specimens 60
Killing specimens 61
Alcohol 61
Chloroform and ether 62
Cyanide of potassium 63
Other agents 65
Special directions for different orders 66
ENTOMOTAXY 67
Care of pinned and mounted specimens 67
Insect pins 67
Preparation of specimens 68
Pinning 69
Mounting on points 70
Mounting duplicates 73
Temporary storage of specimens 74
Envelopes for Lepidoptera, etc. 74
Directions for spreading insects 75
A new apparatus for spreading Microlepidoptera 76
Spreading Microlepidoptera 77
Relaxing 79
Inflation of the larvæ of Lepidoptera 80
Stuffing insects 82
Dry preservation of Aphides and other soft-bodied insects 82
Mounting specimens for the microscope 84
Preparing and mounting the wings of Lepidoptera 86
Preservation of alcoholic specimens 88
Apparatus and methods 88
Vials, stoppers, and holders 89
Preserving micro-larvæ in alcohol 92
Preservative fluids 93
Alcohol 93
Alcohol and white arsenic 93
Alcohol and corrosive sublimate 94
Two fluids to preserve form and color 94
Glycerin 94
The Wickersheim preserving fluid 94
Labeling specimens 95
General directions 95
Labels for pinned specimens 95
Labeling alcoholic specimens 97
Cabinet for apparatus 98
INSECT BOXES AND CABINETS 98
General directions 98
The folding box 98
The cabinet 100
The Lintner display box 101
The Martindale box for Lepidoptera 104
Horizontal _versus_ vertical arrangement of boxes 104
Lining for insect boxes 104
ARRANGEMENT OF INSECTS IN THE CABINET 106
Systematic and biologic collections 106
Economic displays 106
Labeling collections 107
MUSEUM PESTS, MOLD, ETC 108
Museum pests 108
Remedies 109
Naphthaline 109
Bisulphide of carbon 110
Mercury pellets 110
Carbolic acid 110
A means of preserving insects in dry, hot countries 110
Mold 111
Verdigrising and greasing 111
THE REARING OF INSECTS 112
General directions 112
The breeding cage, or vivarium 112
Detailed instructions for rearing 115
The root cage 118
Other apparatus 119
The insectary 120
DIRECTIONS FOR PACKING AND TRANSMITTING INSECTS 121
NOTES AND MEMORANDA 123
INSTRUCTIONS FOR COLLECTING AND PRESERVING ARACHNIDS AND MYRIAPODS 124
Directions for collecting spiders 124
Apparatus 124
Time and locality for collecting 125
Collecting other Arachnids, mites, ticks, scorpions, etc 126
Collecting Myriapoda 130
TEXT BOOKS AND ENTOMOLOGICAL WORKS 131
Comprehensive works most useful for the student of North
American insects 132
General works on classification 132
Hymenoptera 132
Coleoptera 132
Lepidoptera 133
Hemiptera 134
Diptera 134
Orthoptera 135
Neuroptera 135
Myriapoda 135
Arachnida 136
American periodicals 136
Foreign periodicals 138
The more useful works on economic entomology 140
Entomological works published by the United States Entomological
Commission and by the United States Department of Agriculture 141
Works by the United States Entomological Commission 141
Bulletins of the Division of Entomology, U. S. Department of
Agriculture 142
Special reports and bulletins 144
HOW TO OBTAIN ENTOMOLOGICAL BOOKS AND PAMPHLETS 145
INTRODUCTORY.
There is a constant demand, especially from correspondents of the Museum
and also of the Department of Agriculture, for information as to how to
collect, preserve, and mount insects. There is also great need of some
simple directions on a great many other points connected with the proper
packing of insects for transmission through the mails or otherwise;
labeling; methods of rearing; boxes and cabinets; text-books, etc.
Interest in the subject of entomology has, in fact, made rapid growth in
the last few years, and now that nearly every State has an official
entomologist connected with its State Agricultural Experiment Station,
the number of persons interested in the subject may be expected to
increase largely in the near future. I have hitherto made use of the
Smithsonian Miscellaneous Collections, No. 261, which is a pamphlet on
collecting and preserving insects prepared by Dr. A. S. Packard. This is
out of print, and I have been requested by Prof. Goode to prepare for
Bulletin 39, U. S. N. M., something that would cover the whole ground
and give the more essential information needed for collectors and
students of insect life. I have deemed it unnecessary to go too much
into detail, but have studied not to omit anything essential. Customs
and methods vary in different countries and with different individuals,
but the recommendations contained in the following pages are based upon
my own experience and that of my assistants and many acquaintances, and
embrace the methods which the large majority of American entomologists
have found most satisfactory.
Much of the matter is repeated bodily from the directions for collecting
and preserving insects published in my Fifth Report on the Insects of
Missouri (1872) and quotations not otherwise credited are from that
Report. The illustrations, also, when not otherwise credited or not
originally made for this paper, are from my previous writings. Some are
taken from Dr. Packard's pamphlet, already mentioned; others, with the
permission of Assistant Secretary Willits, from the publications of the
Department of Agriculture, while a number have been especially made for
the occasion, either from photographs, or from drawings by Miss L.
Sullivan or Dr. Geo. Marx or Mr. C. L. Marlatt. When enlarged, the
natural size is indicated in hair-line. In the preparation of the
pamphlet I have had the assistance of Mr. E. A. Schwarz, and more
particularly of Mr. C. L. Marlatt, to both of whom I desire here to
express my obligations.
C. V. R.
[Illustration: Pl. 1.--ILLUSTRATION OF BIOLOGIC SERIES.]
MANUAL OF INSTRUCTIONS FOR COLLECTING AND PRESERVING INSECTS.
* * * * *
By C. V. RILEY,
_Honorary Curator of the Department of Insects, U. S. National Museum._
* * * * *
CHARACTERISTICS OF INSECTS.
The term "insect" comes from the Latin _insectum_, and signifies "cut
into." It expresses one of the prime characteristics of this class of
animals, namely, that of segmentation. This feature of having the body
divided into rings or segments by transverse incisions is possessed by
other large groups of animals, and was considered of sufficient
importance by Cuvier to lead him, in his system of classification, to
group with Insects, under the general term Articulata, Worms, Crustacea,
Spiders, and Myriapods. Worms differ from the other four groups in
having no articulated appendages, and in having a soft body-wall or
integument instead of a dense chitinous covering, and are separated as a
special class _Vermes_. The other four groups of segmented animals
possess in common the feature of jointed appendages and a covering of
chitinous plates, and are brought together under the term _Arthropoda_.
The division of the body into a series of segments by transverse
incisions, characteristic of these animals and these only, justifies the
use of Cuvier's old name, Articulates, as this segmented feature
represents a definite relationship and a natural division--as much so as
the vertebral column in Vertebrates. The Cuvierian name should be
retained as a coördinate of Vertebrates, Molluscs, etc., and the terms
Vermes and Arthropods may be conveniently used to designate the two
natural divisions of the Articulates.
The term "insect" has been employed by authors in two different
senses--one to apply to the tracheated animals or those that breathe
through a system of air tubes (tracheæ), comprising Spiders, Myriapods,
and insects proper or Hexapods,[1] and the other in its restricted sense
as applied to the Hexapods only. To avoid confusion, the latter
signification only should be used, and it will be thus used in this
article.
[1] From the Greek [Greek: exapous], having 6 feet.
We see, then, that insects share, in common with many other animals, the
jointed or articulated structure. Wherein, then, do they differ?
_Briefly, in having the body divided into thirteen joints and a
subjoint_, including the head as a joint, and in the adult having six
true, jointed legs, and usually, though not always, wings. The five
classes of Articulates differ from each other in the number of legs they
possess in the adult form, as follows: Hexapoda, 6 legs; Arachnida, 8
legs; Crustacea, 10-14 legs; Myriapoda, more than 14 legs; Vermes, none.
This system holds for the adult form only, because some mites
(Arachnida) when young have only 6 legs, and many true insects in the
larva state either have no legs at all, or have additional abdominal
legs which are not jointed, but membranous, and are lost in the perfect
or adult state. These are called false or prolegs.
It will serve to make these instructions clear if I at once explain that
the life of an insect is marked by four distinct states, viz., the egg,
the larva, the pupa, and the imago, and that the last three words will
constantly recur. We have no English equivalent for the words larva and
pupa, for while some authors have written them with the terminal _e_, so
as to get the English plural, yet "larves" and "pupes" so shock the ear
that the terms have not been (and deserve not to be) generally adopted.
We have seen that an insect in the final state has six true legs. Yet
even here many species depart from the rule, as there are many in which
the perfect insect, especially in the female sex, is apodous or without
legs, just as there are also other cases where they are without wings.
Sometimes the legs seem to be reduced in number by the partial or total
atrophy of one or the other pair, but in all these exceptional cases
there is no difficulty in realizing that we have to deal with a true
insect, because of the other characters pertaining to the class, some of
which it will be well to allude to.
Insects are further characterized by having usually three distinct
divisions of the body, viz.: head, thorax, and abdomen, and by
undergoing certain metamorphoses or transformations. Now, while a number
of other animals outside of the insect world go through similar
transformations, those in the Crustacea being equally remarkable, yet,
from the ease with which they are observed and the completeness of the
transformations in most insects, the metamorphoses of this class have,
from time immemorial, excited the greatest curiosity.
SCOPE AND IMPORTANCE OF ENTOMOLOGY.
But few words are necessary to indicate the importance of entomology,
especially to the farming community; for while insects play a most
important part in the economy of nature and furnish us some valuable
products and otherwise do us a great deal of indirect good, yet they are
chiefly known by the annoyances they cause and by the great injury they
do to our crops and domestic animals. Hence some knowledge of insects
and how to study them becomes important, almost necessary, to every
farmer.
The scope of the science may best be indicated by a statement of the
number of species existing, as compared with other animals. The
omnipresence of insects is known and felt by all; yet few have any
accurate idea of the actual numbers existing, so that some figures will
not prove uninteresting in this connection. Taking the lists of
described species, and the estimates of specialists in the different
orders, it is safe to say that about thirty thousand species have
already been described from North America, while the number of species
already described or to be described in the Biologia Centrali-Americana,
i. e., for Central America, foot up just about the same number, Lord
Walsingham having estimated them at 30,114 in his address as president
of the London Entomological Society two years ago, neither the
Orthoptera nor the Neuroptera being included in this estimate. By way of
contrast the number of mammals, birds, and reptiles to be described from
the same region, is interesting. It foots up 1,937, as follows:
Mammals, 180; birds, 1,600; reptiles, 157.
If we endeavor to get some estimate of the number of insects that occur
in the whole world, the most satisfactory estimates will be found in the
address just alluded to, and in that of Dr. David Sharp before the same
society. Linnæus knew nearly 3,000 species, of which more than 2,000
were European and over 800 exotic. The estimate of Dr. John Day, in
1853, of the number of species on the globe, was 250,000. Dr. Sharp's
estimate thirty years later was between 500,000 and 1,000,000. Sharp's
and Walsingham's estimates in 1889 reached nearly 2,000,000, and the
average number of insects annually described since the publication of
the Zoölogical Record, deducting 8 per cent for synonyms, is 6,500
species. I think the estimate of 2,000,000 species in the world is
extremely low, and if we take into consideration the fact that species
have been best worked up in the more temperate portions of the globe,
and that in the more tropical portions a vast number of species still
remain to be characterized and named, and if we take further into
consideration the fact that many portions of the globe are yet
unexplored, entomologically, that even in the best worked up regions by
far the larger portion of the Micro-Hymenoptera and Micro-Diptera remain
absolutely undescribed in our collections, and have been but very
partially collected, it will be safe to estimate that not one-fifth of
the species extant have yet been characterized or enumerated. In this
view of the case the species in our collections, whether described or
undescribed, do not represent perhaps more than one-fifth of the whole.
In other words, to say that there are 10,000,000 species of insects in
the world, would be, in my judgment, a moderate estimate.
CLASSIFICATION OF HEXAPODS.
Seven orders of insects were originally recognized by Linnæus, namely,
Neuroptera, Diptera, Hemiptera, Lepidoptera, Coleoptera, Hymenoptera,
and Aptera. This classification was based on the organs of flight only,
and while in the main resulting in natural divisions which still furnish
the basis of more modern classifications, was faulty in several
particulars. For instance, the Aptera, which included all wingless
insects, was soon found to be a very unnatural assemblage and its
components were distributed among the other orders. The establishment of
the order Orthoptera by Olivier to include a large and well-defined
group of insects associated with the Hemiptera by Linnæus, restored the
original seven orders, and this classification has, in the main, been
followed by entomologists up to the present time.
[Illustration: FIG. 1.--Pyramid showing the nature of the mouth, and
relative rank of the Orders, and the affinities of the Suborders of
Insects.]
All insects are, in a broad way, referable to one or the other of these
seven primary orders by the structure of the wings and the character of
the mouth-parts in the imago, and by the nature of their
transformations.
Some of these orders are connected by aberrant and osculant families or
groups, which have by other authors been variously ranked as independent
orders, but which, following Westwood substantially, I have considered,
for convenience, as suborders. (_See_ Fifth Report, Insects of Missouri,
etc., 1872.)
In the article just cited, I made use of the accompanying diagram in the
form of a pyramid (Fig. 1), which gives a graphic representation of the
distinguishing characters and the relative rank as usually accepted, of
the orders and suborders.
Full discussion of the different classifications is unnecessary in this
connection. Authors have differed in the past and will differ in the
future as to what constitutes a natural system, and it would require
many pages to give even a brief survey of the various schemes that have
been proposed. As I have elsewhere said, "We must remember that
classifications are but a means to an end--appliances to facilitate our
thought and study--and that, to use Spencer's words, 'we cannot, by any
logical dichotomies, actually express relations which in nature graduate
into each other insensibly.'"
The most philosophical, perhaps, of the more modern systems of
classification is that of Friedrich Brauer, who has carefully studied
the subject, and has given us an arrangement consisting of sixteen
orders. This has many merits and has been adopted, with slight
modifications, by Packard in his "Entomology for Beginners," and by
Hyatt and Arms in their recent and valuable text-book "Insecta."
Comstock, in his "Introduction to Entomology" strongly recommends
Brauer's classification, but for reasons of simplicity and convenience
adheres to a modification of the old classification of Westwood.
For purposes of comparison the classification by Hyatt and Arms, which
is substantially that of Brauer, may be introduced.
In linear arrangement it is as follows:
I. Thysanura (_Spring-tails_, etc.).
II. Ephemeroptera (_Ephemeridæ_; May-flies). (=_Plectoptera_ Pack.)
III. Odonata (_Libellulidæ_; Dragon-flies).
IV. Plecoptera (_Perlidæ_; Stone-flies).
V. Platyptera (_Termites_, _Mallophaga_, etc.).
VI. Dermaptera (_Forficulidæ_; Earwigs).
VII. Orthoptera (Locusts, Grasshoppers, etc.).
VIII. Thysanoptera (_Thripidæ_; Fringe-wings).
IX. Hemiptera (Bugs).
X. Coleoptera (Beetles).
XI. Neuroptera (_Sialidæ_, _Hemerobiidæ_; Lace-wings, etc.).
XII. Mecoptera (_Panorpidæ_; Scorpion-flies).
XIII. Trichoptera (_Phryganeidæ_; Caddis-flies).
XIV. Lepidoptera (Butterflies and Moths).
XV. Hymenoptera (Bees, Wasps, etc.).
XVI. Diptera (Two-winged flies).
The relationship of these orders cannot be indicated in a linear
arrangement, and is admirably shown by Hyatt and Arms by means of
diagrams which I reproduce (Figs. 2, 3.)
[Illustration: FIG. 2.--Scheme illustrating origin and relationship of
Orders. (After Hyatt.)]
The relation of these sixteen orders to the older, septenary scheme is
shown by the following arrangement:
1. Hymenoptera Hymenoptera XV.
2. Coleoptera Coleoptera X.
3. Lepidoptera Lepidoptera XIV.
{Homoptera.
4. Hemiptera {Hemiptera IX. {Heteroptera.
{Thysanoptera VIII.
5. Diptera {Diptera XVI. {Including Aphaniptera or Siphonaptera
{of some authors.
6. Orthoptera {Orthoptera VII.
{Dermaptera VI.
{Trichoptera XIII }
{Mecoptera XII }Neuroptera.
{Neuroptera XI }
7. Neuroptera {Platyptera V }
{Plecoptera IV }
{Odonata III }Pseudo-neuroptera.
{Ephemeroptera II }
{Thysanura I }
It will be seen that the changes are not so great as would at first
appear. The three more important orders, namely, the Hymenoptera,
Coleoptera, and Lepidoptera, remain substantially the same in all
classifications, and so with the three orders next in importance--the
Hemiptera, Diptera, and Orthoptera. All that has been done with these
three has been to rank as separate orders what by former authors were
preferably considered as either families or suborders. The principal
change is in the Neuroptera, of which no less than eight orders have
been made. This is not to be wondered at, because the order, as formerly
construed, was conceded to be that which represents the lowest forms
and more synthetic types of insects, and as such necessarily contained
forms which it is difficult to classify definitely.
[Illustration: FIG. 3.--Cross section of Fig. 2.]
In the discussion of the characteristics, habits, number of species, and
importance of the several groups, I follow, with such changes as the
advances in the science of entomology have made necessary, the
arrangement shown in Fig. 1.
"Order HYMENOPTERA ([Greek: ymên], a membrane; [Greek: pteron], wing).
Clear or Membrane-winged Flies: Bees, Wasps, Ants, Saw-flies, etc.
Characterized by having four membranous wings with comparatively few
veins, the hind part smallest. The transformations are complete: _i.
e._, the larva bears no resemblance to the perfect insect.
[Illustration: FIG. 4.--Bold-faced Hornet, _Vespa maculata_. (After
Sanborn).]
"Some of the insects of this order are highly specialized, and their
mouth-parts are fitted both for biting and sucking, and in this respect
they connect the mandibulate and haustellate insects. The common
Honey-bee has this complex structure of the mouth, and if the editors of
our agricultural papers would bear the fact in mind, we should have less
of the never-ending discussion as to whether bees are capable of
injuring fruit at first hand. The lower lip (_labium_) is modified into
a long tongue, sheathed by the lower jaws (_maxillæ_), and they can sip,
or, more properly speaking, lap up nectar; while the upper jaws
(_mandibulæ_), though not generally used for purposes of manducation,
are fitted for biting and cutting. The Hymenoptera are terrestrial,
there existing only a very few degraded, swimming forms.
[Illustration: FIG. 5.--An Ichneumon Parasite, _Pimpla annulipes_,
showing male and female abdomen.]
[Illustration: FIG. 6.--A Chalcid Parasite, _Chalcis flavipes_.]
"This order is very naturally divided into two sections--the ACULEATA
and TEREBRANTIA. The aculeate Hymenoptera, or Stingers, comprise all the
families in which the abdomen in the female is armed with a sting
connected with a poison reservoir, and may be considered the typical
form of the order, including all the social and fossorial species. The
insects of this section must be considered essentially beneficial to
man, notwithstanding the occasional sting of a bee or wasp, the boring
of a carpenter bee, or the importunities of the omnipresent ant. Not
only do they furnish us with honey and wax, but they play so important a
part in the destruction of insects injurious to vegetation that they may
be looked upon as God-appointed guards over the vegetal
kingdom--carrying the pollen from plant to plant, and insuring the
fertilization of di[oe]cious species, and the cross-fertilization of
others; and being ever ready to clear them of herbivorous worms which
gnaw and destroy. The whole section is well characterized by the
uniformly maggot-like nature of the larva. The transformations are
complete, but the chitinous larval covering is often so very thin and
delicate that the budding of the members, or gradual growth of the pupa
underneath, is quite plainly visible, and the skin often peels off in
delicate flakes, so that the transition from larva to pupa is not so
marked and sudden as in those insects which have thicker skins.
[Illustration: FIG. 7.--A Horn-tail, _Tremex columba_. _a_, larva,
showing Thalessa larva attached to its side; _b_, head of larva, front
view, enlarged; _c_, female pupa, ventral view; _d_, male pupa, ventral
view; _e_, adult female--all slightly enlarged.]
"The terebrantine Hymenoptera, or Piercers, are again divisible into two
subsections: first, the ENTOMOPHAGA, which are, likewise, with the
exception of a few gall-makers, beneficial to man, and include the
parasitic families, and the gall-flies; second, the PHYTOPHAGA,
comprising the Horn-tails (_Uroceridæ_), and the Saw-flies
(_Tenthredinidæ_), all of which are vegetable feeders in the larval
state, those of the first family boring into trees, and those of the
second either feeding externally on leaves or inclosed in galls. They
are at once distinguished from the other Hymenoptera by the larvæ
having true legs, which, however, in the case of the Horntails, are very
small and exarticulate. The larvæ of many Saw-flies have, besides,
prolegs, which are, however, always distinguishable from those of
Lepidopterous larvæ by being more numerous and by having no hooks.
[Illustration: FIG. 8.--Saw-fly and Larva. _Pristiphora grossulariæ_;
_a_, larva; _b_, imago, Walsh.]
"Order COLEOPTERA ([Greek: koleos], a sheath; [Greek: pteron], wing).
Beetles or Shield-winged Insects. Characterized by having four wings,
the front pair (called _elytra_) horny or leathery, and usually united
down the back with a straight suture when at rest, the hind ones
membranous and folded up under the elytra when at rest. Transformations
complete.
[Illustration: FIG. 9.--A Chafer, _Cotalpa lanigera_. (After Packard.)]
[Illustration: FIG. 10.--A Longicorn, _Saperda candida_. _a_, larva;
_b_, pupa; _c_, beetle.]
"This is an order of great importance, and in the vast number and
diversity of the species comprised in it outranks any of the others. The
ease with which the insects of this order are obtained and preserved
make it one of the most attractive to the amateur, and beetles are,
perhaps, of all insects, the best known and understood in the popular
mind. For the same reason they have, in the perfect state, received most
attention from the entomologists, but their transformations and
preparatory forms yet offer a wide and inviting field for the student.
The simplest and best-known classification of the beetles is the tarsal
system, founded on the number of joints to the tarsi, by which we get
four great sections: (1) PENTAMERA, in which all the tarsi are
5-jointed; (2) HETEROMERA, with the four anterior 5-jointed and the two
posterior 4-jointed; (3) PSEUDO-TETRAMERA, with apparently only four
joints to all the tarsi, though, in reality, there is a fifth
penultimate joint, diminutive and concealed; (4) PSEUDO-TRIMERA, with
apparently only three joints to all the tarsi. This system, like most
others, is not perfect, as there are numerous species not possessing
five joints to the tarsi belonging to the first section; and for
practical purposes beetles may be very well arranged according to habit.
We thus get, first, the ADEPHAGA, or carnivorous species, including all
those which prey on other living insects, and to which, following Mr.
Walsh, I have, for obvious reasons, applied the suggestive term
'Cannibal'; second, the NECROPHAGA, comprising those which feed on
carrion, dung, fungi, and decaying vegetation; third, the PHYTOPHAGA,
embracing all those feeding on living vegetation. This arrangement is by
no means perfect, for there are beetles which are carnivorous in the
larva and herbivorous in the imago state; while some of the NECROPHAGA
are actually parasitic. Yet, it is not more artificial than others which
have been proposed. The carnivorous species, broadly speaking, are
_Pentamerous_, the only striking exception being the Coccinellidæ
(Lady-birds), which are _Pseudo-trimerous_. The carrion-feeders are also
_Pentamerous_; but vegetable-feeders are found in all the tarsal
divisions, though the _Pseudo-tetramera_ are the more essentially
herbivorous, and consequently the most injurious."
[Illustration: FIG. 11.--The Plum Curculio, _Conotrachelus nenuphar_.
_a_, larva; _b_, pupa; _c_, beetle; _d_, plum showing egg-puncture and
crescent.]
[Illustration: FIG. 12.--A Soldier-beetle, _Chauliognathus
pennsylvanicus_. _a_, larva; _b-h_, parts of larva enlarged; _i_,
beetle.]
[Illustration: FIG. 13.--The Bogus Potato-beetle, _Doryphora juncta_.
_a_, eggs; _b_, larvæ; _c_, beetle; _d_ and _e_, parts of beetle
enlarged.]
"Order LEPIDOPTERA ([Greek: lepis], a scale; [Greek: pteron], wing).
Butterflies and Moths, or scaly-winged insects. Characterized by having
four branching-veined membranous wings, each more or less densely
covered on both sides with minute imbricated scales which are attached
by a stalk, but which easily rub off, and appear to the unaided eye like
minute particles of glistening dust or powder. Transformations complete.
[Illustration: FIG. 14.--A Butterfly, _Pieris oleracea_.]
"Next to the Lepidoptera, the Coleoptera are, perhaps, most familiar to
the popular mind. Every one admires the beauty of these frail creatures,
dressed in every conceivable pattern, and adorned with every conceivable
color, so as to rival the delicate hues of the rainbow, and eclipse the
most fantastic and elaborate designs of man. When magnified, the scales,
to which this beauty of pattern and color is entirely due, present all
manner of shapes, according to the particular species or the particular
part of the individual from which they are taken. According to
Lewenhoeck, there are 400,000 of these scales on the wing of the common
silkworm.
[Illustration: FIG. 15.--A Sphingid, _Ampelophaga myron_.]
"The transformations of these insects are complete, and the changes are
usually so sudden and striking as to have excited the wonder and
admiration of observers from earliest times.
"The more common form of the larva is exampled in the ordinary
caterpillar--a cylindrical worm with a head, twelve joints and a
sub-joint; six thoracic or true legs, four abdominal and two anal
prolegs. But there is a great variety of these larvæ, some having no
legs whatever, some having only the jointed legs, and others having
either four, six, eight, or ten, but never more than ten prolegs. With
few exceptions they are all vegetable-feeders, and with still fewer
exceptions, terrestrial. The perfect insects make free use of their
ample wings, but walk little; and their legs are weak, and not modified
in the various ways so noticeable in other orders, while the front pair
in some butterflies are impotent.
[Illustration: FIG. 16.--A Moth, _Utetheisa bella_.]
"As an order this must be considered the most injurious of the seven.
"A convenient system of classification for the Lepidoptera is based on
the structure of the antennæ. By it we get two great sections: 1st,
Butterflies (RHOPALOCERA); 2d, Moths (HETEROCERA), which latter may
again be divided into Crepuscular and Nocturnal Moths. Butterflies are
at once distinguished from moths by their antennæ being straight, stiff
and _knobbed_, and by being day-fliers or diurnal; while moths have the
antennæ tapering to a point, and are, for the most part, night-flyers or
nocturnal. The crepuscular moths, composed mostly of the Sphinges or
Hawk-moths, hover over flowers at eve, and connect the two sections not
only in habit, but in the character of the antennæ which first thicken
toward the end, and then suddenly terminate in a point or hook.
[Illustration: FIG. 17.--A Clothes-moth (_Tinea pellionella_)--enlarged.
_a_, adult; _b_, larva; _c_, larva in case.]
"Order HEMIPTERA ([Greek: hêmi], half; [Greek: pteron], wing), Bugs. The
insects of this order are naturally separated into two great sections;
1st, Half-winged Bugs, or HETEROPTERA ([Greek: heteros], different;
[Greek: pteron], wing) having the basal half of the front wings (called
_hemelytra_) coriaceous or leathery, while the apical part is
membranous. The wings cross flatly over the back when at rest; 2d,
Whole-winged Bugs, or HOMOPTERA ([Greek: homos], equal; [Greek: pteron],
wing), having all four wings of a uniform membranous nature and folding
straight down the back when at rest. The latter, if separated, may be
looked upon as a Suborder.
[Illustration: FIG. 18.--A Plant-bug (_Euschistus punctipes_).]
"Transformations incomplete; _i. e._, the larvæ and pupæ have more or
less the image of the perfect insect, and differ little from it except
in lacking wings.
[Illustration: FIG. 19.--A Soldier-bug (_Milyas cinctus_). _b_, beak
enlarged.]
"The genuine or half-winged Bugs (Figs. 18 and 19) are usually flattened
in form, when mature; though more rounded in the adolescent stages. They
may be divided into Land Bugs (_Aurocorisa_) and Water Bugs
(_Hydrocorisa_). The species of the first division very generally
possess the power of emitting, when disturbed or alarmed, a nauseous,
bed-buggy odor, which comes from a fluid secreted from two pores,
situated on the under side of the metathorax. Such well-known insects as
the Bed-bug and Chinch-bug belong here. The habits of the species are
varied, and while some are beneficial, others are quite injurious to
man.
[Illustration: FIG. 20.--A Tree-hopper (_Ceresa bubalus_). _a_, side;
_b_, top view.]
"The Whole-winged Bugs (Figs. 20 and 21), on the contrary, are all
plant-feeders, and with the exception of a few, such as the Cochineal
and Lac insects, are injurious. The secretion of a white, or bluish,
waxy, or farinose substance from the surface of the body is as
characteristic of this section as the nauseous odor is of the first. It
forms three natural divisions, arranged according to the number of
joints to the tarsi--namely TRIMERA, with three joints; DIMERA, with two
joints; and MONOMERA, with one joint to the tarsi."
Suborder THYSANOPTERA ([Greek: thysanos], a fringe; [Greek: pteron],
wing): This suborder contains the single family _Thripidæ_, which
comprises minute insects commonly known as Thrips, and of which a common
species, _Thrips striatus_, is shown in the accompanying figure. (See
Fig. 22.) They bear strong relations to both the Pseudoneuroptera and
the Hemiptera and by later writers are generally associated with the
latter order. They feed on plants, puncturing and killing the leaves, or
on other plant-feeding species of their own class, and are characterized
by having narrow wings crossed on the back when at rest, and beautifully
fringed, from which latter feature the name of the suborder is derived.
[Illustration: FIG. 21.--A Plant-louse (_Schizoneura lanigera_). _a_,
infested root; _b_, larva; _c_, winged insect; _d-g_, parts of perfect
insect enlarged.]
The mouth parts are peculiar in that they are intermediate in form
between the sucking beak of Hemiptera and the biting mouth parts of
other insects.
[Illustration: FIG. 22.--_Thrips striatus_, with wings enlarged at
side.]
Their eggs resemble those of Hemiptera; the larvæ and pupæ are active,
and in form resemble the adult, except in the absence of wings. Some
species, also, are wingless in the adult stage.
The pupæ are somewhat sluggish and the limbs and wings are enclosed in a
thin membrane which is expanded about the feet into bulbous
enlargements, giving rise to the name "bladder-footed" (Physopoda)
applied to these insects by Burmeister.
"Order DIPTERA ([Greek: dis], twice; [Greek: pteron], wing) or
Two-winged Flies. The only order having but two wings, the hind pair
replaced by a pair of small, slender filaments clubbed at tip, and
called halteres, poisers, or balancers.
[Illustration: FIG. 23.--A Mosquito (_Culex pipiens_). _a_, adult; _b_,
head of same enlarged; _e_, portion of antenna of same; _f_, larva; _g_,
pupa. (After Westwood.)]
[Illustration: FIG. 24.--A Hawk-fly (_Erax bastardi_). _a_, perfect
insect; _b_, pupa; larva shown at side.]
[Illustration: FIG. 25.--A Flesh-fly (_Sarcophaga carnaria_, var.
_saracenæ_). _a_, larva; _b_, puparium; _c_, adult insect with enlarged
parts.]
"No order surpasses this in the number of species or in the immense
swarms of individuals belonging to the same species which are frequently
met with. The wings, which are variously veined, though appearing naked
to the unaided eye, are often thickly covered with very minute hairs or
hooks. As an order the Diptera are decidedly injurious to man, whether
we consider the annoyances to ourselves or our animals of the Mosquito,
Buffalo-gnat, Gad-fly, Breeze-fly, Zimb or Stomoxys, or the injury to
our crops of the Hessian-fly, Wheat-midge, Cabbage-maggot, Onion-maggot,
etc. There are, in fact, but two families, Syrphidæ and Tachinidæ, which
can be looked upon as beneficial to the cultivator, though many act the
part of scavengers. No insects, not even the Lepidoptera, furnish such a
variety of curious larval characters, and none, perhaps, offer a wider
or more interesting field of investigation to the biologist. It is
difficult to give any very satisfactory arrangement of these Two-winged
flies, though they easily fall into two rather artificial sections.
These are: 1st, NEMOCERA, or those with long antennæ, having more than
six joints, and palpi having four or five joints. The pupa is naked, as
in the Lepidoptera, with the limbs exposed. This kind of pupa is called
_obtected_. 2d, BRACHOCERA, or those with short antennæ, not having more
than three distinct joints, and palpi with one or two joints. The pupa
is mostly _coarctate_, _i. e._, is formed within, and more or less
completely connected with, the hardened and shrunken skin of the larva.
[Illustration: FIG. 26.--The Sheep Bot (_[OE]strus ovis_). 1, 2, flies;
3, puparium; 4, 5, and 6, larvæ or bots.]
"The most anomalous of the Diptera are the Forest-flies and Sheep-ticks
(_Hippoboscidæ_). They have a horny and flattened body, and resemble
lice in their parasitic habits, living beneath the hair of bats and
birds. Their mode of development has always attracted the attention of
entomologists. The larvæ are hatched in the abdomen of the female, which
is capable of distention. There it remains and, after assuming the pupa
state, is deposited in the form of a short, white, egg-like object,
without trace of articulation, and nearly as large as the abdomen of the
female fly. Closely allied to these are the Bat-ticks (_Nycteribidæ_),
which possess neither wings nor balancers, and remind one strongly of
spiders.
"In this order we may also place certain wingless lice (such as _Braula
c[oe]ca_, Nitzch), which infests the Honey-bee in Europe, northern
Africa, and western Asia, but which has not yet been detected in this
country.
[Illustration: FIG. 27.--A Flea (_Pulex_). (From Packard.)]
"Suborder APHANIPTERA ([Greek: aphanês], inconspicuous; [Greek: pteron],
wing) or Fleas, comprising the single family Pulicidæ, now placed with
the Diptera. Everybody is supposed to be familiar with the appearance of
the Flea--its bloodthirsty propensities and amazing muscular power; and
while everyone may not have the leisure and means to experience the
exhilarating influence of the chase after larger animals, there is no
one--be he never so humble--who may not indulge in the hunt after this
smaller game! In place of wings the flea has four small, scaly plates.
The minute eggs--about a dozen to each female--are laid in obscure
places, such as the cracks of a floor, the hair of rugs, etc., and the
larva is worm-like and feeds upon whatever animal matter--as grease and
blood--or decaying vegetable matter it can find.
"Order ORTHOPTERA ([Greek: orthos], straight; [Greek: pteron], wing), or
Straight-winged Insects. Characterized by having the front wings (called
_tegmina_) straight and usually narrow, pergameneous or parchment-like,
thickly veined, and overlapping at tips when closed; the hind wings
large and folding longitudinally like a fan. Transformations incomplete.
[Illustration: FIG. 28.--A Locust (_Acridium americanum_).]
[Illustration: FIG. 29.--A Tree-cricket (_Orocharis saltator_). _a_,
female; _b_, male.]
[Illustration: FIG. 30.--The Croton Bug or German Cockroach
(_Phyllodromia germanica_). _a_, first stage; _b_, second stage; _c_,
third stage; _d_, fourth stage; _e_, adult; _f_, adult female with
egg-case; _g_, egg-case--enlarged; _h_, adult with wings spread--all
natural size except _g_.]
"The insects of this order have a lengthened body and very robust jaws,
with a correspondingly large head. The legs are strong, and fashioned
either for grasping, running, climbing, jumping, or burrowing. As in the
other orders, where the transformations are incomplete, the young differ
little from the parent, except in the want of wings; and in many
instances even this difference does not exist, as there are numerous
species which never acquire wings. There are no aquatic Orthoptera. Some
are omnivorous, others carnivorous, but most of them herbivorous. They
form four distinct sections: 1st, CURSORIA, Cockroaches; 2d, RAPTATORIA,
Mantes; 3d, AMBULATORIA, Walking-sticks; 4th, SALTATORIA, Crickets,
Grasshoppers, and Locusts.
[Illustration: FIG. 31.--Hind wing of Earwig. (From Comstock.)]
