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Title: The romance of insect life : Interesting descriptions of the strange and curious in the insect world
Author: Selous, Edmund
Language: English
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[Illustration]
THE ROMANCE OF
INSECT LIFE
------------------------------------------------------------------------
[Illustration: FIRE BEETLES AS LANTERNS.]
[Illustration]
The Aztecs of Mexico were accustomed to use these insects to
light them through the forests by night. Fastening them to
their hands and feet, they passed flaming along. It is said
that the Mexicans still use them for this purpose. The fire
beetle is shown to the left of this inscription.
------------------------------------------------------------------------
THE ROMANCE OF
INSECT LIFE
INTERESTING DESCRIPTIONS OF
THE STRANGE AND CURIOUS IN
THE INSECT WORLD
BY
EDMUND SELOUS
AUTHOR OF
“THE ROMANCE OF THE ANIMAL WORLD,” “BIRD LIFE GLIMPSES,”
“BIRD WATCHING,” “TOMMY SMITH’S ANIMALS,” &c.
WITH TWENTY-ONE ILLUSTRATIONS BY
LANCELOT SPEED
&
CARTON MOORE PARK
THIRD EDITION
LONDON
SEELEY, SERVICE & CO. LIMITED
38 GREAT RUSSELL STREET
1914
------------------------------------------------------------------------
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------------------------------------------------------------------------
CONTENTS
CHAPTER I
PAGE
“The natural system”—A middle course—Neuropterous insects—White 13
ants and their ways—Kings and queens—A royal diet—Secondary
majesties—Soldiers and workers—Ant invaders—Methods of warfare
CHAPTER II
Ant language—Stridulatory organs—How white ants 20
communicate—Conversation through convulsions—Nests in
tubes—Detection of a “crepitus”—Mutual recognition—Cannibalistic
propensities—Royal jealousy—Loyal assassins—A kingly
feast—Methods of feeding—Foundation of colonies—Swarming habits
CHAPTER III
Ants and white ants—Guest insects—Ants’-nest beetles—Doubtful 32
relations—A strange forbearance—Yellow ants and white
wood-lice—Beetles fed by ants
CHAPTER IV
Ant parasites—Fleet-footed brigands—Honey-stealing mites—A strange 42
table companion—Privileged cockroaches—Ants and their riders—A
fly-ride on beetle-back
CHAPTER V
From biped to quadruped—Flies that borrow wings—Sit-o’-my-head—A 54
novel cradle—Flies that kill bees—Nature’s sadness—Consolations
of the future—The Tachina fly and the locust
CHAPTER VI
The burden of the locusts—Classical nonsense—Address to 65
Mahomet—Locusts in Europe—Succumb to the English
climate—Described by Darwin—Locusts in Africa—The wingless host
do greatest damage—Hoppers and jumpers—“An army on the march”
CHAPTER VII
The sense of direction—How locusts look flying—Follow no 75
leader—Unanimity of movement—Flight by moonlight—Roosting at
night—Extirpated in Cyprus—The “Chinese Wall” system—Not adapted
to Australia—Deference to aboriginal feeling—Locusts in
Australia—Strange ceremony of egg-laying—Inadequate explanation
CHAPTER VIII
Locusts and _locustidæ_—The most musical grasshoppers—Katydid 85
concerts—A much resembling note—Cricket thermometers—Cicadas and
sounding-boards—Admired musicians—An appreciative audience
CHAPTER IX
A Greek mistake—Nature vindicated—Cicadas provided for—A difficult 98
feat—Perseverance rewarded—Cicadas in story—Dear to Apollo—Men
before the Muses—Plato and Socrates—Athenian views—A mausoleum
for pets—The Greek ploughman—Apollo’s judgment—Hercules’ bad
taste—Modern survivals—A beneficent insect—Elementary education
in Tuscany
CHAPTER X
Cicadas in England—A blower of bubbles—The prolific Aphis—A nice 108
calculation—Scientific curiosity—Dragon-fly armies—The son of
the south-west wind
CHAPTER XI
Aphides and their enemies—Curious interrelations—The biter 119
bit—Altruistic development—Bread and beer protectors—Saved by
ladybirds
CHAPTER XII
Ants and their honey-cows—A mutual benefit—Unity of motive—The end 129
and the means—Two ways of getting honey—Insect cattle—Wasps as
cow-milkers—A cow-keeping bee—Ant cow-sheds—Aphides in ants’
nests—Children of light and darkness—Forethought extraordinary
CHAPTER XIII
Cow caterpillars—The adventures of Theophrastus—Cave-born 144
Ariels—Led to the sky—A strange attraction—Ant slaves and
slave-holders—Slave-making raids—Feeble masters—An ant
mystery—Effects of slavery—The decadent’s reply
CHAPTER XIV
Ant partnerships—How some ants feed—Persuasive methods—An 159
_imperium in imperio_—Amusement by instinct—Begging the
question—Nest within nest—Ant errors _v._ human
perfection—Distorted arguments—How partnerships begin—Housing an
enemy—Ant ogres
CHAPTER XV
Ant wonders—Leaves cut for mushroom growing—How ants plant 172
mushrooms—A nest in a mushroom-bed—“Psychic plasticity”—Two
opinions—Ant stupidity—Unfair comparisons—The ant and the
servant-maid—Mushroom-growing beetles—Choked by
ambrosia—Intelligent uselessness—Automatic phraseology—A curious
insect
CHAPTER XVI
From wood to ambrosia—Wood-boring beetles—Rival claimants—Stag and 188
other beetles—Metempsychosis—Flies with horns—Comical
combatants—Female encouragement—The sacred Scarabæus—A beetle
with a profession—Table companions—Old and new fallacies—From
theft to partnership
CHAPTER XVII
Do ants sow and reap?—Rival observers—The Texan _v._ Macaulay’s 200
schoolboy—More evidence wanted—How ants cross rivers—Tubular
bridges—Ant armies—A world in flight—Living nests—Ants and
plants—Mutual dependence—Nests in thorns and tubers—Ant
honey-pots—Business humanity—Burial customs—A strange
observation—Two views of ants
CHAPTER XVIII
Bees and wasps—A bee’s masonry—What happens to caterpillars—Living 218
food—Variations in instinct—A wasp’s implement—Unreal
distinctions—A cautious observer—Bees that make tunnels—A
wonderful instinct—Leaf-cutting bees—Nests made of
poppy-leaves—Born in the purple—Commercial philosophy—The
appreciative white man—Economy of labour—Bees and rats—Busy
shadows—A bee double
CHAPTER XIX
Natural selection—Protective resemblances—A locust’s 238
stratagem—Mock leaf-cutting ants—Flowery dissemblers—A Malay
explanation—Snake-suggesting caterpillars—A prudent
lizard—Inconclusive experiments—A bogus ant—Flies that live with
bees—A caterpillar that dresses up—A portrait-modelling
caterpillar
CHAPTER XX
Butterfly resemblances—A living leaf—How spiders trap 255
butterflies—Butterfly doubles—Suggested explanation—More
evidence wanted—Warning coloration—A theory on trust—A
straightforward test—Advice to naturalists—A strange omission
CHAPTER XXI
Sights of the forest—A butterfly bridge—Bird-winged 272
butterflies—“What’s in a name?”—Scientific
sensibility—Resemblance _v._ mimicry—A convenient wrong
word—Beauty in nature—Nuptial display—Strange
counter-theory—_Lucus a non lucendo_—Reasoning by
contraries—True in Topsy-turvydom—Butterfly courtship—Form and
colour—A curious suggestion—Powers of defective eyesight
CHAPTER XXII
Beautiful spiders—The “Peckham paper”—Spider courtships—Male 289
antics and love-dances—Occasional accidents—Strength of the
evidence—The one explanation—Darwin’s last words—His theory
established
CHAPTER XXIII
Web-making spiders—Dangerous wooings—An unkind 307
lady-love—Lizard-eating spiders—Enlightened curiosity—Rival
entomologists—Instinct of resignation—A worm-eating
spider—Alternative explanation—The dangers of
patriotism—Trap-door spiders—Web-flying spiders—Spiders that
nearly fly—Spider navigators—The raft and the diving-bell
CHAPTER XXIV
Aquatic insects—Lyonnet’s water-beetle—A floating cradle—Larva and 320
pupa—An ingenious contrivance—Nothing useless—The imaginary
philosopher—How the cradle is made—The mysterious “mast”—Later
observation—The giant water-bug—An oppressed husband
CHAPTER XXV
One remark—Phosphorescent insects—Glow-worms and fire-flies—Fiery 329
courtship—A beetle with three lamps—Travelling by
beetle-light—The great lantern-fly controversy—Is it
luminous?—Madame Merian’s statement—Contradictory evidence—A
Chinese edict—Suggested use of the “lantern”—Confirmation
required—Luminous centipedes
CHAPTER XXVI
Scorpions and suicide—The act proved—Intention 345
probable—Conflicting evidence—Scorpions and
cockroaches—Concentrating backwards—Economy of poison—Decorous
feeding
------------------------------------------------------------------------
LIST OF ILLUSTRATIONS
By Lancelot Speed & Carton Moore Park
PAGE
FIRE-BEETLES AS LANTERNS Frontispiece 335
ANT-EATER AND WHITE ANT-HEAPS 14
AN INSECT FREEBOOTER AND AN INSECT BEGGAR 42
RIDING ON BEETLE-BACK AND A LIVING SWEET-SHOP 52
A BUCCANEER FLY AND A LEAF-RESEMBLING INSECT 58
A PLAGUE OF LOCUSTS 76
A WASP BEARING OFF A CICADA 100
A LUCK-BRINGING GRASSHOPPER 106
THE HERCULES BEETLE 190
GREAT ANIMALS PURSUED BY DRIVER ANTS 206
DRIVEN OUT BY HORNETS 220
SOLITARY WASPS 228
PROTECTIVE MIMICRY—LEAF-RESEMBLING BUTTERFLIES 256
A DANCING SPIDER, AND A COCKROACH ATTACKING A 294
SCORPION
A BIRD-CATCHING SPIDER NET 308
INSECTS THAT CARRY LAMPS 330
------------------------------------------------------------------------
=THE ROMANCE OF
INSECT LIFE=
------------------------------------------------------------------------
CHAPTER I
“The natural system”—A middle course—Neuropterous
insects—White ants and their ways—Kings and queens—A royal
diet—Secondary majesties—Soldiers and workers—Ant
invaders—Methods of warfare.
IF there is any plan in this little book it will, no doubt, appear in
time to its readers, but I myself am only quite clear as to this, that,
not being of a scientific nature, it will not include a definition of an
insect. Why should it? Everybody knows what he thinks an insect is, and
those who may be willing to have their ideas on such a fundamental
subject disturbed will rightly consult some work of greater authority
than this can pretend to. So instead of worrying myself, and others,
about what insects really are, or what are not really insects, as, for
instance, spiders, centipedes, scorpions, and the like, all which I
propose to include in my tale—should they happen to present themselves—I
shall confine myself to saying something about what some insects do, and
I shall let one suggest and lead to the discussion of another, quite at
haphazard, and without any attempt at system or classification whatever.