[Illustration: FIG. 32.--An Earwig. (From Packard.)]
"Suborder DERMAPTERA[2] ([Greek: derma], skin; [Greek: pteron], wing),
or Earwigs, consisting of the single family Forficulidæ, which may be
placed with the Orthoptera. They are rare insects with us, but very
common in Europe, where there prevails a superstition that they get into
the ear and cause all sorts of trouble. The front wings are small and
leathery; the hind ones have the form of a quadrant, and look like a fan
when opened; and the characteristic feature is a pair of forceps-like
appendages at the end of the body, best developed in the males. They are
nocturnal in habit, hiding during the day in any available recess. The
female lays her eggs in the ground, and singularly enough, broods over
them and over her young, the latter crowding under her like chicks under
a hen."
[2] Euplexoptera of some authors from [Greek: eu], well;
[Greek: plechô], folded, referring to the folded wings.
[Illustration: FIG. 33.--A Dragon-fly (_Libellula trimaculata_). (From
Packard.)]
"Order NEUROPTERA ([Greek: neuron], nerve; [Greek: pteron], wing), or
Nerve-winged insects. Characterized by having the wings reticulate with
numerous veins so as to look like net-work. The order forms two natural
divisions, the first including all those which undergo a complete, and
the second, called Pseudo-neuroptera (Dictyotoptera, Burmeister),
those which undergo an incomplete metamorphosis. * * * The insects of
this order are, as a whole, more lowly organized, and more generally
aquatic, than either of the others. A natural arrangement of them is
difficult on account of their degradational character. They present
forms which are synthetic and closely approach the other orders, and the
evolutionist naturally looks upon them as furnishing an idea of what the
archetypal forms of our present insects may have been. They are, as a
rule, large and sluggish, with the body parts soft and little
specialized, and the muscles weak. Their remains are found in the
Devonian and Carboniferous deposits.
"They are mostly carnivorous, and with the exception of the White-ants
and certain Book-lice they none of them affect man injuriously, while
some are quite beneficial."
[Illustration: FIG. 34.--Caddis-fly, larva and its case. (From
Packard.)]
The first division of this order, or the Neuroptera proper,
characterized by having incomplete metamorphoses, may be considered
under the three following suborders:
"Suborder TRICHOPTERA ([Greek: thrix], hair; [Greek: pteron], wing), or
Caddis-flies, containing the single family Phryganeidæ, and placed with
the Neuroptera, though bearing great affinities with the Lepidoptera.
Every good disciple of Walton and lover of the "gentle art" knows the
value of the Caddis-fly, or Water-moth, as bait. These flies very much
resemble certain small moths, the scales on the wings of the latter
being replaced in the former with simple hairs. The larvæ live in the
water and inhabit silken cases, which are usually cylindrical and
covered with various substances, according to the species, or the
material most conveniently obtained by the individual."
Suborder MECOPTERA ([Greek: mêkos], length; [Greek: pteron], wing). This
suborder includes a peculiar group of insects, the most striking
characteristics of which are the mouth-parts, which are prolonged into a
rostrum or beak. The wings are long and narrow, and of nearly equal
size. The abdomen of the male is constricted near its posterior end and
terminates in long clasping organs from which these insects obtain the
common name of Scorpion-flies.
[Illustration: FIG. 35.--Panorpa or Scorpion-fly. (From Packard.)]
The larvæ of one genus (_Panorpa_) are remarkable for their great
resemblance to the larvæ of Lepidoptera. They have, however, eight pairs
of abdominal legs. The habits of these insects are not well known, but
they are supposed to be generally.
Suborder NEUROPTERA. This group as restricted by modern authors is a
small one, including the largest species, as in the Hellgrammite, the
Lace-wing Flies, the Ant-lions, and the Mantispas representing the
families, Sialidæ and Hemerobiidæ, with their subfamilies. The first
includes the so-called Hellgrammite Fly (_Corydalus cornutus_), one of
our largest and most striking insects, the larvæ of which is known as
Dobsons by anglers, and is aquatic and carnivorous in habit. The
Hemerobiidæ is a large family, comprising, as a rule, delicate insects
with rather ample gauzy wings. The larvæ are predaceous. The common
Lace-wing flies are among our most beneficial insects, destroying
plant-lice and other soft-bodied species. To the same family belongs the
Ant-lion (_Myrmeleon_), the larvæ of which have the curious habit of
constructing a funnel-shaped burrow in the sand, in the bottom of which
they conceal themselves and wait for any soft-bodied insects which may
fall into the trap. This family also includes the peculiar Mantis-like
insects belonging to the genus _Mantispa_. As in the true Mantis, the
prothorax of these insects is greatly elongated and the first pair of
legs are fitted for grasping. The larvæ are parasitic in the egg-sacs of
certain large spiders (genera _Licosa_, _Dolomedes_, etc.), and undergo
a remarkable change in form after the first molt. In the first stage the
larvæ are very agile, with slender bodies and long legs. After molting
the body becomes much swollen and the legs are much shortened, as are
also the antennæ, the head becoming small and the general appearance
reminding one of the larva of a bee.
[Illustration: FIG. 36.--Lace-wing fly. _a_, eggs, _b_, larva, _c_,
cocoons, _d_, fly with left wings removed.]
[Illustration: FIG. 37.--An Ant-lion (_Myrmeleon_). (From Packard.)]
[Illustration: FIG. 38.--Myrmeleon larva.]
[Illustration: FIG. 39.--_Mantispa_ with side view beneath. (From
Packard.)]
The second section of the Neuroptera, characterized by complete
metamorphosis, comprises the following suborders:
Suborder PLATYPTERA ([Greek: platys], flat; [Greek: pteron], wing).
Under this head are grouped the White-ants (_Termitidæ_), the Bird-lice
(_Mallophaga_), and the Book-mites (_Psocidæ_). The suborder receives
its name from the fact that in the case of the winged forms the wings,
when at rest, are usually laid flat upon the back of the insect. The
Mallophaga, or Bird-lice, are degraded wingless insects, and are
parasitic chiefly on birds, but also on mammals. In shape of body and
character of the mouth-parts they are most nearly allied to the Psocidæ.
The latter family includes both winged and wingless forms, the
Book-mites belonging to the latter category. The winged forms may be
illustrated by the common species, _Psocus venosus_ (see Fig. 40). The
legs and antennæ are long and slender and the wings are folded roof-like
over the body when the insect is at rest. They feed on lichens and dry
vegetation.
The Termitidæ are represented in this country by the White-ant (_Termes
flavipes_), which is frequently so destructive to woodwork, books, etc.
The term White-ant applied to these insects is unfortunate, as in
structure they are widely separated from ants and resemble them only in
general appearance and also in their social habits. Like the ants they
live in colonies and have a number of distinct forms, as winged and
wingless, males and females, and workers and soldiers.
[Illustration: FIG. 40.--_Psocus venosus._ (From Comstock.)]
Suborder PLECOPTERA ([Greek: plektos], plaited; [Greek: pteron], wing).
Closely allied to the latter suborder is the suborder Plecoptera, which
includes the single family Perlidæ or Stone-flies. The larvæ and pupæ of
these insects are aquatic, being often found under stones in water,
whence the name. The adults are long, flattened insects, with long
antennæ. The wings are ample and are somewhat folded or plaited, from
which character the suborder takes its name.
[Illustration: FIG. 41.--A Stone-fly (_Pteronarcys regalis_). (From
Comstock.)]
Suborder ODONATA ([Greek: othous], tooth). This includes
the Dragon-flies or Libellulidæ, the most common and the best known of
the Neuroptera. The larva and the active pupa or nymph are aquatic and
are predaceous, as is also the adult. A common species is represented at
Fig. 33.
The Suborder EPHEMEROPTERA ([Greek: ephêmeron], a day-fly; [Greek:
pteron], wing) comprises the May-flies, or Ephemeridæ (see Fig. 42).
These insects are very fragile and are often attracted in enormous
numbers to electric lights. They have large front wings, while the hind
wings are small, rudimentary, or wanting. They are furnished with two or
three very long, jointed, threadlike caudal appendages. The larval and
nymphal stages are passed in the water and aquatic vegetation furnishes
the food, although some species may be predaceous. The adults have very
rudimentary mouths and eat nothing; their term of life is also very
limited, not exceeding 2-4 days.
[Illustration: FIG. 42.--A May-fly (_Potamanthus marginatus_). (From
Packard.)]
Suborder THYSANURA ([Greek: thysanos], tassel; [Greek: oura], tail).
This suborder comprises minute, degraded insects commonly known as
Spring-tails, Bristle-tails, Fish-moths, Snow-fleas, etc. They occur in
damp situations and also infest books, wall-paper, etc., eating the
starch paste in the book-bindings, or beneath the wall paper. They
comprise very primitive forms and are interesting because they are
supposed to represent the original stock from which the higher orders of
insects have sprung. They are wingless, usually with simple eyes, and
clothed with scales, and undergo no metamorphosis. Some of them, as the
Fish-moth (_Lepisma sp._), run very rapidly and are furnished at the end
of the body with a number of long bristles. In other forms these anal
bristles or stylets are united at the base and bent under the body and
become a powerful jumping organ, giving them the very appropriate name
of Spring-tails.
[Illustration: FIG. 43.--(_Lepisma 4-seriata_). (After Packard.)]
COLLECTING.
GENERAL CONSIDERATIONS.--"Few departments of natural history offer
greater inducements or facilities to the student than Entomology. He
need not pass his threshold for material, for it may be found on every
hand and at all seasons. The directions for collecting, preserving, and
studying insects might be extended indefinitely in detail, as volumes
have already been written on the subject; but the more general and
important instructions are soon given.
"Beginners are very apt to supply themselves with all sorts of
appliances advertised by natural history furnishing stores. Many of
these appliances, when it comes to real, practical field-work, are soon
abandoned as useless incumbrances; and the greater the experience, the
simpler will be the paraphernalia. My own equipment, on a collecting
trip, consists chiefly of a cotton umbrella, a strong and narrow steel
trowel or digger, a haversack slung across the shoulders, a cigar box
lined with sheet cork, and a small knapsack attached to a waistbelt
which girts a coat, not of many colors, but of many pockets, so made
that in stooping nothing falls out of them. The umbrella is one of the
indispensables. It shields, when necessary, from old Sol's scorching
rays and from the pelting, drenching storm; brings within reach, by its
hooked handle, many a larva-freighted bough which would otherwise remain
undisturbed; and forms an excellent receptacle for all insects that may
be dislodged from bush or branch. Opened and held inverted under a bough
with the left hand, while the right manipulates a beating-stick, cut for
the occasion, it will be the recipient of many a choice specimen that
would never have been espied amid its protective surroundings. Some
collectors use an umbrella painted or lined on the inside with white, to
facilitate the detection of any object that drops into it; but as there
are fully as many, if not more, pale and white insects as there are dark
or black ones, the common dark umbrella is good enough for all ordinary
purposes; and if any improvement on the ordinary cotton umbrella is
desired, it should be in the way of a joint or knuckle about the middle
of the handle, which will facilitate its packing and using. The trowel
is valuable for prying off the loosened bark from old trees, whether
felled or standing, and for digging into the ground or into decaying
stumps and logs. The haversack is for the carriage of different kinds of
boxes (those made of tin being best) intended for larval and other forms
which it is necessary to bring home alive for breeding purposes; and if
made with a partition so that the filled and empty boxes may be
separated, all the better; it may also be used for nets and other
apparatus to be mentioned, and for such provender as is necessary on the
trip. The knapsack may be made on the plan of a cartridge box, of stout
canvas or leather, and should be of moderate size and slung onto the
belt so as to be slipped to any part of the waist and not hinder free
bodily motion. It may be used to carry bottles, phials, and other small
appliances, and should be accordingly partitioned and furnished with
loops or pockets on the inside. The cigar-box is for the reception of
pinned specimens, and may be slipped onto the belt, or buttoned to the
trousers by means of leather.
"The greatest requisites in collecting are a pair of sharp eyes and
ready hands, with coolness and self-possession; but a few traps will
materially aid. One of the most important is the hand-net, which may be
made so as to subserve the two purposes of a sweeping and an air-net."
[Illustration: FIG. 44.--The Butterfly net-frame.]
"The frame of the net which I use is illustrated herewith (Fig. 44), and
will be found strong and serviceable and conveniently portable. It is
constructed as follows: Take two pieces of stout brass wire, each about
20 inches long; bend them half-circularly and at one end by a folding
hinge having a check on one side, _b_. The other ends are bent and
beaten into two square sockets, _f_, which fit to a nut sunk and
soldered into one end of a brass tube, _d_. When so fitted, they are
secured by a large-headed screw, _e_, threaded to fit into the
nut-socket, and with a groove wide enough to receive the back of a
common pocket-knife blade. The wire hoop is easily detached and folded,
as at _c_, for convenient carriage; and the handle may be made of any
desired length by cutting a stick and fitting it into the hollow tube
_a_, which should be about 6 inches long. It is well to have two
separate hoops, one of lighter wire, furnished with silk gauze or some
other light material, for catching flying insects, and one which is
stouter and furnished with a net of stronger material for sweeping
non-flying specimens.
"Another still more simple, but less convenient frame, is thus described
by my friend F. G. Sanborn, of Boston, Mass.:
'Make a loop of strong iron or brass wire, of about 3-16ths of an inch
in thickness, so that the diameter of the loop or circle will not exceed
12 inches, leaving an inch to an inch and a half of wire at each end
bent at nearly right angles. Bind the two extremities of the wire
together with smaller wire (Fig. 45, _a_), and tin them by applying a
drop of muriate of zinc, then holding it in the fire or over a gas flame
until nearly red hot, when a few grains of block tin or soft solder
placed upon them will flow evenly over the whole surface and join them
firmly together. Take a Maynard rifle cartridge tube, or other brass
tube of similar dimensions; if the former, file off the closed end or
perforate it for the admission of the wire, and having tinned it in the
same manner on the inside, push a tight-fitting cork half way through
(Fig. 45, _c_) and pour into it melted tin or soft solder, and insert
the wires; if carefully done, you will have a firmly constructed and
very durable foundation for a collecting net. The cork being extracted
will leave a convenient socket for inserting a stick or walking cane to
serve as a handle.'
[Illustration: FIG. 45.--The Sanborn net-frame.]
"My friend, J. A. Lintner, of Albany, N. Y., makes very good use, in his
ordinary promenades, of a telescopic fish-rod, with a head (Fig. 46)
screwed on to one end, in which to fasten an elastic brass coil on which
the net is drawn, but which when not in use sits snugly inside his silk
hat.
[Illustration: FIG. 46.--Clamp of the Lintner net.]
"The bag should taper to the bottom, and in any case its length should
be fully twice the diameter of the hoop, so that by giving the net a
twist, the mouth may be closed and the contents thus secured. The
sweeping-net may be protected around the hoop with leather, and in use
should be kept in a steady and continued back-and-forth motion, over and
touching the plants, until the contents are to be examined; when, by
placing the head at the opening and quietly surveying the restless
inmates, the desiderata may be secured and the rest turned out. A sudden
dash of the air-net will usually lay any flying object at the bottom. A
net for aquatic insects may be made on the same principle, but should be
stout, with the meshes open enough to allow free passage of water, and
the bag not quite as deep as the diameter of the hoop. A forceps net,
which consists of two gauze or bobbinet covered frames, having riveted
handles, so as to close like a pair of scissors, is employed for small
insects; but I find little use for it. A coarse sieve, together with a
white towel or sheet, will be found of great service for special
occasions, particularly in the spring, when the search for minute
insects found under old leaves, or for pupæ around the butts of trees,
is contemplated. With the sheet spread on the ground, and a few handfuls
of leaves and leafy mold sifted over it, many a minute specimen will be
separated from the coarser particles and drop to the sheet, where the
eye may readily detect it. Conversely, the earth taken from around trees
may be sifted so as to leave in the sieve such larger objects as pupæ,
etc. Another favorite plan, with some collectors, of obtaining
specimens, especially night-flying moths, is by 'sugaring.' This
consists of applying to the trunks of trees or to strips of cloth
attached to the trees some sweet, attractive, and stupefying
preparation. Diluted molasses or dissolved brown sugar, mixed with rum
or beer, is most frequently employed. I have found sugaring of little
use till after the blossoming season, and it is almost impossible to so
stupefy or intoxicate an insect that it will remain upon the sugared
tree till the next morning. I generally sugar at eve, and visit the tree
several times between sundown and midnight, armed with wide-mouthed
killing-bottles and accompanied by a second person, who carries a
dark-lantern. Isolated trees, on the edges of woods, give the best
results. Everybody knows how some poor moths will persist in flitting
around a light until they singe their wings; and, as many insects are
strongly attracted to bright artificial light, it may be employed with
good results, especially during warm and damp evenings. The collector
should never go unprovided with a small box or tube full of different
sized pins (a corked cartridge-tube makes a good box,) a pair or two of
forceps, a pair of scissors, a little mucilage, and the killing
apparatus to be described."
With these general remarks, it will be well to consider some of the
important paraphernalia more in detail.
COLLECTING APPARATUS.
_The Sweeping Net._--A multitude of insects of all orders feed or rest
on grasses and other low plants. Upon close inspection of these plants a
careful observer will be able to secure, without any instruments, not
only many mature insects, but also many larvæ in connection with their
food-plants. This is laborious and slow work, only necessary on special
occasions. The beating net, which is constructed on the same general
plan as the butterfly net, is valuable here as a time saver. By holding
the handle of the net firmly in one hand and quickly sweeping over the
plants first from right to left, and then, after quickly turning the net
again, sweeping from left to right, most insects coming within reach of
the sweep will fall into the bag and may be easily taken out and put
into the collecting-vials. From this mode of operation it is evident
that the sweeping net must be stronger in all its parts than the
butterfly net, but otherwise it may be made on the same plan.
[Illustration: FIG. 47.--The Deyrolle Sweeping Net. _a_, net entire;
_b_, frame; _c_ and _d_, attachment of frame and handle (original).]
The ring should be rigid, made of brass or iron, either of one piece or
of two pieces, and fastened to the handle or stick in the same way as
the butterfly net. The bag need not be as long as in the butterfly net,
about 18 inches being sufficient, but it should be of stout cotton or
linen and the bottom should preferably be sewed in as a round piece, so
as to avoid corners. Care needs to be bestowed on the fastening of the
bag on the ring, for by the use of the net the part of the bag sewed
around the ring is soon chafed through. To prevent this a strip of
leather is sewed over the cotton along the rim, but since even this must
be frequently renewed some other devices are used to give greater
durability to the net. In the pattern of a beating-net originally sold
by Deyrolle in Paris, the metal ring was flattened, with the narrow edge
pointing upwards and the broad side pierced with holes at suitable
intervals and grooved on the outer surface between the holes. The bag is
sewed on to the inner side of the ring by stout twine, which passes from
one hole to the next and is thus prevented from coming in contact with
obstructive objects, and only the bottom of the bag wears and will need
to be occasionally mended or renewed.
Another method of preventing the tearing of the upper rim of the bag is
described and illustrated in Kiesenwetter's useful volume "Der
Naturaliensammler" from which I shall frequently have occasion to quote.
In this net the main ring is of rounded iron wire on which a number of
brass rings are slipped. These must be but little larger than the
diameter of the wire. These little brass rings should not be more than
30 mm. or at most 40 mm., distant from each other, and to them the upper
rim of the bag is sewed with very strong twine and is thus protected
from wear and tear. The handle or stick of the net should be firmly and
solidly attached to the ring and should be stout and not liable to
break. I prefer a rather short stick, say not longer than two feet.
I figure herewith the ring of a very convenient net for sweeping or
beating purposes. It has the advantage of being for sale on the market,
and in fact is an ordinary fishing dip net of small size. It is hinged
in three places, as shown in the figure, and folds into very small
compass. When unfolded and brought together, it screws into a ferrule
which may be attached to a cane or a special handle.
[Illustration: FIG. 48.--Beating net, opened and attached to handle,
with frame of same folded. (After Kiesenwetter.)]
The beating net can be successfully used at almost every season of the
year. Even on warm days in winter time many specimens can be swept from
the dead grass. So long as the dew is on the plants or in rainy weather
no beating should be attempted, as the more delicate species are more or
less spoiled by the moisture. After one or two minutes' sweeping the
contents should be examined. Those insects which are quick to take wing
or which are good runners should first receive attention; the less
active can then be examined more at leisure. The desiderata are then
disposed of, the rest thrown away, and the beating renewed.
[Illustration: FIG. 49.--Folding ring for beating net (original).]
The beating net is an important instrument for collecting all insects
excepting mature Lepidoptera, which are apt to get rubbed. Many larvæ,
especially of Lepidoptera, are caught by beating and are mostly in good
condition, but it is usually difficult to ascertain the food plant.
_The Water Net._--The numerous insects or insect larvæ which live in the
water can not be conveniently collected without the use of a net, except
where they live in small shallow streams or creeks with gravelly or
stony bottoms. A suitable water net can readily be made by using the
frame of the beating net and attaching to it a rather short bag of some
coarse material, _e. g._, "grass cloth," coarse millinet. The mode of
operation with this net is very simple: if some insect is seen swimming
in the water, the net is carefully brought beneath the specimen, which
is thus lifted out of the water. Most water insects are, however, not
seen swimming about freely, but hide amid the various plants, mosses,
etc., or in the mud at the base of the plants, and they can best be
captured by dragging the net through these plants. When taken from the
water the net is more or less filled with mud and parts of plants, and
the water must be allowed to run out and the contents of the net spread
out on a cloth or on a flat stone, if such be at hand. The insects are
at first not readily seen, but after a short while they begin to emerge
from the mud and crawl about, and can readily be taken up with a
forceps.
[Illustration: FIG. 50.--The Water Net. (After Packard.)]
_Water Dip Net._--The small water sieve, shown in the accompanying
illustration (Fig. 51), and somewhat resembling in appearance a jockey
cap, is frequently of service in collecting the larvæ of aquatic
insects, especially where it is necessary to scrape submerged stones or
timbers. In use it is fastened on the end of a cane or stick, and can be
easily made by any tinsmith.
[Illustration: FIG. 51.--Small Water Dip Net (original).]
_The Umbrella._--The umbrella, as already stated, is one of the most
useful instruments of the collector, since it enables him to obtain all
those numerous insects which live on the branches of trees, on shrubs,
and on other large plants. A common stout cotton umbrella is
sufficiently large, but is liable to get out of joint, and moreover the
specimens hide themselves under the ribs. It is well, therefore, to have
the inside of such umbrella lined along the ribs with muslin, or some
other material, preferably of a light color. An umbrella specially
constructed for entomological purposes is offered for sale by E.
Deyrolle, in Paris. It resembles a stoutly built common umbrella, but
has the inside lined with white linen and the handle has a joint near
the middle, so that the umbrella can be more conveniently held and more
readily packed away. The opened and inverted umbrella is held with the
left hand under the branch which the collector intends to relieve of its
entomological inhabitants, while the right hand, armed with a heavy
stick, is free to properly jar the branch. Care must be taken in the
jarring, lest the insects are knocked beyond the circumference of the
umbrella. The larger the umbrella the greater are the chances of making
rich captures, but the more difficult it becomes to manipulate,
especially where the woods are dense or where there are many vines, etc.
In the absence of an umbrella the butterfly net or the beating net can
be used.
A drawback to collecting with the umbrella is that many insects take
wing and escape before being secured. This can hardly be avoided, and
experienced collectors, in southern countries more particularly, have
found it advisable to discard the umbrella and to use in its stead a
very large butterfly net, 2 feet or more in diameter.
[Illustration: FIG. 52.--The Umbrella and its mode of use. (After
Kiesenwetter.)]
_The Beating Cloth._--A very simple substitute for the umbrella, and one
which can always be carried without inconvenience, may here be
described. It consists of a piece of common unbleached cotton cloth (1
yard square), to each corner of which a loop of stout twine is sewed.
Upon reaching the woods, two straight sticks, each about 5 feet in
length and not too heavy, but also not so small as to be liable to break
or to bend too easily, are cut from a convenient bush. The sticks are
placed crosswise over the cloth and fastened to the loops at the four
ends. This is easily and quickly done by making sliding loops of the
simple loops. The cloth is thus kept spread out between the sticks, and
forms a very good substitute for an umbrella. In beating, the sticks are
held at their intersecting points. When not in use one of the loops is
detached from the stick and the instrument can be rolled up and carried
under one arm without seriously interfering with other operations of the
collector. When laid on the ground, with the sticks on the underside,
this simple instrument may be advantageously used as a cloth on which
to sift or examine fungi, moss, pieces of bark, etc., and since the
cloth is always tightly expanded, it offers a smooth and level surface,
where examination of various objects can be made with ease and accuracy.
[Illustration: FIG. 53.--The umbrella beating and sweeping net
(original).]
_The Umbrella Net._--A very convenient form of net for both sweeping and
for use in place of an umbrella for beating has been devised by Dr.
George Marx. (See Fig. 53.) It is constructed from an old umbrella, as
follows: To the handle of the umbrella are attached two steel rods
working on hinges at the apex of the umbrella, as do the ordinary
umbrella ribs, and attached to the sliding piece of the umbrella in the
same manner, as shown at _a_. These rods should be about 2½ feet long.
When the sliding piece is pushed up and caught behind the spring clip,
as shown at _b_, a circular loop is formed giving the framework for the
net. The latter, which should be comparatively shallow, is made of stout
muslin and sewed to the frame, as in the ordinary sweeping net. The
enlarged drawings _c_ and _d_ illustrate clearly the manner of
constructing the frame. The advantage of this net is its convenience in
carrying and its general usefulness, taking the place of both the
umbrella and the sweeping net. When not in use the frame is allowed to
assume the position shown at A, and the net may be wrapped about the
frame and the whole inserted in an ordinary umbrella cover.
_The Sieve._--This useful aid to good collecting has not been generally
employed by American entomologists. It facilitates the finding of small
insects living under old leaves, in moss, in decayed trees, in fungi, in
ants' nests, or in the ground. Any ordinary sieve about a foot in
diameter and with meshes of about one-fifth of an inch will answer,
though for durability and convenience of carriage one made of two wire
or brass rings and muslin (Fig. 54), as follows, is the best. The ends
of the wire netting should be bent around the ring so as not to project.
A piece of common muslin about 1 foot wide and long enough to go around
the circumference of one of the rings is then sewed together so as to
form a kind of cylinder or bag without bottom, and the upper and lower
rims of this bag are then sewed on around the two rings. The whole
instrument thus forms a bag, the top of which is kept open by the simple
wire ring, and the bottom is closed by the second ring covered with the
wire netting. After choosing a suitable locality a white cloth is spread
as evenly as possible on the ground; the collector then takes the sieve,
places therein two or three handfuls of the material to be sifted,
returns to his cloth, and, holding with his right hand the lower ring
and with the left hand the upper ring, shakes the sieve over the cloth.
The larger particles and specimens are retained in the sieve while the
smaller fall through the meshes on to the cloth. Care must be taken that
the siftings form an even and thin layer on the surface of the cloth, so
as to be easily examined from time to time. If the locality is favorable
many insects will be seen at the first glance crawling or running about,
and these can easily be picked up by means of a moistened brush, or with
the forceps. Many other insects, however, either feign death or, at any
rate, do not move until after the lapse of several minutes, and the
proper investigation of a single sifting often requires much time, and
patience will be more fully rewarded here than in any other mode of
collecting.
[Illustration: FIG. 54.--The sieve. _a_, wire netting (original).]
The size of the wire meshes given above is best adapted for sifting the
fragments of old decayed trees, which furnish the most frequent material
for the use of the sieve, but for sifting ants' nests, soil, etc., a
sieve with smaller meshes is desirable.
The sieve is indispensable to the Coleopterist, the Arachnologist, and
to the specialist in the smaller Hemiptera and Hymenoptera, but it is
also useful for most other orders, many interesting species existing
which can be secured in numbers only by this mode of collecting. Many
Tineidæ and even Noctuidæ hide under old leaves, but the specimens are
usually rubbed and rendered useless in the process of sifting. Many
larvæ and pupæ can, however, thus be obtained.
If the locality chosen for sifting prove to be a good one, it pays to
put the sifted material in a small sack and to carry it home where it
can be investigated at leisure, and with a greater thoroughness than is
usually possible outdoors. This sack can be easily arranged to be
attached to or drawn over the lower ring of the sieve, so that the
sifting can be done directly into the sack.
As a rule it may be said that very dry places are least productive,
while more or less moist places are apt to furnish a rich harvest. Old
wet leaves lying immediately along the edges of swamps, or wet moss,
harbor many interesting insects, but such wet material is sifted with
difficulty.
The sieve can be used with great advantage at all seasons of the year,
but more especially late in fall or early in spring, when so many
species are still hibernating.
_The Chisel._--For securing the many insects living or hiding under bark
of dying or dead trees an instrument of some sort is indispensable, as,
in most cases, the bark so firmly adheres to the wood that it cannot be
torn off with the hand. A stout pocket-knife will do good service, but
far better is a common chisel of medium size and with a short handle.
This chisel is also useful as an instrument for digging in the ground or
for investigating the interior of partly decayed logs.
_The Trowel._--Aside from the fact that many insects enter the ground
for the purpose of hibernation in various stages, there is a rich
subterranean life to be found during the summer. There are many
burrowing Coleoptera; many, if not most, ants construct subterranean
nests; the number of other fossorial Hymenoptera is very large, and
there are also various burrowing Orthoptera and many Lepidopterous larvæ
which hide in the ground during the day. Some instrument for digging in
the ground is therefore of great importance, and while, as stated above,
the chisel will answer this purpose if nothing else be at hand, yet
there are other instruments which perform the work much quicker and more
thoroughly. The most available instrument is a rather small steel
trowel, such as can be had at the hardware stores in a great variety of
patterns, and which can be carried on excursions without much
inconvenience. One with a long and narrow blade, made very stout, I have
found very useful, though somewhat awkward to carry.
[Illustration: FIG. 55.--The collecting tweezers.]
_The collecting Tweezers._--In the picking up of specimens and
transferring them into the various bottles, vials, or boxes, the trained
collector will gather by hand the most delicate specimens without
injuring them. Yet this labor will be greatly facilitated by the use of
the tweezers or the brush. The former is a small, light pair of forceps,
made of steel or brass. It should be as pliable as possible, and the tip
should be narrow and rounded off and not pointed. It may be either
straight or curved at tip, according to individual preference.
[Illustration: FIG. 56.--Pinning forceps.]
[Illustration: FIG. 57.--Pinning forceps.]
Suitable tweezers may be obtained at the larger hardware stores or of
watchmakers. Excellent tweezers made of steel (see Fig. 55) are sold for
about 40 cents a pair by Codman, Shurtleff & Co., Tremont street,
Boston, Mass. Aside from their utility in picking up specimens from the
collecting cloth or the umbrella, the tweezers are indispensable for
extracting insects from cracks, or holes in timber, or from their
burrows in branches and stems of plants, or from places whence it is
impossible to dislodge them by hand. The larger "collecting forceps,"
sold by various dealers, do good service in certain emergencies, as when
large scorpions or other very large and ferocious insects are to be
secured.
[Illustration: FIG. 58.--Pinning forceps for Lepidoptera.]
For the handling of mounted insects various special forceps are
employed, a number of styles of which are shown at Figs. 56-8.
_The Brush._--A common camel's hair brush, of smaller or larger size
according to individual preference, is useful for picking up very small
or soft-bodied insects. For this purpose the brush is slightly moistened
with saliva, and the tip brought in contact with the specimen, which
then adheres to the brush, so that it can readily and without injury be
transferred to the collecting bottle or box. The brush is indispensable
also for preparing small specimens for the cabinet. If taken into the
field the handle of the brush should be of a bright color, otherwise the
brush is often lost.
[Illustration: FIG. 59.--The Fumigator. (After Kiesenwetter).]
_The Fumigator._--This is not used by American collectors, but there are
several patterns sold by European dealers. It is intended to smoke out
specimens that hide in otherwise inaccessible places, _e. g._, cracks in
the ground, holes in hard wood, etc. The accompanying figure and the
following description of a fumigator are taken from Kiesenwetter. A
common smoking-pipe mouthpiece (Fig. 59, _a_) with flexible rubber joint
(_b_) is attached to the cover (_c_) of a very large smoking-pipe head
(_d_). To the mouth (_e_) of the latter a rubber hose (_f_) is attached,
which has a convenient discharge at its end (_g_). The pipe is then
filled with tobacco, and the latter ignited by means of a piece of
burning tinder placed on top; the cover is then screwed on, and the
smoke can be directed to any desired point by blowing air through the
mouthpiece. The smoke from a common pipe or cigar is often useful. In
sifting in cold weather a puff of tobacco smoke gently blown over the
débris on the collecting cloth will induce many specimens to move, which
otherwise "play possum" and could not be observed; and, further, tobacco
smoke blown into holes and cracks in timber by means of an improvised
funnel made of a piece of paper will be the means of securing many rare
specimens.
_The Haversack._--In order that the above-mentioned instruments and the
various bottles, vials, and boxes which are needed for the preservation
of specimens may most conveniently and with the least impediment to the
collector be carried along on excursions, a haversack is indispensable.
This is made either of leather or, still better, of some waterproof
cloth, and should contain various compartments of different sizes; one
for stowing away the nets, the sieve, and the larger instruments, and
several smaller ones for boxes and vials--the whole so arranged that
each desired object can readily be taken out and that nothing will drop
out and get lost. The haversack is slung across the shoulders by means
of a leather strap, and a full field outfit need not be very heavy nor
seriously interfere with free bodily movements.
Many of the smaller objects are most conveniently carried in the pockets
of the coat, which acquires, therefore, some importance to the
collector. The coat should be of some durable stuff and provided with
many pockets, so arranged that in stooping nothing falls out of them.
_The Lens and Microscope._--In the examination of the minuter forms of
insect life the naked eye is not sufficient, and a hand-lens, or, for
more delicate work, the compound microscope will be found necessary. I
had, in my early experience, some difficulty in getting a satisfactory
hand-lens, and the use of a poor hand-lens in time injures the eyesight,
as I know by a year's rather disagreeable experience. For a hand-lens
the achromatic lenses formerly manufactured by A. K. Eaton, of Brooklyn,
N. Y., and now made by John Green, 35 Liverpool street, East Boston,
Mass., are most excellent in workmanship and are satisfactory in every
respect. A very good lens can also be purchased of any of the leading
manufacturers of microscopical apparatus in this country. The kind of
compound microscope to be purchased will depend upon the nature of the
work of the investigator. Very serviceable instruments are made by J. W.
Queen & Co., Philadelphia, Pa., and by the Bausch & Lomb Optical
Company, of Rochester, N. Y., and others. The German microscopes are in
many respects superior to those of American make, and if one has
sufficient means, I would recommend the purchase of one of the better
instruments of Zeiss's manufacture, which may be obtained either direct
from the manufacturers or through Queen & Co., or from the Boston
Educational Supply Company. Microscopic material, including slides,
cover glasses, instruments for mounting, mounting media, staining
fluids, etc., may be obtained of either of the firms named above.
Having thus indicated somewhat fully the general methods of collecting,
and the paraphernalia most desirable in collecting, it will be well to
go still further into detail, and in connection with the different
orders give some more specific information that will be valuable as a
guide not only to the general collector, but to the specialist.
COLLECTING HYMENOPTERA.
The insects of this order, including Bees, Wasps, Ants, Ichneumon-flies,
Gall-flies, Saw-flies, and allied insects have always been of unusual
interest both to entomologists and non-entomologists on account of their
diversified and peculiar habits. In abundance of species they exceed
perhaps even the Coleoptera. In general they are day fliers and always
to be found in abundance on bright days about flowers. The best season
for collecting is in early spring, on the bloom of the Willow, Alder,
and other trees. They may also be found at any season of the year, but
the males of many species are only to be taken in fall. In this order,
species of many groups can be most easily obtained by breeding. This
includes the gall-making family, Cynipidæ, and the parasitic families
Chalcididæ, Proctotrypidæ, Ichneumonidæ and Braconidæ. The Chrysididæ
and certain other less important families are also parasitic, but are
more easily obtained by general collecting. The implements necessary for
collecting Hymenoptera are the sweeping-net and the beating-net. Many
rare forms of the smaller parasitic families may be obtained by sweeping
the grass and foliage of all sorts. The Proctotrypidæ may be collected
in quantity by sifting leaves and rubbish collected in the woods. Mr.
William H. Ashmead, who has made an especial study of this group, finds
winter sifting profitable. Dried leaves and rubbish are sifted, the
finer portion being retained and transferred to a bag. When a sufficient
quantity is collected it is removed to a warm room. Many hibernating
species are taken in this way, and, revived by the warmth, are easily
noticed when the material is spread on white paper.
[Illustration: FIG. 60.--A Saw-fly (Nematus ventralis). _a_, _a_, _a_,
young larvæ; _b_, full-grown larva; _c_, cocoon; _d_, adult; all
slightly enlarged.]
On account of the interest attaching to a knowledge of the various hosts
of parasitic insects the collector should always aim to obtain the
latter by breeding as much as possible. This can easily be done by
keeping a lookout for larvæ of all sorts which give evidence of being
parasitized. The larvæ of Lepidoptera found late in the fall are very
apt to be parasitized, and should be collected and kept over the winter.
The parasites will emerge throughout the winter season and in the early
spring. Such larvæ will be found on the trunks of trees, in the crevices
of the bark, and the cocoons of parasites will also be found in similar
situations.
The Tenthredinidæ (Saw-flies) are not so often found about flowers but
usually remain in the vicinity of the food-plant of the larva, and may
many of them be collected by sweeping. The larvæ of this family are in
many cases difficult to breed, as most of them are single-brooded, and
it becomes necessary to carry the larvæ over the winter.
The Gall-flies, Cynipidæ, are the easiest of the families to collect,
because of their abundance and because of the ease with which they may
be reared. Their galls occur in enormous variety on oaks of various
species and also upon brambles and certain common weeds. These should be
collected when mature and be kept in glass jars. The Gall-flies and
inquilinous and parasitic species may thus be easily obtained, the
former appearing at particular seasons and the latter emerging from the
galls at all seasons of the year, and sometimes continuing to escape for
a period exceeding two years.
One of the most interesting families in this order is the Formicidæ,
which comprises the true ants. In the case of these insects isolated
specimens should not ordinarily be collected, and it is especially
desirable to collect the species from colonies so that the three forms
(males, females, and workers) may be obtained together. This holds also
in the case of the social wasps and bees, but the different sexes of the
latter may be collected in a season's collecting about flowers, the
females and workers in early spring and the males in the fall.
[Illustration: FIG. 61.--An Ichneumon (_Ophion_).]
The Uroceridæ or woodborers are to be found only about trees in which
the larvæ breed. They may frequently be taken about tree trunks, or
burrowing with their long gimlet-like ovipositors into the trunks of
trees to oviposit. Breeding is also a satisfactory method of obtaining
these insects.
Some special methods of collecting Hymenoptera may be briefly outlined.
In the case of the social bees, particularly bumble-bees, and also the
smaller wasps and yellow-jackets, a very satisfactory method of
collecting consists in first stupefying the insects in the nest by
introducing a small amount of chloroform, benzine, or bisulphide of
carbon. This should preferably be done in the late evening, after all
the insects have come in for the night. The nest may then be opened and
examined without any danger of being stung, and the different forms may
thus easily be obtained, together with any rare parasitic or inquilinous
insects. In the case of the nests of Bombi this is the best method of
obtaining the inquilinous Apathus species.
On account of the danger of being stung, and also on account of the
extremely quick flight of these insects, the removing of Hymenoptera
from the net is not always an easy task, and in many cases rare
specimens escape. One method of avoiding the danger of being stung is to
have the collecting net constructed with an opening at the bottom which,
during the sweeping, is tied with a string. When a sufficient quantity
of insects is obtained they are, by a few quick motions, driven to the
bottom of the net, and the net is then seized just above the insects
with the hand, the folds of cloth preventing the insects from getting
to the hand, so that there is little danger of being stung. The lower
end is then carefully untied and inserted into a wide-mouthed bottle,
and the contents of the net shaken out into the bottle. After the catch
is stupefied the vial may be turned out and the undesirable material
discarded. A second method consists in the use of an ordinary
sweeping-net of light material. A quantity of Hymenoptera are collected
from flowers and driven to the bottom of the net, and secured as in the
preceding method. The portion of the net containing the insects is then,
by means of a pair of forceps, thrust bodily into a large collecting
bottle. After a few minutes the insects are stupefied and may be readily
examined.
[Illustration: FIG. 62.--The Little Red Ant (_Monomorium pharaonis_).
_a_, female; _b_, worker enlarged.]
COLLECTING COLEOPTERA.
GENERAL DIRECTIONS.--Owing to their hard outer skeleton, Coleoptera can
be collected, handled, and preserved with greater safety and with less
trouble than most other orders of insects. From this fact, and from
their very great diversity in form, Coleoptera have, next to the
Lepidoptera, always been favorites. As a consequence, there are now more
species described in this than in any other order, and in the large
museums they are much better represented than other insects. This rich
material has been studied by numerous and competent specialists, and the
classification of Coleoptera is at present more advanced and more
accessible than that of the other orders. This fact gives stimulus to
neophytes, and though the literature of our North American fauna is much
scattered and we are still in want of comprehensive works (with the
exception of the general "Classification" by Drs. Le Conte and Horn),
yet, except in a few hitherto neglected families and smaller groups, the
species are fairly well worked up.
On the other hand, our knowledge of the earlier states of Coleoptera is
yet very imperfect as compared with the Lepidoptera. Coleopterous larvæ
are, with few exceptions (notably Coccinellidæ and some Chrysomelidæ),
much more difficult to find and rear, and their distinguishing
characters are more difficult to study. The few comprehensive works on
Coleopterous larvæ that have been published are based on rather scant
material and none of them deal with the North American fauna.
[Illustration: FIG. 63.--A Ground-beetle (_Calosoma calidum_). _a_,
larva; _b_, adult.]
Coleoptera occur in all climates and in all localities. Species are
known from the highest northern latitudes ever reached by man, and in
the tropics they occur in an embarrassing richness of forms. They are
found in the most arid desert lands, in the depths of our subterranean
caves, and on our highest mountains up to the line of eternal snow. The
open ocean and the open water of our Great Lakes are the only regions
free from them. As a rule, the number of species gradually increases
from the Arctic regions toward the tropics, but it would be difficult to
decide, speaking of North America, whether or not the fauna of the
Middle States is poorer in the number of species than that of the
Southern States; or whether the beetles of the Atlantic slope outnumber
those of the Pacific States or those of the Central region. On the
Pacific slope the influence of the seasons on insect life is greater
than on the Atlantic slope. While in the latter region a number of
species may be found the whole year round, there is, in the more arid
regions of the West, an abundance of insect life during and shortly
after the rainy season, with great scarcity during the dry season,
except, perhaps, on the high mountains.
Few persons have had a more extended experience in collecting Coleoptera
than Mr. E. A. Schwarz, one of my assistants, and the following account
has been prepared by him at my request and is given _in extenso_.
WINTER COLLECTING.--There are more species of Coleoptera hibernating in
the imago state[3] than in any other order and winter collecting is
therefore most profitable in many respects. For instance, great swampy
tracts which are inaccessible in the summer season harbor an abundance
of rare Coleoptera, which either can not be found in summer time or are
found at that season with the greatest difficulty. At the approach of
winter, however, all or most of these species will leave the swamp and
seek drier ground, where they hibernate under old leaves, under bark of
trees, or in rotten stumps near the edge of the swamp. Such places will,
therefore, give a rich harvest to the Coleopterist late in the fall,
during warm spells in midwinter, and in very early spring. If the
temperature is below the freezing point, or if the ground is frozen
hard, no winter collecting should be attempted, first, on account of
sanitary considerations, and also because the Coleoptera then retreat
more deeply into the ground and can not be found so easily as when the
ground is free from frost. Other good collecting places in winter are
the accumulated old leaves along the edges of forests or under the
shrubbery along water courses, thick layers of moss, and the loose bark
of dead or dying trees, and, finally, also under the bark of certain
living trees, _e. g._ Pines, Sycamore, Shellbark Hickory. Digging in the
ground at the base of large trees or rocks also yields good returns. The
only instruments necessary for winter collecting are the sieve, the
chisel, and the trowel.
[3] There are a few species of Coleoptera known in Europe which belong
to the true "winter insects," _i. e._ such as appear in the imago state
only during winter time, but whether or not we have such species in our
own fauna has not yet been ascertained.
SPRING COLLECTING.--With the first days of spring, collecting becomes a
little more varied. The methods used for winter collecting can still be
continued with good success. Certain spring flowers, notably Willow
blossoms, will furnish many valuable species, which are not seen again
during the rest of the season.
[Illustration: FIG. 64.--A Lamellicorn (_Pelidnota punctata_). _a_,
larva; _b_, pupa; _c_, beetle; _d_, _e_, _f_, enlarged parts.]
_Myrmecophilous and Termitophilous species._--The early spring is also
the best time for collecting the Myrmecophilous and Termitophilous
Coleoptera. Termitophilous species have in North America hitherto been
found only in connection with the White-ants (_Termes flavipes_), and
the inquilinous beetles are found running among the White-ants in the
colonies under stones, loose bark of trees, and more numerously in the
interior of old infested trees. Myrmecophilous Coleoptera are by far
more numerous in species than the Termitophilous species and are found
among many species of ants which have their nests either under stones or
loose bark of trees, in stumps or logs, or which construct larger or
smaller hills. Upon uncovering a colony of ants under a stone, the
underside of the latter as well as the galleries of the ants in the
ground should be carefully examined for inquilines, which from their
greater or slighter resemblance to the ants are liable to be overlooked
by an inexperienced collector. If such colony of ants harbors a rare
beetle the subterranean part of the colony itself should be dug out and
sifted, but since from the stony nature of the ground this is not always
practicable it is to be recommended to carefully replace the stone under
which the colony has been found. Upon revisiting the spot again the next
day or even a few hours after the first visit additional specimens of
the inquilines are usually to be obtained on the stone or in the
superficial galleries of the ants. Ant colonies in hollow trees and in
rotten logs should be sifted and there is no particular difficulty
connected with this operation. Owing to the pugnacious character of the
hill-constructing ants it would seem to be a rather unpleasant task to
examine a strong and vigorous colony for inquilinous beetles, but the
collector must not mind being bitten and stung by the infuriated ants,
and after a little experience he will find that it is not such a
difficult thing after all to attack even the largest ant-hill. The only
thorough way of investigating such ant-hills is to sieve the same, which
can be easily done if the hill is composed of sticks and other vegetable
débris. If it is built of earth or sand the process of sifting is more
difficult and tedious. Another method of securing specimens of these
inquilinous beetles is to place flat stones or similar objects on the
surface of the ant-hill and to examine them occasionally, when the
beetles will be found on the underside of the traps.
_Spring Flights of Coleoptera._--On the first really warm days of spring
commences the "swarming" season of Coleoptera, when all winged species
are flying about, especially toward evening. On favorable days the
number of specimens and species that can thus be found is astonishingly
great, and this is one of the few occasions when the Coleopterist can
advantageously use a light butterfly net. The flying beetles preferably
alight and rest on the top of wooden fences (especially newly made
ones), on the railings of bridges, etc., where they can be easily seen
and secured, or they are attracted in great numbers by the white-painted
surface of buildings. This flying season lasts in the latitude of
Washington from the end of April to the middle of June, but favorable
days are not of frequent occurrence, since a peculiar combination of
atmospheric conditions appears to be necessary to induce the Coleoptera
to fly about in great numbers.
_Beach collecting._--Along the shores of the ocean and the Great Lakes
untold numbers of Coleoptera and other insects fall at this season into
the water, and, if the tides, the currents, and the winds be favorable,
they are washed ashore by the waves on the sandy beaches, where they
often form windrows several inches in height and width. If the collector
is happy enough to be at the right place on the right day he has then
the opportunity to pick up hundreds of rare species within a very short
time and without any trouble. Many of the specimens thus washed ashore
are dead and decayed, but the majority are alive and in excellent
condition. This "beach collecting" affords also an excellent opportunity
for the Hymenopterist and Hemipterist to secure large numbers of rare
species, but favorable days are also here of rare occurrence.
_Attracting by Lights._--On the beaches, day and night flying insects
can thus be captured. Away from the beach night-flying Coleoptera can
best be collected at the electric lights of our cities; but, as in the
Lepidoptera, not all night-flying species are attracted by the light.
Gas and other lights also attract Coleoptera, and the various "light
traps" that have been devised and described can advantageously be used
for collecting these insects.
_Traps._--The method of "sugaring," so important to the Lepidopterist,
is by far less favorable for collecting Coleoptera. Still, certain rare
Carabidæ, Elateridæ, and Cerambycidæ are attracted by this bait, and the
Coleopterist should not entirely ignore this mode of collecting. There
are a few other methods of trapping certain Coleoptera. By laying out
dead mammals, birds, fishes, snakes, etc., on suitable places and so
that they are protected from dogs, rats, etc., the carrion-feeding
Coleoptera can be found in great abundance, but a cleaner and less
disagreeable method of obtaining them is to bury in the ground tin cans
or glass jars so that the top is even with the surrounding ground and to
bait them with pieces of meat, fried fish, boiled eggs, etc. Many
Curculionidæ, Scolytidæ, and numerous other wood-inhabiting species can
be successfully trapped in the following way: A number of branches,
preferably of only one kind of tree, are cut and tied up into bundles of
convenient size. The bundles are then laid on the ground in a shady
place or firmly fastened on trunks of trees. When the cut branches begin
to get dry they will attract many of these Coleoptera, which can then be
readily collected by shaking the bundles out over the collecting cloth.
[Illustration: FIG. 65.--An Elaterid (_Pyrophorus noctilucus_). (From
Packard.)]
_Freshets._--Freshets usually take place in springtime in most of our
rivers and creeks, and furnish the means of obtaining a multitude of
Coleoptera, among which there will be many species which can not, or
only accidentally, be found otherwise. These freshets, sweeping over the
low banks or inundating wide stretches of low land, carry with them all
insects that have been caught by the inundation. Intermingled with, and
usually clinging to, the various floating débris, these insects are
eventually washed ashore by the current at various points and the
Coleopterist should not miss this rare opportunity, but go out to the
river bank at a time when the water is still rising, or at least when it
has attained its highest point. Among, or on the washed up débris, a
multitude of Coleoptera of various families can be found, and the
specimens can either be gathered up on the spot or a quantity of the
débris be put in sacks and taken home, where it can be examined more
thoroughly and with greater leisure than out of doors. A day or so after
the floods have receded the washed up specimens will have dispersed and
only a few will remain in the débris for a longer period. Still more
profitable than the spring floods are the summer freshets, because a
larger and more diversified lot of Coleoptera is then brought down by
the water. A similar opportunity for collecting is offered near the
seashore if unusually high tides inundate the low marshes along the
bayous and inlets.
[Illustration: FIG. 66.--A Longicorn (_Prionus laticollis_).]
SUMMER COLLECTING.--During the latter part of spring and throughout the
whole summer, when the vegetation is fully developed, every possible
collecting method can be carried on with success, so that the beginner
hardly knows what particular method to use. There are stones to be
turned over; old logs, stumps, and hollow trees to be investigated;
newly felled or wounded trees to be carefully inspected; here a spot
favorable for sifting claims attention; promising meadows and low
herbage in the woods invite the use of the sweeping net; living or dead
branches of all sorts of trees and shrubs to be worked with the
umbrella; the mud or gravel banks of ponds, lakes, rivers, and creeks
afford excellent collecting places; the numerous aquatic beetles are to
be collected in the water itself; the dung beetles to be extracted from
their unsavory habitations; in the evening the electric and other lights
are to be visited, the lightning beetles chased on meadows and in the
woods, or the wingless but luminous females of some species of this
family to be looked for on the ground, and the trees and shrubs are to
be beaten after dark in search of May beetles and other nocturnal
leaf-feeding species which can not be obtained at daytime; and, finally,
some of the rarest Scarabæidæ and some other species fly only late at
night or again only before sunrise.
In view of this embarrassing multitude of collecting opportunities in a
good locality, the beginner is apt to be at a loss what course to
pursue. Experience alone can teach here, and only an expert collector is
able to decide, at a glance at the locality before him, what collecting
method is likely to produce the best results, and his judgment will
rarely be at fault.
It is impossible to go into details regarding the various collecting
methods, just mentioned, and only a few general directions can be given
regarding those methods which have not previously been alluded to.
_Collecting under Stones._--Turning over stones is a favorite method
among beginners and yields chiefly Carabidæ, the larger Staphylinidæ,
certain Curculionidæ, and a multitude of species of other families.
Stones on very dry ground are productive, only early in spring or in the
fall, while those on moist ground, in the shade of woods, are good at
all seasons. In the Alpine regions of our mountainous districts,
especially above the timber line, collecting under stones becomes the
most important method, and is especially favorable along the edges of
snow fields. In often frequented localities the collector should
carefully replace the stones, especially those under which he has found
rare specimens. The neglect of this rule is one of the principal causes
for certain rare species having become extinct in the vicinity of our
cities.
_Collecting in rotten Stumps and Logs._--Success in collecting in rotten
stumps depends much upon the more or less advanced stage of decay as
well as upon the situation of the log and upon the particular kind of
wood. If the decay is very much advanced neither the loose bark nor the
interior of the log will harbor many Coleoptera excepting a multitude of
_Passalus cornutus_ and its larvæ. If the decay is less advanced, but if
such log is exposed to the scorching rays of the sun, it will be far
less productive than a log in a shady situation. The investigation of
the bark of a favorably situated log in the right stage of decay does
not need any special instruction, but the decayed wood itself should be
pried off with a chisel or trowel, put in the sieve and sifted on the
collecting cloth. This is the best way of obtaining the numerous species
of rare Micro-coleoptera of various families that inhabit such places. A
"red rotten" oak or beech log is more favorable for this mode of
collecting than a "white rotten" of the same or other kinds of trees.
_Collecting in dying or dead Trees._--Dying or dead trees almost always
harbor a large number of Coleoptera and offer an excellent collecting
opportunity until the wood becomes thoroughly dry, which usually takes
place in large trees two or three years after the death of the tree, and
in less time with smaller ones. The bark of such trees is the best
collecting place for Cucujidæ, Colydiidæ, Scolytidæ, Histeridæ, etc.,
and it will be found that the shady side of the tree is more profitable
than the side exposed to the sun. The numerous Buprestidæ, Elateridæ,
Ptinidæ, Cerambycidæ, Melandryidæ, etc., which breed in the wood can be
obtained only with difficulty. Some specimens may be cut out from their
holes by a skillful use of the knife or hatchet; others (especially the
Buprestidæ) may be found resting on or crawling over the trunk in the
bright sunshine, while the more nocturnal species may be found on the
tree toward evening or after dark, when, of course, a lantern must be
used. A large proportion of the species living in the trunks of dead
trees also breed in the dead branches of otherwise healthy trees from
which they can be beaten into the umbrella, or where the use of the
knife is more practicable than in the large trunks. The trunks of
freshly felled trees attract numbers of Cerambycidæ and Buprestidæ and
have to be carefully looked over, while the drying foliage of such trees
affords an excellent opportunity for the use of the umbrella.
_Beating living Trees, Shrubs, and Vines._--The success of beating into
the umbrella branches of living trees and shrubs depends on the
particular kind of tree or shrub, on the condition and situation of
these, and largely also upon the season. Pine trees are very productive
from early in the spring to early in the summer, but much less so in
midsummer and later on. Young Oak trees or Oak shrubs are much more
preferred by the leaf-eating Coleoptera peculiar to this tree than the
older trees. The Beech, which, next to the Oak, is the best tree for
wood-boring species, harbors but few leaf-eating species. The leaves of
the Chestnut are also generally not attacked by Coleoptera; still a
surprising number of species can be beaten from this tree when it is in
blossom. There is not a single species of Coleoptera known to live in
the wood or to feed on the leaves of the Holly (_Ilex glabra_); still it
will pay the Coleopterist to beat this tree when it is in bloom. Trees,
shrubs, and vines in the interior of unbroken forest districts are, as a
rule, unproductive, while the edges of the woods, narrow strips of
hedges, and especially solitary trees are excellent collecting places.
In the Rocky Mountains, especially in the more southern sections, long
stretches of mountain slopes are occasionally perfectly bare of
vegetation with the exception of a few solitary, sickly-looking, and
dwarfed trees, but every one of these is a veritable gold mine to the
Coleopterist with his umbrella.
_Sweeping._--The use of the beating net continues profitable from spring
till fall, a different set of species appearing with each season. Low
and swampy meadows, meadows on the slopes of mountains or surrounded by
woods, low underbrush, and herbage in smaller patches of woods are very
good beating grounds. Dry and sandy meadows are less productive, but
harbor usually a different set of species on account of the difference
in the flora. Pastures and meadows much frequented by cattle and horses
are much less productive, and where a large number of sheep are kept
there is usually no chance for using the beating net, since neither
grass nor specimens are left. The lawns in our parks and gardens are
usually poor collecting ground on account of the limited variety of
plants in such places; but the few species found there occur in enormous
number of specimens. The endless stretches of our western prairies swarm
at the right season (in June) with numerous Coleoptera (mostly
Malachiidæ, Chrysomelidæ, Mordellidæ, Curculionidæ, etc.), provided
prairie fires have not swept too frequently over the place. Fires and
cattle produce a remarkable change in the flora and fauna of the
prairies; many indigenous species disappear or become scarce and are
replaced by a much smaller number of imported species.
[Illustration: FIG. 67.--A Dermestid (_Anthrenus scrophulariæ_). _a_,
larva, dorsal view; _b_, larva, ventral view; _c_, pupa; _d_, adult--all
enlarged.]
Sweeping may commence in the forenoon as soon as the dew has
disappeared; it is less profitable in the heat of the midday, but
produces the best results late in the afternoon and more especially in
the short interval from just before sunset until dark. At this time many
rare Pselaphidæ and Scydmænidæ, species of the genera _Colon_ and
_Anisotoma_, and other small Silphidæ can be beaten from the tips of
grasses, all being species which can not, or only accidentally, be found
during daytime, when they hide between the roots of plants.
_Collecting on mud and gravel Banks._--The mud or gravel banks of
rivers, creeks, and stagnant bodies of water are inhabited, especially
early in summer, with an astonishing multitude of Coleoptera. Countless
specimens of smaller Carabidæ (_Dyschirius_, _Clivina_, _Bembidium_,
_Tachys_, etc.) and Staphylinidæ (_Tachyusa_, _Philonthus_, _Actobius_,
_Stenus_, _Lathrobium_, _Trogophlæus_ and many other genera) will be
seen actively running over the mud or sand; many other specimens are
hiding under the pebbles in company with other species (_Cryptohypnus_,
_Georyssus_, etc.) or in little subterranean galleries (_Dyschirius_,
_Bledius_, _Heterocerus_). All these beetles must be collected by
picking them up with the fingers, an operation which, owing to the
activity of the specimens, requires some little practice. The beginner
will at first crush or otherwise injure many of the delicate specimens,
the capture of which is moreover by no means facilitated by the rapidity
with which most of them are able to take wing. The collector must
necessarily kneel down and he must not mind getting covered with mud. A
good device for driving these species out of their galleries or from
their hiding places under stones or in cracks of the ground is to pour
water over the banks, and this can in most cases be done with the hand.
Larger stones and pieces of wood or bark lying on the bank are favorite
hiding places of certain larger Carabidæ (_Nebria_, _Chlænius_,
_Platynus_, etc.), and should of course be turned over. Finally, the
moss growing on rocks and logs close to the water's edge, and in which,
besides other beetles, some rare Staphylinidæ and the Byrrhid genus
_Limnichus_ can be found, should be scraped off and investigated on the
collecting cloth or on the surface of a flat rock, if such be
conveniently at hand.
_Collecting aquatic Beetles._--The fishing for water beetles in deeper
water by means of the water net has already been alluded to (p. [32]),
but many species live in shallow brooks with stony or gravelly bottom,
where the water net can not be used. The Dytiscidæ and Hydrophilidæ
living in such places usually hide under stones, and can in most cases
be easily picked up with the hand, or a little tin dipper or a spoon
will be found convenient for catching them. The species of the family
Parnidæ are found on the underside of rough stones or logs which are
either partially or entirely submerged. They are more numerous, however,
in the moss or among the roots of other plants that grow in the water.
Such plants have to be pulled out and examined over the collecting
cloth.
[Illustration: FIG. 68.--A Tiger Beetle (_Cicindela limbata_), drawn by
Miss Sullivan--enlarged.]
_Collecting at the Seashore and on sandy Places._--A large number of
species belonging to various families live exclusively in the vicinity
of the ocean, some on the open beach, others along the inlets, bayous,
or salt marshes, and still others on the dry sand dunes. The Cicindelæ
are actively running or flying about close to the water's edge and have
to be captured with the butterfly net. The remaining maritime species
live hidden under the seaweed and other débris cast up by the waves, or
in the sand (sometimes quite deep below the surface) beneath the débris
or between the roots of the plants growing on the dunes. The majority of
the maritime species do not appear before June (in the Middle States),
but the collecting remains good until September.
[Illustration: FIG. 69.--The Beaver Parasite (_Platypsyllus castoris_),
adult--greatly enlarged.]
In dry sandy places away from the seashore, the collecting at the roots
of plants is especially to be recommended, and the plants, and more
especially the bunches of coarse grasses usually growing in such places,
should be pulled up and shaken out over the collecting cloth. This mode
of collecting acquires a great importance in the arid regions of the
West and Southwest, where, in the warm season, nearly all Coleoptera are
hiding during daytime in the ground at the roots of plants.
_Collecting Dung-beetles._--The collecting of the numerous species
(_Hydrophilidæ_, _Staphylinidæ_, _Histeridæ_, _Scarabæidæ_, etc.) which
live in the droppings of various animals is by no means an agreeable
task. The collector should provide himself with a pointed stick and
collecting tweezers, and must manage to pick up the specimens as best he
can. The larger specimens are best collected in alcohol, while the more
delicate species can be collected in a cleaner condition by removing the
droppings and sifting the ground beneath the same. Some species hide
deep in the ground beneath the droppings and have to be dug out. Summer
freshets, when pasture lands are inundated, offer an excellent
opportunity for collecting the dung-inhabiting species in a clean
condition.
_Night Collecting._--The beating of trees and shrubs after dark is a
good method of obtaining Lachnosternas and other species, and here the
collector will do well to secure the assistance of a companion, who
takes charge of the lantern and the collecting bottles, while the
collector himself works the umbrella.
FALL COLLECTING.--From the first of August the number of species
gradually diminishes, but late in the summer or early in fall quite a
number of other species make their appearance, _e. g._, some
Chrysomelidæ, Cerambycidæ, and many Meloidæ. Many of these frequent the
blossoms of Golden-rods, umbelliferous and other late-flowering plants.
The fall is also the best season for collecting Coleoptera living in
fungi. Although puff-balls, toadstools, and the numerous fungi and
moulds growing on old trees, etc., furnish many species of Coleoptera
also earlier in the season, yet most fungi, and more especially the
toadstools, flourish best in the fall, and consequently there is then
the greatest abundance of certain species of Coleoptera. Decaying
toadstools are especially rich, and should be sifted, and the collector
should also not omit to examine the soil beneath them.
During the "Indian summer" there is usually a repetition of the "spring
flight" of Coleoptera, though on a smaller scale, and collecting on the
tops of fence posts and on whitewashed walls again becomes good. The
first really sharp frost causes these late species to disappear, and
winter collecting commences again.
COLLECTING LEPIDOPTERA.
In this order the importance of collecting the early states and of
rearing the adult insects rather than of catching the latter should, if
the collector has the advancement of knowledge and the greatest pleasure
in mind, be insisted upon. Collected specimens, in the majority of
cases, will be more or less rubbed or damaged and unfit for permanent
keeping, and will always be far inferior to freshly reared specimens.
All Lepidopterists, therefore, rely to a great extent upon breeding
rather than upon field collecting. There are, however, many species of
which the early states are still unknown, and these can only be taken by
field collecting, and by attracting to various lights or traps. This
subject, therefore, naturally falls into two categories--(1) the general
collecting of the adult, and (2) collecting the early stages and rearing
the perfect insects.
[Illustration: FIG. 70.--The Eight-spotted Forester (_Alypia
octomaculata_). _a_, larva; _b_, enlarged segment of same; _c_, moth.]
_Collecting the Adult._--The implements for the general collecting of
butterflies comprise the collecting net, and in some cases the beating
net, although the use of the latter will not often be called for. The
Rhopalocera or Diurnals may be taken about flowers, and the best season
is in the early spring. Most of them are double-brooded, and the second
brood will be in the greatest abundance during July and August. They
are, however, to be found throughout the summer. They are also to be
looked for in the neighborhood of the food-plants of their larvæ, and in
the case of many species, examination of such plants affords the most
satisfactory means of collecting. The food of butterflies is almost
exclusively the nectar of flowers, but strangely enough they are also
attracted to decaying animal matter, and many species, including rare
forms, may be taken about decaying animal matter or resting on spots
where dead animals have lain, or beneath which they have been buried.
Moist spots of earth are also frequented by them, especially in dry
seasons. Many of the larger butterflies, whose larvæ feed on the taller
shrubs and the foliage of trees, will be found fluttering about the open
spaces in forests, but by far the larger number, as the Browns, the
Blues, the Yellows, and the Whites, which develop on the lower
herbaceous and succulent plants, will be found flying over fields,
prairies, and gardens. Crepuscular and nocturnal Lepidoptera, comprising
most of the Heterocera, the Sphingidæ, Bombycids, Noctuids, etc., have
different habits. The Sphingidæ or Hawk Moths fly in early evening, and
may be collected in quantity about such plants as the Honeysuckle,
Thistle, Verbena, Petunia, etc. The Bombycids and many Noctuids also fly
in the early evening, but mostly at night. The former, however, do not
frequent flowers, except such as are the food-plants of their larvæ, as
their mouth-parts are rudimentary, and they take no nourishment.
[Illustration: FIG. 71.--Collecting Pill-box. _a_, glass bottom
(original).]
Collecting by the aid of strong light is a favorite means for moths as
well as other insects, and nowadays the electric lights in all large
cities furnish the best collecting places, and hundreds of species may
be taken in almost any desired quantity. In woods or in other situations
they may be attracted to a lantern or to a light placed in an open
window. Various traps have been devised, which comprise a lamp with
apparatus for retaining and stupefying the insects attracted to the
light. The common form is made by providing a lantern with a strong
reflector. Under the light a funnel several inches larger than the
lantern reaches down into a box or bottle containing the fumes of
chloroform, ether, or benzine.
[Illustration: FIG. 72.--Method of holding and manipulating collecting
pill-box in capturing (original).]
Mr. Jerome McNeill describes at length and figures in the _American
Naturalist_, Vol. XXIII, p. 268-270, an insect trap to be used in
connection with electric lights. It consists of a tin pail or can
charged with cyanide after the manner of a collecting bottle, which is
attached beneath the globe of the electric light.
The insects attracted by the light strike against a vertical tin screen
fixed above the can and fall into a tin funnel the small end of which
enters and closes the mouth of the can, and they are thus conducted into
the last. A support or post in the center of the can bears a hollow tin
cone, the apex of which is pierced with a number of small holes to admit
light, and enters and partly closes the lower end of the funnel. The
entire interior of the can is painted black and the chief light comes
through the holes in the apex of the interior cone. The entrapped
insects endeavor to escape by crawling up the central post towards the
light coming through the small holes in the end of the cone rather than
by the entrance slit about the latter and fall back repeatedly until
overcome by the cyanide.
Many of the Lepidoptera will be ruined by the beetles and other insects
or by their own ineffectual attempts to escape, but Coleoptera,
Hymenoptera, Neuroptera, and Hemiptera are secured in satisfactory
condition.
Many of the devices are very complicated and can not be described in
this connection. The nocturnal species, also, fly into our houses, and
this is especially the case in the country, and an open window, with a
strong light reflected onto a table covered with either a white paper or
a white cloth will keep one busy, on favorable nights, in properly
taking care of the specimens thus attracted.
Another favorite method of collecting moths early in the evening, or as
late as or later than midnight, is by sugaring. This consists in
smearing a mixture of sugar and vinegar, or some similar compound, on
the bark of trees or on the boards of fences, and visiting the spot from
time to time to collect the moths attracted to the bait. It has been
found that the use of beer or some other alcoholic liquor, as rum or
brandy, with the sugar or molasses water, greatly adds to its efficiency
in attracting the moths. This method of collecting moths will be found
especially efficient on warm, moist, cloudy nights. The collector should
be provided with a dark lantern and a good net, and a number of
wide-mouthed cyanide collecting bottles. The smearing should be done
just before dark, and I have always found that better success attends
this method of collecting when two are engaged in it--one to hold a
bull's eye lantern while the other bottles the specimens. Experience
will soon teach the surest way of approaching and capturing the
specimens.
For collecting Microlepidoptera, in addition to the ordinary net, some
special apparatus will be found very essential. Lord Walsingham makes
use of a special glass-bottomed pill-box, with which to capture
specimens, and the satisfactory nature of the work done with this box,
and the dexterity acquired by practice with it, I can vouch for by
personal experience. These glass pill-boxes are useful, also, in
admitting of the examination of specimens, so that worthless or common
species can be discarded and only desired forms kept. The method of
holding these boxes is illustrated in the accompanying illustrations.
(Figs. 72, 73.) A drop of chloroform on the bottom of the box at once
stupefies the capture so that it can be taken out and otherwise disposed
of.
[Illustration: FIG. 73.--Same, showing method of closing pill-box after
the specimen is secured (original).]
The necessity of rearing to obtain perfect specimens is even more
important in the case of the Microlepidoptera than with the larger
forms, and many species are very easily reared and can thus be obtained
in quantity. The Micros are abundant from early spring to late fall
about shrubbery, in open fields, and along the edges of woods. They are,
for the most part, day fliers, being on the wing chiefly in the latter
part of the day and early evening. As soon as collected they should be
transferred to pill-boxes and the greatest care should be exercised to
avoid mutilating them, as the slightest touch will denude them of a
portion of their scales or break their limbs or antennæ. Lord Walsingham
thus gives his experience in collecting Micros:
I go out with a coat provided with large pockets inside and out,
containing an assortment of pill-boxes, generally of three sizes,
glass-bottomed pill-boxes preferred, a bag slung over my shoulder, and a
net. Unless searching for particular day-flying species, I prefer the
last three hours before dark. As the sun goes down many species move
which do not stir at other times. I watch the tops of the grass, the
stems of the flowers, the twigs of the trees; I disturb leaves and
low-growing plants with a short switch and secure each little moth that
moves, taking each out of the net in a separate pill-box, selected
according to the size of the insect, as he runs up the net to escape.
Transferring the full boxes to the bag I continue the process until
moths cease flying or night sets in. Many species can be taken with a
lamp after dark.
_Collecting the early States._--The careful entomologist who prides
himself on the appearance of his specimens, will, as stated above, rely
largely on collecting the early states and on rearing the insects, for
his material. The Macrolepidoptera have either a single or two broods,
or more, in a season, and the collection of the early states will be
greatly facilitated if a knowledge of the insect's life-habits is first
obtained. The eggs are often found on the food plants of the species,
and where they are deposited in masses they afford a very easy method of
getting the larvæ in numbers. In many cases, however, the eggs are
deposited singly and their discovery then becomes a difficult matter.
More satisfactory in some respects is the method of obtaining the eggs
from captured gravid females, and the general collector should always be
on the lookout for females of rare species from which he may be able to
obtain eggs. A single battered female may, in this way, be the source of
large numbers of excellent reared specimens. Many rare Lepidopterous
larvæ may be obtained by the use of the beating net and by beating
foliage over an umbrella. A very satisfactory method consists in
collecting pupæ, which may frequently be found in numbers about the
bases of the trees on which the larvæ feed. Many larvæ of the large
family of Owlet Moths (_Noctuidæ_) are found either on the surface of
the ground or under various substances, while others burrow into the
stems of the different herbaceous plants, some being subaquatic and
feeding on the underside of leaves or in the stems of aquatic plants. In
the case of Microlepidoptera, their habit as larvæ, of mining leaves or
tying or webbing them together, affords an easy means of detecting their
presence in most cases. The miners are easily noticed by the discolored
spots on the leaves or the wavy, pale, or brown lines marking their
burrows. The presence of others is indicated by the leaves being drawn
together and united with webs, or withered and brown from being
skeletonized by the larvæ. Many species are case-bearers, and live upon
the leaves and branches of trees and plants, dragging their cases along
with them. Others burrow in grasses or in the stems of plants or the
trunks of trees, or in fungi. In the case of the leaf-miners and
leaf-tiers, little difficulty is experienced in rearing the imagoes.