This, in fact, is my own idea as to what is “the natural system,” and
the only trouble about it is knowing where to begin, because, as there
are some 300,000 known insects,[1] and any one of them will do as well
to start from as any other, there is a great _embarras de richesses_. In
such cases the usual thing to do is to take either the head or the tail
of the series—to commence with the _Hymenoptera_, which include the
highest and most intelligent forms, such as the ants and bees, or else
with the _Collembola_ or _Thysanura_, which are understood to contain
the lowest. I shall not adopt either of these methods. The _Neuroptera_,
as far as I can make out (and if they don’t it doesn’t matter), stand
somewhere about the middle, and with them accordingly—as being between
the two extremes—I decide to break ground. Having done so, as I said
before, I may go anywhere—absolute freedom will be mine. Like Plato, I
can follow the argument whithersoever it leads; inspired with which
reflection I hasten to begin it.
Though the order of neuropterous—which, by the way, means
nerve-winged—insects does not contain any ants, yet the so-called white
ants or termites—which are very like ants in their ways, and almost, or
quite, as interesting to talk about—are included in it. They are
commonest in tropical or, at any rate, very hot countries, such as
Africa, Australia, and South America, and here the conical, or
dome-shaped structures, made of red earth, which they erect above the
surface of the ground, and which contain the greater part of the nest,
are of such dimensions as to take a very prominent part in the features
of the landscape. Often they are covered with vegetation, including
bushes, or even small trees, on which, in Africa, antelopes are
accustomed to browse. In Australia there is no reason, that I can see,
why kangaroos should not, at least upon the grass which must often
clothe them, and which is their staple of food.
------------------------------------------------------------------------
[Illustration: WHITE ANT HEAPS]
[Illustration]
These great mounds are made by the white ants, and contain
their nests; but large and strong as they are, the ant-eater
breaks them down and devours the ants. A queen white ant is
shown at the right-hand corner with the extraordinary
development in which the eggs are carried.
These great mounds are pierced in every direction with innumerable
galleries, leading to and from the various cells and chambers in which
the domestic economy of the white ants is principally performed, one of
which, known as the royal cell, contains the king and queen, and is
situated beneath all the others. Not all white ants, however—for there
are several species—are governed or presided over in this way. Grassi,
who studied them in Sicily,[2] declares that the whole of the Termitidæ,
whether belonging to Southern Europe or the still hotter countries from
which they have, no doubt, been unknowingly imported, fall into two
primary types. In the first of these the colony is presided over by a
king and queen, representing the fully developed male and female forms,
which have once, unlike the workers and soldiers—for, like ants, these
insects are divided into castes—possessed fully developed wings, which
they have subsequently got rid of in the same way that the queen ant
does hers. In the second type the colony possesses several kings and
queens, but these, though they marry and produce offspring, are not
perfect males and females, and never possess wings. They are, in fact,
produced artificially by the working termites, just as the hive-bees are
able to make themselves a new queen—should they require one—by feeding
an ordinary worker with royal jelly, and by a method somewhat similar
though not precisely the same, the royal substitutes being fed, not on
any extraneous substance, but on a salivary fluid secreted by the
workers themselves—saliva, in fact. The colony, however, is, in this
case, not founded by the royalties thus bred up, but by a portion of a
pre-existent colony which, migrating from the parent nest, takes this
method of augmenting its numbers.[3]
In the termite nest, as amongst ants, all members work for the good of
all. The soldiers, which are furnished with large heads and long
scythe-like jaws, take upon themselves the duties of attack and defence,
though in some species they only do so when the enemy is of a formidable
nature, leaving unimportant foes to their less specialised companions.
These are equal to such inglorious tasks, but when the colony is invaded
by hostile members of their own race, or by some fierce ant enemy, they
retreat into the inner recesses, leaving the danger and honour to
others. Such an enemy is _Cremastogaster scutellaris_—or call him
Cremas—who, though never invaded by the white ants, enters their nest—or
termitary, to use the learned word—intent upon massacre. Under such
circumstances “the soldiers place themselves, with gaping mandibles,
waiting for any ant that may come within reach. They then snap their
jaws rapidly, shearing off antennæ and legs, tearing the abdomen, or
even cutting the ants in two. The soldiers’ mandibles are seen to act
like extremely sharp shears.”[3] This should be somewhat discouraging
for the ants, and, indeed, they seem rather shy of the soldiers,
avoiding their heads, and “only daring occasionally to attempt to lop
off their mandibles.” Their more considered method, which they adopt
whenever practicable, is to approach them from behind, and bite their
abdomens, the soldiers, on their part, endeavouring to protect this
vulnerable portion—and it is a fairly large one—of their anatomy by
creeping backwards under pieces of wood or stones, from which the head,
with its murderous jaws, is alone allowed to project.
In these encounters the advantage does not seem to lie so decidedly with
the ants as to explain their conduct in making the invasion, since
peace, according to Professor Grassi’s observations, is usually
concluded “after about an hour’s conflict, with a certain number of
killed and wounded on both sides.”[3] As a result, however, it would
appear that the ants often remain in possession of a portion of the
nest, whilst the original occupants have to be contented with what
remains. If this, therefore, is their object, the invaders have carried
the day, but if, as seems likely under natural conditions, they should
prefer to return to their own home, they can hardly be said to have done
so. Information seems wanting on these points.
As with ants, war is also waged between the various species of
Termitidæ. _Termes lucifuga_, for instance—for where there is no English
name there is nothing for it but to speak Latin—is, though much smaller,
a terrible enemy of _Calotermes_. The soldiers of the latter can,
indeed, without much difficulty, cut their own in two, but their greater
activity is often more than a match for the superior strength of their
opponents. The workers are more easily disposed of, but with these the
soldiers of _Calotermes_ do not often concern themselves. They are left
to the nymphs[4] and larvæ, the equivalents, with the latter species, of
a true worker caste which has not yet been developed amongst them, as it
has with others of the family. When Professor Grassi placed a worker of
Termes in one of his Calotermite tube-nests[5] it was at once placed
_hors de combat_ by a nymph (somewhat a shrewish one) of the latter,
which, rushing upon it, cut off a portion of its mouth. Other nymphs, as
well as several large larvæ, then hurried up and proceeded to further
the good work by severing the unfortunate creature’s legs, and tearing
open its abdomen. In all this the soldiers took no part until one,
towards the end of the struggle, advanced and added his single bite to
those which had been so plentifully bestowed. Similar observations were
made upon various other occasions, from which it appears plain that, as
before remarked, the soldiers of this—very probably of all the
termites—are accustomed, purposely, to reserve their strength for foemen
worthy of their steel.
It will be seen from the above account that termites differ from true
ants in one very important particular, namely, that they are as active
and free-moving in the larval and pupal states as in the mature, or
imago, one. “The termite society,” indeed, “consists, for the most part,
of wingless sexually immature individuals, children potentially of both
sexes, which do not grow up.”[6] Out of the majority of these the worker
caste, when it exists, is formed, whilst a much lesser number develop
into the large-headed, long-jawed soldiers. Both of these castes,
apparently, are produced independently of sex, that is to say, they are
potentially either males or females, and not composed exclusively, as is
the case with ants and bees, of undeveloped females. Only the genuine
king and queen of the termitary would seem to have attained the true
imago state; such substitute royal forms as the workers, by feeding the
larvæ with saliva, are able to produce, retaining larval
characteristics, though sexually mature—a phenomenon scientifically
known as _neoteinia_. As with the bees, these potential future royalties
are bred up by the working termites to meet possible future emergencies.
They are never allowed to leave the nest, and, should any accident
befall the reigning king and queen, a pair of them are chosen to rule
and produce offspring.
-----
Footnote 1:
The Concise Natural History, p. 551.
Footnote 2:
In conjunction with Dr. Sandias, whose name must be understood as
accompanying Grassi’s—for the most part—when the latter is referred
to.
Footnote 3:
Quarterly Journal of Microscopical Science, vols. 39 and 40.
Footnote 4:
A nymph is the free-moving active equivalent of the chrysalis amongst
moths and butterflies.
Footnote 5:
Nests built in chemical glass tubes and thus under close observation.
Footnote 6:
Chambers’s Encyclopædia.
------------------------------------------------------------------------
CHAPTER II
Ant language—Stridulatory organs—How white ants
communicate—Conversation through convulsions—Nests
in tubes—Detection of a “crepitus”—Mutual
recognition—Cannibalistic propensities—Royal jealousy—Loyal
assassins—A kingly feast—Methods of feeding—Foundation of
colonies—Swarming habits.
IT used to be supposed that such communication as ants are capable of
holding with one another took place entirely, or almost entirely,
through the mutual stroking of the antennæ, and Sir John Lubbock (now
Lord Avebury) was unable to satisfy himself, after numerous experiments,
that they could either hear or utter any sound. It is now known,
however, that not only can some ants emit various sounds at their
pleasure—as, indeed, is sufficiently obvious in the case of one or two
species—but also that they possess special structures enabling them to
do so, and the existence of which is inconceivable, except on the
supposition that they both hear and attach a meaning to the notes thus
evolved. Thus at a meeting of the Entomological Society held in the year
1893, Dr. David Sharp (author of the “Insects” portion of _The Cambridge
Natural History_) declared that “examination revealed the existence in
ants of the most perfect stridulating or sound-producing organs yet
discovered in insects, these being situated on the second and third
segments of the abdomen in certain species. The sounds produced were of
the greatest delicacy, and it appeared doubtful whether the microphone
would be able to assist the human ear in their detection”—which, indeed,
it has not yet done.[7] Later, in the work above mentioned, Dr. Sharp
remarks, “In many ants these parts”—that is to say the abdominal
segments—“bear highly developed stridulating organs, and the delicacy
and perfection of the articulations allow the parts to be moved, either
with or without producing stridulation.”[8]
As these ant utterances are not sufficiently loud to be audible to our
human ears, they must, I suppose, be inferred from the existence of the
organs above-mentioned, and the way in which they work; but this is
surely sufficient data to go upon, since it is hardly possible for one
hard substance to grate upon another silently. Forel, accordingly, as
well as Janet and other observers, now believe sound to be one of the
principal means by which ants hold converse with each other, and it is
interesting to find that Grassi and Sandias have arrived at the same
conclusion in regard to white ants, or termites. Their opinion, together
with the facts upon which it has been founded, is thus expressed:—
“Several writers have mentioned the convulsive movements characteristic
of Termites. These movements, or quiverings, are easily observed in
Calotermes, and may be repeated periodically at very short intervals,
almost at the frequency of the pulse-rate. In the act of quivering, the
legs are held motionless, whilst the body is shaken forwards and
backwards. Sometimes a white ant may stop, whilst running, in order to
quiver one or more times. Occasionally these convulsive movements are
repeated a few times only, and then stop altogether; but at other times
they recur after a few seconds’ or, at most, a few minutes’ rest, and
may thus be continued, sometimes, for hours, at regular or irregular
intervals. In the intervals between successive convulsions the insect
remains still, or progresses for a short distance only. These movements
are executed by all members of the colony except the newly hatched ones.
I have satisfied myself,” continues Professor Grassi, “by careful
observation of the phenomena exhibited in tube-nests, that these
convulsions serve as a cry to summon help or give alarm, or as a lament:
in short as a mode of intercommunication.”[9]
The same observers then go on to tell us that if white ants are
disturbed in any sudden way, as by the too rough shaking of their nest,
or by a light being suddenly flung upon it, or if otherwise annoyed,
“all the members of the colony begin to quiver, except those that are
running briskly about in search of a better situation.”[9] When dying,
too, they will sometimes quiver in this way, at intervals of a few
minutes, for as much as an hour or two, or even longer. Should an
enemy—such as those we have been speaking of—be introduced of a sudden
into the nest, the less valiant members of it prefer to run away, but in
the midst of their retreat they may often be seen to stop and quiver
with unusual energy. Their object in these cases seems to be to raise a
general alarm, nor is it long before they are successful. Again, if
whilst one insect is burrowing into wood another outside should quiver
in this way, the burrower quickly comes out, as though in response to
some signal of alarm. From all this it seems evident that these curious
movements must be accompanied by some sound, or sounds, inaudible to our
human ears, and perhaps having a varied range, and with considerable
power of modulation. To produce them, however, some stridulating or
other organs would seem to be necessary, and of these, though they must,
if there, be visible under the microscope, Professor Grassi says
nothing. Possibly, however, sounds may be produced by the rubbing
together of various parts of the body without any special apparatus
having been developed, in which case the language, if we may call it so,
cannot be so rich or copious.