The care of the larvæ, the outfit required, and the methods of breeding
will be described in later sections.
COLLECTING HEMIPTERA.
[Illustration: FIG. 74.--A Pentatomid (_Stiretrus anchoraga_).]
[Illustration: FIG. 75.--The Blood-sucking Cone-nose (_Conorhinus
sanguisuga_). _a_, mature bug; _b_, pupa.]
For the most part the directions for collecting Coleoptera will apply to
this order of insects equally well, especially so far as concerns the
first section of the order (Heteroptera), and the higher families of the
second section (Homoptera). A few directions may be given for the lower
forms, including the Aphididæ, Coccidæ, Aleurodidæ, and Psyllidæ, and
the suborder Parasita, including the degraded forms which infest man and
the lower animals. The Plant-lice or Aphides should always be collected
in connection with their food-plants, and it is very essential also to
collect the same species at different seasons of the year to obtain the
different forms or generations, which frequently present very marked
differences. It is also very necessary to secure the winged forms, which
are usually produced toward autumn, and without which the species are
not easily identified. The Bark lice or Scale-insects should also be
collected in connection with the leaves or twigs which they infest. The
males of these insects are minute and, as a rule, two-winged, resembling
small gnats, and may be bred from the male scales. The females are for
the most part stationary, being fixed to the plant by the protecting,
waxy, excretion or scale. The Flea-lice (_Psyllidæ_) frequently produce
galls, and these should always be collected with the insect architects.
Some species do not produce galls, and may be collected by sweeping. The
Hackberry is infested by large numbers of species of Psyllids, and these
produce a great variety of interesting galls. The Aleurodidæ
(Fringe-scales) are delicate insects, and easily injured in the
taking; they are therefore best reared from their stationary and
fringed larvæ and pupæ, which occur on the leaves of many plants. Leaves
bearing the latter should also be collected and pinned or preserved in
alcohol. The Parasita, the lowest representatives of the order, may be
obtained from the domestic and wild animals which they infest.
[Illustration: FIG. 76.--The Bed-bug (_Acanthia lectularia_). _a_,
young; _b_, adult--enlarged.]
[Illustration: FIG. 77.--The Short-nosed Ox-louse (_Hæmatopinus
eurysternus_). _a_, female; _b_, rostrum; _c_, ventral surface, last
segments of male; _d_, female; _e_, egg; _f_, surface of egg greatly
enlarged.]
COLLECTING DIPTERA.
[Illustration: FIG. 78.--Ox Bot-fly (_Hypoderma bovis_) enlarged. (After
Brauer.)]
[Illustration: FIG. 79.--The Collecting Shears. (After Kiesenwetter.)]
[Illustration: FIG. 80.--A Bee-fly (_Anthrax hypomelas_). _a_, larva
from side; _b_, pupal skin protruding from cutworm chrysalis; _c_, pupa;
_d_, imago--all enlarged.]
Most Diptera frequent flowers and may be collected with a sweeping net
without much difficulty. The best season is from April to June, and the
bloom of the Willow, Alder, Plum, Cherry, Dogwood, Blackberry, etc.,
will ordinarily yield a bountiful supply of specimens and species.
Parasitic and saprophytic forms may also readily be obtained by
breeding, the former as in the case of the parasitic Hymenoptera, and
the latter from decaying vegetable matter and fungi. The Diptera
require the most delicate treatment, and the greatest care must be
exercised both in collecting and handling. A light sweep net is the best
implement for collecting and the contents of the net should frequently
be emptied into bottles provided with blotting paper to absorb the
excess of moisture. Very small Diptera should not be killed when they
can not be immediately pinned, and hairy flies should never be taken
from the net with the hand, but should be handled with fine forceps. A
pair of special collecting shears has been used by Lord Walsingham very
successfully. It is represented in the accompanying figure, and consists
of a pair of screen-covered disks, between which the fly is caught. The
insect is at once pinned through the screen and may be removed and
transferred to a box containing a sponge soaked in chloroform. The use
of this implement is especially advisable in the case of the Bee-flies
(_Bombiliidæ_) and other hairy forms which are liable to be rubbed when
collected in the ordinary net. The Gall-making Diptera (_Cecidomyidæ_)
are of little value unless accompanied with their galls, and the aim
should always be to collect the galls and rear the insects rather than
the keeping of specimens taken in the course of general collecting with
a sweep net. The rearing of Cecidomyidæ is, however, a delicate task,
and requires considerable experience. Some knowledge of the habits of
the species is very essential to success. From immature galls no
rearings need be expected. A good plan is to examine the galls from time
to time and collect them when it is found that the larvæ are beginning
to abandon them. In the case of species like the common Cone Gall-gnat
of the Willow, the larvæ of which do not leave the gall to undergo
transformation in the earth, it is advisable not to gather the galls
until the transformation to the pupa state takes place, which, in this
species, occurs in early spring. The various leaf-mining and seed
inhabiting species can be treated as in the case of the
Microlepidoptera.
[Illustration: FIG. 81.--A Syrphus-fly.]
COLLECTING ORTHOPTERA.
[Illustration: FIG. 82.--A blind Cricket (_Hadenalcus_) from Mammoth
Cave. (From Packard.)]
The insects of this order may all be collected by the use of the
sweeping net. Some of the families are attracted to light, as certain of
the roaches and green locusts, or Katydids (_Locustidæ_). Our common
roaches (_Blattidæ_) are cosmopolitan insects, and infest dwellings.
Certain species are also found about ponds, under rotten logs, the bark
of trees, and particularly in decaying vegetable matter. In the tropics
the species are very abundant, but aside from the domestic forms, they
occur rarely in northern latitudes. The collection of the egg-cases
(oötheca) is important as they furnish many interesting characters. The
Mantidæ, of which the Preying Mantis (_Phasmomantis carolina_) is a
type, are sluggish, carnivorous insects frequently found about houses
and may best be collected by general sweeping of vegetation. The
Phasmidæ or Walking-sticks are herbivorous and may be collected in the
midst of vegetation by sweeping or by the hand. The crickets
(_Gryllidæ_) frequent, for the most part, moist situations. Certain
forms, like the Mole-cricket and the Jumping Water-crickets
(_Trydactylus_ spp.), burrow in moist soil and occur in numbers near the
edges of ponds and water courses. The katydids and locusts are abundant
on low shrubs or trees and in pasture and meadow land, but are most
numerous in the somewhat dry, arid regions of the West. Most of these
insects mature in late summer and fall and should be collected at this
season. The Forficulidæ or Earwigs are very odd-looking insects,
resembling somewhat the Rove-beetles (_Staphylinidæ_), and are provided
with a prominent anal forceps. They are very rare in the United States,
are nocturnal in habit; and, flying about at dusk, may be attracted to
light or may be secured by sweeping after nightfall. They feed on
flowers and fruit.
COLLECTING NEUROPTERA.
As indicated in the preliminary outline of classification, this large
order has been divided into many orders by later entomologists. It has
also been divided, as indicated, into two grand divisions, the
Pseudoneuroptera, comprising those insects with incomplete
transformations, and the Neuroptera proper, comprising those insects
whose metamorphoses are complete. It will be convenient to discuss these
insects under these two heads.
_Pseudoneuroptera._--Spring-tails, Bird-lice, Stone-flies, White-ants,
Dragon-flies, May-flies.
[Illustration: FIG. 83.--A Spring-tail (_Degeeria lanuginosa_).]
The Spring-tails, Fish-moths, etc., representing the primitive stock
from which the higher forms have developed, have a varied habit and
hence are to be found in divers situations. The Spring-tails
(_Collembola_, etc.), occur in damp and moist places, usually in immense
numbers. The Fish-moths and Book-mites are common household pests, but
also occur outdoors under logs, boards, bricks, and rubbish of all
sorts. In houses they feed on the starch paste beneath wall-paper and
also on the starch in bookbindings and other domestic articles. They may
be collected at all seasons and a sieve is the only implement necessary.
[Illustration: FIG. 84.--A Mallophagan (_Trichodectes latus_). (After
Denny.)]
The Bird-lice or Mallophaga may be collected at all seasons on birds and
mammals. A number of species infest domestic animals, horses, cattle,
etc., but the majority of them can be found only by the examination of
domestic fowls and wild birds. The Stone-flies (_Perlidæ_) are found in
the neighborhood of water courses and ponds, are very sluggish in
flight, and easily captured with the sweep-net. They are also attracted
to light. The Psocidæ are a small family of certain degraded wingless
forms, comprising the Book-lice, which, as the name implies, infest
books, feeding on the starch of the binding. Others have ample wings and
closely resemble large Aphides. They occur on the trunks of trees and on
foliage, and feed on lichens and other dried vegetable matter. They are
gregarious in habit and frequently occur in immense numbers together. In
the case of the Termitidæ or White-ants, their abundance renders their
collection an easy matter. Effort, however, should be made to discover
the different forms, the females and soldiers as well as the workers.
The former may be found in rotten tree trunks, but are very rarely met
with. In the tropics many species occur and construct curious nests,
either attaching them to the boughs of trees or building them in the
form of pyramids on the ground. The Dragon-flies (_Libellulidæ_,) are
collected in the same way as the Diurnal Lepidoptera. They are very
swift flyers, and are practically always on the wing. Their collection
requires some degree of skill in the use of the net. A good method
consists in visiting, in the early morning, water courses in which the
larval and pupal states are passed, and capturing the adults just as
they issue from their pupal skins at the edges of the pond or stream. In
cold weather they are less active and may frequently be found clinging
to trees and plants, particularly in the vicinity of their breeding
places. May-flies (_Ephemeridæ_) occur in immense numbers near their
breeding places in ponds and streams and are also attracted in large
quantities to electric lights. Their collection is therefore an easy
matter, but on account of the very fragile nature of these insects the
utmost care must be employed in handling them. The early states of all
the aquatic forms mentioned above may be obtained for breeding by the
use of the dip net by dragging it forcibly against water plants.
[Illustration: FIG. 85.--_b_, a May-fly (_Palingenia bilineata_); _c_,
its larva; _a_, a Caddis-fly (_Macronema zebratum_).]
[Illustration: FIG. 86.--A Dragon-fly (_Libellula_). (From Packard.)]
[Illustration: FIG. 87.--A Dragon-fly (_Agrion_). (From Packard.)]
_Neuroptera proper_ (Hellgrammites, Lace-wings, Ant-lions, Caddis-flies,
etc.)--Among the largest insects of this order are the Sialidæ, which
includes the enormous Hellgrammite Fly, _Corydalus cornutus_. The larvæ
of this insect are carnivorous and occur in streams, under stones, etc.
The adults may be collected in neighboring situations and are also
attracted to light. The Lace-wing flies (_Chrysopa_), Ant-lions, etc.,
are carnivorous as larvæ, and occur, the former among the Aphides which
infest various plants and the latter at the bottom of pits in loose,
sandy soil. The adults may be obtained by general sweeping and are also
attracted to light. The most interesting insects of this order are the
Caddis-flies, on account of the peculiar and frequently very beautiful
cases constructed by their larvæ, which it is important to collect. The
Caddis-flies breed in ponds and lakes and the adults may be collected in
such situations or at light. The larvæ may easily be reared, and should
be collected for this purpose. Most of the insects named in this order
are extremely delicate and require great care in handling.
[Illustration: FIG. 88.--An Ant-lion, adult (_Myrmeleon_). (From
Packard.)]
KILLING AND PRESERVING INSECTS.
Between the collecting of the specimens and their final disposition in a
well-arranged cabinet, a good deal of mechanical work is necessary,
involving a skill and dexterity which can be thoroughly acquired only by
practice.
FIRST PRESERVATION OF LIVING SPECIMENS.--Larvæ, pupæ, or imagoes,
intended for rearing purposes, must be kept alive, and are best placed,
after capture, in tin boxes of various sizes, according to the number of
specimens to be put in each and according to the size or nature of the
food plant, etc., on or in which the specimens are found, and of which a
quantity must always be taken home. For larger tin boxes those known as
"Seidlitz powder boxes," described and figured below, which can be made
to order at any tinner's shop, are well adapted, and smaller tin boxes
of a convenient round form can be obtained of the watchmaker. The
collector will find it advisable to take with him on his longer jaunts a
larger tin collecting box as well as the smaller boxes, and for this
purpose nothing is better than a good botanist's collecting can or
vasculum. All tin boxes used for entomological purposes should be tight,
and the cover should so fit that it neither drops off too readily nor
closes too tightly. Larvæ of Lepidoptera and Tenthredinidæ should be
placed in a box with a quantity of the leaves of the plant on which they
were found. Larvæ, especially of Coleoptera, found in the earth or in
decayed wood, should be placed in a box filled with such earth or wood,
so as to prevent shaking or rattling about. Larvæ found in roots or
stems of living plants can generally be reared to maturity only if the
whole plant with a quantity of the surrounding soil is taken home, and
for this purpose the large collecting box, just mentioned, is very
useful. Most Coleopterous or other larvæ found under bark or in solid
wood can be reared only if large sections of the wood are obtained and
the larvæ are full grown or nearly so. This holds true, also, of species
breeding in seeds and with most leaf-mining species. The greatest
difficulty is experienced with carnivorous Coleopterous larvæ, and care
should be taken with such not to inclose two or more specimens in one
box. Most larvæ die quickly if placed in an empty box, and this is
especially true of predaceous species; so that it is always advisable to
pack the box with moist soil, decaying wood, leaves or other similar
substance. Aquatic larvæ should be carried in tin boxes filled with wet
moss or some water plant, for, if placed in corked vials with water,
they die quickly.
KILLING SPECIMENS.--Specimens not intended for rearing should be killed
immediately after capture unless for each specimen a separate vial or
box can be provided. If a number of miscellaneous insects are put in the
same vial the stronger specimens will, in a short time, crush or
otherwise injure the more delicate ones or the predaceous species will
devour any others they can master. But even where the specimens are
killed immediately the following rule should be observed: Do not put
large and small specimens in the same vial, but provide a larger bottle
for the larger specimens, and one, or still better, several, smaller
vials for the medium-sized and very small specimens. The importance of
this rule is recognized by all experienced collectors.
There are several methods of killing insects, each having its own
peculiar advantages and drawbacks.
_Alcohol._--The use of alcohol will, on the whole, prove the most
satisfactory method of killing Coleoptera, many Hemiptera, some
Neuroptera, and larvæ of all sorts. Only the best quality of alcohol
should be used, but it should be diluted with from 30 to 40 per cent of
pure water, the greatest care being taken to keep the alcohol as clean
as possible. During the collecting a mass of débris and dirt is apt to
be thrown into the bottle, and when this is the case the alcohol should
be changed even during short excursions. At any rate, upon the return
from the excursion, the specimens should be at once taken from the
bottle and washed in pure alcohol in a shallow vessel. The larvæ and
other material intended for permanent preservation in alcohol should be
transferred to suitable vials and the material to be mounted cleansed
with chloroform or acetic ether and then prepared for the cabinet. If it
is inconvenient or impossible to mount the Coleoptera, etc., soon after
the return from the excursion they should be washed, dried, and placed
in pill boxes between layers of soft paper, or they may be replaced in a
vial with pure alcohol. On longer collecting trips, lasting several days
or weeks, specimens will keep thus very well, provided they are not
shaken up, and this can be prevented by filling the empty space in the
vial with cotton or soft paper. If the bottle is a large one and
contains many large specimens the alcohol should be renewed three or
four times at intervals of eight or ten days; otherwise the specimens
are liable to decompose. Small and delicate specimens, if they are to
be kept in alcohol, should be treated with still greater care. Upon the
return from the excursion they should also be cleaned in pure alcohol
and placed in small vials into which a very few drops of alcohol, just
sufficient to keep the contents moist, are poured. The vial should be
corked as tightly as possible and the specimens will keep pretty well
for an indefinite time.
The drawbacks to the use of alcohol are: 1st, that all hairy specimens
are liable to spoil; 2ndly, that all Coleoptera with soft integuments
spread the wing-cases apart if kept too long in it. The advantage of the
alcohol is that it is the simplest and least troublesome fluid for
naturalists traveling in distant countries who are not specialists in
entomology. Specimens killed in alcohol are also less liable to be
attacked by verdigris when pinned than those killed by some other
method. Rum, whisky, or similar strong alcoholic liquors may be used as
substitutes where no pure alcohol can be obtained, but are not
especially to be recommended.
_Chloroform and Ether._--Killing with the fumes of _chloroform_ or
_ether_ (sulphuric or acetic) or _benzine_, or some other etheric oil,
is often practiced and advocated by those who, for any reason, dislike
the use of alcohol or object, on account of its poisonous nature, to the
use of cyanide of potassium, and they are of especial value in the case
of butterflies and moths, Hymenoptera and Diptera. "A small and stout
bottle of chloroform or ether, with a brush securely inserted into the
cork (Fig. 89), will be found very serviceable. A slight moistening
through the air net will stupefy most insects caught in it, and
facilitate their removal to the cyanide bottle; while a touch or two
with the wet brush under the head and thorax, will kill the more
delicate specimens outright, without in the least injuring them. Another
way of using chloroform is by means of a small, hollow tube passed
through the cork, what is called jeweler's hollow wire answering the
purpose. The liquid evaporates more readily in such a bottle, and I
altogether prefer the first mentioned. Some large insects, and
especially female moths, whose size prevents the use of the ordinary
cyanide bottles, are difficult to kill. With these, fluttering may be
prevented by the use of chloroform, or they may be killed by puncturing
the thorax or piercing the body longitudinally, with a needle dipped in
liquid cyanide, or oxalic acid. A long bottle with a needle thrust into
the cork may be kept for this purpose; but the needle must be of ivory
or bone, as those of metal are corroded and eaten by the liquids. * * *
[Illustration: FIG. 89.--Chloroform bottle with brush.]
"For killing small and delicate moths which have been bred, I find
nothing more handy than chloroform. They may be caught in turned wooden
boxes which are kept by every druggist; and a touch of the chloroform on
the outside of the box immediately stupefies them. It has a tendency to
stiffen them, however, and they are best set immediately after death."
[Illustration: FIG. 90.--Bottle with liquid cyanide.]
[Illustration: FIG. 91.--The Cyanide bottle with paper strips to give
support to the insects.]
A piece of heavy blotting paper or heavy cloth soaked with chloroform or
ether or benzine and placed at the bottom of a jar or bottle makes an
excellent killing bottle for large-sized insects. For smaller specimens
the collecting vial should be half filled loosely with narrow strips of
soft paper, upon which a few drops of the liquid are poured, not so
much, however, as to wet the paper. While collecting, the vial must be
kept closed as much as possible. Some collectors prefer chloroform,
others ether. If this method of killing is practiced with the necessary
care, there is no objection whatever to it; the specimens are not wetted
as they are in alcohol, and remain cleaner than those killed by any
other method. The drawback is that the substances mentioned evaporate
very rapidly and have to be renewed even on short excursions. On account
of this great volatility, one can never be certain that all the
specimens in the collecting bottle are dead after a given time and there
is always some danger that one or the other of the hardier insects may
regain activity. What mischief such revived specimens are capable of
doing, many collectors have experienced to their sorrow. Another
disadvantage of these volatile substances is that if used in too large
quantities they will, in delicate specimens, especially beetles, cause
an extension of the soft ligaments between the head and prothorax or
between the latter and the mesothorax, and thus bring the specimen into
an unnatural position, or cause the head, or head and thorax to drop
off.
_Cyanide of Potassium._--The method of killing which, of late years, has
found most favor with collectors, is the use of cyanide of potassium.
For killing large sized specimens they are simply put in what is now
universally known as the "cyanide bottle." This may be constructed as
follows:
Take a 2-ounce quinine bottle, or still better a shorter bottle with a
wide mouth; break up a quantity of cyanide of potassium into pieces of
convenient size (about a cubic centimeter); put these pieces in the
bottle so that they form an even layer at the bottom; mix in a
convenient vessel a quantity of plaster of Paris with water just
sufficient to make the mixture semifluid and then pour it over the
cyanide so as to cover this last to a depth of about 5 millimeters. The
bottle is then left open for an hour or two until the plaster is
thoroughly dry. The walls of the bottle are then cleansed from particles
of the plaster which may have splashed on them, and the bottle is ready
for use. If not used too frequently, especially in warm weather, it will
last for an entire year or longer. Bottles or vials of different sizes
can be prepared in the same way, and a very small cyanide vial which can
be carried in the vest pocket will be found most convenient for use on
all occasions. Fig. 92 represents a medium-sized chemist's test tube,
converted into a very convenient cyanide bottle, in which, however, a
cotton wad has been used to keep the poison in place. When the collected
specimens have been removed from the bottle the latter should be
carefully wiped clean with a piece of cloth or paper. The surface of the
plaster soon becomes dirty and, on account of the hygroscopic property
of the cyanide, more or less moist, especially during warm weather. The
cyanide bottle is, therefore, not well adapted for the killing and
temporary preservation of small and delicate specimens. This difficulty
can be altogether obviated by placing a circular piece of blotting
paper, cut to neatly fit the interior of the bottle, on the surface of
the plaster. This can be renewed once a week or so, or oftener if it
becomes necessary. It will frequently be advisable, also, especially in
the collection of Diptera, Hymenoptera, and other delicate insects, to
put a strip of blotting paper partially round the inner side of the
bottle. This will absorb any moisture which may gather on the inside of
the bottle and which would otherwise wet and injure the specimens. The
accompanying figure (Fig. 93) illustrates a bottle arranged as described
above. A similar result is attained by some collectors by partially
filling the bottle with narrow strips of bibulous paper to support and
separate the insects as shown at Fig. 91.
[Illustration: FIG. 92.--Pocket cyanide bottle.]
For delicate specimens, also, the collecting bottle may consist of a
test-tube of about the size of Fig. 92. This is half filled with loose,
thin strips of soft white paper. A piece of cyanide about the size of a
pea is then wrapped carefully in paper and so placed in the middle of
the strips that it can not come in contact with the sides of the
glass. Some prefer to pin the paper containing the cyanide to the
lower surface of the cork. The latter should be rather short and
tapering toward its lower end. It is longitudinally perforated through
its center by a round hole just large enough to insert a goose-quill,
which is cut straight at the lower end and obliquely at its upper end.
By means of this goose-quill the specimens may be introduced into the
bottle without taking off the cork. This form of cyanide bottle lasts
for only one day's collecting, except in cold weather, and in very warm
weather it is advisable to take two prepared bottles along, so that the
first used can be stowed away as soon as the cyanide begins to moisten
the paper strips. Most insects are quickly killed in such a bottle, but
some Coleoptera must be left in for five or six hours, while others
resist death for a still longer time. This is especially true of the
Coleopterous families Curculionidæ, Trogositidæ, and Tenebrionidæ.
Submersion in alcohol will prove a satisfactory method of killing these
or other beetles with similar vitality.
[Illustration: FIG. 93.--The cyanide bottle with blotting-paper lining
(original).]
_Other Agents._--Prof. E. W. Claypole has found the use of benzine or
gasoline very cheap and satisfactory for killing Lepidoptera, as the
largest are at once killed thereby without injury to their scales.
(_Can. Ent._, XIX, p. 136.) He squirts it onto the specimen within the
net or in the open air by means of a druggist's dropping tube. Hot water
kills rapidly and leaves the specimens in good flexible condition for
mounting. The heads of large insects may be held for a few moments in
the water, while smaller specimens should first be thrown into a corked
bottle and the bottle submitted to heat. Where the laurel grows its
bruised leaves may be used in place of cyanide; they kill less quickly.
The leaves of the Laurel-cherry (_Prunus laurocerasus_), a plant
commonly grown in England for screens and hedges, are also used for this
purpose.
Some collectors, with indifferent olfactory sense, moisten the cork of
their boxes with creosote. Its killing power lasts for several days. A
few whiffs from a cigar, when nothing else is at hand, will also kill
many of the more tender insects.
SPECIAL DIRECTIONS FOR DIFFERENT ORDERS.--A few brief directions for the
special treatment of different orders may be given. Certain Coleoptera,
notably those of the Curculionid genus Lixus, are covered with a
yellowish pruinosity resembling pollen, which is of an evanescent
nature, so that if the specimens are collected and killed by the
ordinary methods, the pruinosity is completely lost. To preserve the
natural beauty of such species it is necessary to put each specimen
alive in a small vial and to kill it at once by means of a lighted match
held under the vial for a few seconds. In pinning or otherwise mounting
the specimen it should not be handled between the fingers.
Many Hymenoptera and Lepidoptera, especially species with yellow
markings, if kept for any length of time in a cyanide bottle, will
become discolored, the yellow changing to reddish, and hence such
insects should not be left longer than necessary in the bottle. If care
is exercised in this respect, no danger of discoloration need ordinarily
be feared. The chloroform collecting bottle may be used with these
insects if discoloration is anticipated. All the more delicate insects,
including Hymenoptera, Diptera, the smaller Lepidoptera, and the
Neuroptera, require special care in killing. Large numbers should not be
thrown into a killing bottle together, and plenty of bibulous paper
should be kept in the bottle to prevent moisture from accumulating and
wetting and ruining the specimens. It is frequently advisable to pin
Diptera, especially the hairy forms (as the Bee-flies), in the net and
transfer them at once to a cigar box containing a sponge moistened with
chloroform. When the collecting shears are used, the insects are always
thus pinned at once, which is, in fact, the only method of securing
them. This is also necessary in the case of many Lepidoptera. Delicate
Neuroptera may be killed by the use of the cyanide bottle, or,
preferably, placed at once in a vial of alcohol, as these insects, in
many instances, cannot be kept securely if pinned or mounted. Large
Lepidoptera, as the Bombycids, may be killed by pouring benzine,
naphtha, or chloroform over the thorax and abdomen. These substances
evaporate rapidly and do not appreciably injure the vestiture of the
insects. Some collectors, in the case of butterflies, seize them
dexterously between the thumb and finger, and give a sharp pinch on the
sides of the thorax. This will prevent the fluttering of the insect when
transferred to the cyanide bottle, and, if carefully done, the scales
need not be rubbed off. It is objectionable, however, because the thorax
is distorted and subsequent anatomical study interfered with, and, in
the case of moths, should never be practiced, as the thorax affords
important characters used in classification. Orthoptera may be killed by
the use of the cyanide bottle but should be transferred at once to the
vials of alcohol. If placed in a cyanide bottle, especially in the case
of Locusts (_Acrididæ_), they are apt to exude colored juices from the
mouth, so that the specimens become soiled. Hence the use of vials of
alcohol is preferable, and these insects should never be thrown into
vials containing delicate insects of other orders. Plant-lice, together
with the plant which they infest, should be placed at once in vials of
alcohol, and specimens of the Aphides, representing all the forms
present, should be mounted on slides for microscopic examination. The
fixed forms of Coccids, comprising the majority of the species, require
no special treatment, and the leaves, twigs, or bark on which they occur
may be pinned at once and placed in the collection. The free forms are
treated as in the case of plant-lice.
ENTOMOTAXY.
Under this term may be considered the preparation of insects for the
cabinet.
CARE OF PINNED AND MOUNTED SPECIMENS.
_Insect Pins._--In mounting insects for the cabinet, expressly made
entomological pins should be used. These come from three different
sources: Kläger pins, made by Hermann Kläger, Berlin, Germany; Karlsbad
pins, made by one or several firms in Karlsbad, Bohemia, Austria; and
Vienna pins, made by Miller, Vienna, Austria.[4] These three kinds of
pins have each their own slight advantages and disadvantages, so that it
is difficult to say which is the best. All have the disadvantage that
the pinned specimens are liable to be ruined by verdigris, and to
obviate this japanned ("black") insect pins are made by Kläger and
Miller. These black pins are, however, much softer than the "white"
pins, and therefore more difficult to handle. A pin of 35 millimeters in
length will be found most convenient for pinning all insects excepting
the larger Lepidoptera and other heavy-bodied insects, for which a
longer pin may advantageously be used. According to the different
degrees of fineness, the pins are numbered from No. 00 (the finest in
the trade) to No. 7 or 8, but the numbers used by the different
manufacturers do not correspond with each other. In experience, pins of
Nos. 1, 2, 3, and 4 (Kläger numbers) are more often needed than the
others. The long pins of the finer numbers (Nos. 0 and 00) are difficult
to handle in the collection and, for this reason, not to be recommended.
[4] In North America, Kläger pins and Karlsbad pins can be obtained
through Mr. John Ackhurst, 78 Ashland Place, Brooklyn, N. Y., and
possibly also through Messrs. Blake & Co., 55 North Seventh street,
Philadelphia, Pa. The Vienna pins and the Minutien-Nadeln have to be
ordered direct through the manufacturer, Mr. Miller.
For many small insects, especially Microlepidoptera and Microdiptera,
which _must_ be pinned, even the finest ordinary insect-pins are too
large, and two special makes of pins are in use for this purpose. The
"elbow pin" (formerly made and sold by Dr. Kuenow, of Königsberg,
Prussia, Germany) consists of a piece of fine silver wire, pointed at
one end, and with a coil loop at the other end, into which a longer pin
(No. 3 or No. 4) is thrust. This pin is illustrated in Fig. 94. Still
more satisfactory are the "Minutien-Nadeln" (pins for minute insects)
manufactured by Mr. Miller, of Vienna, Austria, and which consist of a
straight piece (about 14 mm. long) of extremely fine steel wire which is
pointed at one end, and which is used in connection with a piece of
pith or cork. The mode of using this pin is shown in Fig. 101. These
fine and elbow pins may be obtained either "white" or japanned.
[Illustration: FIG. 94.--Insect mounted on "elbow-pin."]
"Many English entomologists use short pins, very much like those of
ordinary make, and my late friend Walsh never gave up the custom, and
most vehemently opposed the use of what he ridiculed as 'long German
skewers.' But the only advantage that can possibly be claimed for the
short pins is that they are less apt to bend, consequently more easily
stuck into the bottoms of boxes, and require less room; while, compared
with the long pins, they have numerous disadvantages. Long pins admit of
the very important advantage of attaching notes and labels to the
specimen; render it more secure from injury when handled, and from
museum pests in the cabinet; and on them several rows of carded
duplicates may be fastened, one under the other, so as to economize
room."
I have seen few old collections in better condition than that of the
late E. Mulsant, of Lyons, France; and he used iron wire, cut
slantingly, of the requisite length--a common custom in France. These
wires bend so easily and have such dull points that they require much
more careful manipulation than the pins, and the claim made for them
that they do not verdigris would, perhaps, be offset by their rusting in
moist climates or near the sea. Silver wire or silver-plated wire is
also used.
_Preparation of Specimens._--Upon the return from an excursion the
specimens should be prepared for the collection as soon as practicable.
If they have been collected in the forenoon they should be mounted the
same evening, and those collected during an afternoon or evening
excursion should be mounted the following morning, or, at any rate,
before they get dry and brittle. Even specimens collected in alcohol
should be attended to as soon as possible.
Specimens are taken from the collecting bottle, spread out on a sheet of
white blotting paper and cleaned from adhering impurities either with a
soft dry brush, or, in the case of species with hard covering, by
washing them with chloroform or ether or benzine where necessary.
Theoretically the best way of mounting would be to pin all specimens,
since the under side with its important characters then remains free for
examination. Pins adapted for pinning even the smallest insects have
been described above, but this pinning is such a delicate operation and
requires so much time that considering the large number of small
specimens that may be collected on a single short excursion it is next
to impossible to carry out this method, and therefore only the larger
specimens need be pinned and the smaller may be glued onto the paper
points described later. If the work is done with proper care all
insects can be prepared for the cabinet so that both the upper and under
surface of the specimen may be examined without further manipulation.
_Pinning._--"Insects should be pinned through the middle of the thorax,
when, as is more generally the case, this portion (the mesothorax) is
largely developed. Beetles (_Coleoptera_) and Bugs (_Hemiptera_),
should, however, be pinned, the former through the right elytron or
wing-cover (Fig. 95), and the latter through the scutel or triangular
piece behind the thorax, the pin issuing between the middle and hind
legs (Fig. 96). The specimens look very pretty with all the legs neatly
spread out, but for practical purposes it is better to let them dry in
the natural, partly bent position. It is a saving of time and space, and
the limbs are not so apt to break. The legs must also not reach too far
downward or they will interfere with the proper labeling and the secure
pinning of the specimen in the cabinet. Moreover, the antennæ and legs
must be brought into such position that they will not obstruct the view
of any important part of the undersurface. The pin should always project
about half an inch above the insect to facilitate handling, and
uniformity in this regard will have much to do with the neat appearance
of the collection. In pinning very large and heavy insects on a No. 4 or
No. 5 pin, it is a good plan to first flatten the pin by a few blows of
a hammer, in order to prevent the specimen from subsequently turning
round on the pin."
[Illustration: FIG. 95.--Method of pinning and labeling Coleoptera
(original).]
In pinning specimens which have a flat or nearly flat undersurface and
short legs (as in many Coleoptera and Hemiptera and some Hymenoptera,
_e. g._ the Saw-flies) the specimens are laid on a piece of cork and
held in place there with the fingers or with a forceps. The pin is then
pushed through the insect at the proper point, care being taken not to
strike one of the legs or coxæ, and that the pin passes through the
specimen in a vertical direction.
[Illustration: FIG. 96.--Method of pinning Hemiptera (original).]
After the pin has been pushed through the specimen it is taken out of
the cork and the specimen is pushed up to its proper height. This can be
done either by holding the specimen between the fingers or by placing it
on the upper edge of a thick book. A piece of cardboard provided with a
small hole may also be used for this purpose. The perforations in
ordinary sheet-cork, or the lapel of one's coat, will answer the same
purpose. In pinning Lepidoptera or Hymenoptera the specimen should lie
lightly in the angle formed by the thumb and first two fingers of the
left hand and the pin be carefully thrust through at the proper angle.
In pinning all insects the pin should be so inserted that the insect is
nearly at right angles with the pin, the posterior end being slightly
depressed.
_Mounting on Points._--Most insects which are too small to be pinned on
a No. 2 pin may be fastened to cardboard by means of gum tragacanth, gum
shellac, or any good glue. It is not always easy to determine whether to
pin a medium specimen or to glue it to a triangle. Pinned specimens are
more secure, and not so apt to fall or be knocked off, but they are
liable to become corroded by verdigris and ultimately lost, especially
in families the larvæ of which are endophytous or internal feeders. It
is better to glue wherever there is doubt. A drop of corrosive sublimate
added to the water in which the gum tragacanth is dissolved will
indefinitely prevent its souring, but should not be used where the gum
is to come in contact with the pin, as it inclines the latter to
verdigris. In such cases a little spirits of camphor mixed with the gum
tragacanth is best. Shellac should be dissolved in alcohol and this
requires some time. This glue is not affected by moisture, and if it is
desired to remove the specimens, they must be immersed in alcohol until
the shellac is again dissolved.
A number of different kinds of glue are used by entomologists. The
requirements of a good glue are that it be colorless, and, what is of
greater importance, that the specimens adhere firmly to the paper points
so that there is little or no danger of their being jarred off. Those
glues which are readily soluble in cold or lukewarm water are perhaps
more convenient than those which require alcohol or chloroform for
dissolving. Gum arabic and gum tragacanth have the disadvantage that
they are more liable to attract mites and are more brittle, so that they
do not hold specimens as well as some of the liquid glues that are on
the market. Spalding's glue answers a very good purpose, as also the
preparation known to European entomologists as Leprieur's gum. White
bleached shellac, while requiring alcohol to dissolve it, has the
advantage that a very minute quantity suffices. In olden times the
method employed was simply to glue the specimen by the ventral side to
the middle of a quadrangular piece of cardboard, which was then pinned
on a No. 3 or No. 4 insect pin. This method is still in vogue with
English entomologists, but can not be recommended except for mounting
duplicates. Much better are the small isosceles triangles which, before
mounting the specimen, are pinned through near the base on a No. 2 or
No. 3 insect pin. Only the best and finest cardboard should be used for
this purpose, since that of poor quality is liable to be broken while
passing the pin through it and will yellow with age. "Reynolds's
Superfine Board," which may be ordered through any dealer in artist's
supplies of Devoe & Co., Fulton street, New York City, is perhaps the
best for this purpose. Some of the neatest mounting which I have had
done by any of my agents or assistants is by Mr. Albert Koebele, who
has used mica or gelatine instead of cardboard, the object being not
only to show the whole of the under side of the specimen, but to obscure
less of the light from the labels and to render the triangles less
conspicuous in the cabinet. These have been in use in the museum
collection only for the last two or three years, and whether they will
eventually tend to corrode the pins is not yet settled. Mica and
isinglass are also used for the same purpose. The points used in
mounting may easily be cut by hand to a convenient size, say one-fourth
of an inch (6-8 mm) long by one-sixteenth or less at the base, and
tapering to a point. The point may be narrower or wider to accommodate
insects of different sizes.
For cutting these triangles or points, various forms of punches similar
to the appended figure (Fig. 97) known to the trade as conductor's
punches may be used, and points thus cut are to be preferred to those
made by other means, on account of the greater uniformity secured.
An experienced hand, however, will cut these points very rapidly and
accurately with a pair of shears, and most collectors use no special
instrument for this purpose.
The punches mentioned may be obtained of the manufacturers[5] of such
instruments at from $2 to $3. Care should be observed in ordering to
state explicitly the length, width at base and point, or, what is
better, to inclose sample of the size of point it is desired to cut; but
above all, to state that the block of paper to be cut out is the result
desired, and that the instrument should cut clean and even, with no
ragged edges.
[5] Montgomery & Co., 105 Fulton street, New York City.
[Illustration: FIG. 97.--Insect punch for cutting triangles or points
(original).]
For mounting different forms and sizes the fastidious collector uses
four or five sizes of points, but for all practical purposes one to cut
a card point not less than 1.3 mm at the base and prolonged as nearly as
possible to a point, and another a trifle wider at the base, say 1½ or 1
2/3 mm and with a point about 1½ mm in width will suffice.
[Illustration: FIG. 98.--Points for mounting insects (original).]
For mounting most long-bodied insects, _e. g._, Staphylinidæ and
Elateridæ, an oblong card say 1½ mm in width is desirable. With a little
care these may be cut with sufficient uniformity with scissors. Seven
and one-half millimeters may be taken as a standard of length, as this
is about the size used by the majority of our best collectors. Shorter
points, say 6 mm or one-quarter inch long, are sometimes preferred,
where economy of space is a desideratum.
A series of four points of different sizes for mounting insects is shown
in the accompanying illustration. The sharp-pointed one, _a_, is
designed for the minutest forms and the larger points for large insects.
The largest should be mounted on points of a nearly rectangular shape,
shown at _d_. The dimensions of these points as adopted by most
entomologists, are as follows:--
+------+---------+----------+--------+
| | Length. | Breadth. | Point. |
+------+---------+----------+--------+
| _a_ | 7.5mm. | 1.5mm. | .0mm. |
| _b_ | 7.5 | 1.5 | .4 |
| _c_ | 7.5 | 1.5 | .6 |
| _d_ | 7.5 | 1.6 | 1.6 |
+------+---------+----------+--------+
The point or triangle should be mounted on the pin and directed to the
left, the height from the top of the pin varying somewhat with the
specimen, but averaging about one-half an inch. The insect is then glued
to the point with the head pointed forward. In the case of Coleoptera
and Hymenoptera, and in fact of most insects, the specimen is mounted
with the back uppermost, but in the case of the smaller Hymenoptera it
is advisable to mount some of the specimens, at least, on the left side
(see Fig. 99). This directs the legs toward the pin, as a matter of
safety, prevents their being broken in handling, and also gives
opportunity for subsequent examination of the back, side, and venter of
the specimen. Coleopterists always mount specimens on the venter, and in
the case of a correctly mounted specimen the whole underside of the body
should be available for examination except the right half of the
metasternum, as shown in figure 100.
[Illustration: FIG. 99.--Insect mounted on cardboard triangle.]
[Illustration: FIG. 100.--Method of gluing beetle on paper point
(original).]
In mounting minute insects a few precautions are necessary. The beginner
usually uses too much glue or shellac, and the result is that the
mounted specimens are more or less covered with the fluid, so as to
render them unfit for examination. If, on the other hand, too little of
the glue is used, the specimens are not securely fastened to the paper
point, and are liable to be jolted off by the slightest jar. Before
mounting specimens the legs and antennæ must be brought into the proper
position by means of a brush or with a dissecting needle, so that they
may easily be seen. A supply of paper points should always be at hand,
and after selecting one of the proper size for the specimen, with an
acute tip for a very small specimen and with a more obtuse point for a
larger one, a small quantity of glue is applied to the tip by means of a
pointed stick, such as a toothpick, the amount varying with the size of
the specimen. The tip of a moistened brush may be used to transfer the
specimen to the point, or one will soon become dextrous enough to do
this without the aid of the brush. The specimens are then allowed to dry
in a horizontally placed box. If the drying box is placed in a vertical
position the specimens, especially long-bodied ones, are liable to
topple over before the glue has become firm.
[Illustration: FIG. 101.--Cecidomyiid mounted on pith (original).]
Delicate flies and Microlepidoptera, which it will not do to fasten with
mucilage, may first be mounted on the fine pins described above and
these thrust into oblong or triangular bits of pith or cork, which are
mounted on larger pins as shown in Figures 101 and 102. This affords a
very satisfactory method of mounting, particularly as the different
sexes may be brought together on the same bit of pith, or the adult and
puparium in Diptera, as shown at Figure 101. Strips of stout cardboard
with the pins run through the narrow edge may also be used. The method
of mounting minute Hymenoptera and Diptera and other insects on a bent
wire, mentioned above, is illustrated at Figure 94. This method has not
proved so satisfactory, as the wires are apt to become loose on the pin.
[Illustration: FIG. 102.--Microlepidoptera mounted on pith (original).]
[Illustration: FIG. 103.--Method of mounting duplicates (original).]
_Mounting Duplicates._--If the collector finds more specimens of a rare
species than he cares to have in his collection, the excess may be
mounted as duplicates. If the species happens to be of a large size the
specimens are pinned in the ordinary way, but if small enough to be
gummed, there is a most convenient method of rapidly mounting the
specimens so that they may be sent through the mail with much less risk
of getting broken or knocked off than if glued on paper points, and will
also take up very little room in the duplicate boxes. It consists in
gluing the specimens in a transverse row on a strip of white card paper
with one of the glues soluble in water, care being taken that between
the individual specimens some space be left, and further that the heads
and antennæ do not project beyond the edge of the paper. The width of
the paper strip must be somewhat greater than the length of the
specimen, so that below the latter there is sufficient room for
inserting a pin through the paper. After the glue has become dry the row
of specimens is cut with scissors into several smaller rows of
convenient size, so that on each of these rows there are two or three or
more specimens, according to the size of the species. A locality label
is pushed high up on a No. 3 or No. 4 pin, and one of the mounted rows
of specimens is then pinned and pushed up near the locality label; a
second row is then pinned and pushed near the first row, and the same
process continued with the third row and so on. A single pin will thus
bear five or six rows, and in giving away or sending away specimens the
lowest row is taken from the pin and repinned for mailing. The
accompanying figure (Fig. 103) illustrates the mounting of a
moderate-sized species in rows of two specimens each. This method of
mounting duplicates may be adopted not only for Coleoptera, but also for
Heteroptera, Homoptera (excepting Aphididæ and allied families), smaller
Orthoptera, and Hymenoptera. It is, however, impracticable for
Lepidoptera, Diptera, and most Neuroptera.
_Temporary Storage of Specimens._--If the entomologist is prevented from
mounting his captures soon after returning from an expedition, or if, on
extended collecting trips, time does not offer for this purpose,
specimens of almost all orders except the Lepidoptera, Orthoptera, and
Neuroptera may be placed in a small, tightly closing pill box, care
being taken to keep the larger specimens apart from the small ones. In
this way specimens will keep for an indefinite period, provided they are
properly packed. In the case of the traveling collector, where the
material is to be carried from point to point at great risk of breaking,
specimens should be packed very carefully to prevent any shaking or
rattling about in the boxes. This may be done by placing a round piece
of soft paper on the top of the specimens in the pill box. This paper
should be gently pressed down and the empty space above filled with
other layers of paper or with cotton. The packing of specimens between
cotton is not recommended, as it is a difficult and tedious task to
afterwards free them from the adhering fibers. Layers of soft paper or,
yet better, velvet, are preferable.
[Illustration: FIG. 104.--Method of preserving Diurnal Lepidoptera in
paper envelopes. (After Kiesenwetter.)]
_Envelopes for Lepidoptera, etc._--On an extended trip, it will be found
impracticable to mount and prepare insects requiring cumbersome
apparatus for spreading, as Lepidoptera or Neuroptera, and a very
excellent plan consists in folding the wings of the insect so that the
lower surfaces come together and then placing it in a triangular
envelope, as shown in the accompanying illustration. The collector
should be provided with a quantity of paper of the requisite dimensions
for making these envelopes, and specimens, as they are taken from the
collecting bottle, may be rapidly inclosed in them, labeled, and packed
away in a tight wooden (not tin) box containing a supply of naphthaline,
the specimens thus occupying the minimum of space. Specimens secured in
this way may be kept without further manipulation indefinitely or until
time is found to relax and set them. This is also an excellent method
of sending diurnal Lepidoptera and Dragon-flies through the mails and is
preferable in some respects to mailing spread specimens.
[Illustration: FIG. 105.--Spreading board for Lepidoptera.]
[Illustration: FIG. 106.--Needle for spreading insects.]
_Directions for Spreading Insects._--"For the proper spreading of
insects with broad and flattened wings, such as butterflies and moths, a
spreading board or stretcher is necessary. One that is simple and
answers every purpose is shown at Fig. 105. It may be made of two pieces
of thin whitewood or pine board, fastened together by braces at the
ends, but left wide enough apart to admit the bodies of the insects to
be spread; strips of cork or pith, in which to fasten the pins, may then
be tacked or glued below so as to cover the intervening space. The
braces must be deep enough to prevent the pins from touching anything
the stretcher may be laid on, and by attaching a ring or loop to one of
them the stretcher may be hung against a wall, out of the way. For
ordinary-sized specimens I use boards 2 feet long, 3 inches wide, and
1/3 inch thick, with three braces (one in the middle and one at each
end) 1½ inches deep at the ends, but narrowing from each end to 1 1/6
inches at the middle. This slight rising from the middle is to
counteract the tendency of the wings, however well dried, to drop a
little after the insect is placed in the cabinet. The wings are held in
position by means of strips of paper (Fig. 105) until dry. For
stretching the wings and for many other purposes, a handled needle will
be found useful. Split off, with the grain, a piece of pine wood 3 or 4
inches long; hold it in the right hand; take a medium-sized needle in
the left hand; hold it upright with the point touching a walnut table,
or other hard-grained wood, and bring a steady pressure to bear on the
pine. The head of the needle will sink to any required distance into the
pine, which may then be whittled off, and you have just the thing you
want (Fig. 106). To obtain uniformity in the position of the wings, a
good rule is to have the inner margins of the front wings as nearly as
possible on a straight line. When the specimens are thoroughly stiff and
dry, they should be taken from the stretcher and kept for several weeks
in the drying box before being permanently placed in the cabinet. The
drying box is simply a box of any required dimensions, containing a
series of shelves on which to pin the specimens, and without a solid
back or front. The back is covered on the inside with fine gauze and on
the outside with coarser wire, and the door in front consists of a
close-fitting frame of the same material, the object being to allow free
passage of air, but at the same time to keep out dust and prevent the
gnawings of mice and other animals. The shelves should be not less than
2 inches deep, and if made in the form of a quadrangular frame, braced
with two cross-pieces on which to tack sheet cork, they will serve for
the double purpose of drying spread specimens and for the spreading of
others, as there are many insects with long legs which are more
conveniently spread on such a board, by means of triangular pieces of
stiff cardboard braces or 'saddles,' than on the stretcher already
described. Two of these braces are fixed on the setting board, by means
of stout pins, at sufficient distances apart to receive the body between
them. The wings are then spread upon them and kept in place until dry by
means of additional braces. In the case of bees, wasps, etc., the pin
may be thrust well into the cork or pith so that the wings may be
arranged in the proper position and braced and supported by strips of
stout cardboard. This method is especially recommended in the case of
the Fossorial wasps, the legs of which, if mounted in an ordinary
spreading board, can not be properly arranged.
In spreading Lepidoptera I have used, in the place of a number of paper
strips pinned across the wings, blocks of glass of various sizes to hold
the wings in position. My method of mounting, with a large amount of
material on hand to be attended to, consists in pinning a row on the
spreading-board and fixing the wings in position with spreading needles,
fastening them with a single narrow strip of paper placed next the body.
The entire spreading-board is filled with specimens in this way, a
single long strip of paper on either side answering to keep the wings of
all the specimens in position. Then, instead of pinning additional
strips to hold the wings flat and securely in position, the pieces of
glass referred to are used, placing them on the wings of the insect.
With the use of glass the spreading-board must always be kept in a
horizontal position and must never be disturbed. The advantage of the
glass is that the wings can be seen through it and more truly adjusted.
Spreading-boards may be made as described above, or it may be of
advantage, when a good deal of work is to be done, to adopt a somewhat
different method. Five or six spreading-boards may be made together,
forming a sort of shelf. A number of these shelves may be constructed
and the whole combined in a case with a screen cover to exclude insects.
The individual shelves may be arranged with grooves to slide on tongues
in the side of the case. A screen-covered case for spreading-boards is
always desirable, as the insects are otherwise very liable to be eaten
by roaches or other insects. A spreading-case of the form described is
shown at Fig. 107.
_A new Apparatus for Spreading Microlepidoptera._--For the spreading of
Microlepidoptera my assistant, Mr. Theo. Pergande, has devised an
apparatus, represented in the accompanying illustration, which he finds
very convenient. It consists of a small spreading-block represented at
_B_ and the support with attachment shown at _A_. The former is made in
a long strip of the shape shown in the illustration, having a square
groove, _c_, cut in the top. Over this is glued a thin strip of wood,
_b_, say 1/8 inch thick, and a narrow slit is sawed in the center of
this above, cutting through into the groove _c_. This is then sawed up
into pieces of uniform length, say 1½ to 2 inches, and the block is
completed by the insertion of a rectangular strip of pith or cork into
the groove. The Micro is pinned on a short black pin, and the pin is
thrust down into the narrow opening made by the saw and is held firmly
by the pith or cork. This block is then slid into the groove in the
setting-board _A_, which narrows slightly from _e_, and pushed along
until firmly secured (_d_). The operator can then rest his hands and
arms on either side of the support, and, if necessary, bring a large
hand lens over the object by means of a support with ball-and-socket
joint shown at _e_. The wings may thus be easily and accurately arranged
and fixed in position with pins or strips of paper, as in the ordinary
mounting of such insects. Two or three specimens may be mounted on each
of these blocks. The construction of the support is indicated in the
annexed drawing. One side is attached by clamps, shown enlarged at
_f_, which afford means of adjusting the width of the slit in which the
small sawed blocks slide and correct the shrinking or swelling which may
take place in moist or dry seasons. The advantage of the apparatus is
that the operator has the setting block firmly fixed before him and
has both hands free to manipulate the wings of the insect in addition to
having the lens in a convenient position, the use of which is necessary
in the preparation of the very minute forms.
[Illustration: FIG. 107.--Spreading-case (original).]
[Illustration: FIG. 108.--Spreading apparatus for Microlepidoptera
(original).]
_Spreading Microlepidoptera._--The mounting of Microlepidoptera is about
the most delicate work in entomotaxy, and I can not do better than
quote the explicit directions given by Lord Walsingham on the subject.
Returning to camp I put a few drops of liquid ammonia on a small piece
of sponge and place it in a tin canister with such of the boxes as do
not contain the smallest species, and put these and the remainder away
until morning in a cool place. In the morning I prepare for work by
getting out a pair of scissors, a pair of forceps, my drying-box
containing setting-boards, a sheet of white paper, and some pins.
First, I cut two or three narrow pieces of paper from 3 to 6 lines wide,
or rather wider, according to the size of the largest and smallest
specimens I have to set. I then double each of these strips and cut it
up into braces by a number of oblique cuts. Now I turn out the contents
of the canister and damp the sponge with a few drops of fresh ammonia,
refilling with boxes containing live insects. Those which have been
taken out will be found to be all dead and in a beautifully relaxed
condition for setting. Had the smallest specimens been placed in the
canister over night there would have been some fear of their drying up,
owing to the small amount of moisture in their bodies.
If the weather is very hot there is some danger of killed insects
becoming stiff while others are being set, in which case it is better to
pin at once into a damp cork box all that have been taken out of the
canister, but under ordinary circumstances I prefer to pin them one by
one as I set them.
Taking the lid off a box, and taking the box between the finger and
thumb of the right hand, I roll out the insect on the top of the left
thumb, supporting it with the top of the forefinger and so manipulating
it as to bring the head pointing toward my right hand and the thorax
uppermost. Now I take a pin in the right hand and resting the first
joint of the middle finger of the right against the projecting point of
the middle finger of the left hand to avoid unsteadiness, I pin the
insect obliquely through the thickest part of the thorax, so that the
head of the pin leans very slightly forward over the head of the insect.
After passing the pin far enough through to bring about one-fourth of an
inch out below,[6] I pin the insect into the middle of the groove of a
setting board so that the edge of the groove will just support the under
sides of the wings close up to the body when they are raised upon it.
The board should be chosen of such a size as will permit of the
extension of the wings nearly to its outer edge. The position of the pin
should still be slanting a little forward. The wings should now be
raised into the position in which they are intended to rest, with
especial care in doing so not to remove any scales from the surface or
cilia of the wings. Each wing should be fastened with a brace long
enough to extend across both, the braces being pinned at the thick end,
so that the head of the pin slopes away from the point of the brace;
this causes the braces to press more firmly down on the wing when fixed.
The insect should be braced thus: The two braces next the body should
have the points upwards, the two outer ones pointing downwards and
slightly inwards towards the body, and covering the main portion of the
wings beyond the middle. Antennæ should be carefully laid back above the
wings, and braces should lie flat, exercising an even pressure at all
points of their surface. The fore wings should slope slightly forwards
so that a line drawn from the point of one to the point of the other
will just miss the head and palpi. The hind wings should be close up,
leaving no intervening space, but just showing the upper angle of the
wing evenly on each side. I can give no more precise directions as to
how this desirable result may most simply and speedily be attained; no
two people set alike. Speed is an object; for I have often had to set
twelve dozen insects before breakfast. A simple process is essential,
for a man who is always pinning and moving pins, and rearranging wings
and legs, is sure to remove a certain number of scales and spoil the
appearance of the insect, besides utterly destroying its value. I raise
each of the fore wings with a pin, and fix the pin against the inner
margin so as to keep them in position while I apply the braces. Half the
battle is really in the pinning. When an insect is pinned through the
exact center of the thorax, with the pin properly sloped forward, the
body appears to fall naturally into its position on the setting board,
and the muscles of the wings being left free are easily directed and
secured; but if the pin is not put exactly in the middle it interferes
with the play of the wings. Legs must be placed close against the body
or they will project and interfere with the set of the wings. Practice,
care, and a steady hand will succeed. When all the insects that have
been killed are set the contents of the canister will be found again
ready, twenty minutes being amply sufficient to expose to the fumes of
ammonia. Very bright green or pale pink insects should be killed by some
other process, say chloroform, as ammonia will affect their colors.
[6] This applies to the use of short pins, which should subsequently be
connected through strips of pith with longer pins. For some of the
larger micros the long pins may be used directly and a different
spreading board employed.
Insects should be left on the setting boards a full week to dry; then
the braces may be carefully removed and they may be transferred to the
store box.
In my own experience I have found that a touch or two of the chloroform
brush on the pill-box containing small moths is sufficient to either
kill or so asphyxiate them that they can easily be mounted. I have also
found that strips of corn pith or even of soft cork, with grooves cut
into them, are very handy for the pinning and spreading, and that by
means of a small, broad-tipped, and pliable forceps the smallest
specimens can be deftly arranged in the groove and kept in place until
pinned. In fact, for all persons who have not very great experience and
dexterity this method is perhaps more to be recommended than that of
holding them between the thumb and fingers. Where chloroform is used
either to kill or deaden specimens, it is important that after they are
once spread and in the drying box they should be subjected to an
additional asphyxiation, as the larger species may revive and are apt to
pull away from the holding strips, and thus rub off their scales.
Microlepidoptera, together with Microhymenoptera and Diptera may be
conveniently pinned on fine, short pins, and these thrust into an oblong
bit of cork or pith. This form of mounting has already been described
and is represented in figure 102. The neatest mounting of
Microlepidoptera which I have seen is the work of my assistant, Mr.
Albert Koebele, who mounts these insects on an oblong strip of pith.
This is very light and presents no difficulty in pinning. The strips may
be made of considerable length and both sexes may be pinned on the same
block (see Fig. 103). Most Lepidoptera present on the under surface an
entirely different aspect from that on the upper surface, and, in such
cases, it is a good plan to mount a number of specimens obversely.
_Relaxing._--It will frequently be desirable to re-spread insects which
have been incorrectly mounted, or to spread specimens which have been
collected and stored in papers, or pinned and allowed to dry without
being prepared for the cabinet. Such specimens may be relaxed by placing
them in a tight tin vessel half filled with moist sand to which a little
carbolic acid has been added to prevent molding. Small specimens will be
sufficiently relaxed to spread in twenty-four hours. Larger specimens
require from two to three days. More rapid relaxing may be caused by the
use of steam, and a flat piece of cork with the specimens laid or pinned
thereon and floated on the top of hot water in a closed vessel
constitutes an excellent relaxing arrangement.
_Inflation of the Larvæ of Lepidoptera._--The larvæ of Lepidoptera
preserved in alcohol are excellent for anatomical and general study, but
are not very suitable for use in economic displays. This means of
preservation also has the disadvantage of not generally preserving the
natural color and appearance of the specimens. These objections may be
avoided, however, by the dry method of preserving larvæ, viz, by blowing
or inflation. The process may be described as follows: The larva may be
operated upon alive, but should preferably be first killed by dipping in
chloroform or alcohol, or in the cyanide bottle. It is then placed on a
piece of blotting paper and the alimentary canal caused to protrude from
one-eighth to one-fourth of an inch, by rolling a pencil over the larva
from the head to the posterior extremity. The protruding tip is then
severed with a sharp knife or pair of dissecting scissors, and the
contents of the abdomen are forced out by passing a pencil, as before, a
number of times over the larva. Great care should be exercised in
expressing the fluids not to press the pencil too strongly against the
larva or to continue the operation too long, as this will, especially in
delicate larvæ, remove the pigment from the skin, and the specimen when
dried will show discolored spots and be more or less distorted. The
larva should be moved from place to place on the blotting paper during
the operation, so as not to become soiled by its own juices. A straw, or
a glass tube drawn to a point at the tip, is then inserted in the
protruding portion of the alimentary canal. If a straw is used the larva
may be fastened to it by thrusting a pin through the wall of the canal
and the straw. In the case of the glass tube the alimentary canal can be
caused to adhere by drying for a few minutes and this operation may be
hastened and the fastening made more secure by touching the point of
union with a drop of glue. The straw or glass tube is then attached to a
small rubber bag, previously inflated with air, the ordinary dentist's
or chemist's gas bag answering admirably for this purpose. The larva is
now ready for drying, and for this purpose a drying oven is required
into which it is thrust and manipulated by turning it from side to side,
to keep it in proper shape and dry it uniformly until the moisture has
been thoroughly expelled. An apparatus which I have found very
convenient for this purpose is represented at Fig. 109. It consists of a
tin box with mica or glass slides, _e_, to allow the larva to be
constantly in sight. It has also a hinged top, _b_, which may be kept
closed or partly open, or entirely open, as may be necessary, during the
operation. The ends of the box are prolonged downward about 5 inches,
forming supports for it, _g_. Beneath it is placed an alcohol lamp, _f_,
which furnishes the heat. In the end of the box is a circular opening,
_d_, for the introduction of the larva, and this may be entirely or
partly closed by a sliding door, _a_. It will be found of advantage to
line the bottom of the box (inside) with a brass screen of very fine
mesh to distribute and equalize the heat. This apparatus can be very
easily made by any tinsmith and will answer every purpose.
[Illustration: FIG. 109.--Drying oven for the inflation of larvæ
(original).]
The larvæ of Microlepidoptera or young larvæ may be dried without
expressing the body contents, and will keep, to a great extent, their
normal shape and appearance. The method consists in placing them on a
sand bath, heated by an alcohol lamp. The vapor generated by the heat in
the larvæ inflates them and keeps the skin taut until the juices are
entirely evaporated. They may then be glued at once to cardboard and
pinned in the cases.
In the mounting of large inflated larvæ I have adopted the plan of
supporting them on covered copper wire of a size varying with the size
of the larva. A pin is first thrust through a square bit of cork and the
wire brought tightly about it and wrapped once or twice, compressing the
cork and giving a firm attachment to the pin. The wire is then neatly
bent to form a diamond-shaped loop about one-sixth of an inch in length
and again twisted loosely to the end--the length of the twisted portion
about equalling that of the larva to be mounted. This is then either
thrust into the blown skin of the larva through the anal opening, the
larva being glued to the wire by the posterior extremity, or the larva
is glued to the wire by the abdominal legs and venter, thus resting on
the wire as on a twig. This style of mounting is illustrated in Pl. I.
With a little experience the operator will soon be able to inflate the
most delicate larvæ and also the very hairy forms, as for instance
_Orgyia leucostigma_, without the least injury, so that the natural
colors and appearance will be preserved.
Another very good method, and still safer, is to blow with straw, cut
the straw square off at the anus, and then preserve the thoroughly dried
and blown specimen in a glass tube of about the same length and diameter
as the larva. This arrangement in conjunction with the tube holder,
which will be described further on, is one of the most satisfactory for
the preservation of inflated larvæ.
For the biological-display collection, larvæ may be blown in various
natural positions, to be subsequently fastened on leaf or twig or in
burrows which they have occupied. Fastened to artificial foliage in
which nature is imitated as much as possible, such blown larvæ are quite
effective.
_Stuffing Insects._--Large larvæ may sometimes be satisfactorily
preserved for exhibition purposes by stuffing them with cotton. The
method consists simply in making a small slit with the dissecting
scissors or a short scalpel between the abdominal prolegs, and removing
the body contents. Powdered arsenic or some other preservative should be
put in the body of the larva with the cotton used in stuffing it, and
the slit closed by a few stitches, when the larva may be dried and
mounted on a twig or leaf. This method of stuffing with cotton is also
applicable in the case of certain large-bodied insects which, if mounted
and put away without preparation, would be liable to decompose, as, for
instance, the larger moths, grasshoppers, etc. A slit can be made in the
center of the abdomen or near the anus beneath, and the body contents
removed and replaced with cotton. Stuffing in this way with cotton is of
especial advantage in the case of certain of the large endophytous
insects which grease badly. The cut will not be noticed after the insect
has dried, or it may be closed by a stitch or two.
_Dry Preservation of Aphides and other soft-bodied Insects._--Difficulty
has always been experienced in preserving soft-bodied insects,
particularly Aphides, in a condition serviceable for subsequent
scientific study. Kept in alcohol or other antiseptic fluid, they almost
invariably lose much of their normal appearance, and many of the
important characteristics, especially of color, are obscured or lost.
The balsam mount is also unsatisfactory in many respects, as the body is
always more or less distorted and little can be relied upon except the
venation and the jointed appendages. A method of preserving soft-bodied
insects by means of the sudden application of intense heat was
communicated to the _Entomologische Nachrichten_, Vol. IV, page 155, by
Herr D. H. R. von Schlechtendal. It is claimed for this method that the
Aphides and other soft-bodied insects can be satisfactorily preserved in
form and coloring, the success of the method being vouched for by a
number of well-known German entomologists, Kaltenbach, Giebel,
Taschenberg, Mayr, and Rudow. A condensed translation of the method
employed by Schlechtendal is given by J. W. Douglas in the
_Entomologists' Monthly Magazine_ for December, 1878, which I quote:
The heat is derived from the flame of a spirit or petroleum lamp. Above
this is placed a piece of sheet-tin, and over this the roasting
proceeds. A bulging lamp cylinder, laid horizontally, serves as a
roasting oven. In this the insect to be dried, when prepared as
directed, and stuck on a piece of pith, is to be held over the flame; or
the cylinder may be closed at the lower end with a cork, which should
extend far inwards, and on this the insect should be fastened; the
latter mode being preferable because the heat is more concentrated, and
one hand is left free. The mode of procedure varies according to the
nature of the objects to be treated. For the class of larger objects,
such as Hemiptera, Cicadina, and Orthoptera, in their young stages of
existence, the heat must not be slight, but a little practice shows the
proper temperature required. If the heat be insufficient, a drying up
instead of a natural distention ensues. The insect to be roasted is to
be pierced by a piece of silver wire on the under side of the thorax,
but it is not to be inserted so far as to damage the upper side, and the
wire should then be carried through a disk of pith, placed beneath the
insect, on which the legs should be set out in the desired position. But
with some objects, such, for instance, as a young _Strachia_, the drying
proceeds very quickly, so that if distention be not observed then the
heat is too great, for the expansion of the air inside will force off
the head with a loud report; also, with softer, thicker Pentatomidæ care
must be taken to begin with a heat only so strong that the internal
juices do not boil, for in such case the preparation would be spoiled.
It is of advantage to remove the cylinder from time to time, and test,
by means of a lens, if a contraction of the skin has taken place on any
part; if so, the roasting is to be continued. The desired hardness may
be tested with a bristle or wire. For _Aphides_ the _living Aphis_ is to
be put on a piece of white paper, and at the moment when it is in the
desired position it is to be held over the flame, and in an instant it
will be dead and will retain the attitude. Then put it, still on the
paper, into the oven; or, still better, hold it over the heated tin,
carefully watching the drying and moving the paper about in order to
prevent it getting singed. The roasting is quickly accomplished in
either way, but somewhat slower out of the oven especially in the larger
kinds, such as Lachnus. If the paper turn brown it is a sure sign that
caution is requisite. To pierce these brittle preparations for
preservation is hazardous, and it is a better way to mount them with gum
on card, placing some examples on their back.
For Cecidomyidæ, Agromyzidæ, Cynipidæ, and other small insects liable to
shrink, yet containing but little moisture, such as Poduridæ,
Pediculidæ, Psyllidæ, etc., another method is adopted. Over the insect,
mounted on a wire, etc., as above directed, a thin chemical reagent
glass or glass rod, heated strongly at one end, is held, and the heat
involved is generally sufficient to bring about the immediate drying and
distention, but if the heat be too little the process must be repeated;
and, although by this method the danger of burning is not obviated, yet
the position of the legs is maintained much better than by the aforesaid
roasting.
Larvæ of all kinds, up to the size of that of _Astynomus ædilis_, even
when they have long been kept in spirits, may be treated successfully by
the roasting method; but with these objects care must be taken that the
heat is not too strong or else the form will be distorted. For small
larvæ it is preferable to use a short glass, in order better to effect
their removal without touching the upper part, which becomes covered
with steam, and contact with which would cause the destruction of the
preparation. Larvæ of Coleoptera, which contain much moisture or have a
mucous surface, must lie on a bed of paper or pith in order to prevent
adhesion and burning, and these may be further avoided if the cylinder
be slightly shaken during the process, and the position of the object be
thereby changed.
Many Aphides and Coccids are covered with a waxy secretion which
interferes very materially with their easy examination. Mr. Howard has
overcome this difficulty by the following treatment:
"With Aphides and Coccids which are covered with an abundant waxy
secretion which can not be readily brushed away, we have adopted the
plan of melting the wax. We place the insect on a bit of platinum foil
and pass it once over the flame of the alcohol lamp. The wax melts at a
surprisingly low temperature and leaves the insect perfectly clean for
study. This method is particularly of use in the removal of the waxy
cocoon of the pupæ of male Coccidæ, and is quicker and more thorough
than the use of any of the chemical wax solvents which we have tried."
(_Insect Life_, I, p. 152.)
_Mounting Specimens for the Microscope._--The study of the minuter forms
of insect life, including Parasites, Thysanura, Mallophaga, the newly
hatched of most insects, etc., requires the use of the microscope, and
some little knowledge of the essentials of preparing and mounting
specimens is needed. The subject of mounting the different organs of
insects and the preparation for histological study of the soft parts of
insects opens up the immense field of microscopy, the use of the
innumerable mounting media, the special treatment of the objects to be
mounted, staining, section-cutting, and many other like topics, a full
description of which is altogether out of place in the present work.
Anyone desiring to become thoroughly versed in the subject should
consult some of the larger manuals for the microscopist, of which there
are many. For the practical working entomologist, however, a knowledge
of all these methods and processes is not essential, and in my long
experience I have found that mounting in Canada balsam will answer for
almost every purpose. The softer-bodied forms will shrink more or less
in this substance, and it is frequently necessary to make studies or
drawings of them when freshly mounted; or, if additional specimens are
preserved in alcohol, they will supplement the mounted specimens and the
material may be worked up at the convenience of the student. The
materials for the balsam mounts may be obtained of any dealer in
microscopical supplies. They consist of glass slides, 3 inches by 1
inch, thin cover-glasses of different dimensions, and the prepared
balsam. The balsam is put up very conveniently for use in tin tubes. A
sufficient quantity is pressed out on the center of the glass slide,
which has previously been made thoroughly clean and dry, the insect is
removed from the alcohol, and when the excess of liquor has been removed
with bibulous paper, it is placed in the balsam, the limbs and antennæ
being arranged as desired by the use of fine mounting-needles. A
cover-glass, also made thoroughly clean and dry, is then placed over the
specimen and pressed gently until the balsam entirely fills the space
between the cover and the glass slide. The slide should then be properly
labeled with a number referring to the notes on the insect, preferably
placed on the upper edge of the slide above the cover-glass, and also a
label giving the number of the slide and the number of the slide box. On
the opposite end of the slide may be placed the label giving the name of
the specimen mounted and the date. If a revolving slide table is
employed to center the mounts, the appearance of the slide may be
improved by adding a circle of asphalt or Brunswick black. With the
balsam mounts, however, this sealing is not necessary. The slide (Fig.
110) should then be placed in a slide case with the mount uppermost, and
should be kept in a horizontal position to prevent sliding of the
cover-glass and specimen until the balsam is thoroughly dried. For
storing slides I have found very convenient the box shown at Fig. 111.
It is constructed of strong pasteboard and is arranged for holding
twenty-six slides. The cover bears numbers from 1 to 26, opposite which
the name of each insect mounted, or the label on the slide, may be
written. This box when not in use is kept in a pasteboard case, on which
may be placed the number of the box. These slide cases may be stored in
drawers or on shelves made for the purpose. In mounting specimens taken
from alcohol it is advisable to put a drop of oil of cloves upon them,
which unites with the balsam and ultimately evaporates. The occurrence
of minute air bubbles under the cover-glass need occasion no uneasiness,
for these will disappear on the drying of the balsam.
[Illustration: FIG. 110.--Balsam mount, showing method of labeling, etc.
(original).]
[Illustration: FIG. 111.--Slide case, showing method of labeling case
and of numbering and labeling slides (original).]
In mounting minute Acarids or mites it has been found best to kill the
insects in hot water, which causes them to expand their legs, so that
when mounted these appendages can readily be studied. If mounted living,
the legs are almost invariably curled up under the body and can not be
seen. This method may also be used in the case of other minute insects.
Some insects, such as minute Diptera, are injured by the use of hot
water, and for these dipping in hot spirits is recommended.