The above remarks apply more especially to the larger of the two white
ants of Southern Europe. In regard to the smaller one, Professor Grassi
makes the following interesting remarks: “Termes makes the same
convulsive movements as does Calotermes, but the soldier of this species
is able to produce a special creaking sound, which arises, whenever the
head is held horizontally, during the act of quivering, by friction
between the back of the head and the front part of the thorax. But
whenever the head, during this act, is held in the usual position, which
is not quite horizontal, no perceptible sound is produced, owing to the
absence of such friction. The soldiers of Termes, therefore, possess two
distinct modes of communication, whilst those of Calotermes have only
one, in which no perceptible sound is produced. This characteristic
_crepitus_,” continues the Professor, “may be heard, at frequent
intervals, by applying the ear to a tube containing a nest of Termites.
This proves that the quivering motions are a constant feature in
undisturbed nests, so that they cannot be employed only as signals of
alarm or distress. I conclude, therefore, that besides such special
significations these convulsive movements must also have the value of
ordinary speech; that they constitute, in short, a means of
intercommunication. The same conclusion holds good for Calotermes (the
one we have hitherto been talking about), and I imagine that the
quivering of both species produces a sound which is perceptible to the
insects themselves, but inaudible to the human ear.”[9]
Members of the same ant community are known to recognise each other, and
this is no less the case with the white ants, or termites. Thus when a
few of the latter were removed from the termitary and returned to it
after five or six hours, the population showed no signs of alarm—not
scurrying wildly about as they would have done had strangers been
introduced—but remained quiet and orderly. It was objected, however,
though I cannot see the force of such an objection, that the exiles, on
their return, would have instantly recognised their old nest, and thus,
knowing exactly where to go and what to do, they would have created no
disorder, and consequently roused no suspicion, amongst the other
members of the colony. To meet this theory Professor Grassi provided one
of his colonies with a new nest from which he excluded a certain number
of individuals, so that when these were introduced into it, an hour or
two after their companions had settled down in their fresh abode, it
was, of course, quite unfamiliar to them. In spite of this, however,
they caused no disturbance, but were clearly recognised as friends.
When, however, a few strangers of the same species were introduced, they
created great alarm amongst the rightful proprietors, who scattered in
all directions. In a little while, however, all was again quiet, and as
no fighting was observed, it would appear that, amongst the termites,
strangers from different nests soon become friendly with one another.
This, however, applies to the commoners only, it is not the same where
royalty is concerned. Thus when a second king and queen were introduced
into a termitary already provided with a pair, they were at once
attacked by the subjects of the latter, who loyally bit off their legs.
Two days afterwards the reigning queen was herself seen to attack the
male pretender, or rather unfortunate victim of scientific curiosity.
He, however, though without legs to assist him, managed to drag himself
away, but was afterwards found dead, with the outraged queen nibbling
vindictively at his mutilated stumps. Next day the stranger queen was
also found dead, and the same thing always happened whenever the
experiment was repeated. Sometimes, indeed, the supernumerary royal
pair, or pairs, had disappeared altogether, from which it seems clear
that they must have been not only killed, but eaten.
Cannibalism, indeed, is rather an institution than a vice in the
termitary. To begin with, the cast skin of every member is eaten by the
others as a matter of course. With this view, any individual who is
ready to moult receives the skilled aid of two or more assistants, who
either eat the outer portion of their friend, bit by bit, as they shred
it off, or else carry it away whole and devour it at their leisure.
Sometimes, moreover, one, after licking another affectionately, in the
way that ants do, may be seen to give it a covert bite, as though
desirous of something more filling, whilst any sick member is eaten by
its companions before it is dead. Royalty is not exempt from this
treatment, and, on one occasion, nine individuals, including one
soldier, were observed by Professor Grassi in the act of enjoying a meal
on the body of a substitute king who was in process of moulting. The
wretched animal was still alive, and writhed all over its body, to free
itself from the torture. The nine assassins were probably annoyed at the
light, for they at once stopped eating, and jointly carried off the
victim to a darker part of the nest. Meanwhile many others crowded up to
partake in this feast of royal flesh.[9]
A soldier, too, has been observed to kill and partially eat one of its
worker companions, nor is it altogether uncommon for an individual of
any class, after licking, for some little while, the leg of another,
suddenly to snap it off. The bond of union, therefore, though
sufficiently developed to allow of an elaborate social organisation, is
not so strong between members of the same termitary as it is in the case
of ants, amongst which latter such unseemly conduct is never known to
occur. So, too, unless a particular chemical substance, which seems to
have a maddening effect, be flung amongst them, ants of one community
never attack each other. Amongst white ants, however, warfare will
occasionally break out within the nest, more especially if this be
disturbed, in which case the soldiers are apt to turn savagely on those
nearest to them, perhaps considering them as the cause of the calamity.
Still, upon the whole, order, and, if not friendship, at least
co-operation, is conspicuously displayed, and the majority often
interfere to put a stop to such individual or partial combats as may
from time to time break out.
There is more excuse for the soldier termites in their cannibalistic
propensities, since owing to the special development of their jaws,
which are long and slender, they are unable to triturate wood, which is
the basis of diet of these insects. They might die, therefore, but for
such occasional lapses, were it not the common practice for all members
of the community to feed one another, though the soldiers, for the above
reason, are much more dependent on such aid. The food thus administered
has just been swallowed by the individual who parts with it. Such
transfer is performed in two ways, the first of which is familiar
enough—that process, namely, known as regurgitation—but the second and
more staple one is too peculiar to be dealt with in a non-scientific
work. When a termite regurgitates, an exceedingly small round pellet of
reddish-brown colour may be seen, by attentive observation, to form
about the mouth, and gradually to increase in size till it becomes
plainly apparent, and is seen to consist of food—that is to say,
wood—which has previously been swallowed, in a moistened and softened
condition. Sometimes this pellet is used for building purposes, but
often another termite comes forward, receives, and swallows it.
Another article of diet which has a peculiar efficacy, and is used for a
certain purpose, has been already alluded to—viz. saliva. This, we are
told, “issues,” when required to do so, “as a colourless and distinctly
alkaline liquid. It collects on the labium (the insect equivalent of
lips) as a small drop, which may be employed either as a cement in
building or as food for others. These may either possess themselves of
the drop and then retreat a little way in order to swallow it gradually,
or they may receive it from the one which secretes it and clearly
provides it for them as an article of diet. The assimilation of a drop
requires a certain number of acts of deglutition, which may be counted,
and are usually four or five.”[9] Very young larvæ (the whole community,
it must be remembered, are either in this or the pupal state) are fed
after this fashion, until sufficiently advanced to be able to swallow
wood-meal. Under this course of diet the abdomen becomes remarkably
transparent, and this, in older individuals, is an indication that they
are being bred up by the workers to become royal substitutes. The
development, therefore, of termites from the larval to the perfect, or,
at least, the sexually perfect form, seems to be wholly dependent on
their being fed with this substance.
As is well known, the body of the queen termite, in the African and
other tropical species, swells, when about to lay, to an enormous size,
but this is not nearly so noticeably the case with her European
representatives. Neither is a cell, in this case, constructed for her
accommodation, but the royal pair, whether they are true king and queen,
or only substitutes, “remain, in close proximity, in the heart of the
nest, where the inmates are always most crowded.” They are not
imprisoned, therefore; but can go from one place to another, should
they, as sometimes happens, wish to change their situation. In this they
would seem to be happier than their more specially accommodated royal
cousins, but no doubt, with the latter, or at any rate with the queen,
the instinct of locomotion ceases with the capacity to indulge in it.
The purpose of the specially made cell is probably rather to guard than
to restrain the queen.
In regard to the swarming of white ants—another habit in which we are
reminded both of ants and bees—with the subsequent founding of a new
colony, Professor Grassi has the following remarks to make. They apply
more especially to the larger of the two European species, viz.
Calotermes. “Before swarming,” he tells us, “they collect near one of
the exit-holes of the termitary, and when the proper time comes, issue
from it in ones or twos, so that the twenty or thirty members who are
ready to take flight emerge in perhaps a quarter of an hour. Once
outside, they run upwards, if the locality admits of it, for a few
metres, and then only do they take wing. In a room they fly towards the
light, and if a wind is blowing they follow its direction. Some,
becoming tired, settle soon upon trunks of trees, and all may do this
eventually. Here they group themselves into pairs, the males and females
of which must frequently be derived from separate nests, since the sexes
swarm separately; this acts as a safeguard by which Calotermes
habitually avoids in and in breeding. Matrimonial alliances having been
thus formed, the work of excavation commences, each pair seeking for
some decayed spot in which to bury themselves and become, in time, the
parents of a fresh community. The wings, by this time, have been got rid
of. They may be shed by coming into contact with an obstacle, or by
getting damp and adhering to some spot, while the insect continues to
move. But, if not favoured by chance, the Calotermite purposely rids
itself of these now useless encumbrances. Thus four perfect insects were
captured after flying about the room, and put under a piece of rotten
wood. Hardly had they settled when they stripped off their wings by
resting the tips against some projecting corner of the wood, and then
moving backwards a little, so that the wings bent near the base, broke,
and dropped off. When rid of them they began to gnaw the wood, at first
along and then across the grain. When they encountered each other by
chance they first threatened to bite one another, and then ran off in
opposite directions. This was because they were of the same sex. Had
they been of opposite ones, an attachment, under such circumstances,
would no doubt have been formed between them.”[9]
This is all the space which I can afford to these interesting insects.
There are many other points in connection with them which I might have
touched upon, but I thought it better to say less about what may be read
by anyone in a score or so of works, and select as my text-book a series
of the closest and most interesting observations, which lie buried in
the pages of a scientific journal not at all likely to meet the public
eye. Where possible, I shall be guided by the same or a similar
principle throughout this small work.
-----
Footnote 7:
Nature, March 23rd, 1893.
Footnote 8:
The Cambridge Natural History, vol. 6, p. 134.
Footnote 9:
Quarterly Journal of Microscopic Science, vols. 39 and 40.
------------------------------------------------------------------------
CHAPTER III
Ants and white ants—Guest insects—Ants’-nest beetles—Doubtful
relations—A strange forbearance—Yellow ants and white
wood-lice—Beetles fed by ants.
FROM what has been said about the Termites in the last chapter, it is
clear that they very much resemble ants in their habits, so that it is
no wonder that they have long passed for ants in popular estimation.
Such a similarity is quite enough to justify one part of the name, as
names go; and as for the word white, which entomologists are always
complaining about, that is quite near enough too, for though their
bodies are not white, but yellow, yet the greater part of them—the soft
fat abdomen, which particularly catches the eye—is of such a light
yellow that it suggests white in contrast to the darker colouring of
most ants. Scientific men—unless their particular science is
philology—are dreadful pedants in regard to names, and always want to
substitute their own manufactured ones, which have no real life in them,
for what has sprung up naturally on the lips of the people. Thus,
instead of hedge-sparrow—a name that explains itself to anyone who has
seen the bird and knows something of its ways—ornithologists would have
us say “hedge-accentor”—a preposterous concoction—and stormy petrel
should, according to them, be “storm-petrel,” because the bird itself
cannot be stormy, whatever the sea may be. No imagination behind the
common use of language, then. No poetic transference of attributes. All
is to be as prosy as professors can make it, and “we must speak by the
card, or equivocation will undo us.” But names, which are a part of
language, come into being as language itself does—spontaneously, that is
to say, and by a natural growth. They are right because they exist; and
the very errors contained in them—telling, as they do, of popular
beliefs and superstitions—are of greater and wider interest than the
rectitudes of a few pedants. Could they play with substance as they can
with breath, these wise simpletons would first draw up a theory of
anatomy, and then annul all bodies that did not conform to it. Such and
such a word or name is wrong, in their eyes, though it exists quite as
naturally as any nerve or muscle, and is quite as tough though only made
of air. This last they will find if they live long enough, and
“hedge-sparrow” and “stormy petrel” will survive all their lifeless
substitutions, though embalmed in many dull paragraphs of many dull
books.
But let us come back from words to things. Much as the white ants
resemble real ones in many of their habits, the more remarkable ones
that distinguish the latter are not practised by them. They make no
slaves and keep no domestic animals—at least I have never heard of their
doing so, though in natural history one must always be prepared for new
discoveries. Many insects do, in fact, live with them in the termitary,
just as others live in the formicaries of ants, and it is quite possible
that, when these have been better studied, some of them will be found to
have special relations—involving mutual intelligent action—with their
landlords.
At present, however, we seem to have little or no information on this
head. With ants it is different, and perhaps one of the most interesting
chapters in their history is that which has to do with these
_myrmecophilous_, or guest insects, as they are called.[10] Take, for
instance, the ants’-nest beetles, and especially one family—the
_Paussidæ_—which numbers some 200 species, every one of which passes the
whole of its life, when not flying by night, within the nest of some
species of ant. These beetles are small, as might be expected, the
largest being not more than half an inch in length, but present an
extraordinary appearance owing to the antennæ ending in two broad
palmated surfaces, like the horns of a moose deer, which project
outwards, one on each side, at right angles with two short stalks,
forming the only serviceable joints of these strangely modified feelers.
All the other ones (in some species, at any rate) have been fused and
welded together to form these flattened club-like structures, the use of
which is not at first-sight apparent, and may not be fully understood.
If, however, a _paussus_ is laid on its back upon a flat surface, a
predicament which would be as embarrassing to many beetles as it is to a
turtle, one of their special functions is at once seen. Turning back the
two clubs till they rest on the ground, and making the joint rigid, the
insect uses the one most conveniently placed as a lever, and soon gets
on to its legs again. Could we imagine that such an expedient would
often need to be resorted to, the curious modification of the antennæ is
at once explained; but it probably rarely happens that any small beetle
finds itself on its back in a place where there are no irregularities to
aid it in righting itself. Possibly, however, the smooth galleries or
chambers of some of the larger ants might expose these _Myrmicophilæ_ to
such a catastrophe, though, for my part, I suppose that the antennæ are
used in some other special way which is of far more importance to their
owners.
The relations existing between the ants and these curious beetles has
not yet been fully made out. It is true that the various species of
_Paussidæ_ have upon some part of their bodies a smooth downy
substance—a _pubescence_, to use the word dear to entomologists—which in
other ants’-nest beetles is known to exude a sweet honey-like dew which
the ants, not unnaturally, are very fond of, and for which they
assiduously lick them. As they have also been seen to lick their
_Paussi_, we seem, here, to have at least the root of the matter, nor
does the fact that, at other times, when perhaps these have ceased to
supply the attraction, they pay little attention to them, seem of much
importance, since we are all neglected when we have given what we have
to give. But there are other circumstances not of so straightforward a
nature. It has been lately discovered by a French observer—M.
Péringuey—that these _Paussidæ_, welcome guests as they generally are,
will yet, sometimes, eat the larvæ of the ants with whom they live, when
any small worker is engaged in carrying them from one place to another.
The ants resent this, and occasionally a large one, who feels himself
equal to the undertaking, will attack and even kill a _Paussus_ that he
sees behaving in such a manner. Yet, with all this, so valued are these
beetles by the ants that they often drag them back into their nests,
when they have approached, or emerge from, the entrance. On such
occasions, and also when the ants attack and even dismember them, the
_Paussidæ_ make no sort of resistance. Yet they are extremely well able
to do so, being armed with a weapon of tremendous efficiency, by which
in a moment they could kill or stun a whole crowd of ants round about
them. For they are bombardier beetles, having the power at any moment of
discharging a fluid of a highly acrid nature, and so volatile that, on
coming in contact with the air, it explodes with a puff of blue smoke,
exhaling at the same time a very pungent and unpleasant odour. When they
are tickled with a straw, even, this bombardment at once takes place,
and ants all round are seen to stagger or drop to the earth. Small
workers are killed, large ones retreat in confusion; yet the owner of
this deadly battery, which can only have been developed for the express
purpose of overwhelming an enemy, will not, even to save life or limb,
discharge it against an ant—not one, at least, to whom it stands in
these somewhat doubtful relations.
How have these relations—whatever in their entirety they may be—come
about? My own idea is that these beetles, like some other
creatures—amongst them the little white wood-louse that lives with our
own _Formica flava_—found ants’ nests very comfortable places of
retirement, since, by reason of their peculiar weapon of defence, they
could defy any attempt to interfere with them, on the part of the ants.
The ants, on their side, would soon have given up molesting them, so
that, never requiring to defend themselves against the creatures by whom
they were surrounded, the intruders got to associate them with quite
other ideas, and, having first lost the habit, at length lost the power
of turning their artillery in this direction. Meanwhile _Paussus_, owing
to its sweet secretion, which, after relations had once become amicable,
the ants would soon have discovered, had got to be a very welcome guest,
so much so that, even when it took to eating their larvæ, they retained
their love for it, as a species, though resenting such conduct upon the
individual. And now the once redoubtable invader could be punished with
impunity, for the habit of never discharging against an ant had become a
fixed, inherited instinct, not to be got rid of even though life were at
stake. Thus, as it appears to me, it may have come about that, though
armed with dynamite, and carrying bombs, no living _Paussus_ has ever
defended itself against an ant, and no living ant, perhaps, ever seen a
_Paussus_ discharge its artillery. Of course these are only conjectures,
and the last, especially, may be opposed to fact, since it has been
suggested that one way in which _Paussus_ may make itself useful within
the nest of its hosts, may be by bombarding certain obnoxious parasites,
or other would-be invaders. This does not, however, appear to me to be
likely, for how could these explosion take place, under such
circumstances, without doing damage to the ants themselves? In one’s own
house one would hardly wish a bomb to be thrown, even against one’s
greatest enemy—at any rate not in the drawing-room. That the ants
should, by this means, be able, or, if able, willing to rid themselves
of the mites which infest them, as has been conjectured, seems
especially unlikely—indeed, hardly possible. On the whole, it seems to
me that the relations at present existing between the two insects could
only have grown up through _Paussus_ having ceased to discharge, not
only at an ant, but even—owing, probably, to there never being any
occasion for it—in an ants’ nest. The experimental tickling with a straw
was, of course, an artificial stimulus. In spite of its sweet secretion,
I cannot see how a beetle with such a power at its command as _Paussus_
has, can have been originally selected by the ants for domestication,
but, on the other hand, an armed invader might easily, by coincidence,
possess some property which would make it, in time, of use and value to
the population on which it forced itself.
An example of an invader having no such merit, but harmless, and that
has become tolerated through necessity, is, in my opinion, the little
white wood-louse before mentioned. It apparently has now lost the power
of rolling itself into a ball, but when it first began to penetrate into
the galleries of _Formica flava_—our little yellow ant—it may very well
have had it, and this would have rendered it impervious to attack,
whilst its weight and round scaly surface would have made the task of
removing it almost an impossible one. Thus, perforce, it stayed where it
wished to stay, penetrating, perhaps, deeper and deeper into the
labyrinth of galleries, as successive generations of cave animals have
retreated farther and farther from the light of day, until at length,
finding the wherewithal to live, it became wholly subterranean in its
habits, lost the power of doing what it never required to do—namely, of
rolling itself into a ball—and, through the absence of all sunlight,
lost, too, its colouring matter, and became of its present dead,
bleached white. Whether its eyesight, if it ever had any, is also gone,
I do not know; but it can hardly, under present conditions, have any use
for it, whereas its antennæ are constantly moving, and seem to be of
extreme delicacy. I could never observe—for I have kept nests of
_Formica flava_—the smallest sign of any kind of relations between these
wood-lice and their hosts; and if any scavenger work is done by the
former, from which the latter derive benefit, I believe that this is
merely incidental, and that the ants know nothing about it. But they
have got accustomed to the wood-lice being there, and put up with them
because they cannot help it.
It must be remembered, in regard to _Paussidæ_, that the family is
represented by some two hundred species, all of which pass the greater
part of their lives with ants. In regard to this Mr. Kirby remarks: “The
observations made upon the family are so contradictory that the
discrepancies can only be accounted for by supposing that different
species have very different habits. Possibly some species may perform
various useful services to the ants, while others are hostile; or they
may be so useful that the ants are willing to pay toll of a certain
number of their offspring, in return.”[11]
This last, however, does not seem very well to accord with recorded
observations as to ants attacking any individual _Paussus_ whom they may
chance to see devouring their larvæ, nor with the latter refusing to
bombard, under these circumstances, even when in danger of their lives.
It is impossible to imagine a hostile _Paussus_ not bombarding, in such
a case, unless, indeed, we suppose it to have first lost its hostility,
and then again to have become hostile, without, however, regaining the
power of using its natural weapon. But this is a state of affairs hardly
to be conceived.
We probably do not know the whole round of occupations which make up the
life by day, of the _Paussidæ_; of their life by night, we know nothing
at all. The nefarious raids upon the larvæ or eggs (for both are
appreciated) of the ants can hardly be of frequent occurrence, or the
partnership, one would think, must come to an end. Other ant-guests,
however, including sometimes smaller members of their own family, are
likewise preyed upon by these curious beetles, but very frequently, when
observed, they seem to be asleep, nor do they appear then to be taken
much notice of by the ants. Where or under what conditions their eggs
are hatched, or what is the larval and pupal history of each species, we
do not know, but only the perfect insect has as yet been found in any
ants’ nest.
Other beetles that live with ants are either indifferent or hostile to
them, but others, again, are kept and tended in the same manner as are
the aphides, and for a similar purpose. All or most of these secrete
some sweet substance, which their hosts lick up, and, in return, offer
them an asylum from all enemies, and are ready to give them their
personal protection, should this be necessary. They go even further than
this, and actually feed them as they do their own larvæ, with honey, or
something of a similar nature, which they regurgitate from their crops.
One little beetle—_Atemeles_ by name—is extremely fond of such a meal,
and solicits it from the ants by stopping in front of them and assuming
a certain attitude, accompanied with insinuating motions of the antennæ.
Whether _Atemeles_ is able to feed itself, or must live wholly upon
these ministrations, I am not quite sure; but another beetle—poor
_Clavigertestaceus_—is, according to Janet, so entirely dependent upon
the ants for subsistence that, if separated from them, he has nothing to
do but to die.