In the mounting of Aphides the same difficulty is avoided in a measure
by Mr. G. B. Buckton, author of "A Monograph of the British Aphides," by
first placing a few dots of balsam on the glass slide, to which the
insect is transferred by means of a moistened camel's-hair brush. The
efforts of the insect to escape will cause it to spread out its legs in
a natural position and a cover glass may then be placed in position and
a drop of the balsam placed at the side, when, by capillarity, it will
fill the space between the slide and cover glass and the limbs will be
found to have remained extended. If three or four drops of the balsam
are put on the glass the wings may also be brought down and caught to
them so that they will remain expanded in shape for examination.
_Preparing and Mounting the Wings of Lepidoptera._--The student of
Lepidoptera will frequently find it necessary in the study of the
venation of wings to bleach them or denude them of their scales in some
way. Various methods of bleaching and mounting the wings of these
insects have been given, and a few of them may be briefly outlined.
The simplest and quickest, but perhaps the least satisfactory, method is
to remove the scales with a camel's-hair brush. This will answer for the
larger forms and where a very careful examination is not required. For
more careful examination and study the wings are first bleached by the
action of some caustic solution and then mounted in balsam for permanent
preservation. Chambers's method for Tineina, Tortricina, Pyralidina, and
the smaller moths generally, is as follows: The wing is placed on a
microscopic slide in from 3 to 4 drops of a strong solution of potash,
the amount varying according to the size of the wing. A cover of glass
is then placed in position on the wing as in ordinary mounting.
The quantity of liquid should be sufficient to fill the space beneath,
but not sufficient to float the cover glass. The mount is then placed
over an alcohol flame, removing it at the first sign of ebullition, when
the wing will be found denuded, if it be a fresh specimen. An old
specimen, or a larger wing, will require somewhat more prolonged
boiling. The fluid is drawn off by tilting the glass or with bibulous
paper, and the potash removed by washing with a few drops of water. The
cover glass is then removed and the wing mounted either on the same
slide in balsam or floated to another slide, or at once accurately
sketched with the camera lucida. Permanent mounting, however, is always
to be recommended.
The Dimmock method of bleaching the wings of Lepidoptera, given in
Psyche, Vol. I, pp. 97-99, is as follows: He uses for bleaching a
modification of the chlorine bleaching process commonly employed in
cotton bleacheries, the material for which is sold by druggists as
chlorate of lime. The wings are first soaked in pure alcohol to dissolve
out the oily matter, which will act as a repellant to the aqueous
chlorine solution. The chlorate of lime is dissolved in 10 parts of
water and filtered. The wings are transferred to a small quantity of
this solution and in an hour or two are thoroughly bleached, the veins,
however, retaining a light brown color. If the bleaching does not
commence readily in the chlorine solution the action may be hastened by
previously dipping them in dilute hydrochloric acid. When sufficiently
decolorized the wings should be washed in dilute hydrochloric acid to
remove the deposit of calcic carbonate, which forms by the union of the
calcic hydrate solution with the carbonic dioxide of the air. The wings
are then thoroughly washed in pure water and may be gummed to cards or
mounted on glass slides in Canada balsam, first washing them in alcohol
and chloroform to remove the moisture. If either of the solutions known
as _eau de labaraque_ and _eau de javelle_ are used in place of the
bleaching powder, no deposit is left on the wings and the washing with
acid is obviated. This process does not dissolve or remove the scales,
but merely renders them transparent, so that they do not interfere with
the study of the venation.
Prof. C. H. Fernald (_American Monthly Microscopical Journal_, I, p.
172, 1880), mounts the wings of Lepidoptera in glycerin, after having
first cleared them by the Dimmock process. After bleaching and washing,
the wings are dried by holding the slides over an alcohol flame, and a
drop of glycerin is then applied and a cover glass put on at once. By
holding the slide again over the flame until ebullition takes place the
glycerin will replace the air under the wings and no injury to the
structure of the wings will result, even if, in refractory cases, the
wing is boiled for some little time. The mount in this method must be
sealed with some microscopic cement, as asphalt or Brunswick black.
A method of mounting wings of small Lepidoptera for studying venation,
which I have found very convenient, is thus described by Mr. Howard in
_Insect Life_, Vol. I, p. 151:
"Some years ago we used the following method for studying the venation
of the wings of small Lepidoptera. We have told it since to many
friends, but believe it has not been published. It is in some respects
preferable to the so-called 'Dimmock process,' and particularly as a
time-saver. It is also in this respect preferable to denudation with a
brush. The wing is removed and mounted upon a slide in Canada balsam,
which should be preferably rather thick. The slide is then held over the
flame of an alcohol lamp until the balsam spreads well over the wing.
Just as it is about to enter the veins, however, the slide is placed
upon ice, or, if in the winter time, outside the window for a few
moments. This thickens the balsam immediately and prevents it from
entering the veins, which remain permanently filled with air and appear
black with transmitted light. With a little practice one soon becomes
expert enough to remove the slide and cool it at just the right time,
when the scales will have been rendered nearly transparent by the
balsam, while the veins remain filled with air. We have done this
satisfactorily not only with Tortricidæ and Tineidæ, but with Noctuids
of the size of _Aletia_ and _Leucania_. The mounts are permanent, and we
have some which have remained unchanged since 1880. Prof. Riley had for
some years before this been in the habit of mounting wings in balsam, in
which of course the scales cleared after a time."
Prof. John B. Smith recommends a modification of the Dimmock process of
bleaching the wings of Lepidoptera, publishing it in Insect Life, Vol.
I, pp. 291, 292, as follows:
"By the Dimmock process the wings are first acted upon by a saturated
solution of the chloride of lime, chlorine being, of course, the
bleaching agent. Afterward they are washed in water to which
hydrochloric acid has been added, to get rid of the slight deposit of
lime. The process is a slow one for thickly scaled, dark-colored
insects, and it occurred to me to try a mixture of the chloride and
acid, liberating the chlorine gas. The method was absolutely successful,
the wings decolorizing immediately and being ready for the slide within
two minutes. In fact, very delicate wings can scarcely be taken out
quick enough, and need very little acid. The advantage is the rapidity
of work and the certainty of retaining the wings entire, the chloride of
lime sometimes destroying the membrane in part before the bleaching is
complete. The disadvantage is the vile smell of the chlorine gas when
liberated by the combination of the two liquids. For quick work this
must be endured, and the beauty and completeness of the result are also
advantages to counterbalance the discomfort to the senses."
For further special directions for mounting, for microscopic purposes,
different insects and the different parts of insects, representing both
the external chitinous covering and the internal anatomy, the student is
referred to special works.
PRESERVATION OF ALCOHOLIC SPECIMENS.
APPARATUS AND METHODS.--The collections of most value, especially to our
various agricultural colleges and experiment stations will be largely of
a biologic and economic character, and the interest attaching to a
knowledge of the life history of insects will induce many collectors to
build up independent biologic collections. Very much of this biological
material will be alcoholic, and though many immature states of insects
may be preserved by dry processes, still the bulk must needs be kept in
liquid. This material may, when not abundant, be kept with the general
systematic collection, but experience has shown that it is better to
make a separate biological collection, and this is recommended
especially for State institutions where the collections may be expected
to attain some considerable proportions. In the case of such collections
it is very desirable to adopt some method of securing the vials in such
a manner that they can easily be transferred from one place to another
and fastened in the boxes or drawers employed for pinned insects. For
directions in this regard I reproduce from an article on the subject in
_Insect Life_, Vol. II, pp. 345, 346, which was republished, with slight
changes, from my annual report for 1886 as Honorary Curator.[7]
[7] Annual Report of the Smithsonian Institution for 1886, Part II,
Report of the National Museum, pp. 182-186. Washington, 1890.
_Vials, Stoppers and Holders._--The vials in use to preserve such
specimens as must be left in alcohol or other liquids are straight glass
tubes of varying diameters and lengths, with round bottom and smooth
even mouth. The stoppers in use are of rubber, which, when tightly put
into the vial, the air being nearly all expelled, keep the contents of
the vial intact and safe for years.
Various forms of bottles are used in museums for the preservation of
minute alcoholic material. I have tried the flattened and the square and
have studied various other forms of these vials; but I am satisfied that
those just described, which are in use by Dr. Hagen in the Cambridge
Museum, are, all things considered, the most convenient and economical.
A more difficult problem to solve was a convenient and satisfactory
method of holding these vials and of fastening them into drawers or
cases held at all angles, from perpendicular to horizontal. Most
alcoholic collections are simply kept standing, either in tubes with
broad bases or in tubes held in wooden or other receptacles; but for a
biologic collection of insects something that could be used in
connection with the pinned specimens and that could be easily removed,
as above set forth, was desirable. After trying many different
contrivances I finally prepared a block, with Mr. Hawley's assistance,
which answers every purpose of simplicity, neatness, security, and
convenience. It is, so far as I know, unique, and will be of advantage
for the same purpose to other museums. It has been in use now for the
past six years, and has been of great help and satisfaction in the
arrangement and preservation of the alcoholic specimens, surpassing all
other methods for ease of handling and classifying.
The blocks are oblong, one-fourth of an inch thick, the ends (_c c_,
Fig. 112) beveled, the sides either beveled or straight, the latter
preferable. They vary in length and breadth according to the different
sizes of the vials, and are painted white. Upon the upper side of these
blocks are fastened two curved clamps of music wire (_b b_), forming
about two-thirds of a complete circle. The fastening to the block is
simple and secure. A bit of the wire of proper length is first doubled
and then by a special contrivance the two ends are bent around a mandrel
so as to form an insertion point or loop. A brad awl is used to make a
slot in the block, into which this loop is forced (_e_, Fig. 112, 5), a
drop of warm water being first put into the slot to soften the wood,
which swells and closes so firmly around the wire that considerable
force is required to pull it out. Four pointed wire nails (_d d d d_),
set into the bottom so as to project about one-fourth inch, serve to
hold the block to the cork bottom of the case or drawer in which it is
to be placed. The method of use is simple and readily seen from the
accompanying figures, which represent the block from all sides.
The advantages of this system are the ease and security with which the
block can be placed in or removed from a box; the ease with which a vial
can be slipped into or removed from the wire clamps; the security with
which it is held, and the fact that practically no part of the contents
of the vial is obscured by the holder--the whole being visible from
above.
The beveled ends of the block may be used for labeling, or pieces of
clean cardboard cut so as to project somewhat on all sides may be used
for this purpose, and will be held secure by the pins between the block
and the cork of the drawers.
[Illustration: FIG. 112.--Vial holder; 1, block, with vial, beveled on
all sides; 2, do., beveled only on ends; 3, block, end view; 5, do.,
section; 4, 6, do., side views; _a_, block; _b_, spring-wire clamps;
_c_, beveled ends of block; _d_, pointed wire nails; _e_, point of
insertion of clamp. (Lettering on all figures corresponds.)]
The use of rubber stoppers in this country was first instituted by Dr.
H. A. Hagen in connection with the Cambridge biological collection, and
he has made some very careful records to determine the durability of
such stoppers. From an examination of some seven thousand vials with
rubber stoppers, two-thirds of which had been in use for from ten to
twelve years, he comes to the conclusion that less than one in a
thousand gives out every year after twelve years' use, and in the first
six years probably only one out of two thousand. Stoppers of large size
keep much longer than those of small size. American rubber stoppers are
all made of vulcanized India rubber and have the disadvantage of forming
small crystals of sulphur about the stopper, which become loosened and
attach themselves to the specimens. It is supposed that pure
rubber-stoppers used for chemical purposes would not present this
disadvantage, which may be obviated, however, or very much reduced, if
the stoppers are washed or soaked, preferably in hot water, for an hour
or two at least.
If stoppers are stored for a considerable time and exposed to the air
they become very hard and unfit for use, and Dr. Hagen has drawn
attention to a method recommended by Professor W. Hemple, of Dresden,
Saxony, of preventing them from becoming thus hardened. He says that to
keep rubber stoppers or rubber apparatus of any sort elastic, they
should be stored in large glass jars in which an open vessel containing
petroleum is placed. This treatment prevents the evaporation of the
fluids which are fixed in the rubber in the process of vulcanization. It
is better also to keep the light from the jar. To soften stoppers which
have already become hardened, they should be brought together in a jar
with sulphuret of carbon until they are pliable and afterward kept as
recommended above.
In the use of the rubber stopper the novice may find some difficulty in
inserting it in a vial filled with alcohol. The compression of the
alcohol, or alcohol and air when the vial is not completely filled,
forces the stopper out, and this is true whether of rubber or cork. If a
fine insect pin is placed beside the cork when this is thrust into the
bottle, the air or liquid displaced by the cork will escape along the
pin and the latter may then be removed and the cork remains securely in
position.
If cork stoppers have been used the vials may be stored in large
quantities together in jars filled with alcohol. This will prevent
evaporation of the alcohol from the vials, and the specimens may be
preserved indefinitely. This is only desirable in the storage of
duplicate specimens and unarranged material and is not recommended as a
substitute for the use of the rubber stopper. With cork stoppers
evaporation can be in a measure prevented if the cork is first anointed
with the petroleum preparation known as vaseline. This substance is
practically unaffected at ordinary temperature and is sparingly soluble
in cold alcohol. Experiments with it have shown that at ordinary spring
and summer temperatures there is no appreciable loss of alcohol from
vials and jars.
My old method of keeping alcoholic specimens, which I abandoned for the
method outlined above, was fairly serviceable, inexpensive, and warrants
description.
I had special folding boxes constructed resembling in exterior
appearance a large insect box. The bottom of the box was solid and was
made by gluing together two 1½-inch planks.
Holes extending nearly through the lower plank and of various sizes to
accommodate vials of different diameters were bored as closely together
as the wood justified without splitting or breaking.
The holes were numbered consecutively and the vials when placed in them
were numbered to correspond; the box also had its number, and in the
notes the vial was referred to by number of box and vial thus, 3/73 (box
3, vial 73). The vial should project one-half to 1 inch above the hole,
and should be loose enough to provide for the swelling of the wood in
moist weather.
To protect the vials a cover having a depth of about 1½ inch was hinged
to the back and secured in front by hook-and-eye fastenings.
This method of storing vials is satisfactory enough for private
collections, but for larger public collections is not so suitable.
[Illustration: FIG. 113.--The Marx tray for alcoholic specimens
(original.)]
A rather convenient and inexpensive method of storing vials is that used
by Dr. Marx. In this method the vials are stored in a wooden frame,
shown at Fig. 113. The top piece of the tray into which the vials are
thrust has a cork center, in which holes corresponding to the size of
the vials are made with a gun-wad punch. The outer end of the tray bears
a label or labels describing the material in the tray. The vials used by
Dr. Marx are of thinner glass than those which I recommend and flare
slightly at the top, as shown in the accompanying illustrations. They
are made in various sizes to accommodate larger and smaller specimens. A
vial thrust into the hole punched in the cork rests on the bottom piece
of the tray, the flange or neck preventing it from sliding through.
These trays are arranged on shallow shelves in a case or cabinet,
especially constructed for the purpose and a large quantity of material
may be stored by their use in small compass. The use of the cork center
piece in the upper part of the tray is not a necessity, and a wooden
piece may be used in which holes are bored with a bit of proper size.
[Illustration: FIG. 114.--Vials used in the Marx tray (original.)]
_Preserving Micro-larvæ in Alcohol._--The following is quoted from
Packard's "Entomology for Beginners," for which it was translated from
the "_Deutsche Ent. Zeitg._," 1887, Heft I:
"Dr. H. Dewitz mounts the larvæ and pupæ of Microlepidoptera, and also
the early stages of other small insects, in the following way: The
insects are put into a bottle with 95 per cent alcohol. Many larvæ turn
black in alcohol, but boiling them in alcohol in a test tube will bleach
them. They may then be finally placed in glass tubes as small and thin
as possible, varying from 0.003 to 0.006 meter in diameter, according
to the size of the insects. About 0.07 meter's length of a tube is
melted over a spirit lamp, and the tube filled three-quarters full with
95 per cent alcohol, the insects placed within and the contents of the
tube heated at the end still open, and then closed by being pulled out
with another piece of glass tubing. After the glass has been held a few
minutes in the hand until it is slightly cooled off, the end closed last
is once more held over the lamp so that the points may be melted
together, and this end of the glass may be finished. During the whole
time from the closure of the tube until the complete cooling of the
glass it should be held obliquely in the hand, so that the alcohol may
not wet the upper end, for if the tube is too full it is difficult to
melt it, as the steam quickly expanding breaks through the softened mass
of glass. The tube may be mounted by boring a hole through a cork
stopper of the same diameter as the glass. The stopper is cut into the
shape of a cube, a strong insect pin put through it, and the glass tube
inserted into the hole. It can then be pinned in the insect box or
drawer, near the imago, so that the free end of the glass may touch the
bottom, while the other end stands up somewhat; while to keep the tube
in place the free end resting on the bottom may be fastened with two
strong insect pins. The specimens thus put up can easily be examined
with a lens, and if they need to be taken out for closer examination the
tube can be opened and closed again after a little practice."
[Illustration: FIG. 115.--Method of preserving minute larvæ etc. (After
Dewitz.)]
PRESERVATIVE FLUIDS.--The principal liquids in which soft-bodied insects
may be successfully preserved are the following:
_Alcohol._--As indicated in the foregoing portions of this work, alcohol
is the standard preservative used for soft-bodied specimens, and may be
used either full strength or diluted with water. Diluted alcohol should
always be first used with larvæ, since the pure alcohol shrivels them
up. The weak spirits can afterwards be replaced by strong, for permanent
preservation.
_Alcohol and White Arsenic._--The method of preserving insects
recommended by Laboulbène and quoted in Packard's Entomology for
Beginners, consists in plunging the insects in the fresh state into a
preservative liquid, consisting of alcohol with an excess of the common
white arsenic of commerce. The larva placed in this mixture absorbs .003
of its own weight, and when removed and pinned is safe from the attacks
of museum pests. This liquid is said not to change the colors, blue,
green or red of beetles, if they are not immersed for more than
twenty-four hours. This treatment is applicable to the orders
Coleoptera, Hemiptera, and Orthoptera. If the insect is allowed to stay
in this mixture for a considerable time, say three or four weeks, and
then removed and dried, it becomes very hard and brittle and can not be
used for dissection or study, but makes a good cabinet specimen. The
white deposit of arsenic which will appear on drying can be washed off
with alcohol.
_Alcohol and Corrosive Sublimate._--The same author recommends another
preparation consisting of alcohol with a variable quantity of corrosive
sublimate added, the strength of the solution varying from 100 parts of
alcohol to 1 part of corrosive sublimate for the strongest, to one-tenth
of 1 part of sublimate in 100 parts of alcohol for the weakest. The
insects are allowed to remain in this mixture not longer than two hours
before drying. The last-described preparation is said to preserve the
specimens from mold. Both of these solutions are very poisonous and
should be used with care.
_Two Liquids to preserve Form and Color._--Professor Packard also quotes
the formula of A. E. Verrill for preserving insects in their natural
color and form. Two formulas are given; the first consists of 2½ pounds
of common salt and 4 ounces of niter dissolved in a gallon of water and
filtered. The specimens should be prepared for permanent preservation in
this solution by being previously immersed in a solution consisting of a
quart of the first solution and 2 ounces of arsenite of potash in a
gallon of water. Professor Packard gives also the formula of M. H. Trois
for preserving caterpillars, for which it is claimed that the colors of
the caterpillars are preserved perfectly, even when exposed to strong
light. The formula for this solution is as follows:
Common salt grams 2.35
Alum do. 55
Corrosive sublimate centigrams 18
Boiling water liters 5
Allow the liquid to cool and add 50 grains of carbolic acid, and filter
after standing five or six days.
_Glycerin._--Glycerin, either pure or mixed with water or alcohol, is
frequently used to preserve the larvæ of delicate insects. It preserves
the color and form better than alcohol, but particularly in the case of
larvæ, it causes a softening of the tissues which renders them unfit for
study.
_The Wickersheim Preserving Fluid._--This valuable preserving fluid has
been known for some time, but is not very commonly used, on account of
frequent disappointment due to the difficulty attending its preparation.
It is claimed for it that animal or vegetable bodies impregnated with it
will retain their form, color, and flexibility in the most perfect
manner. The objects to be preserved are put in the fluid for from six to
twelve days, according to their size, and then taken out and dried in
the air. The ligaments remain soft and movable, and the animals or
plants remain fit for anatomical dissection and study for long periods,
even years. It is said to be especially valuable for the preservation of
larvæ and soft-bodied insects. In order to perfectly preserve the
colors, it is necessary to leave the specimens in the fluid, or, if they
are taken out, they should be sealed up in air-tight vials or vessels.
The formula for the fluid is as follows:
Dissolve 100 grams alum, 25 grams common salt, 12 grams saltpeter, 60
grams potash, 10 grams arsenious acid in 3,000 grams boiling water.
Filter the solution, and when cold add 10 liters of the liquid to 4
liters of glycerin and 1 liter of methyl alcohol.
LABELING SPECIMENS.
_General Directions._--It matters little how much care and pains have
been taken in the preparation and mounting of specimens, they will have
little value unless accompanied by proper labels giving information as
to locality and date of collection, name of collector, and a label or
number referring to notebooks, if any biological or other facts
concerning them have been ascertained. There should be pinned to the
specimen labels referring to, or giving all the information obtainable
or of interest concerning it. A somewhat different style of label will
be found necessary in the case of the two forms of collections described
in the foregoing pages, namely, the biological or economic collection,
and the systematic collection. For the former, numbers may be attached
to the specimens which will refer to the notes relating to the specimen
or species. For the latter, in most cases, all necessary information may
be recorded and made available by written or printed labels attached
directly to the specimens. In most cases, however, I find a combination
of these two systems convenient and desirable. The numbering system is
very simple, and is the one which I have followed in all the species for
which I have biological or other notes. It consists in giving each
species, as it comes under observation, a serial number which refers to
a record in a notebook. With this number may be combined, if convenient,
the date of rearing or collection of the specimen, and also the locality
and food-plant if known. The vast number of species represented in a
systematic collection renders the numbering system entirely out of place
and inadequate, and the labeling system alone is generally available. If
it becomes necessary in the systematic collection to refer to
food-plants or life-history or any other fact of interest, the numbering
system should be used, and I recommend that the numbers be written in
red ink on the labels, to distinguish at a glance the numbers referring
to biological notes from other numbers that will occur in the
collection.
_Labels for pinned Specimens._--The following labels should be employed
in the collection: (1) _Locality label_, which should be as explicit as
possible. (2) _Date of capture_, which is very useful and sometimes
quite important in various ways. It indicates at what time additional
specimens of some rare species may be secured, and greatly assists in
elaborating the life history of the species, and in other cases assists
in the correct determination of closely allied insects, which differ
chiefly in habit or date of appearance. (3) _A label to indicate the
sex_. This label has recently acquired greater importance than formerly,
on account of the value of the sexual differences in the distinction of
species. The well-known signs for male, female, and worker, printed in
convenient form, are well adapted for collections. (4) _The name of the
collector_. This label is of less value, but sometimes becomes important
in determining the history of the specimen or the exact place of
capture. The name of the species is not necessarily attached to all the
specimens in a collection, and ordinarily will be placed with the first
specimen in a series in the cabinet. This and other labeling of insects
in cabinet is discussed in another place. Other labels are useful to
indicate type specimens, namely, those of which descriptions have been
drawn up and published, and which should be designated by a special
label written by the author himself. Determinations by an authority in a
special group should be indicated, and the labels placed on specimens by
such an authority should not be removed.
It will not be found necessary to use a separate label for each of the
data indicated above, and a single label may be made to combine many of
them, as, except for the specific names of the insects themselves (which
should always be on the lowermost label), most other words will bear
abbreviation, especially localities and dates. "A combination label,
which has given general satisfaction to all to whom it has been
communicated, is a two-line label printed in diamond type, on heavy
writing paper. The upper line consists of the name of the locality, _e.
g._, 'Washngtn' (a name consisting of more than eight letters to be
abbreviated), and the lower line has at the right-hand corner 'DC'
(interpunctuation and spacing to be avoided so as to save space). This
leaves on the second line sufficient room for inserting the date, which
can be quickly and neatly written with ink if the labels are printed in
columns of ten or more repetitions. The label thus combines locality
with date of capture. Or the upper line reads 'Arizona' and the lower
line 'Morrison,' the label thus combining locality with the name of the
collector."[8]
[8] E. A. Schwarz, Proc. Ent. Soc., Wash., II, No. 1, 1891.
In general I indorse the system of labeling suggested in the above
condensation from Mr. Schwarz, but there is no particular disadvantage,
and in fact many advantages, in special cases, in a larger label or in
folded labels. Particularly in visiting large foreign collections I have
found it convenient to use large labels of thin paper which will contain
a good deal of information closely written in pencil and bear folding
several times, so as not to occupy more than the ordinary label space
when pinned to the specimens. This involves detaching the label when the
specimen or species comes to be studied, but this additional labor is
insignificant compared with the large amount of valuable information
which in time is thus brought together in condensed availability for the
student; for brief notes of opinions of experts, of comparison with
types, of special studies, of reference to descriptions, etc., may thus
be all brought together. Where there is not room to indicate the
authority for a determination on the upper side of a label, I also find
it convenient to do so on the lower side.
[Illustration: FIG. 116.--Cabinet for apparatus used in mounting and
labeling. (Original).]
_Labeling alcoholic Specimens._--Alcoholic specimens, including
alcoholic biologic material and collections of Arachnida and Myriapoda,
are well adapted to the labeling system, as the vials are always of
sufficient size to allow the insertion of one or more labels large
enough to contain a pretty full record of the specimen. The label may
consist of a number referring to notes, or of a number together with the
other data indicated for the systematic collection. The label in my
experience is preferably written in pencil, which, in alcohol, is
practically permanent. Waterproof inks are sometimes used, and of these
the oak-gall ink is undoubtedly the best. Dr. George Marx, in labeling
his Arachnida, uses onion-skin paper and waterproof ink, such as
Higgins's drawing ink. There is some danger, in placing a label in a
vial, of its settling against the specimen and injuring it. This,
however, can generally be avoided if a little care is used. The label
may be long and narrow and folded lengthwise so as to occupy one side
only of the vial, or short and inserted in such manner that it will pass
around the inside of the vial, where it will be held by the natural
adhesion to the glass in the upper portion of the vial, as shown at Fig.
114.
_Cabinet for Apparatus._--The work of preparation of insects for the
cabinet may be greatly facilitated if a convenient case is provided with
drawers and compartments for the keeping of pins of different sizes,
labels, braces, implements, tweezers, dissecting apparatus, and the
like, with microscopical supplies--slides, cover glasses, mounting
media, etc. I present a photograph of a cabinet of this sort used in my
earlier work and found very convenient and serviceable (Fig. 116).
INSECT BOXES AND CABINETS.
_General Directions._--The boxes or cases which are used to keep insects
in permanently may be made of any dimensions to suit the fancy, 12 by 16
inches inside being a convenient size and allowing economic use of cork.
They must, however, be perfectly tight and should not be more than 2½
inches deep on the inside. The bottoms should be lined with something
which will hold the pins, and the whole inside covered with white paper,
which, if delicately cross ruled, will facilitate the regular pinning of
specimens. While the size and style of the box and cabinet may be left
to individual taste, some choice must be had of material. _Red cedar
should never be used._ I have learned, to my sorrow, the baneful effects
of this wood, notwithstanding it is recommended--evidently by those who
are guiltless of having used it--as having the advantage over other wood
of keeping off museum pests. It seems impossible to get this wood so
seasoned but that a certain amount of resin will continually exude from
it; and insects in boxes of this material are very apt to soften and
become greasy. Paper boxes are also bad, as they attract moisture and
cause the specimens to mold. Well-seasoned pine and whitewood are the
most satisfactory; and, in such boxes as have glass covers and are
intended to form part of a neat cabinet for parlor ornament, the fronts
may be of walnut or cherry.
The character of the boxes and cabinets used for storing insects will
depend largely on the nature and extent of the collection and the object
of the collector. For temporary use, nothing is more convenient and
economical than a cigar box lined with cork or pith. Such boxes,
however, should be employed only for the temporary storage of fresh
specimens, as they afford free access to museum pests, and insects kept
in them for any length of time are apt to be destroyed or rendered
useless.
_The Folding-box._--The use of folding-boxes for the working collector
is to be especially recommended in the case of those orders comprising
small insects like Coleoptera, Hymenoptera, etc. These boxes have the
great advantage of being readily rearranged on the shelves and of being
very easily used in study. The boxes of this type now manufactured by
John Schmidt, of Brooklyn, N. Y., and John Burr, of Camden, N. J., based
on the experience which I have had, have proved so serviceable and
satisfactory in this respect that I have employed them for the bulk of
the collection in the National Museum. These boxes (Fig. 117) are
constructed as follows:
[Illustration: FIG. 117.--The Schmidt folding insect box, opened and
showing arrangement of insects (original).]
They are of white pine, shellacked and varnished, the bottom and top
double and crossgrained, to prevent warping, and projecting slightly at
all sides except the hinged back. They are 13 by 8¼ inches outside
measurement. The inside measurement is 11¾ by 7. The sides, back, and
front are five-sixteenths of an inch thick, with a machine joint, which
is neat and very secure. The boxes are 2 5/8 inches in outside depth,
unequally divided, the lower portion 1½ inches outside depth, lined
inside with a thin whitewood strip, projecting three-fourths of an inch
above the rim of the outside box. Over this projecting lining the lid
closes as tightly as practicable and is kept from springing by hooks and
eyes. The bottom is cork-lined and covered with a fine, white, glazed
paper.
Similar folding boxes with both sides of equal depth and both lined with
cork, when properly covered, may be made to look like books and be set
on end in an ordinary bookcase, but the single lining is preferable, as
there is less danger of the breakage of specimens and the boxes may
either be laid flat one on the other on shelves, or, what is more
convenient, placed side by side resting on the front edge, so that the
label is attached to one of the narrow ends. The rows of insects are
then pinned crosswise, not lengthwise, of the box, with the abdomens
turned toward the front which rests on the shelf.
All the boxes are furnished with neat brass label-holders, in which a
card containing a list of the contents can readily be placed and removed
at pleasure. The chief demerit of this box which I have endeavored to
overcome by the above details is the tendency to warp and crack in the
trying steam heat of our Government buildings.
_The Cabinet._--For larger insects, such as Lepidoptera, Neuroptera,
etc., a larger box is desirable, and for these orders I have adopted for
use in the National Museum a cabinet which resulted from a careful study
in person of the different forms and patterns used for entomological
collections both in this country and Europe, whether by private
individuals or public institutions. The drawer and cabinet are
essentially after the pattern of those used in the British (South
Kensington) Museum, but adapted in size to our own requirements. In the
use of the National Museum these cabinets have proved eminently well
adapted to their object.
[Illustration: FIG. 118.--Construction of insect cabinet drawer of the
National Museum. A, cross-section _f_ front; B, same _f_ side; C, view
of front end of side, 2/3 natural size (original).]
The drawers (Fig. 118, A, B, C) are square, with an outside measurement
of 18 inches and an outside depth of 3 inches. The sides and back have a
thickness of three-eighths of an inch, while the front is five-eighths
of an inch thick. The pieces are firmly dovetailed together, the front
being clean and the dovetailing blind. The bottom, _a_, is of three-ply
crossgrained veneer, run into a groove at the sides, leaving a clear
inside depth of 2 1/16 inches to the frame of the cover. The bottoms are
lined in all but forty of the drawers with first quality cork, _b_,
one-fourth of an inch thick. At a distance of one-fourth of an inch from
the sides and back and three-eighths of an inch from the front there is
an inside box of one-eighth inch whitewood, _c_, closely fitted, and
held in place by blocks between it and the outer box. There is thus
between the inner and outer box a clear space, _d_, all round, in which
insecticides or disinfectants can be placed to keep out Museum pests,
making it impossible for such to get into the inner box containing the
specimens without first passing through this poison chamber. The entire
inside is lined with white paper, or, in the case of the uncorked boxes,
painted with zinc white. The front is furnished with a plain knob. The
cover is of glass, set into a frame, _f_, three-fourths of an inch wide,
three-eighths of an inch thick, with a one-fourth inch tongue fitting
closely into the space between the inner lining and outer box, which
here serves as a groove. This arrangement furnishes a perfectly tight
drawer of convenient size and not unwieldy for handling when studying
the collection.
The material of which these drawers are made is California red wood,
except the cover frame, which is mahogany. The cabinets containing these
drawers are 36 inches high, 40 inches wide, 21 inches deep (all outside
measurements), and are closed by two paneled doors. Each cabinet
contains twenty drawers in two rows of ten each, and the drawers slide
by means of a groove, _g_, on either side, on hard-wood tongues, and are
designed to be interchangeable.
_The Lintner display Box._--For beauty and security and the perfect
display of the larger _Lepidoptera_, I have seen nothing superior to a
box used by Mr. J. A. Lintner, of Albany, N. Y. It is a frame made in
the form of a folio volume, with glass set in for sides and bound in an
ordinary book cover. The insects are pinned onto pieces of cork fastened
to the inside of one of the glass plates and the boxes may be stood on
ends, in library shape, like ordinary books. For the benefit of those
who wish to make small collections of showy insects, I give Mr.
Lintner's method, of which he has been kind enough to furnish me the
following description:
Figs. A, B, and C represent, in section, the framework of the volume,
_a_ showing the ends, _b_ the front, and _c_ the back. The material can
be prepared in long strips of some soft wood by a cabinet-maker (if the
collector has the necessary skill and leisure for framing it) at a cost
of 60 cents a frame, if a number sufficient for a dozen boxes be
ordered. Or, if it be preferred to order them made, the cost should not
exceed 80 cents each.
Before being placed in the hands of the binder the mitering should be
carefully examined and any defect in fitting remedied, so that the
glass, when placed in position, may have accurate bearings on all the
sides. The interior of the frame is covered with tin foil, made as
smooth as possible before application, to be applied with thoroughly
boiled flour paste (in which a small proportion of arsenic may be mixed)
and rubbed smoothly down till the removal of the blisters, which are apt
to appear. The tin foil can be purchased, by weight, at druggists', and
the sheets marked off and cut by a rule in strips of proper width,
allowing for a trifle of overlapping on the sides. Its cost per volume
is merely nominal.
First-quality single-thick glass for sides must be selected, wholly free
from rust, veins, air-bubbles, or any blemish. Such glass can be
purchased at 15 cents a pane. The lower glass, after thorough cleaning,
especially of its inner surface, with an alkaline wash, and a final
polishing with slightly wetted white printing paper, is to be firmly
secured in its place by a proper number of tin points; the upper glass
is but temporarily fastened. The binder must be directed to cover the
exposed sides of the frame with "combed" paper, bringing it over the
border of the permanent lower glass and beneath the removable upper
glass.
[Illustration: FIG. 119.--Construction of the Lintner box.]
The covers of the volume are of heavy binders' board (No. 18), neatly
lined within with glazed white paper. On one of the insides of the lids
may be attached, by its corners, a sheet with the numbers and names of
the species contained in the volume, or these may be placed on the pin
bearing the insect. If bound in best quality of imitation morocco, with
cloth covers, lettered and gilded on the back, the cost (for a dozen
volumes) need not exceed $1 each. If in turkey morocco, it will be
$1.50.
The lettering and ornamentation of the back will vary with the taste of
the individual. The family designations may be permanently lettered, or
they may be pasted on the back, on a slip of paper or gum label, as are
the generic names, thus permitting the change of the contents of a
volume at any time if desired.
The bits of cork to which the insects are to be pinned are cut in
quarter-inch squares from sheet-cork of one-fourth of an inch in
thickness. If the trouble be taken to trim off the corners, giving them
an octagonal form, their appearance will be materially improved and much
less care will be required in adjusting them on the glass.
The cement usually recommended for attaching the cork to the glass is
composed of equal parts of white wax and resin. My experience with this
has not been favorable, for, after the lapse of a few years, I have
invariably been subjected to the serious annoyance of being compelled to
renew the entire contents of the volume, clean the glass, and replace
the corks with new cement. From some cause, inexplicable to me, a
gradual separation takes place of the cork with its cement from the
glass, first appearing at the angles of the cork, and its progress
indicated by an increasing number of iridescent rings which form within
until the center is reached, when, if not previously detached, the
insect falls with the cork, usually to its injury and that of others
beneath it.