-----
Footnote 10:
Others call them _inquilines_.
Footnote 11:
Kirby, Marvels of Ant Life, p. 100.
------------------------------------------------------------------------
CHAPTER IV
Ant parasites—Fleet-footed brigands—Honey-stealing mites—A
strange table companion—Privileged cockroaches—Ants and
their riders—A fly-ride on beetle-back.
LEAVING the beetles—though as there are probably some thousands that
live habitually in ants’ nests, we have said very little about them—we
may glance at an extraordinary little creature, in appearance something
like a wood-louse with a fish’s tail, that resides with certain ants on
the footing of a freebooter, constantly stealing from them, and eluding
their resentment by extreme activity, living, as it were, in a state of
perpetual motion. The legs of these persistent yet withal timid brigands
are many and long, which, together with their shape and general
lightness of build, enables them to run with great speed, so that they
easily outdistance the ants, and, escaping to some less frequented part
of the nest, with which they are always well acquainted, remain there
quiet for a time. Should a single ant approach them, however, they
immediately run away, or, if forced by circumstances to be near one or
more—which, in an ants’ nest, must be often difficult to avoid—make a
point, apparently, of never keeping still, as though to confuse them,
or, perhaps, to be the better able to dash off at any instant.
------------------------------------------------------------------------
[Illustration: AN INSECT FREEBOOTER, AND AN INSECT BEGGAR.]
The extraordinary looking insect shown towards the top is the
lepismid, or fleet-foot, who lives by stealing food from
ants when they are in the act of passing it from one to the
other. The atemeles beetle shown below is begging food,
which will not be refused, from the ant in front of him.
The way in which these fleet-foots secure their food is highly
remarkable, each little theft—which has about it more of the parasite
than the brigand—occasioning a group of three. The ants upon which they
live are of the species known as _Lasius umbratus_, and, like many other
kinds, often feed one another, the hungry asking of the full, by whom he
is rarely, if ever, denied. In the process of regurgitation—with which
we are now familiar—the two stand fronting each other, with mandibles
interlocked, and a drop of honey passes from mouth to mouth. For an
instant it trembles between the two, resting on both, and that instant
is the opportunity of the _Lepismid_. Darting forward, he interposes his
own, and having absorbed some portion of the drop _in transitu_, speeds
swiftly away to make a third elsewhere. Such a life, however great may
be the thief’s agility, is full of danger, and, from time to time, an
individual is captured and killed. In nests under observation such
executions may be witnessed, and _Lepismid_ corpses—or, as various
professors prefer calling them, _cadavers_—are sometimes noted. Under
artificial conditions, however, opportunities of escape are much more
limited, unless, indeed, some special provision is made. Thus, when
Professor Wheeler first introduced a colony of _Lasius umbratus_ into
one of his _formicariums_, he found, after a couple of _dies_,[12] five
_Lepismid cadavers_. But having, by the addition to the said
_formicarium_ of a _refugium_, or asylum, made it more as _in natura_,
this mortality ceased, and the remaining _Lepismids_ continued
henceforth _existentes_.
A similar mode of feeding, but under circumstances of much greater
security, is indulged in by _Antennophorus_, another ant-guest, whose
relations with its host are of a still closer description.
_Antennophorus_ is a mite which, according to M. Janet, fixes itself on
to the head, or the sides of the abdomen, of the ant which it affects,
and clings there as long as it sees fit. This it is enabled to do owing
to a special adaptation of the feet, which end in little horny cups
(_cornicula_ is the word here) furnished with some substance of so
adhesive a quality that it might well be called “stickphast,” if no
Latin word were at hand. Not all the feet, however, are of this
description, for the anterior ones are transformed into a pair of long
waving antennæ, which contain olfactory organs of the greatest
sensibility. With these their owner makes up for the want of eyes, and,
smelling and feeling its way, walks, when it wishes to, along the bodies
of its hosts, passing from one to another. Sometimes, either by accident
or otherwise, it becomes detached, and is then helpless as far as
locomotion is concerned, but by no means so in other respects. Its
object, now, is to reaffix itself: nor is it long before it succeeds in
doing so. As it “lies upon the soil in one of the galleries of the nest
it raises and stretches forward its first pair of ambulatory feet, and,
at the same time, explores the space around it with its long antenniform
ones. These appendages are much more agitated when an ant passes close
by. Should it pass near enough, the _Acarid_ (which has a finer sound
than ‘mite’) glues itself on to its body by means of the cup of sticky
material at the end of one of its ambulatory feet, which it holds up
ready for this operation, and it can, in this way, soon climb up and fix
itself in a good position on its host. The latter is surprised, and
seeks to rid itself of its strange companion, but failing in this, it
becomes resigned very quickly (as we do to increased taxation) as soon
as the _Acarid_ has taken up one of its normal positions.”[13] It will
carry two indeed, or even three, without complaining. An ant with one of
these burdens fixed, like the income-tax, to the under side of its head,
and two others, which may stand for a rise in tea and sugar, is a very
common sight.
The feeding of _Antennophorus_ has been closely observed by M. Janet in
his artificial nests, and is thus described by him: “The ants had
acquired a habit of placing themselves, crowded one against another, in
one corner of the nest, and thither came such as had their crops well
filled, after a meal of honey, and disgorged it before the mouths of
their comrades who had none. While the fasting ant was eating the honey
thus disgorged, _Antennophorus_, riding on its head, took its share. To
do this, it pushed itself forward, and thrust its rostrum into the
droplet, and generally, whilst holding itself in position by means of
the two hinder pairs of legs, it attached itself by means of the forward
pair (which in this case, however, would represent antennæ) to the head
of the disgorging ant.”[13] Perhaps there is some little mistake
here—possibly I have not copied the passage correctly. There has been no
hint before as to the modified antenniform legs of the parasite
performing any other office than that of feeling and smelling, whilst
the word “attach” or “affix” is that always used to describe the working
of the sticky, cup-footed ones. In the position described the antennæ
might very well act as supports, but hardly, one would think, in such a
way as that their owner could be described as attaching himself through
their means. Possibly it is the first pair of true legs that act in this
way, but the matter is of no great consequence—not more than a war, say,
or the fall of a ministry, in the general run of things. Suffice it that
we have our picture, the little parasite stretched, like a bridge,
between the heads of the feeding and disgorging ants, and taking its
share with the latter.
_Lasius something_ is the name of the ant which _Antennophorus_ utilises
in this way, and it is, I think, a European species. Another
one—_Pachycondyla harpax_—the large, black ant of America—wears its
parasite round its neck, like an Elizabethan ruff. In this case both
host and guest are in the larval state, and the involuntary partnership
between them—involuntary probably on the part of either—is not dissolved
until both have attained full maturity. The position of affairs is this:
the ant larva apparently lies on its back upon earth a little hollowed,
to receive it, by the workers of the nest. The parasitic larva—that of
an unknown species of fly—has a long, slender neck, as we may call the
anterior part of the body, and whilst this is wound about the
corresponding portion of its host, the body, which broadens out after
the manner of an oil-flask, is affixed by a disc at its end to some part
of the back of the latter. When the ants feed the larvæ, they place the
food—which consists either of grain that has been stored, or of insects
captured and torn up by them—on the broad surface of the abdomen, which
forms a sort of trough for its reception. Immediately upon feeling the
welcome load, the hungry larva stretches down its head to the banquet,
but that of the parasite moves with it, and its small, sharp jaws take
eager toll of each dish. Thus the two feed together, cheek by jowl, and
should what has been provided prove insufficient for this double
onslaught, the unbidden guest will stretch its snake-like neck, and move
it ceaselessly until the ever-ready jaws come into contact with a second
feast, upon the table next it. Should none, however, be within reach,
the guest will give vent to its irritated feelings by biting the bodies
of such unbounteous Timons, or even that of its own host. They wriggle
with pain, and this may possibly induce the ants to bring them fresh
supplies, under the impression that they are hungry, as indeed they may
be, with meals shared in this way. If so, we can hardly suppose a
parasitic larva to act with such a motive, but as the best biters would
in this case get the most food, natural selection may possibly have
helped to develop the habit, which would have a compensating advantage
for the wrigglers too. As the French say, “_Il y a compensation en
tout._”
The parasite, whilst stretching out as far as it can from the body of
its host, in quest of food, remains, all the while, attached to the
latter by the disc in which its body ends. It can, however, leave one
ant larva for another, though Professor Wheeler, to whom we owe this
interesting discovery, believes that it does this “with great
reluctance, and only under urgent circumstances, such as extreme hunger,
the death of the larva to which it is attached, and perhaps, when fully
mature, and about to pupate.”[14] So long, indeed, as its original host,
on whose body, when quite young, it was probably hatched from the egg,
continues well and is well fed, it has no reason to seek farther, since
all its wants are provided for. It is not only fed by the worker ants,
but shares in any other of the benefits which these may bestow upon the
rising generation of the nest. Thus, if they move larvæ, as is
customary, to give them change of temperature, and produce the requisite
hygienic conditions, the parasite is moved along with them, and it is
cleaned also—a still more important advantage possibly—at the same time
as they are. At such times the ants never seem to notice the uncouth
incubus upon the bodies of their infant sisters, though one would
suppose the difficulty would be not to do so. They are, it is true,
blind, or nearly so, but it seems strange that their sense of touch,
which is no doubt delicate, should not be able to inform them, since the
parasite, though small enough, absolutely, is of great size regarded as
an excrescence on its host’s body. This probably is the way in which the
matter presents itself to the ants, if they think about it at all, for
since the two lives are passed constantly together, and are subjected to
the same conditions, it is likely that they share one smell between
them.
But this curious parasitic relation between ant and fly is not confined
to the larval stage of each. Continued observation led to a further
discovery which I give in Professor Wheeler’s own words: “As the days
passed, the mature ant-larvæ spun their brown cocoons one by one, and
one by one the mature commensals (the larval parasites, that is to say)
disappeared. No traces of them could be discovered. The only remaining
resource was to open the cocoons. Five were opened, and in two of recent
formation commensals were found! Having shared the table of their host,
they had come to share its bed as well. The dipteron (the parasite, as I
have said, is a fly) had pupated after the manner of its kind, forming a
puparium, that is, instead of spinning a cocoon like the ant larva: the
dead larval skin, somewhat shrivelled and contracted, was used as an
envelope, and within this the pupa proper was found. In all cases the
puparium was located in the caudal pole (at the bottom) of the ant
cocoon, and was immovably stuck to the wall of the cocoon, its anterior
end directed towards the cephalic pole”[14] (the top). But what, asks
Professor Wheeler, does the commensal larva do “while the ant-larva is
weaving its cocoon? Does it move about to avoid the swaying jaws of the
spinning larva? or does it take up its position, from the first, at the
posterior end of the larval ant, and there remain motionless while the
posterior pole of the cocoon is being completed? It is very difficult to
answer these questions.”[14]
One might think that young ants thus deprived, day by day, of a portion
of every meal, would be stunted in their growth, and not make such large
and healthy workers as those who had never been encumbered with a
parasite. This, however, does not seem to be the case, and no difference
can be detected between the one and the other. Perhaps, therefore, ants
habitually eat, if not more than is good for them, at least more than
they require. This is the case almost universally amongst civilised men,
at least in Northern Europe, and with savages to a still greater extent
whenever the wherewithal is at hand. In the above case we have, as
Professor Wheeler remarks, a very perfect example of what is termed
commensalism, in the original meaning of the word—that is to say, of two
or more individuals dining together at the same table. As applied to
natural history, the individuals in question must be of different
species, but it is not often that the definition otherwise is so
rigorously adhered to.