A number of years ago I happened to employ, in attaching a single piece
of cork in one of my cases, a cement originally made for other purposes,
consisting of six parts of resin, one of wax, and one of Venetian red.
Several years thereafter my attention was drawn to this piece by finding
it as firmly united as when at first applied, and at the present time
(after the lapse of twelve years) it is without the slightest indication
of separation. Acting upon this hint, I have, of late, used this cement
in the restoration of a number of my cases, and with the most
satisfactory results. It is important that the cement, when used, should
be heated (by a spirit lamp or gas flame) to as high a degree as it will
bear without burning. An amount sufficient to cover the bottom of the
small, flat metal vessel containing it to the depth of an eighth of an
inch will suffice and prevent the cork from taking up more than its
requisite quantity. It should be occasionally stirred to prevent the
precipitation of its heavier portions. The cork may be conveniently
dipped by the aid of a needle inserted in a handle, when, as quickly as
possible, it should be transferred to the glass, for the degree of
adhesion seems to depend upon the degree of fluidity of the cement. From
some experiments made by me, after the corks had been attached as above,
in heating the entire glass to such a degree as thoroughly to melt the
cement until it spreads outward from beneath the weight of the cork, and
then permitted to cool--the glass meanwhile held horizontally, that the
corks might not be displaced--the results appear to indicate that the
above cement, applied in this manner on glass properly cleaned, will
prove a permanent one. It is scarcely necessary to state that this
method is not available where the glass has been bound as above.
Preparatory to corking the glass for the specimens assigned to it, the
spaces required for them are to be ascertained by arranging them in
order on a cork surface or otherwise. On a sheet of paper of the size of
the glass, perpendicular lines, of the number of the rows and at their
proper distances, are to be drawn, and cross lines equal in number to
the insects contained in the rows. The distances of these lines will be
uniform, unless smaller specimens are to occupy some portion of the
case, when they may be graduated to the required proportion. With the
sheet ruled in this manner and placed beneath the glass, the points
where the corks are to be applied are indicated by the intersections of
the lines. The sheet, marked with the family of the insects for which it
was used and with the numbers designating its divisions, may be laid
aside for future use in the preparation of other cases for which it may
be suitable. In a series of unbound cases in my collection, in which the
glasses measure 11 by 14½ inches, I have used for my Lepidoptera and
laid aside the following scales, the citation of which will also serve
to show the capacity of the cases: 3 by 8, Catocalas; 2 by 7 and 3 by 9,
Sphingidæ; 4 by 11 to 4 by 14, Bombycidæ; 5 by 13 to 6 by 16, Noctuidæ;
8 by 16 and 8 by 20, Lycænidæ and Tortricidæ.
The unbound cases above referred to are inexpensive frames, made by
myself, of quarter-inch white wood or pine, the corners mitered, glued,
and nailed with three-quarter inch brads, lined within with white paper
(better with tin foil), and covered without with stout manila paper. The
glasses are cut of the size of the frame, and when placed in position
thereon are appressed closely to it by laying upon them, near each
corner, a heavy weight, and strips of an enameled green paper, cut to
the width of 1 inch, are pasted over their edges, extending a little
beyond the thickness of the frame, and brought downward over the outside
of the frame. On its back two gum labels, indicating the insects
inclosed, are placed at uniform heights (7 and 12 inches), when, if all
has been neatly done, they present a tasteful appearance upon a shelf.
When there is reason to believe that the case will need to be opened
for the change or addition of specimens, it will be found convenient to
employ, for the fastening of the left-hand side of the upper glass,
paper lined with a thin muslin, to serve as a hinge when the other sides
have been cut.
Should it become desirable to bind these cases, outside frames may be
constructed after the plans above given, with the omission of the inside
quarter inch (the equivalent of these frames), in which these may be
placed and held in position by two or three screws inserted in their
sides.
_The Martindale Box for Lepidoptera._--Mr. Isaac C. Martindale, in the
October, 1891, number of _Entomological News_, pp. 126, 127, describes a
new form of cabinet for butterflies, the drawers of which present some
new features. They are for the same end as the Lintner box described
above--namely, for the display of the upper and under surface of the
wings of Lepidoptera, and promise to be more useful. The drawer is
described as follows:
The especial feature is the drawer itself, which, instead of having a
cork bottom, as is usually the case, has both the top and bottom of
glass. The top part of the drawer frame fits tightly over a ledge one
inch in height, effectually preventing the intrusion of destructive
insects, the pest of the entomologist; but it is readily lifted when it
is desirable to add to the contents or change the location of the
specimens. For the inside arrangement I have taken a strip of common
tin, one inch wide, and turned up each side five-sixteenths of an inch,
thus leaving three-eighths of an inch for the bottom. The length of the
strip of tin, being about two inches longer than the width of the
drawer, admits of each end being turned up one inch. Into this tin
trough is tightly fitted a cork strip three-eighths of an inch square.
The whole being covered with white paper, such as is usually used for
lining drawers, conceals the inequalities of the cork and makes a fine
finish. They should be made to fit neatly in the drawer, and can be
readily moved about to suit large or small specimens. For _Lycænas_,
_Pamphilas_, etc., as many as fifteen of these strips may be used in one
drawer, and as few as five for _Morphos_, _Caligos_, etc. The upturned
ends are fastened in place by using the ordinary thumb tacks that can be
procured at any stationer's. The frame work of the drawers should be of
white pine, well seasoned. Into this the thumb tacks are readily
inserted and as easily withdrawn when a change in the position of the
cork strips is needed.
_Horizontal vs. vertical Arrangement of Boxes._--I have elsewhere
discussed the availability of the upright vs. the horizontal arrangement
of insect boxes.[9] In the case of Lepidoptera and large-bodied insects
I have found the horizontal drawer or box to be preferable. If
large-bodied insects are placed in a vertical position they are very
liable to become loose on the pins, swing from side to side, and damage
themselves and other specimens; but for the smaller insects of all
orders, the vertical arrangement is quite safe and satisfactory. If the
pin is slightly flattened, as described on p. 69, the danger of large
specimens becoming loose is to a great extent avoided.
[9] _American Naturalist_, Vol. XV, p. 401, 1881.
_Lining for Insect Boxes._--The old lining of insect boxes was the
ordinary sheet cork of commerce, and if a good quality of cork is
procurable it will answer the purpose. A better substance, however, for
the lining of insect boxes is the prepared or ground cork, which is now
almost exclusively used. It is simply ground cork mixed with a small
amount of glue, compressed into sheets and covered with paper. This
gives a very homogenous composition, and is much better than the
ordinary cork, having a more uniform and neat appearance, and admitting
the insertion of the pins more freely. It may be purchased from H.
Herpers, 18 Crawford street, Newark, N. J.
A less expensive substitute is paper stretched upon a frame. Prof. E. S.
Morse has given in the "American Naturalist" (Vol. i, p. 156) a plan
which is very neat and useful for lining boxes in a large museum, which
are designed to be placed in horizontal show-cases (Fig. 120). "A box is
made of the required depth, and a light frame is fitted to its interior.
Upon the upper and under surfaces of this frame a sheet of white paper
(drawing or log paper answers the purpose) is securely glued. The paper,
having been previously damped, in drying contracts and tightens like a
drumhead. The frame is then secured about one-fourth of an inch from the
bottom of the box, and the pin is forced down through the thicknesses of
paper, and if the bottom of the box be of soft pine, the point of the
pin may be slightly forced into it. It is thus firmly held at two or
three different points, and all lateral movements are prevented. Other
advantages are secured by this arrangement besides firmness: when the
box needs cleaning or fumigation, the entire collection may be removed
by taking out the frame; or camphor, tobacco, or other material can be
placed on the bottom of the box, and concealed from sight. The annexed
figure represents a transverse section of a portion of the side and
bottom of the box with the frame. A A, box; B, frame; P P, upper and
under sheets of paper; C, space between lower sheets of paper and bottom
of box."
[Illustration: FIG. 120.--Paper lining for insect box. (After Morse.)]
Other substitutes are the pith of various plants, especially of corn.
Palm wood and "inodorous felt" are also used, being cut to fit the
bottom of the box.
Pita wood or the light porous wood of the Agave or Century plant when
cut into proper strips also makes a very light and satisfactory lining,
while good close bog-peat cut into proper thicknesses is not
infrequently used in France and Germany. Druce & Co., 68 Baker street,
London, W., England, have lately been manufacturing what is known as
cork carpet, which seems to be a combination of ground cork and rubber.
It comes in various colors and of the proper thickness, and makes a very
smooth and desirable lining, holding the pins very firmly. It cost 90
cents per square yard in England, and I have had one cabinet lined with
it as an experiment, as there is a probability that the pins may corrode
in contact with the rubber.
ARRANGEMENT OF INSECTS IN THE CABINET.
_Systematic and biologic Collections._--The permanent arrangement of
specimens in boxes and drawers will vary somewhat with the nature of the
insects. The almost universal custom of collectors, however, is to
arrange the insects in vertical columns. In the case of the smaller
forms, as Coleoptera, Hymenoptera, Diptera, 2½ to 3 inches in width is
allowed for the columns; and for the larger insects, as Lepidoptera,
Orthoptera, for which larger drawers are recommended, a greater width of
column is needed and 4½ to 5 inches will be found necessary. With
alcoholic material, a similar arrangement in columns may be followed.
In spacing or dividing insect boxes into columns for the arrangement of
specimens, I have followed the plan of pinning narrow strips of colored
paper in the boxes at regular distances to divide the columns of
insects. A fine line made with a medium pencil will answer the same
purpose and will not materially disfigure the box.
The appearance of the collection will largely depend on the care used in
the alignment of the specimens, both vertically and horizontally. It is
advisable to have at least four specimens of a species, which,
entomologically speaking, constitute a set. The collector, however,
should not limit the number of his specimens to four, as it is
frequently necessary to have a larger number to represent, firstly, the
sexes; secondly, varieties; and thirdly, geographical distribution.
In the systematic collection the species should be arranged serially in
accordance with the latest catalogue or monograph, and if the collector
intends making a complete study of the group, space should be left for
the subsequent insertion of species not at present in his possession and
also for new species. This will avoid the rearrangement of the entire
collection at brief intervals.
_Economic Displays._--In the case of economic displays, which will
include pinned specimens, alcoholic material, early states and specimens
illustrating the work of the insect--also the parasitic and predaceous
enemies--the horizontal arrangement can be followed, and I have found it
advisable, in making such displays, to arrange them in this manner, so
that any needed width for the display of particular species may be had.
A good idea of the system of arrangement adopted for an economic exhibit
may be obtained from the accompanying illustration (Pl. I). Every insect
will require a somewhat different treatment, owing to its different
habit, but the plan indicated in the illustration should, in the main,
be followed. Prof. J. H. Comstock uses and recommends a sort of block
system, which consists in pinning the insects and specimens showing
their work, and alcoholic material, to blocks of soft wood. These are
then arranged in the display cases. The advantage claimed for the system
is facility in transferring and rearranging the exhibits. This method is
somewhat cumbersome, and in making and handling economic exhibits I have
found pinning specimens directly to the cork lining of the box, as
already described, to be entirely satisfactory. A biologic exhibit
should be carefully planned beforehand, and when once completed is
permanent and does not require rearrangement, as is frequently necessary
in a systematic collection, owing to the constant changes in
classification. The only alteration necessary is a renewal of specimens
which have become injured, or faded by exposure to light.
_Labeling Collections._--I have already fully discussed the subject of
labeling insects before placing them in their final resting place in the
collection. In the collection certain additional labels are required,
viz, labels for the order, family, subfamily, genus, species, and
sometimes variety. The label for the order should be placed above the
first species in the collection, and should be in large type, as should
also be the name of the family, which is to be placed above the first
species in the family. The genus label should be in prominent type,
somewhat smaller than the family label, and should be placed at the head
of the genus. Custom varies as to placing the label of the species. In
my practice I have adopted the plan of placing the label below the
series of specimens representing the species. Some entomologists reverse
this plan and place the label above the series of specimens. Others
recommend pinning the label to the first and best-determined specimen of
the series. This has the advantage of always keeping the label with the
species and preventing the danger of mistake or confusion of the latter.
In the case of large insects, however, this plan has the disadvantage
that the label can not be seen except by taking out the specimen, and,
on the whole, the plan which I have adopted of placing the label below
the series of specimens is preferable, but may be supplemented by the
other, as in addition to the independent label, one of the specimens
should have a label pinned with it. The labels should be neatly written
on blanks printed for the purpose; but a better plan, perhaps, and one
which I have followed, where possible, in labeling the national
collection, is to cut the names neatly from a catalogue of the insects,
which will furnish all the labels from order to species, and fasten them
with short, inconspicuous pins in their proper places in the collection.
Where it is not desired to keep the collection as compact as possible,
or where one has limited space, I would advise labeling the species, not
only with the recognized name, but also with the synonyms. This requires
some space, and will hardly be followed except in public collections. It
is also desirable to arrange together, and label as such, the varieties
of any given species. The appearance of the collection will depend
largely on the uniformity of the labeling, and too much care can not be
exercised in this respect.
MUSEUM PESTS, MOLD, ETC.
Unfortunately for the well-being of collections, dried insects are
liable to the attacks of various museum pests, the most troublesome of
which are themselves insects, but altogether out of their proper place
and rôle in the general collection. Unless constant precautions are
taken, the collector will discover after a few months that instead of
the rare specimens with the preparations of which he has taken no little
pains there remains only a series of fragmentary specimens, which a few
years' neglect will reduce to little more than a mass of dust or powder.
The price, then, of a good collection is eternal vigilance. Most
insects, when exposed for any length of time to strong light, fade or
lose color, and the only way to prevent such achromatism is to exclude
the light.
Insect pests affecting collections include Psocidæ, Mites, Tineidæ,
Coleoptera of the families Ptinidæ and Dermestidæ, these last being the
most injurious.
[Illustration: FIG. 121.--_Tineola biselliella_: _a_, adult; _b_, larva;
_c_, cocoon and empty pupa--skin enlarged.]
The Psocidæ--degraded wingless insects already referred to in the
classification (p. 24)--will find their way into the tightest boxes, but
ordinarily do little if any damage, except in the case of delicate
insects, such as Ephemerids, Microlepidoptera, and Microdiptera. The
common forms found in collections are _Atropos divinatorius_ and
_Clothilla pulsatoria_. Mites or Acari are rarely troublesome in
collections, though Dr. H. A. Hagen reports having found a species
(probably of Tyroglyphus) with imported insects, and considers them as
liable to become dangerous enemies. Tineid larvæ are rarely found in
collections, and only affect the larger moths. They are not easily
discovered, since they make no dust, as do most other pests. Some
persons have been considerably annoyed by one of the common clothes
moths, _Tineola biselliella_ (Fig. 121). Dr. Hagen found that it
attacked freshly collected or newly spread insects, where the
spreading-boards were left uncovered, but Mr. F. M. Webster has found it
injurious to the general collections at Columbus, Ohio.
Of beetles, the Ptinidæ are sometimes found in collections but are not
common. Two species are known to attack entomological specimens, namely,
_Ptinus fur_, which is quite rare, in this country, but much more
abundant in Europe, and _Tribolium ferrugineum_, a cosmopolitan species
which, however, has several times been associated in injurious numbers
with large collections of insects imported from the East Indies.
But by far the most dangerous enemies of insect collections are the
larvæ of some half dozen or more species of Dermestidæ belonging to the
genera Anthrenus, Attagenus, Trogoderma, and Dermestes. Of these
_Anthrenus varius_ is the more common pest, in museums, especially in
the North and East. In the South and West _Trogoderma tarsale_ and _T.
ornatum_ (?) replace Anthrenus. The European species _Anthrenus
musæorum_, is, on the authority of Hagen, rare in this country, and
probably occurs chiefly in collections of imported insects. It is the
common injurious species of Europe. _Anthrenus scrophulariæ_ (see Fig.
67) occurs also in collections, Dr. Hagen stating that he has found it
nearly as common as _A. varius_, and certainly more dangerous. In my own
experience it is rarely found in insect collections. Two species of
Attagenus (_A. pellio_ and _A. megatoma_) have also been found in
collections. _A. megatoma_ has been found by Dr. Hagen to do not a
little damage to insect collections in Cambridge, as well as to equal if
not exceed the Carpet Beetle in its disastrous attacks upon carpets and
household furniture. The other species, _A. pellio_, is rarely found in
this country, but is much more common and obnoxious in Europe than _A.
megatoma_. _Dermestes lardarius_ is sometimes found in collections, and
is attracted by the presence of animal matter such as skins, etc. The
two particularly destructive pests, as pointed out, are _Anthrenus
varius_ and _Trogoderma tarsale_. These species, together with most of
the others, have no definite breeding period, but, in the uniform
temperature of the laboratory or museum, breed all the year round and
present no definite broods. It is the experience at the Museum that the
boxes on the lower tier of shelves are very much more subject to attack
than those on the upper tiers, from which it would seem that the parent
beetle deposits her eggs outside the boxes on the floor of the cases and
that the young larvæ work their way into the smallest crevices. The
danger of infection by these pests is greater in warm climates like that
of Washington than in regions further north, as the warm season begins
earlier, lasts longer, and furnishes better conditions for breeding and
multiplication.
[Illustration: Fig. 122.--A naphthaline cone.]
REMEDIES.--The following remedies and preventives will prove efficient
in checking or preventing the work of these pests.
_Naphthaline._--Where tight boxes are employed little fear of the work
of these destructive agents need arise, especially if the boxes are kept
supplied with repellent naphthaline cones. These are hard cones of
naphthaline, mounted on pins for convenient placing in the boxes (see
Fig. 122), and may be obtained of dealers in entomological supplies.
Naphthaline cones act as repellents to these insects and also to some
extent retard the development of the larvæ in all stages and
particularly of the eggs.
Mr. Schwarz states (_Proc. Ent. Soc. of Washington_, Vol. I, page 63)
that in place of these cones a form of naphthaline may be used which is
known in commerce as "white carbon," and is put up in the form of small
square rods for use in intensifying the flames of gaslight. The material
is very cheap, costing only 8 cents per pound wholesale, and may be
broken up into small pieces, wrapped in paper, and pinned. The use of
naphthaline cones is not advisable in boxes containing delicate
specimens, as it leaves a deposit which dulls the colors and encourages
greasing. The deliquescence of the naphthaline cones produces a
blackish, oily residuum which will soil the lining of the box, and it is
always advisable either to pin a piece of blotting paper beneath the
cone or to wrap this in paper.
Constant watchfulness is necessary to see that the eggs which have been
deposited and checked in development by the application of this
insecticide do not ultimately hatch and start a new generation in the
insect box.
_Bisulphide of Carbon._--If the collection is found to be infested with
insect pests, it may be renovated by pouring a little bisulphide of
carbon into the boxes and closing them at once. This substance
evaporates rapidly and will destroy all insect life, and does not injure
specimens or pins nor stain the boxes. If infested specimens are
received, these should be inclosed in a tight box and treated with
bisulphide of carbon before being added to the general collection, and
it is always well for those who are receiving pinned specimens by
exchange or otherwise to keep a quarantine box of this kind on hand.
_Mercury Pellets._--The use of mercury pellets is recommended to free
boxes from Mites, Psoci, etc., and also to collect any particles of dust
which may gain entrance. A few small pellets of mercury, placed free in
the bottom of the horizontal box will, by the movement of the box, be
caused to roll to and fro and accomplish the desired end.
_Carbolic Acid._--Mr. A. T. Marshall (_Entomologist's Monthly Magazine_,
Dec., 1873, p. 176) records that he washes the paper of his boxes with
the common disinfecting solution of carbolic acid in two-thirds water,
which dries without staining and protects the specimens from Psoci.
_A Means of preserving Insects in dry hot Countries._--In the "_Horæ
Societatis Entomologicæ Rossicæ_," XXIV, pp. 233, 234 (1889), M. A.
Wilkins, writing from Tachkent in Turkestan, alludes to the inefficiency
of ordinary preservatives in Central Asia, on account of their rapid
volatilization through the hot dry air, so that if a collection be
neglected for only two or three months _Anthreni_ are sure to be found
in the boxes. He has hit upon a plan which he finds effective, and at
the same time very simple. He employs India-rubber bands about 1½ inches
in width and less than the length of the boxes to which they are to be
applied. These bands are stretched over the opening line of the boxes,
and effectually prevent the entrance of the most minute destroyers.
Possibly a similar plan might be adopted in other countries with a like
climate. At any rate, the method has the merit of extreme simplicity.
(The _Ent. Mo. Mag._, Apr., 1891, p. 107.)
MOLD.
Collections kept in damp places or in a moist climate are very liable to
mold, and under such conditions it is difficult to avoid this evil.
Carbolic acid is recommended, but Mr. Ashmead, who has kept a large
collection in the moist climate of Florida, has found the use of
naphthaline much more satisfactory. Mr. Herbert H. Smith who has had
more extensive experience in the tropics prefers the carbolic acid.
Moldy specimens may be cleansed by washing with carbolic acid applied
with a fine camel's hair brush.
VERDIGRISING AND GREASING.
The action of the acid juices in the bodies of certain specimens--as
many of the Lepidoptera, Coleoptera, and Diptera--will cause the
formation of verdigris about the pin, which in time accumulates and
disfigures and distorts the specimen, and ultimately corrodes the pin,
so that the slightest touch causes it to bend or break. There is no
preventive yet known for this trouble other than the use of pins which
have no brass to be corroded. Japanned pins are made for this purpose,
and are, on the whole, satisfactory, but they bend easily and some
caution is required in handling them. In place of these pins, which are
somewhat more expensive than the steel pins, iron pins may be used.
These are very soft and bend too easily for satisfactory use. The steel
pins may be rendered available for use by an immersion in a silver bath,
which is comparatively inexpensive.
Insects the larvæ of which live in wood are particularly subject to
verdigris, as the Cerambycidæ and Elateridæ in Coleoptera, the Uroceridæ
in Hymenoptera and Sesiidæ in Lepidoptera. In Hymenoptera the families
Formicidæ, Mutillidæ, and the endophytous Tenthredinidæ verdigris very
rapidly, and most Diptera also. With all these insects japanned or
silvered pins should be used, or when not too large the insects should
be mounted on triangles. This verdigrising is associated with what is
known as greasing, and this, as just indicated, is also associated with
endophytous larval life. The verdigris may be prevented by the methods
indicated, and I would strongly advise, as a good general rule to be
followed, the rejection of the ordinary pins for all species which, in
the larva state, are internal feeders. But there is no way of preventing
greasing or decomposition of the fats of the body, which may affect a
specimen years after it has been in the cabinet. If the specimen is
valuable the grease may be absorbed by immersion in ether or benzine, or
by a longer treatment with powdered pipe-clay or plaster of Paris.
Insects collected on seabeaches, and saturated with salt water, also
corrode the common steel pin very quickly and should be mounted on
japanned pins. It is also advisable to rinse such specimens thoroughly
in fresh water before mounting.
The conviction has been forcing itself on my mind for some time that the
naphthaline cones tend to promote greasing and verdigris, and carbolic
acid in some small vessel secured to the cork, were, perhaps,
preferable.
THE REARING OF INSECTS.
_General Directions._--The importance, even to the mere collector, of
rearing insects to obtain specimens for the cabinet has been referred to
from time to time in these pages. The philosophic study of entomology,
however, requires much more than the mere collecting of specimens, and
one of the most profitable and, at the same time, most fascinating
phases of the study relates to the life-history and habits. In no branch
of natural history are biologic studies more easily carried on, or the
biologic facts more remarkable or interesting. The systematist by such
study will be saved from the narrow and hair-splitting tendencies which
study of slight difference of characters tends to, while to the economic
entomologist it is most essential.
In the rearing of insects success will be attained in proportion to the
extent to which the conditions of nature in the matters of temperature,
moisture, food-supply, and conditions for pupation, are observed.
"In the hands of the careful breeder an insect may be secured against
its numerous natural enemies and against vicissitudes of climate, and
will, consequently, be more apt to mature than in a state of nature. The
breeding of aquatic insects requires aquaria, and is always attended
with the difficulty of furnishing a proper supply of food. The
transformations of many others, both aquatic and terrestrial, can be
studied only by close and careful outdoor observation. But the great
majority of insect larvæ may be reared to the perfect state indoors,
where their maneuverings may be constantly and conveniently watched. For
the feeding of small species, glass jars and wide-mouthed bottles will
be found useful. The mouths should be covered with gauze or old linen,
fastened either by thread or rubber, and a few inches of moist earth at
the bottom will furnish a retreat for those which enter it to transform
and keep the atmosphere in a moist and fit condition.
_The Breeding Cage or Vivarium._--"For larger insects I use a breeding
cage or vivarium which answers the purpose admirably. It is represented
in figure 123, and comprises three distinct parts: First, the bottom
board _a_, consisting of a square piece of inch thick walnut with a
rectangular zinc pan _ff_, 4 inches deep, fastened to it above, and with
two cross pieces _gg_ below, to prevent cracking or warping, facilitate
lifting, and allow the air to pass underneath the cage. Second, a box
_b_ with three glass sides and a glass door in front, to fit over the
zinc pan. Third, a cap _c_, which fits closely on to the box, and has a
top of fine wire gauze. To the center of the zinc pan is soldered a zinc
tube _d_ just large enough to contain an ordinary quinine bottle. The
zinc pan is filled with clean sifted earth or sand _e_, and the quinine
bottle is for the reception of the food plant. The cage admits of
abundant light and air, and also of the easy removal of excrement or
frass which falls to the ground; while the insects in transforming enter
the ground or attach themselves to the sides or the cap, according to
their habits. The most convenient dimensions I find to be 12 inches
square and 18 inches high: the cap and the door fit closely by means of
rabbets, and the former has a depth of about 4 inches to admit of the
largest cocoon being spun in it without touching the box on which it
rests. The zinc pan might be made 6 or 8 inches deep, and the lower half
filled with sand, so as to keep the whole moist for a greater length of
time."
The sand or earth in the zinc pan at the bottom of the breeding cage
should be kept constantly moistened, and in the case of hibernating pupæ
the constant adding of water to the top of the earth or sand causes it
to become very hard and compact. To overcome this objection it was
suggested in the _Entomologists' Monthly Magazine_ for June, 1876, page
17, that the base should be made with an inner perforated side, the
water to be applied between it and the outer side, and I have for some
years employed a similar double-sided base, which answers the purpose
admirably (See Figure 124). It is substantially the same as that made
for the Department by Prof. J. H. Comstock in 1879. It consists of a
zinc tray _a_, of two or three inches greater diameter than the breeding
cage, which surrounds the zinc pan proper containing the earth, and the
tube _d_ for the reception of the food-plant. The lower portion of the
inner pan _b_ is of perforated zinc. Zinc supports, _c c_, are
constructed about halfway between the bottom and the top of this pan, on
which the breeding cage rests. In moistening the earth in the cage,
water is poured into the tray, which enters the soil slowly, through the
perforations in the zinc pan. I have found this modification of very
decided advantage and use it altogether in the work of the Division, and
heartily recommend it.
[Illustration: FIG. 123.--Insect breeding-cage or vivarium.]
The base of the vivarium or breeding cage should never be made of tin,
but always of zinc. If made of tin, it will soon rust out. Galvanized
iron may be used in place of the zinc, and will doubtless prove equally
satisfactory.
"A dozen such cages will furnish room for the annual breeding of a great
number of species, as several having different habits and appearance,
and which there is no danger of confounding, may be simultaneously fed
in the same cage. I number each of the three parts of each cage to
prevent misplacement and to facilitate reference, and aside from the
notes made in the notebook, it will aid the memory and expedite matters
to keep a short open record of the species contained in each cage, by
means of slips of paper pasted on the glass door. As fast as the
different specimens complete their transformations and are taken from
the cage the notes may be altered or erased, or the slips wetted and
removed entirely. To prevent possible confounding of the different
species which enter the ground, it is well, from time to time, to sift
the earth, separate the pupæ and place them in what I call 'imago
cages,' used for this purpose alone and not for feeding. Here they may
be arranged with references to their exact whereabouts.
[Illustration: FIG. 124.--Improved base for breeding-cage (original).]
"A continued supply of fresh food must be given to those insects which
are feeding, and a bit of moist sponge thrust into the mouth of the
bottle will prevent drowning, and furnish moisture to such as need it.
By means of a broad paste brush and spoon the frass may be daily removed
from the earth, which should be kept in a fit and moist
condition--neither too wet nor too dry. In the winter, when insect life
is dormant, the earth may be covered with a layer of clean moss, and the
cages put away in the cellar, where they will need only occasional
inspection, but where the moss must nevertheless be kept damp. Cages
made after the same plan, but with the sides of wire gauze instead of
glass, may be used for insects which do not well bear confinement
indoors, the cages to be placed on a platform on the north side of a
house, where they will receive only the early morning and late evening
sun."
_Detailed Instructions for Rearing._--In the rearing of insects every
worker will develop a number of methods of value, and it is only by
careful study and comparison of the experiences of all that the best
system can be elaborated. For this reason I have, in what follows,
quoted, in a more or less fragmentary way, the experiences of different
entomologists.
As is remarked by Miss Murtfeldt, in an interesting paper read before
the Entomological Club of the American Association for the Advancement
of Science, August 20, 1890, "there is a great individuality, or rather
specificality, in insects, and not infrequently specimens of larvæ are
found for which the collector taxes his ingenuity in vain to provide.
Not the freshest leaves, the cleanest swept earth, or the most
well-aired cages will seem to promote their development."
The greatest care and watchfulness, therefore, are necessary to insure
success in the rearing of larvæ. In many cases such larvæ can only be
successfully reared by inclosing them in netting on their food-plant out
of doors. It is a frequent device of Lepidopterists also to inclose a
rare female in netting placed on the food plant of the species, where
the male may be attracted and may be caught and placed in the bag with
the female, when copulation usually takes place successfully, or a male
may be caught in the field and inclosed with such female. Mr. W. H.
Edwards, where the plant is a small one, uses for this purpose a
headless keg covered at one end with gauze, which he places over the
plant inclosing the female.
Mr. James Fletcher, of Ottawa, Canada, one of our most enthusiastic
rearers of insects, has given some details of his methods in a recent
very interesting account of "A Trip to Nepigon." One style of cage used
by him in securing the eggs of large Lepidoptera "is made by cutting two
flexible twigs from the willow or any other shrub and bending them into
the shape of two arches, which are put one over the other at right
angles and the ends pushed into the ground. Over the penthouse thus
formed a piece of gauze is placed, and the cage is complete. The edges
of the gauze may be kept down either with pegs or with earth placed upon
them." This kind of cage is used for all the larger species which lay
upon low plants. The species which oviposit on larger plants or trees
are inclosed in a gauze bag tied over the branch. This is applicable to
insects like _Papilio_, _Limenitis_, _Grapta_, etc. Care must be taken,
however, that the leaves of the plant inside the net are in a natural
position, for some species are very particular about where they lay
their eggs, some ovipositing on the top of the leaves, others near the
tip, and many others on the under surface. "When a bag made beforehand
is used, the points must be rounded, and in tying the piece of gauze
over the branch care must be taken to pull out all creases and folds, or
the insect will be sure to get into them and either die or be killed by
spiders from the outside of the bag. It is better to put more than one
female in the same cage. I have frequently noticed that one specimen
alone is apt to crawl about and settle on the top of the cage, and not
go near the food plant. When there are two or three they disturb each
other and are frequently moving and falling on the food plant, when they
will stop for a moment and lay an egg. A stubborn female of _Coleus
eurytheme_ was only induced to lay by having a male placed in the cage
with her, and by his impatient fluttering and efforts to escape she was
frequently knocked down from the top, and every time she fell upon the
clover plant beneath, she laid an egg before crawling to the top again."
Some insects, even with all care in making their surroundings as natural
as possible, will persistently refuse to lay. Mr. Fletcher has
successfully obtained eggs from some of these by a method which he says
one of his correspondents styles "Egg-laying extraordinary." It consists
simply in "gently pressing the abdomen of a female which has died
without laying eggs, until one and sometimes two perfect eggs are passed
from the ovipositor." Mr. Fletcher has secured a number of eggs from
rare species in this way, and successfully reared the larvæ. The
following directions for obtaining the eggs and rearing the larvæ of
Lepidoptera, given in this paper by Mr. Fletcher, are excellent, and I
quote them entire:
"There are one or two points which should be remembered when obtaining
eggs and rearing larvæ. In the first place, the females should not be
left exposed to the direct rays of the sun; but it will be found
sometimes that if a butterfly is sluggish, putting her in the sun for a
short time will revive her and make her lay eggs. Confined females,
whether over branches or potted plants, should always be in the open
air. If females do not lay in two or three days they must be fed. This
is easily done. Take them from the cage and hold near them a piece of
sponge (or, Mr. Edwards suggests, evaporated apple), saturated with a
weak solution of sugar and water. As soon as it is placed near them they
will generally move their antennæ towards it, and, uncoiling their
tongues, suck up the liquid. If they take no notice of it the tongue can
be gently uncoiled with the tip of a pin, when they will nearly always
begin to feed. It is better to feed them away from the plant they are
wanted to lay upon, for if any of the sirup be spilled over the
flowerpot or plant it is almost sure to attract ants. I kept one female
_Colias interior_ in this way for ten days before eggs were laid. When
eggs are laid they should, as a rule, be collected at short intervals.
They are subject to the attacks of various enemies--spiders, ants,
crickets, and minute hymenopterous parasites. They may be kept easily in
small boxes, but do better if not kept in too hot or dry a place. When
the young caterpillars hatch they must be removed with great care to the
food plant; a fine paint brush is the most convenient instrument. With
small larvæ or those which it is desired to examine often, glass tubes
or jelly glasses with a tight-fitting tin cover are best. These must be
tightly closed and in a cool place. Light is not at all necessary, and
the sun should never be allowed to shine directly upon them. If
moisture gathers inside the glasses the top should be removed for a
short time. Larvæ may also be placed upon growing plants. These can be
planted in flowerpots and the young caterpillars kept from wandering
either by a cage of wire netting or, by what I have found very
satisfactory, glass lamp chimneys. These can be placed over the plant,
with the bottom pushed into the earth, and then should have a loose wad
of cotton batting in the top. This has the double effect of preventing
too great evaporation of moisture and keeping its occupants within
bounds. Some larvæ wander very much and climb with the greatest ease
over glass, spinning a silken path for themselves as they go. When
caterpillars are bred in the study it must not be forgotten that the air
inside a house is much drier than it is out of doors amongst the trees
and low herbage, where caterpillars live naturally. The amateur will
require some experience in keeping the air at a right degree of moisture
when breeding upon growing plants. In close tin boxes or jars, where the
leaves must be changed every day, there is not so much trouble. An
important thing to remember with larvæ in jars is to thoroughly wash out
the jars with cold water every day. If, however, a caterpillar has spun
a web on the side and is hung up to moult, it must not be disturbed. In
changing the food it is better not to remove the caterpillars from the
old food, but having placed a new supply in the jar, cut off the piece
of leaf upon which they are and drop it into the jar. If they are not
near the moult a little puff of breath will generally dislodge them.
Some caterpillars, as _Papilio turnus_, which spins a platform to which
it retires after feeding, can best be fed upon a living tree out of
doors, but must be covered with a gauze bag to keep off enemies. A piece
of paper should be kept _attached_ to each breeding jar or cage, upon
which regular notes must be taken _at the time_, giving the dates of
every noticeable feature, particularly the dates of the moults and the
changes which take place in the form and color at that time."
The necessity of outdoor work is further felt in the determination of
the facts in the life-history of some insects which have an alternation
of generations, as some Gall-flies (_Cynipidæ_), and most Aphides. To
successfully study these insects constant outdoor observation is
necessary, or the species must be inclosed in screens of wire or netting
outdoors on their food-plant. Many insects which breed on the ground or
on low herbage may be very successfully watched and controlled by
covering the soil containing them or the plant on which they feed with a
wire screen or netting. The use of wire screens is also advisable in the
case of wintering pupæ or larvæ out of doors. Many species can be more
easily carried through the winter by placing them outdoors under such
screens during the winter, which insures their being subjected to the
natural conditions of climate, and then transferring them to the
breeding cage again early in the spring. This is advisable in the case
of Microlarvæ and pupæ. Species which bore in the stems of plants may be
easily cared for and leaf-mining and leaf-webbing forms can be secured
under screens or covers out of doors for the winter in sheltered
situations. Many species which, if kept in a warm room can not be
reared, will, if subjected to freezing weather under slight protection
in the open air, emerge successfully the following spring.
The greatest care is necessary in the breeding of Tenthredinidæ, as most
of them transform under ground and are single brooded, the larvæ
remaining in the ground from midsummer until the following spring.
Nothing but constant care in maintaining uniform moisture and
temperature of the soil will insure the success of such breeding. Some
species bore into rotten wood or the stems of plants to undergo their
transformations, as for instance the Dogwood Saw-fly (_Harpiphorus
varianus_). This species, unless supplied with soft or rotten wood in
which to bore, will wander ceaselessly round the cage, and in most cases
eventually perish.
Where a small room can be devoted to the purpose, an excellent wholesale
method of obtaining wood-boring insects (_Coleoptera_, _Lepidoptera_,
etc.) is to collect large quantities of dead or dying wood of all sorts
or any that indicates the presence of the early states of insects, and
store it in such apartment. The following spring and summer the escaping
insects will be attracted to the windows and may be easily secured. The
objection to this method is that, in many cases, it will be impossible
to determine the food habit of the insect secured, owing to the variety
of material brought together.
_The Root Cage._--For the study of insects which affect the roots of
plants a root cage has been devised by Prof. J. H. Comstock which is of
sufficient importance to warrant full description. It consists of a zinc
frame (Fig. 125_a_) holding two plates of glass in a vertical position
and only a short distance apart, the space between the plates being
filled with soil in which seeds are planted or small plants set. Outside
of each glass is a piece of zinc or sheet iron (_b_) which slips into
grooves and which can be easily removed. When these zincs are in place
the soil is kept dark.
The idea of the cages is, that the space between the glasses being very
narrow, a large part of the roots will ramify close to the surface of
the glass, so that by removing the zinc slides the roots may be easily
seen, and any root-inhabiting insects which it maybe desirable to breed
may thus be studied in their natural conditions without disturbing them.
Prof. Comstock has used this cage very successfully in studying the
habits of wire-worms, and its availability for many of the underground
insects, such as the Cicadas, root-lice, larvæ, etc., is apparent. These
frames may be made of various sizes, to accommodate particular insects.
It will be of advantage in many cases, in order to secure the natural
conditions as nearly as possible, to sink the cage in the soil, and for
this purpose Prof. Comstock has had constructed a pit lined with brick
for the reception of his cages, and employs a small portable crane to
lift them out of the ground when it is desirable to examine them.
_Other Apparatus._--Much of the breeding of insects can be done with the
simplest apparatus, and for the rearing of Microlepidoptera,
Gall-insects, and the keeping of cocoons and chrysalides of small
species, nothing is more convenient than a medium sized test-tube, the
end of which may be plugged with cotton. I have recently successfully
carried over the winter the larva of _Sphecius speciosus_, which had
been removed early in the fall from its earthen pod or cocoon, the larva
transforming to a perfect pupa in the spring. In this case the test tube
was plugged with cotton and inserted in a wooden mailing tube to exclude
the light. Smaller jars with glass covers or with a covering of gauze
may be employed for most insects, with the advantage of occupying
comparatively little space and of isolating the species under study.
[Illustration: FIG. 125.--Root cage: _a_, frame with slide removed; _b_,
movable slide; _c_, top view (original).]
Long glass tubes, open at both ends, are useful in many other ways,
especially in the rearing and study of the smaller hypogean insects or
those which bore and live in the stems of plants. An infested stem cut
open on one side and placed in such a tube will generally carry any
insect that has ceased feeding, or any species like the wood-boring bees
which feed upon stored food, successfully through their transformations;
while root-lice may be kept for a lengthy period upon the roots in such
tube, providing a portion of the root extends outside of the tube and is
kept in moistened ground or water. In all such cases these tubes, with
their contents, should be kept in the dark, either in a drawer or else
covered with some dark material which can be wound around or slipped
over them, and the ends must be closed with cotton or cork.
The rearer of insects will frequently experience difficulty in carrying
his pupæ through the winter, and, even though ordinary precautions are
taken, the mortality will frequently amount to 50 per cent of the
specimens. Mr. H. Bakhaus, of Leipzig, thus describes a device which is
substantially the base of the vivarium shown on page 114.
"The base consists of a round plate of strong zinc, with two vertical
rims, an inch high, placed one within the other, an inch apart, and
soldered to the basal plate so that the outer one is water-tight. The
inner rim must be perforated with small holes as close to the bottom as
possible. The space inside the inner rim must be filled with fine sand,
on which the pupæ should be laid. The space between the two rims is then
filled with water, which, finding its way through the holes in the inner
rim to the sand, causes the necessary moisture. Over the whole is put a
bell-shaped cover of wire gauze, which must fit tightly over the outer
rim. In this receptacle the pupæ remain untouched, and receive fresh
moisture, as above indicated, if required by the drying of the sand."
The hardy pupæ of most Noctuids and Bombycids, as well as those of many
Rophalocera, may be handled with little danger, but other species, if
handled at all, or if the cocoons which they make for themselves are
broken, can seldom be reared. Constant precautions also must be
exercised in the care of the soil and the breeding cages. One of the
great drawbacks is the presence of mites and thread worms (Entozoöns),
etc., which affect dying or dead pupæ and larvæ in the soil. They also
affect living specimens and are capable of doing very considerable
damage. To free the soil of them it is necessary at times to allow the
earth to become dry enough to be sifted, and then after removing the
pupæ submit it to heat sufficient to destroy any undesired life there
may be in it.
_The Insectary._--Up to the present time the work of rearing insects has
been largely confined to the breeding cage and breeding jar, already
described, which have been kept in the rooms of the investigator. The
advantages of having a special building for this purpose are at once
apparent and need not be insisted upon. One of the best establishments
of this kind is that of the Cornell University Experiment Station, which
was fully described in Bulletin No. 3, of that station, November, 1888.
The Kansas Experiment Station has a similar building, and one has
recently been built for the use of the Entomological Division of the
United States Department of Agriculture. The insect-breeding house, or
insectary, should comprise a building having workrooms, or laboratories,
for microscopic and general work in the study and preparation of
specimens, and also a conservatory for the rearing of specimens and the
growth of plants, and, where applied entomology is concerned, special
rooms for the preparation and the test of insecticides. The building
proper should also have a basement storage room for hibernating insects.
The laboratory should be fitted with all the apparatus used in the study
of insects, including microscopes and accessories and a dark-room for
photographic purposes.
DIRECTIONS FOR TRANSMITTING INSECTS.
It is very desirable in transmitting insects from the field of
exploration, or from one entomologist to another, for information,
exchange, or other purpose, that they be properly secured and packed.
Pinned and mounted specimens should be firmly fixed in a cigar box, or a
special box for mailing, and this should be carefully but not too
tightly wrapped with cotton or other loose packing material to a depth
of perhaps an inch, and the whole then inclosed in stiff wrapping paper.
It is preferable, however, to inclose the box containing the specimens
in a larger box, filling the intervening space, not too firmly, with
cotton or other packing material. Where specimens are to be sent to a
considerable distance it is advisable also to line the box in which they
are placed with cotton, which serves to catch and hold any specimens
which may become loose in transit. In the case of alcoholic specimens
each vial should be wrapped separately in cotton and placed in a strong
wooden or tin box. Special mailing boxes for alcoholic specimens have
been devised, and a very convenient form is herewith figured. It is an
ordinary tube of wood, with a metal screw top, and the interior lined
with rough cork. These tubes are made in various sizes to accommodate
vials of different dimensions.
[Illustration: FIG. 126.--Wooden-tube mailing-box: _a_, tube; _b_, cover
(original.)]
In mailing living specimens the essential thing is a strong box,
preferably tin, made as nearly air-tight as possible. I have found it
very convenient on long trips to carry with me a number of tin boxes in
the flat (Fig. 127), combined in convenient packages, ready to be bent
and improvised in the field. For this purpose get any tinsmith to make
out of good tin a number of pieces cut of the requisite dimensions both
for the bottoms and the covers, carefully cutting the corners to permit
the proper bending of the sides. These improvised boxes will prove
useful for keeping living larvæ with their food-plants, especially if
tied up in stout brown paper to prevent any exit from the unsoldered
angles. They will also answer admirably for mailing or otherwise sending
specimens to their ultimate destination. In the case of larvæ a quantity
of the food-plant should always be inclosed in the box.
[Illustration: FIG. 127.--Tin mailing-box in the flat: _a_, box; _b_,
cover (original).]
In transmitting insects for information the greatest care should be
taken to relieve the person of whom information is sought of as much
unnecessary work as possible. It is easy for any beginner to collect
more in a single day than an experienced entomologist can well mount,
study, and determine in a week, and as those who have the means and
information to give determinations or otherwise to assist beginners are
generally very much occupied, and their time is valuable, they are
justified in ignoring miscellaneous collectings where the sender has
made no effort to either properly mount or otherwise study and care for
his specimens.
[Illustration: FIG. 128.--Tin mailing-box, bent into shape for use
(original.)]
Living specimens, especially larvæ, should be packed in tin, with a
supply of their appropriate food. The tighter the box the fresher will
the food as well as the specimens keep. Insects do not easily suffocate,
and it is worse than useless, in the majority of cases, to punch
air-holes in such boxes. Dead specimens, when not pinned, may be sent in
a variety of ways. Small ones may be dropped into a quill and inclosed
in a letter, or a small vial fitted into a piece of bored wood. Those
which do not spoil by wetting may be sent in alcohol, provided the
bottle is absolutely filled, or, what is better, in sawdust moistened
with alcohol, or between layers of cotton saturated with alcohol.
The postal regulations permit the sending by mail of "dried insects
* * * when properly put up, so as not to injure the persons of those
handling the mails, nor soil the mail bags or their contents." Specimens
in alcohol may also be sent by mail, provided that the containing vial
be strong enough to resist the shock of handling in the mail, and that
it be inclosed in a wooden or papier-maché tube not less than
three-sixteenths of an inch thick in the thinnest part, lined with cork
or other soft material, and with a screw top so adjusted as to prevent
the leakage of the contents in case of breakage. Entomological specimens
are of the fourth class of mail matter, the postage on which is 1 cent
an ounce or fraction thereof, the limit of weight for a single package
being 4 pounds, and the limit as to bulk 18 inches in any direction.
Saleable matter is also non-mailable at fourth-class rates; so that the
safer method, with small packages, is to send under letter postage. It
is far better, however, for long journeys, and especially for
transatlantic shipment, to send by express.
NOTES AND MEMORANDA.
In the foregoing pages are given some of the more useful directions for
those wishing to commence to collect and study insects. Experience will
soon teach many other important facts not mentioned here, and the best
closing advice I can give the novice is, to get acquainted, if possible,
with some one who has already had large experience. He will be very apt
to find such a person pleasant and instructive company whether in the
field or in the closet. One important habit, however, I wish to strongly
inculcate and emphasize: The collector should never be without his
memorandum or note book. More profitless work can scarcely be imagined
than collecting natural-history specimens without some specific aim or
object. Every observation made should be carefully recorded, and the
date of capture, locality, and food-plant should always be attached to
the specimens when these are mounted. More extended notes may be made in
a field memorandum book carried in the pocket or in larger record books
at home. For field memoranda I advise the use of a stylographic pen, as
pencil is apt to rub and efface in time by the motions of the body. The
larger record book is especially necessary for biologic notes. Notes on
adolescent states which it is intended to rear to the imago can not be
too carefully made or in too much detail. The relative size, details of
ornamentation and structure, dates of moulting or transformation from
one state to another--indeed, everything that pertains to the biography
of the species--should be noted down, and little or nothing trusted to
mere memory where exact data are so essential. Many insects,
particularly dragon-flies, have brilliant coloring when fresh from the
pupa, which is largely lost afterward. The time of laying and hatching
of eggs, the number from a single female, the character of the eggs,
general habits, records of parasites and their mode of attack--all
should be entered as observed. A great many species have the most
curious life histories, which can not be ascertained except by continued
and persevering observation, not only in the vivarium or insectary but
in the field. It is almost impossible to follow, under artificial
conditions, the full life cycle of many species like the Aphididæ, or
the Gall-flies, etc., which involve alternation of generations,
dimorphism, heteromorphism, migration from one plant to another, and
various other curious departures from the normal mode of development,
without careful field study and experiment. These studies are possible
only to those who are able to frequent the same localities throughout
the whole year, and can hardly be carried on by the traveling naturalist
or collector.
INSTRUCTIONS FOR COLLECTING AND PRESERVING ARACHNIDS AND MYRIAPODS.
The foregoing portions of this manual have dealt almost exclusively with
the subject of the securing and preservation of Hexapods, but it is
deemed advisable to include brief instructions for the collection and
care of the near allies of the true insect, Spiders and Myriapods, the
study of which will in most cases be associated with that of Hexapods.
DIRECTIONS FOR COLLECTING SPIDERS.
_Apparatus._--Many of the directions and methods given in the foregoing
pages for the collection of Hexapods apply also to the animals named
above. Little apparatus is necessary in the collection of spiders and
other Arachnids. The essentials are vials containing alcohol, an insect
net, a sieve, and forceps. Narrow vials without necks are best for
collecting purposes, as the corks can be more quickly inserted. They
should be of different sizes, from 1 dram to 4 or 6 drams, and the
alcohol used should be at least 50 per cent strong and in some cases it
is advisable to use it at a strength of 70 or 80 per cent. The net may
be of the same construction as that used to collect insects and is used
in the same way. Some arachnologists, however, use a net of a somewhat
different make, which is much stronger. The iron ring is heavier and
larger than in the case of the insect net, resembling in this respect
the ring of the Deyrolle net. The bag is short and the handle is
fastened to both sides of the ring. This net is used for beating the
leaves of trees, bushes, and grass. Dr. Marx uses a net which is already
described and figured under the name of the Umbrella Net (see p. 34,
Fig. 52). The sieve is the same as that described on p. 35, Fig. 54, and
is used to sift the spiders from leaves and rubbish, especially during
winter. A mass of leaves and other material is thrown into the sieve and
then shaken, the spiders falling through on a piece of white cloth,
which is spread under the sieve on the ground. Many hibernating
species can be readily secured in this manner. A forceps similar to that
described for the collecting of hexapods should be used to capture or
pick up specimens, for if handled with the fingers they are apt to be
crushed, especially the smaller forms. As soon as the collecting is
finished or the vial is filled a label should be placed in this last
indicating place and date of collection. Egg sacs and cocoons should be
collected in pill boxes and properly labeled, and if possible the adults
should be reared. Both sexes should be collected and descriptive notes
or drawings made of the webs as found in nature.
[Illustration: FIG. 129.--A ground Spider (_Oxyopes viridans_). (After
Comstock.)]
[Illustration: FIG. 130.--An orb-weaver (_Argiope argyraspides_ Walck):
_a_, male; _b_, female; _c_ and _d_, enlarged parts.]
_Time and Locality for Collecting._--The best time to collect spiders is
in the early fall, during the months of September and October. The great
majority of the species are then mature. Many forms, however, occur in
the adult state in late spring and early summer. Numerous species may
also be collected during winter, some of these hibernating under stones,
the bark of dead trees, etc., and others, more particularly the small
forms, under dead leaves and rubbish on the ground in woods. Other
species which have hibernated may be found about the earliest flowers in
spring. No particular localities can be indicated for the collection of
spiders, since they occur in all sorts of places, in wooded or open
regions and also in and about dwellings. Many Lycosidæ are found in dry
and rocky situations and quite a number in open fields. Thomisidæ may be
found on flowers. The Therididæ affect shady places, and many Epeiridæ
will be found in similar situations. The Attidæ love the sun and are
found very actively engaged in hunting insects on plants and dead
leaves. Many species of this family will be found in cases under loose
bark in winter. Evergreen trees are also quite good collecting grounds
for Attidæ. The Drassidæ are ground spiders and are mostly nocturnal,
hiding during the day under leaves and stones; a few forms, however,
disport in the hottest sunshine. Some genera are found most frequently
near water or in damp places, as Dolomedes and Tetragnatha; others in
sandy places, as Micaria, Targalia.
COLLECTING OTHER ARACHNIDS: MITES, TICKS, SCORPIONS, ETC.
Other Arachnids--as mites, ticks, scorpions, daddy longlegs or
harvest-men--may be collected in the same way as spiders.
The Phalangidæ (Harvest-men) somewhat resemble spiders, and are at once
recognized by their extremely long legs. They occur about houses,
especially in shady places, under the eaves, etc., and in the woods and
fields. They are carnivorous and feed on small insects, especially
Aphides. They should be pressed a little when captured to extrude the
genital apparatus, if possible, and are best collected in the early
fall.
[Illustration: FIG. 131.--A Harvest-man (_Phalangium
ventricosum_).--From Packard.]
The Phrynidæ are very peculiar looking animals, the anterior legs being
very long and slender and the maxillary palpi very large. The genus
_Thelyphonus_ is not uncommon in the South, and is known by its oblong
body, ending usually with a long, slender, many-jointed filament, from
which they are called Whip-tailed Scorpions. _T. giganteus_ is the
common species. They occur in moist situations, and are carnivorous,
feeding on insects and small animals.
The false scorpions, Chermetidæ, may at once be recognized by their
large maxillary palpi, resembling the maxillæ of the true scorpion. They
are small insects, rarely exceeding a quarter of an inch in length, and
are found in dark shady places and feed upon mites, Psoci, and other
small insects. A common species is represented at figure 132.
[Illustration: FIG. 132.--False Scorpion (_Chelifer cancroides_
L.).--From Packard.]
The true scorpions, Scorpionidæ, are well-known forms, and are easily
recognized by their large, powerful, forceps-like maxillæ, and the long
slender tail continuous with the thorax and ending with a sting, which
is, in most cases, quite poisonous. They are found mostly in the Western
and Southwestern States, and are dangerous in proportion to their size.
The poisonous nature of the sting of these animals is, however,
generally overrated, and the wounds, even of the larger species, are
rarely fatal.
The Acarina or true mites are the lowest representatives of the
Arachnida and include many genera and species differing very widely in
habit and characters. Some of them are mere sacs, on which the mouth
parts or other organs are scarcely discernible. In general they resemble
spiders. The young, however, when they leave the egg, almost invariably
have but three pairs of feet, resembling in this respect the Hexapods.
The fourth pair is added in the later stages. They are parasitic on
insects and other animals, and some of them are vegetable feeders or
live in decaying vegetable and animal matter.
A very interesting group is comprised in the family Phytoptidæ or
gall-making mites which occur on the leaves of various trees and shrubs
and produce curious galls or abnormal growths. These mites are elongate
in form, have rudimentary mouth-parts and but four legs. A common form,
_Phytoptus quadripes_, produces a gall on the leaves of the soft maple.
The galls of all species should be collected and pinned and also
preserved in alcohol, and specimens of the mites should be mounted in
balsam.
The members of the genus Sarcoptes are very minute and are the active
source of the itch in the lower animals and man. Another common genus is
Tyroglyphus, which includes the common cheese mite, _T. siro_. Other
species of this genus also sometimes occur in enormous numbers in
grocers' supplies. Still others are parasitic on insects, and one
species, _T. phylloxeræ_ Riley, is very beneficial, since, as its name
indicates, it feeds on the Phylloxera of the grapevine.
[Illustration: FIG. 133.--A true Scorpion (_Buthus carolinianus_).--From
Packard.]
The Ixodidæ comprise the ticks which attach themselves to cattle, hogs,
and man, and are not at all uncommon objects. These insects can be found
on the animals they infest, and distinct species will be found to occur
on most wild mammals. The common Cattle tick _Boophilus bovis_ Riley, is
represented at Fig. 134.
[Illustration: FIG. 134.--The Cattle-tick. (After Packard.)]
The family Orobatidæ includes a number of small terrestrial mites, which
occur on the moss on trees and stones. Some species are known to feed on
the eggs of insects, and the one shown in the accompanying figure,
_Nothrus ovivorus_ has been observed, by Dr. Packard to eat the eggs of
the Canker Worm.
[Illustration: FIG. 135.--_Nothrus ovivorus_ Packard.]
The members of the family Gamasidæ are parasitic upon animals, but
chiefly upon insects. The Hydrachnidæ are parasitic also upon the
aquatic insects, and also affect fish or mussels or occur on fresh-water
plants.
One of the most important families of mites is the Trombidiidiæ which
includes a large number of species, some of which occur in immense
numbers. Most of them are vegetable feeders, but some species feed on
the eggs of insects.
[Illustration: FIG. 136.--_Trombidium locustarum_: _a_, female with her
batch of eggs; _b_, newly hatched larva--natural size indicated by the
dot within the circle; _c_, egg; _d e_, vacated egg-shells.]
The genus Trombidium includes a number of the Red Mites which feed on
insects in all their stages. The Locust Mite, _Trombidium locustarum_
Riley, is one of the most interesting as well as one of the most
important of our locust enemies, and will serve to illustrate the habits
of the group. It differs so much in infancy and maturity that it has
been referred to different genera and is known under different names.
The mature form lives on the ground and feeds on all sorts of animal or
decomposing vegetable matter, and wherever the ground is filled with
locust eggs these afford an abundance of food and the mites flourish and
multiply rapidly. In the spring the female lays 300 or 400 minute
spherical orange-red eggs in the ground (Fig. 136_a_). From these eggs,
as shown enlarged at _c_, _d_, and _e_ (the two latter being the vacated
egg shells) emerge the six-legged larva shown at _b_. These are mere
specks and crawl actively about, fastening themselves to the locusts
mostly at the base of the wings or along the upper veins. They subsist
on the juices of their host. They firmly attach themselves by the mouth
and increase rapidly in size, the legs not growing and becoming mere
rudiments. In this form they are shown at Fig. 137_a_. When fully
developed they let go their hold, drop to the ground, and crawl under
the shelter afforded by holes in the earth or under sticks. Here, in the
course of two or three weeks, they transform within the larval skin to
the pupal stage shown at _b_, and eventually break through the old
larval skin and escape in the form shown at _c_ and _d_. This mature
form passes the winter in the ground and is active whenever the
temperature is a few degrees above the freezing point. A larger species
_T. giganteum_ Riley, also attacks locusts, while a third species
attacks the common House-fly. This was formerly known in the larva state
only and was referred to the genus Astoma, to which also the larval form
of Trombidium was referred. I have described the adult together with the
larva and pupa as _Trombidium muscarum_. An allied mite, _Hydrachna
belostomæ_, attacks the large aquatic water bug, Belostoma, and has a
mode of development precisely similar to that of Trombidium.
[Illustration: FIG. 137.--_Trombidium locustarum_. _a_, mature larva
when about to leave the wing of a locust; _b_, pupa; _c_, male adult
when just from the pupa; _d_, female--the natural sizes indicated to the
right; _e_, palpal claw and thumb; _f_, pedal claw; _g_, one of the
barbed hairs; _h_, the striations on the larval skin.]
To this family also belong the common greenhouse mite, _Tetranychus
telarius_, and also the Bryobia mite, _B. pratensis_, which of late
years has attracted very considerable attention by its appearance in
immense numbers about dwellings, coming from the adjoining fields of
clover or grass. Generically allied to the greenhouse mite is the
Six-spotted Mite of the Orange (_T. 6-maculatus_ Riley), which is shown
in the accompanying figure.
[Illustration: FIG. 138.--The Six-spotted Mite of the Orange
(_Tetranychus 6-maculatus_): _a_, from above--enlarged; _b_, tarsus;
_c_, rostrum and palpus--still more enlarged; _d_, tip of palpus--still
more enlarged.]
Spiders and mites thus collected may be transferred to alcohol. Dr.
Marx, who has had a very considerable experience in the preservation of
spiders, recommends the use of the following mixture: Glycerin and
Wickersheim's fluid, 1½ ounces of each, and distilled water 3 ounces,
the whole to be shaken and thoroughly mixed and added to 30 ounces of 95
per cent alcohol. Alcohol which has previously been used for preserving
spiders, and which has therefore dissolved some of the fatty matters
from the specimens, he prefers to pure alcohol, using with this,
however, somewhat less of the distilled water. The liquid thus composed
answers all demands and keeps the specimens flexible and preserves their
coloring. Should the stopper become loose and the liquid evaporate,
there is always sufficient liquid, water or glycerine, left in the vial
to keep the specimens from drying and thus save them from destruction.
Dr. Marx also prefers to use cork stoppers rather than the rubber
stoppers recommended for other alcoholic material. His objection to the
rubber stopper is that, in a collection in which the specimens are often
used and the stoppers are frequently removed, he finds that small
particles of the rubber stopper come off and settle upon the specimens
as a white dust, which it is difficult to remove. This objection applies
only to a poor quality of rubber, and in all other respects the rubber
is much to be preferred. The colors of spiders are apt to fade somewhat
if exposed to light, and the collection should therefore be kept in
closed boxes or in the dark.
COLLECTING MYRIAPODA.
Centipedes and Millipedes are collected in the same manner as spiders.
They live in damp places, under sticks and stones, and in decaying
vegetation. They should be preserved in alcohol, and on account of their
usually strong chitinous covering, precautions as to the strength of the
alcohol are less necessary here than with softer-bodied specimens.
[Illustration: FIG. 139.--A Milliped (_Cambula annulata_).]
The members of this subclass comprise a number of well-marked groups.
The Iulidæ are cylindrical insects and occur in moist places, as do most
of the representatives of this subclass. A common form is represented in
the accompanying figure. The Chiliopodæ comprise the flattened forms
having many-jointed antennæ and but a single pair of limbs to each
segment of the body, and are the forms to which the name centipede may
properly be applied. They are predaceous in habit, live largely on
living animal matter, and are very quick in their movements. Some forms
are poisonous, having poison glands at the base of the first pair of
legs, but the majority of the species are entirely harmless. A number
of common species belong to the genus Geophilus and occur under stones
and logs. The genus Scolopendra includes some of the larger species of
the order. The largest known species, _S. gigantea_, occurs in the East
Indies and attains a length of from 9 inches to more than a foot.
Several species found within the limits of the United States attain a
length of 5 inches or more. The family Cermatiidæ includes the very
common species _Cermatia forceps_, which, while abundant in the South
and West, occurs somewhat more rarely in the North. It is commonly found
in moist situations, in houses or conservatories, and on account of its
long legs and agile movements frequently creates considerable
consternation. It is, however, an entirely harmless and very beneficial
species, since it feeds on various household pests, including flies,
roaches, etc.
TEXT BOOKS--ENTOMOLOGICAL WORKS.
Bulletin No. 19 of the Division of Entomology, U. S. Department of
Agriculture, contains an enumeration of the published synopses,
catalogues, and lists of North American insects, together with other
information intended to assist the student of American entomology. This
can be had upon application, and I would refer the student to it for
specific information as to synopses, catalogues, and lists. I have
deemed it advisable, however, to include here an enumeration of the more
useful works of a general character; a list of the entomological
periodicals, both home and foreign; and the entomological works
published by the different departments of the Government, with some
information as to how and of whom they can be obtained. Many of these
publications are no longer to be had except as they may be picked up
through book-dealers; but the titles even of those which are out of
print will be useful to the student as a guide to what he should find in
every good library. Requests for this kind of information are constantly
received at the Department of Agriculture and at the National Museum.
The most useful general works are given first, and, while a great many
others in foreign languages might be cited, I would strongly advise the
beginner in America to confine himself to these, and especially to read
Harris's Insects Injurious to Vegetation, Kirby & Spence's Introduction,
and Westwood's Introduction. This last, though published over half a
century ago, is still one of the most useful entomological works in the
English language. While these Introductions will be of great service in
arranging and classifying material and in giving a knowledge of the
relationships of species, there is no better text-book than the great
book of nature, which is always ready to unfold its truths to every
earnest inquirer. In field and wood alone can he become familiar with
the insects in all their wondrous life habits, instincts, and
intelligence. There alone will he receive the fullest inspiration and
pleasure in his work or find the highest reward for his efforts.
COMPREHENSIVE WORKS MOST USEFUL FOR THE STUDY OF NORTH AMERICAN INSECTS.
H. C. C. BURMEISTER.--Handbuch der Entomologie. Berlin, 1832-1855.
5 vols.
MANUAL OF ENTOMOLOGY.--A translation of the above, by W. E. Shuckard.
London, 1836.
J. O. WESTWOOD.--An introduction to the modern classification of
insects, founded on the natural habits and corresponding organization of
the different families. 2 vols. London, 1839-'40.
THOMAS SAY.--Complete writings on the Entomology of North America;
edited by John L. Le Conte. New York, 1859.
H. A. HAGEN.--Bibliotheca Entomologica. Die Litteratur über das ganze
Gebiet der Entomologie bis zum Jahre 1862. Leipzig, 1862.
A. S. PACKARD.--Guide to the Study of Insects. Henry Holt & Co.,
Philadelphia and New York. (First edition, Salem, 1869.)
---- Entomology for Beginners. Henry Holt & Co., New York, 1888.
THE STANDARD NATURAL HISTORY.--Edited by John Sterling Kingsley. S. E.
Cassino & Co., Boston, 1884-'85.
Volume II contains the insects, which are treated by the following
authors: _Hymenoptera_, J. H. Comstock and L. O. Howard;
_Coleoptera_, George Dimmock; _Lepidoptera_, H'y Edwards and C. H.
Fernald; _Diptera_, S. W. Williston; _Orthoptera_, C. V. Riley;
_Hemiptera_, P. R. Uhler; _Neuroptera_, A. S. Packard; _Arachnida_,
J. H. Emerton.
J. H. COMSTOCK.--An Introduction to Entomology. Published by the author.
Ithaca, N. Y. 2 parts. Part I, 1888.
ALPHEUS HYATT AND J. M. ARMS.--Guides for Science Teaching, No. III.
Insecta. Bos. Soc. Nat. Hist. D. C. Heath & Co., Boston, 1890.
GENERAL WORKS ON CLASSIFICATION.
HYMENOPTERA.
E. T. CRESSON.--Synopsis of the Families and Genera of the Hymenoptera
of America, north of Mexico, together with a Catalogue of the described
Species and Bibliography. Transactions Am. Entom. Society, Supplementary
volume. 2 parts. Philadelphia, 1887.
COLEOPTERA.
JOHN L. LE CONTE AND GEORGE H. HORN.--Classification of the Coleoptera
of North America. Prepared for the Smithsonian Institution. Washington,
Smithsonian Institution, 1883.
This is the most recent and the only complete classification of
North American Coleoptera. It contains also Appendix II, a "list of
bibliographical references to memoirs, in which more or less
complete synopses of the families, genera, and species of the
Coleoptera of the United States have been published."
J. T. LACORDAIRE.--Histoire naturelle des Insectes. Genera des
Coléoptères, ou exposé méthodique et critique de tous les genres
proposés jusqu'ici dans cet ordre d'insectes. [Completed by J. Chapuis.]
Paris, France, 1854-1876. 12 vols, and 1 vol. plates.
[Out of print.]WILLIAM LE BARON.--Outlines of Entomology, published in
connection with the author's Annual Reports upon injurious insects. Part
first. Including the Order of Coleoptera. Fourth Annual Report on the
Noxious and Beneficial Insects of the State of Illinois. Sep. Edit.
Springfield, 1874.
LEPIDOPTERA.
G. A. W. HERRICH-SCHAEFFER.--Sammlung neuer oder wenig bekannter
aussereuropäischer Schmetterlinge. Vol. I. Regensburg, 1850-'58; Vol.
II, Pt. 1, 1869.
Contains a classification of the Lepidoptera, which forms the basis
of our present arrangement.
JOHN G. MORRIS.--Synopsis of the described Lepidoptera of North America.
Part I. Diurnal and Crepuscular Lepidoptera. Washington, Smithsonian
Institution, 1862.
Compiled descriptions of the North American Lepidoptera, from the
Rhopalocera to the Bombycidæ.
H. STRECKER.--Lepidoptera, Rhopaloceres et Heteroceres, indigenous and
exotic; with descriptions and colored illustrations. Reading, Pa.,
1872-'77.
Fifteen parts of this work have been published containing figures
and descriptions of many North American species.
JOHN B. SMITH.--An Introduction to a Classification of the North
American Lepidoptera. rearing
p 5: Spiders, and Myriopods -> Myriapods
p 5: comprising Spiders, Myriopods -> Myriapods
p 7: If we endevor -> endeavor
p 8: of the Sub-orders-> Suborders
p 9: Springtails -> Spring-tails
p 9: Plectoptera -> Plecoptera
p 14: the case of the Horntails -> Horn-tails
p 14: FIG. 8.--Sawfly -> Saw-fly
p 14: Beetles or-> duplicate "or" deleted
p 16: of the common silk-worm -> silkworm
p 16: variety of these larvae -> larvæ
p 17: structure of the antennae -> antennæ
p 17: HETEROPTERA ([Greek: heteros], -> comma added
p 17: looked upon as a Sub-order -> Suborder
p 17: A Plant-bug Euschistes -> Euschistus
p 18: DIMERA, with two joints; -> comma changed to semicolon
p 19: four or five joints. -> period added
p 20: hatched in the abodmen -> abdomen
p 21: A Locust Acrideum -> Acridium
p 21: Orthoptera -> changed from smallcaps to all capital letters
p 21: Tree-cricket Ocharis -> Orocharis
p 21: Phyllodromia germanica.) -> germanica).
p 22: "Earwigs, consisting -> Earwigs
p 26: A May-fly Protamanthus -> Potamanthus
p 28: (Fig. c) -> (Fig. 45, c)
p 30: frequently have occassion -> occasion
p 47: put in the seive -> sieve
p 51: butterflies, whose larvae -> larvæ
p 51: as their mouthparts -> mouth-parts
p 53: and otherwiise dsposed -> otherwise disposed
p 54: animals. The Plantlice -> Plant-lice
p 55: imago--all enlarged -> closing round bracket deleted
p 58: Rove-beetles Staphilinidæ -> Staphylinidæ
p 58: A Spring-tail -> --A Spring-tail
p 59: Palingenia bilneata -> bilineata
p 70: specimen in the cabinet. -> period added
p 70: e. g. the Sawflies -> Saw-flies
p 71: Moanting -> Mounting
p 73: glue or shell-lac -> shellac
p 75: After Kiesenvetter -> Kiesenwetter
p 75: shown in the accompaying -> accompanying
p 76: FIG. 105. Spreading -> FIG. 105.--Spreading
p 76: FIG. 106. Needle -> FIG. 106.--Needle
p 83: they almost invariable -> invariably
p 83: spirit or petroleum lamp. -> period added
p 89: the external chytinous -> chitinous
p 91: pieces of clean card-board -> cardboard
p 91: beveled on all sides: -> sides;
p 93: bored with a bitt -> bit
p 94: Many larvae -> larvæ
p 98: Myriopoda -> Myriapoda
p 99: keeping off musuem -> museum
p 106: all lateral movemnts -> movements
p 106: After Marse -> Morse
p 110: The two particuliarly -> particularly
p 112: endophytous Ienthredinidæ -> Tenthredinidæ
p 114: (See Figure 124.) -> (See Figure 124)
p 118: Gall-flies Cynipidae -> Cynipidæ
p 119: brooded, the larvae -> larvæ
p 129: FIG. 125 -> FIG. 125.
p 121: Bakhaus, of Leipsic -> Leipzig
p 132: of the published synoposes -> synopses
p 134: species of each genius -> genus
p 136: HENRI DE SAUSSURE. -> period added
p 136: Amer. Philos. -> period added
p 137: 1874 to 1883 -> 1883)
p 137: 1875 to 1879 -> 1879)
p 138: See Mittheil. -> period added
p 142: plates 2., -> plates 2,
p 143: it or counteractering -> counteracting
p 143: for general distribution -> distribution)
p 144: of the Entomlogist -> Entomologist
p 144: [pp. 46, figs. 8.)-> [pp. 46, figs. 8.]
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