This curious parasite inhabits the nests, or, more strictly speaking,
the bodies, of an ant, native to Texas, that has long been famous as a
storer of grain, but whose supposed still further achievements in an
agricultural direction would now seem open to doubt. In the nest of
another American ant, which most certainly does grow mushrooms, the same
observer found another “_myrmecophile_,” or ants’ nest insect, viz. a
minute species of cockroach that lives its life amongst the caves and
galleries of the great vegetable mass which forms, and is designed to
form, the mushroom bed, upon the product of which it feeds. Here again
the ants have become thoroughly reconciled to the presence amongst them
of a guest from which, as far as can be seen, they derive no benefit,
whilst having to submit to a loss, through its agency, of some part of
the fruits of their labours. These little cockroaches are fairly
numerous, and have become so adapted to living in darkness that their
eyes have almost disappeared. Another loss, or partial loss, is of a
more curious nature, and, one might think, would be a great privation to
them. Their antennæ, namely, are always incomplete, but this does not
seem to have come about by a gradual process of atrophy, but rather to
have been caused by mutilation during their owners’ lifetime. But how
has this happened, and what has been the mutilating agency? Professor
Wheeler’s explanation, which he believes to be the only one, is that
their antennæ have been unconsciously sheared off by the ants, whilst
engaged either in clipping their mushrooms or in cutting up the pieces
of leaves which they are continually bringing into the nest, to add to
the bed on which they grow. “It is easy,” he says, “to understand how an
insect like a cockroach, living in the midst of thousands of ants which
are continually opening and closing their scissor-like mandibles, should
be certain, sooner or later, to have its long antennæ cropped. One
wonders how the tarsi (the legs, that is to say) of the cockroach escape
the same treatment.”[15] This wonder, however, if there is really any
reason for it, suggests a doubt as to the sufficiency of the explanation
here offered. The antennæ, one would think, might be held high, in which
case, if sheared at all, it could only be at the base, but if here (as
would not, however, seem to be the case) why should not the legs be
sheared too? Again, it seems possible that the insects themselves may be
in the habit of gnawing one another’s antennæ. As the cockroaches live
and flourish it would seem that this mutilation of their antennæ, if
that, indeed, be the explanation, can do them no great injury. Yet these
organs are supposed to be of great importance to insects, and, judging
by their length and delicacy, one would think that they were especially
so to the members of the cockroach family. In this case they would
probably be extremely careful of them, and the fact that these
ants’-nest cockroaches do not seem to be so, may show that subterranean
conditions, contrary to what one might have expected, have affected
their efficacy.
------------------------------------------------------------------------
[Illustration: A RIDE ON BEETLE-BACK, AND A LIVING SWEET-SHOP.]
Enjoyment seems to be the only motive the fly has for riding
on the back of the African beetle shown in the upper part of
this illustration. Beneath is shown the well named honey-pot
ant with its distended body full of honey, which it gives
away to any hungry working ant.
A diet of mushrooms, or fungus, is not the only thing for which these
little blind, light-shunning cockroaches are indebted to their
landlords, the ants, for often one of them may be seen to mount upon one
of the latter, and take a ride on its back. They seem especially fond of
the soldiers, as horses, and will sit perched on their enormous heads,
as they walk up and down in a stately sort of way, sometimes for quite a
long time. Enjoyment seems here to be the only motive, and perhaps it is
a natural one, since there is a fly in Africa which seems to have quite
a passion for riding on the back of a beetle. “Across the mouth of the
Seyhouse,” says the Rev. Mr. Eaton, “on sandy pasture-land bordering the
seashore, big _coprophagous_ beetles—it sounds abusive, but no harm is
meant—are common, sheltering in large holes in the soil, when at rest,
and running about on business. A small species of _Borborinæ_ (that is
the fly) may often be seen riding on their backs, chiefly on the
pronotum and about the bases of the elytra, sometimes half a dozen
females on one beetle. The beetles occasionally throw themselves on
their backs, and try to get rid of them by rolling; but the flies elude
all their efforts to dislodge them, dodging out of harm’s way into the
jointures of the thorax, and darting from back to breast, and back
again, in a way that drives the beetle nearly mad. In vain she scrapes
over them with her legs, in vain does she roll over, or delve down
amongst the roots of the herbage: the flies are as active as monkeys
(not perhaps a very striking simile here), and there is no shaking them
off. It is difficult (such is their strange predilection) to get them
off into the killing-bottle. Nothing (not even the killing-bottle)
persuades them to fly, and they would very much rather stick to the
beetle than——” what? Not go to heaven, but “be driven off it down the
tube.”[16] The tube must be the neck of that same bottle. This, surely,
is a case of infatuation if ever there was one. Eccentric fly! And what
must be the charms of a beetle that can prevail over those of cyanide of
potassium! But the beetle, it must be remembered, is a _coprophagous_
one. There may be a world of explanation in a word like that.
-----
Footnote 12:
If _cadaver_ for corpse or carcase, why not _dies_ for day, which is
just as good English? Or why not all Latin, with a glossary, or—better
still—a translation?
Footnote 13:
Charles Janet, _Comptes Rendus_, 1897, pp. 583-5.
Footnote 14:
The American Naturalist, December, 1901.
Footnote 15:
Ibid., November, 1900.
Footnote 16:
The Entomologist’s Monthly Magazine (quoted in the _American
Naturalist_), August, 1896.
------------------------------------------------------------------------
CHAPTER V
From biped to quadruped—Flies that borrow
wings—Sit-o’-my-head—A novel cradle—Flies that kill
bees—Nature’s sadness—Consolations of the future—The Tachina
fly and the locust.
ALTHOUGH from the way in which the story is told, one might imagine that
the fly here was merely enjoying a ride upon beetle-back, yet, from the
efforts made by the latter to shake off its persecutors, and, still
more, because these were of the female sex, the probability is that we
have here to do with a case of parasitism. The fly, we may almost feel
certain, was endeavouring to lay its eggs, and the reason why she took
so long about it was that she required a certain spot upon the beetle in
order to do so, and that the beetle’s efforts, though appearing futile,
were more or less successful in guarding this spot. At any rate, if this
was not the case here, it is so in many other instances, various flies
being parasitic on various other insects. Not all of these are fatal to
the object of their choice, which, if it affords them board as well as
lodgings, may only do so to the extent of its blood. Such are the
curious family of _Hippoboscidæ_, or Bird Ticks, who begin life with
wings, but are so little appreciative of the powers which these confer
that, having found the creature upon whom they elect to live, they bite
them off, or otherwise wilfully rid themselves of them, after the manner
of ants and termites, thus offering yet another example in the insect
world of
“one whose hand,
Like the poor Indian, flung a pearl away
Richer than all his tribe.”
For what can be imagined more glorious to possess, speaking of physical
attributes, than the power of flight?
The course of life of these flies—if all be truth that is spoken of
them—is, indeed, very extraordinary, for during the first or winged
stage of their adult life they live on birds, but migrate from them to
some quadruped—as, say, a deer—as soon as they find themselves within
easy reach of it, and then, as having reached their final place of
abode, do away with their wings. Thus, being too lazy or lethargic to
fly themselves, they choose rather to stand indebted to another being
for a power which they no doubt once possessed in perfection, and which
they are still quite capable of exercising. What the larval stage of
these flies is, whether they lay their eggs upon their first or last
habitation—or on both, and if not, where or in what manner the larva
passes its life, I do not know, and as my authority, who should be up to
date, holds his peace upon the matter, I conclude that it is not yet
made out. Possibly the grub is a vegetable feeder, or possibly, again,
it is as fatal to some other insect as is that of a little fly with a
big name—_Apocephalus pergandei_ to wit—to ants. The victim here
chosen—if there be not others also—is a black tree-climbing ant, common
in Pennsylvania. As it runs over the ground or up and down the trunks of
trees, the fly darts after it on tiny wings, intent on laying her egg
upon its neck. The ant tries to elude her endeavours, but
_Apocephalus_—or Sit-o’-my-head—has a mission to fulfil, and will take
no denial. The egg is laid, it cannot be detached, and, when hatched,
the issuing grub bores, with enthusiasm, into the head of the ant.
Coming to the brain he has nothing to do but to eat it, and he does so
until the whole cavity of the skull has become an empty chamber, except
for his own presence there. The movements of the ant during this
process—of its feelings we have no record—have become more and more
erratic, and it feels itself less and less capable of performing its
duties as a member of an active and industrious community. At length it
falls down, and not long afterwards its head falls off, giving to the
maggot inside it its first opportunity of looking out into the world
through the window of the neck-hole. Hitherto its life, however easy and
pleasant, has been of a sedentary nature, but now it can enjoy the
pleasures of a walk, and moves about something after the manner of a
snail, dragging its cephalic shell behind it. But this active state is
not of long duration. The time of change is at hand, and snug within the
ant’s head and its own last larval skin, which, as is the way with fly
caterpillars, serves it in lieu of a cocoon, the fortunate little
creature turns into a chrysalis, and dreams away its time till, on some
sunny day, it issues from its cradle a happy, active fly, feeling
strangely attracted by ants.
Another little fly belonging to this same family group—the hump-backed
flies or _Pharidæ_—has it fate linked with that of bees, in whose hive
it is hatched and on whose eggs and larvæ it feeds; nor does the grown
bee itself, though armed with its sting, escape from the more rapacious
members of the order. These are known by the name of Robber Flies,
though as the robbery involves the death of the victim, and consists of
the juices of its body, murder would seem to be the better word. These
flies, though of somewhat slender build, which the better fits them for
their swift and darting flight, are excessively strong, as might be
expected from their long muscular-looking legs and rough hairy bodies.
All sorts of insects are their prey, for the despatch of which they are
furnished with a hard tubular beak, enclosing, as in a sheath, a
lancet-like instrument, which, being protruded at will, severely
lacerates the body of the captive. The beak, or sheath, is also struck
some way into the wound, and being tipped with bristles, these serve as
so many barbs to keep it in position, whilst the blade continues to
probe and hack the victim, on whose back the fly has descended,
embracing it with its powerful legs. “These flies,” says Dr. Fitch—who
seems strangely unalive to the moral beauty underlying the mere
mechanical expression of it—“are inhuman murderers, they are savages of
the insect world, putting their captives to death with merciless
cruelty. Their large eyes, divided into such a multitude of facets,
probably give them the most acute and accurate vision for espying and
seizing their prey; and their long, stout legs, their bearded and
bristly head, their whole aspect indicates them to be of a predatory and
ferocious character. Like the hawk, they swoop upon their prey, and
grasping it securely between their fore feet, they violently bear it
away.”[17] Bees, beetles, butterflies, moths, even grasshoppers are thus
treated, and sometimes, by a beautiful retributive arrangement—enough to
throw one into ecstasies—they turn cannibals, and prey upon each other.
Nay, there is even more than this to arouse our admiration, for so stern
and unbending is the law of eternal justice, that even the softest
feelings of nature are not allowed to interfere with it, and the female,
wooed by the male, is frequently compelled to eat him. Thus the noble
maxim of _fiat justitia ruat cælum_, though, for a time, it may seem to
be in abeyance, finds, at last, unconscious expression, if not in the
breast, at least in the appetite of a cruel and murderous insect; and
thus in the animal world, not less than in our human one, “the whirligig
of time brings in his revenges.”
To bee-keepers—and to bees perhaps still more so—these terrible
buccaneer flies are especially obnoxious. Poised in air, in the
neighbourhood of some hive, they watch the issuing and returning stream,
and, making swift choice of a victim, sweep, like the wingéd furies that
they are, upon him. There is a sharp, shrilly sound, as the bee’s wings
vibrate, for a moment, more rapidly, then the fatal legs wrap her round,
and, pressed tightly to the oppressor’s body, she is borne to some shrub
or flower, in the shade or pleasant fragrance of which the juices of her
body are sucked out, through a hole specially made to allow of their
passage. When nothing remains but the empty shell, the fly drops this,
and returns to the scene of its labours. Through all the hot sunny hours
these raids are continued, till hundreds of empty bee-shells strew the
ground. As the sun declines the sport flags and gradually ceases, but it
begins again the following morning as merrily as ever. America seems to
be the home _par excellence_ of these flies, but they are represented,
under various forms, in many parts of the world. The United States has
been accorded its fair share of them, and according to their numbers,
each season, the labours of the bee-farmer are rewarded or otherwise. So
much is this the case that the fact that “during certain seasons, in a
bee-raising district of New York, not a single hive threw off a
swarm”[17] has been attributed to this cause alone.
------------------------------------------------------------------------
[Illustration: A BUCCANEER FLY, AND A LEAF-RESEMBLING INSECT.]
Poised in the air, the buccaneer fly selects its victim from
the bees issuing from a hive, pounces on it like a winged
fury, and kills its hapless prey. The insect depicted
beneath is protected from its enemies by its strange
resemblance to a dead leaf.
It would appear from these facts either that no bee ever succeeds in
stinging its assailant, or else that the latter is proof against the
injection of poison. The former seems to me the most probable, since the
system of the bee itself has no such immunity. It seems strange that so
deadly a weapon should fail thus constantly, at a pinch, and it would be
interesting to know if these redoubtable adversaries attack wasps as
well as bees. As it is not stated that they do so—as wasps are pointedly
omitted from the list made out of their victims—the contrary may, I
think, be assumed, and also, as a corollary, that if wasps were attacked
they would be able to use their sting, probably with fatal effect. This
superior capability is, no doubt, owing to the superior flexibility of a
wasp’s abdomen over that of a bee; and if we ask ourselves what is the
cause of this—how and for what reason the superiority has been
acquired—the answer seems “as ready as a borrower’s cap,” viz. “as a
means of self-defence through a process of natural selection.” Nothing
could be better adapted to bring this process into play than the very
ordeal through which the bee is passing; for if some could only succeed,
through superior flexibility, in stinging the flies, they ought to
increase at the expense of those unable to do so. As far as it goes,
this seems to point to the wasp having gone through a longer course of
development than the bee—to its ancestry dating farther back in time;
but when we think of the latter’s more elaborate social organisation and
the greater perfection of its cells, one feels inclined to reverse this
opinion. As no bees possess such powers of twisting about and doubling
round their abdomens as do wasps, though some can do so in a very fair
degree, it seems probable that the common ancestor of all the species
was more thickly built than that of the wasps, or at least that the
potential capacity handed down by it of development in this direction
was less. But precisely the same argument may be used in regard to the
brain of the ancestral wasp, and thus we see that unless we have
geological evidence on the subject it is very difficult to say which of
two species has the more ancient descent.
The Robber Flies—whose scientific name I have forgotten—however
disagreeable they may be, are at least not parasites. They attack their
prey and kill it quickly, instead of handing it over to prolonged
torture at the hands of the next generation. This last is what the
Tachina flies—to say nothing of other kinds—do, who, as they principally
attack caterpillars, may be considered beneficial to man. In the United
States of America there is no greater destroyer of all sorts of trees
than the so-called army-worm caterpillar, or rather grub—for it
represents a fly merely—which gathers together in enormous numbers when
about to enter the pupal state. “I have seen,” says Mr. Leland Howard,
“vast armies of the army-worm, comprising, unquestionably, millions of
individuals, and have been unable to find a single specimen which did
not bear the characteristic eggs of a Tachina fly. These flies were
present in such numbers that their buzzing as they flew over the army of
caterpillars could be heard at some distance, and the farmers were
unnecessarily alarmed, since they conceived the idea that the flies were
the parents of the caterpillars, and were flying everywhere and laying
their eggs in the grass and wheat. As a matter of fact, one great
outbreak of the army-worm in northern Alabama in the early summer of
1881 was completely frustrated by the Tachina flies, aided by a few
other parasites and predatory insects. They also attack grasshoppers,
bugs, beetles, saw-flies and saw-fly larvæ, humble bees, and wasps. (How
they avoid the sting of the latter we are not told; perhaps their
insignificant size is a protection.) The eggs are stuck by some sort of
gummy substance to the surface of the preyed-on insect; and the small
white eggs are frequently seen sticking to the back of some unfortunate
caterpillar. From the under side of each egg there hatches a little
maggot, which bores its way through the skin of the host, and penetrates
into its body, where it lives, nourishing itself upon the fatty matter
and lymph until it reaches full growth, usually, if not always,
destroying before it emerges some vital organ, so as to cause the death
of the host insect. It almost invariably issues, when full grown, from
the body of the insect attacked, and pupates, at or near the surface of
the ground, within the last larval skin, which hardens into a brown oval
puparium.”[17] There are some points of special interest about the
parasitism of these Tachina flies, which seem to be directed by a less
perfect instinct than that which guides other insects of similar habits;
for instance, the Ichneumon flies, which, however, are such merely in
name, being members of the order _Hymenoptera_, which includes the bees
and ants.
These latter, by merely touching an insect with their antennæ, can tell
if it is already occupied—in which case they withdraw—nor do they ever
lay eggs in excess of the number of issuing larvæ that can be supported
by the little world of provender into which they will be born. Neither
do they choose a caterpillar to lay on, which is just about to cast its
skin, by which manœuvre the host would escape, and the guests be left to
perish. All these mistakes, however, are frequently made by the Tachina
fly, the consequence being that many poor children die of starvation;
whilst others, from wanting their necessary complement of food, have
their growth checked and become poor pitiable objects, less than half
the size that, with a more generous diet, they would certainly have
attained to. It is painful to know that such privation exists and to
have no means of relieving it; but nature is full of sadness, and it is
best to look truth in the face. Some comfort may perhaps be derived by
looking forward to a distant future, when the instinct which is now
liable to these errors shall have been perfected. Such comfort, at any
rate, lives in Mr. Leland Howard’s views that “the parasitic mode of
life in the Tachina fly is one of comparatively recent acquirement, and
that sufficient time has not elapsed since they began to take on this
habit”[17] to allow of its having reached the final goal towards which
it is always advancing. It is difficult, however, to console oneself for
the imperfections of a work-a-day world in a far distant prospect of
Elysium.
In the somewhat numerous list of insects distinguished by the attentions
of the Tachina fly, grasshoppers have been mentioned. In Africa they,
or, at any rate, one species of the family, attack the terrible plague
locust, that has from time to time committed, and still apparently
commits, such terrible devastations. The latter seems quite aware of the
fate in store for it, and makes vigorous efforts to evade its destiny.
Buzzing in the air, above the ravenous horde, the fly waits for one to
hop or rise on the wing, and then darts swiftly upon it. To avoid her,
the locust rises or sinks, tacks suddenly to right or left, scudding
this way and that like a ship to meet a varying breeze. The Tachina, in
the meanwhile, circles about her quarry, awaiting a favourable
opportunity, which generally arises just as the locust alights, or is on
the point of alighting, when, descending upon it before the lost impetus
can be renewed, she clings lovingly, and deposits her eggs, either on
the neck or under one of the wings,
“——and with a little pin
Bores through his castle wall, and farewell king.”
It is not, however, as a rule, till after the grub or grubs have made
their exit from the body that the locust dies, though it has drooped and
become languid for some time. Of the vast swarms that darken the sky and
descend upon the country, like a mantle, a very small proportion would
seem to perish in this way, since everywhere the females may be seen
drilling with their abdomens into the ground, preparatory to laying
their eggs. The check upon their numbers, whatever it may be—and on the
whole it must be very effective—supervenes, for the most part, at this
early stage, before the egg is hatched, that is to say.
-----
Footnote 17:
Leland O. Howard, The Insect Book.
------------------------------------------------------------------------
CHAPTER VI
The burden of the locusts—Classical nonsense—Address
to Mahomet—Locusts in Europe—Succumb to the English
climate—Described by Darwin—Locusts in Africa—The wingless
host do greatest damage—Hoppers and jumpers—“An army on the
march.”
LOCUSTS are insects famous in story, and when one reads about them in
various entomological or other writings, one might imagine that the
whole world had been doing little else, ever since it began, than play a
losing match with these creatures. It is only after one has gone a
little about the world, and lived for some time in regions noted as
their head-quarters without seeing anything whatever of them, that one
begins to doubt this view, and lean towards another one, viz. that they
are fabulous animals; but truth, as in other cases where two extreme
views are held, lies somewhere betwixt and between. The whole matter is
this, that when one reads one narrative after another, with its burden
of a darkened sun, devastated territories, strong winds, drownings in
the sea, and pestilences engendered by innumerable carcases cast up
along hundreds of miles of beach, the intervals, as well as the
countries, between each one of these occurrences, are annihilated in the
imagination, and the dates, if seen, are forgotten. Thus, to use the
Kaffir expression—which has not yet lost its meaning for a civilised
European—one sees everything red; locusts are very convincing—“you may
almost hear the beating of their wings.”
However, there is no doubt that these insects, in relation to man, have
played what the Germans call “_eine bedeutende Rolle_” in the world, and
are worth saying something about, if only one has something not too
desperately antique to say, and this, by virtue of a work which I, at
any rate, have never seen quoted, and a paper in a certain Antipodean
organ, which for the majority of people here might as well be in the
_Faerie Queene_ or _Paradise Lost_, I think I may have. But first let us
turn to what, though it be antique, is also classical, and—though this
would not be a corollary for everyone—very delightful: “To look,” say
the authors of the famous _Introduction_, “at a locust in a cabinet of
insects, you would not, at first sight, deem it capable of being the
source of so much evil to mankind as stands on record against it. ‘This
is but a small creature,’ you would say, ‘and the mischief which it
causes cannot be far beyond the proportion of its bulk. The locusts so
celebrated in history must surely be of the Indian kind mentioned by
Pliny, which were three feet in length, with legs so strong that the
women used them as saws. I see, indeed, some resemblance to the horse’s
head, but where are the eyes of the elephant, the neck of the bull, the
horns of the stag, the chest of the lion, the belly of the scorpion, the
wings of the eagle, the thighs of the camel, the legs of the ostrich,
and the tail of the serpent, all of which the Arabians mention as
attributes of this widely dreaded insect destroyer, but of which, in the
insect before me, I discern little or no likeness?’” Personally, I do
not for a moment imagine that even in 1815, the date of the first
edition of the work in question, any reasonably educated person would
have spoken or thought in this way, without any conception, apparently,
of what numbers can effect, but it is interesting to know what the Arabs
think, or say, about the locust, and especially that they represent
it—as we are told a few lines on—as thus addressing Mahomet: “We are the
army of the Great God; we produce ninety-nine eggs; if the hundred were
completed, we should consume the whole earth and all that is in it.”
The authors then proceed to give a short résumé of the various locust
plagues under which the earth, over a large part of its surface, has at
different times groaned. The first and best authenticated goes back to a
very early period—about 4000 B.C.—after which the evidence does not
conform quite so strictly to the test demanded of it by the modern
scientific spirit. Pliny, however, we are told, “mentions a law in
Cyrenaica by which the inhabitants were enjoined to destroy the locusts
in three different states, three times in the year—first their eggs,
then their young, and lastly the perfect insect. And not without reason
was such a law enacted; for Orosius tells us that in the year of the
world 3800 Africa was infested by such infinite myriads of these animals
that having devoured every green thing, after flying off to sea they
were drowned, and being cast upon the shore, they emitted a stench
greater than could have been produced by the carcases of 100,000 men (a
very confident statement, surely). St. Augustine also mentions a plague
as having arisen in that country from the same cause, which destroyed no
less than 800,000 persons (_octingenta_ _hominum millia_) in the kingdom
of Masanissa alone, and many more in the territories bordering upon the
sea.” After this we make a jump to A.D. 591, and find the locusts in
Europe. In that year “an infinite army of them, of a size unusually
large, grievously ravaged part of Italy; and, being at last cast into
the sea, from their stench arose a pestilence which carried off near a
million of men and beasts. In the Venetian territory also, in 1478, more
than 30,000 persons” (but this seems pitiful) “are said to have perished
in a famine occasioned by these terrific scourges.”
Many other instances of their devastations in Europe, in France, Spain,
Italy, Germany, etc., are recorded by the same authors. “In 1650 a cloud
of them was seen to enter Russia in three different places, which from
thence passed over into Poland and Lithuania, where the air was darkened
by their numbers. In some places they were seen lying dead, heaped one
upon another to the depth of four feet; in others they covered the
surface, like a black cloth, the trees bent with their weight, and the
damage they did exceeded all computation.” Nay, “even this happy island
(_lucus a non lucendo_), so remarkably distinguished by its exemption
from most of those scourges to which other nations are exposed (as fog,
sunshine, etc.), was once alarmed by the appearance of locusts. In 1748
they were observed here in considerable numbers, but providentially they
soon perished without propagating”—the “happy island” apparently having
been too much for them. These unfortunates would appear to have been
stragglers from far vaster numbers which a year before had devastated
Eastern Europe, one swarm of which, “entering Transylvania in August,
was several hundred fathoms in width. At Vienna the breadth of one of
them was three miles, and extended to so great a length as to be four
hours in passing over the Red Tower: and such was its density that it
totally intercepted the solar light, so that when they flew low one
person could not see another at the distance of twenty paces.” Another
host that appeared in India is said to have formed a column five hundred
miles long, and “so compact was it when on the wing that, like an
eclipse, it completely hid the sun, so that no shadow was cast by any
object, and some lofty tombs not more than 200 yards off were rendered
quite invisible.”
Dr. Clarke in his _Travels_ speaks of locusts covering “his carriage and
horses, and says the Tartars assert that people are sometimes suffocated
by them.” He mentions two species, “the first of which is almost twice
the size of the second, and, because it precedes it, is called by the
Tartars the herald or messenger.” From 1778 to 1780 a dreadful curse of
locusts, alluded to by Southey in his “Thalaba”—or, perhaps, forming the
subject of that poem—I really don’t know—fell upon the Empire of
Morocco. “Everything green was eaten up, not even the bitter bark of the
orange and pomegranate escaping. A most dreadful famine ensued. The poor
were seen to wander over the country deriving a miserable subsistence
from the roots of plants; and women and children followed the camels,
from whose dung they picked the undigested grains of barley, which they
devoured with avidity; in consequence of which numbers perished, and the
roads and streets exhibited the unburied carcases of the dead.” Again,
“From Mogador to Tangier, before the plague of 1799, the face of the
earth was covered by them. At that time a singular incident occurred at
El Araiche. The whole region from the confines of the Sahara was ravaged
by them; but on the other side of the river, El Kos, not one was to be
seen, though there was nothing to prevent their flying over it. Till
then they had proceeded northwards; but upon arriving at its banks they
turned to the east, so that all the country north of El Araiche was full
of pulse, fruits, and grain—exhibiting a most striking contrast to the
desolation of the adjoining district.” Lastly—that is to say, to make a
last quotation from the classics—“The Arabs of the Desert, whose hands
are against every man, and who rejoice in the evil that befalls other
nations, when they behold the clouds of locusts proceeding from the
north, are filled with gladness, anticipating a general mortality, which
they call _El Khere_ (the benediction), for when a country is thus laid
waste they emerge from their arid deserts and pitch their tents in the
desolated plains.”
Darwin, in his _Journal of Researches_, gives the following account of a
flight of locusts: “Shortly before we arrived at the village of Luxan we
observed to the south a ragged cloud of a dark reddish-brown colour. At
first we thought that it was smoke from some great fire on the plains;
but we soon found that it was a swarm of locusts. They were flying
northward, and with the aid of a slight breeze they overtook us at a
rate of ten or fifteen miles an hour. The main body filled the air from
a height of twenty feet to that, as it appeared, of two or three
thousand above the ground; ‘and the sound of their wings was as the
sound of chariots of many horses running to battle,’ or rather, I should
say, like a strong breeze passing through the rigging of a ship. The
sky, seen through the advanced guard, appeared like a mezzotinto
engraving, but the main body was impervious to sight; they were not,
however, so thick together but that they could escape a stick waved
backwards and forwards. When they alighted, they were more numerous than
the leaves in the field, and the surface became reddish instead of being
green: the swarm having once alighted, the individuals flew from side to
side in all directions.” At that time—the year was 1835—locusts were
“not an uncommon pest in this country: already during this season
several smaller swarms had come up from the south, where, as,
apparently, in all other parts of the world, they are bred in the
deserts. The poor cottagers in vain attempted by lighting fires, by
shouts, and by waving branches to avert the attack.” This locust, Darwin
tells us, closely resembled the famous _Gryllus migratorius_ of the
East—the one that spoke to the Prophet—if, indeed, it was not identical
with it.
Though these accounts are all interesting in their way, they none of
them tell us much—or, indeed, anything—about the locusts themselves, for
which reason I will supplement them with some which have that advantage,
and are also, in some sort, a check or commentary upon the others. It is
to be noted that, in all these, we hear only of flying locusts, and
anyone would imagine by reading of them that it was by such, and no
others, that all the damage was done. In Africa, however, and also in
Cyprus—from which we may assume that it is the same elsewhere—the case
is widely different. Writing evidently as a locust expert of the former
country, Dr. Æneas Munro tells us that it is in their early wingless
state—answering to the caterpillar one, though far less differentiated
from the perfect form—that the most terrible, the overwhelming, injury
is inflicted by these insects. Of the full-grown flying locusts he says,
“To a certain extent, they do injure here and there, where they select
to settle and feed; but they do not devour everything clean before them,
like the army of the larval stage or jumpers.”[18] Of the latter and its
doings _ab ovo_ we have the following interesting account: “When the
tiny creatures issue from their nest they are of a greenish white or
creamy colour, about an eighth of an inch in length,” and on the day
that they do so “the very dust of the ground, which was so still before,
now seems to waken into life. They begin to move by a process of
twisting or rolling over one another, so that, for the first few days,
they receive the name of twisters. Within eight or ten days, however,
they can jump four or six inches, and at the age of three or four weeks
a new characteristic makes its appearance. A desire to explore manifests
itself, and in a surprising manner. The whole company moves in a body in
one general direction, and more or less in a straight line, as if by one
common instinct, without apparently having any recognised leader or
commander,”[18] which is just the way, in my opinion, that rooks and
starlings move.[19]
Marching in this way they spread themselves out over the country,
“eating everything that comes in their way—wheat (if sufficiently young
and tender), maize (even if strong and old), corn, sugar-cane, linseed,
alfalfa (lucerne), pasture of all kinds, vegetables of all kinds
(tomatoes and celery), and all garden produce, potatoes (ordinary and
sweet), the leaves and sometimes even the bark of the trees, causing
their ruin. The fruit, of course, is lost for the season. Orange,
willow, poplar, palm, banana, peach, pear, plum, vine, acacia, roses,
etc., are stripped,” but not “the gum and paradise trees, which seem to
be poisonous to them. They make everything ‘clean bare’; sometimes they
will enter houses, and eat the very clothes and curtains at the
windows.”[20] They will even eat the wool off the backs of the sheep,
and “last stage of all that ends this strange, eventful history,” on a
pressing occasion they will eat one another. Continuing his interesting
account—the graphic and convincing one of an eye-witness— Dr. Munro
tells us that “when these hoppers and jumpers (_voetgangers_, as the
Boers call them) are on the march, they sometimes appear so determined
and bent on the fearful execution of their work, that they resemble and
have got the name of ‘an army on the march.’ They move in open file, and
carry themselves in a proud, haughty way, with heads high up and fixed.
It is beautiful and interesting to see them on the march, if we only
divest ourselves for the moment of the idea of their devastating
object.”[20] And again, “The whole of the company begin to walk at the
same time, as if by order; the head is kept erect, and the neck is as if
stiffened. They go straight on, irrespective of danger,”[20] and are
deterred, as is well known, by hardly any obstacle. “The sight of this
army is a very impressive one, and once seen will never be forgotten. In
some respects it is an awful sight; the spectacle strikes you with pity
and sorrow to see at once before you that the toil and the labour for
the season, or, indeed, the year, is lost.”[20]
“It is in this marching stage,” continues Dr. Munro, “that the
_voetgangers_ do enormous damage and eat every edible thing in their
path, and completely destroy the work of the husbandman. They are not
content with levying toll merely, but they will have all, and will leave
nothing behind but desolation. They are therefore unlike the flying
company of locusts, which only levy toll here and there, but these, when
they pass, leave nothing.”
Some curious facts are then given in regard to the uniform
direction—varying according to the country—in which these wingless
locusts march. The account will be remembered of how a flying host came
to the banks of a river which they refrained from crossing. One might
almost think that a mistake had here been made, and that the locusts
were really _voetgangers_, but had they been so, the river, unless a
large one, need not have deterred them—at least, they will pass streams,
though doubtless great numbers are sacrificed in doing so. If, however,
the stream had run parallel to the direction in which the swarm was
advancing, we can understand, in the light of what seems to be now
established, their not crossing it.
-----
Footnote 18:
Dr. Æneas Munro, The Locust Plague and its Suppression.
Footnote 19:
E. Selous, Bird Watching, pp. 213-15, 271, etc.
Footnote 20:
Dr. Æneas Munro, The Locust Plague and its Suppression.
------------------------------------------------------------------------
CHAPTER VII
The sense of direction—How locusts look flying—Follow no
leader—Unanimity of movement—Flight by moonlight—Roosting at
night—Extirpated in Cyprus—The “Chinese Wall” system—Not
adapted to Australia—Deference to aboriginal feeling—Locusts
in Australia—Strange ceremony of egg-laying—Inadequate
explanation.
IN regard to the faculty of direction with which locusts seem endowed,
Dr. Munro says: “The flying locusts in the Argentine come from a
northerly direction, and the hoppers or creepers march towards the
south, although it might be, so far as abundance of suitable food goes,
to their manifest advantage to go in an opposite direction. In certain
countries the direction may be known. In this country (South Africa) it
will be found that they march towards the south, and not towards the
north, east, or west, though either of these directions might have been
better for them. The direction may not be true south; it may incline at
one time to the south-east, at another to the south-west; but, taken as
a whole, it will be southwards.” And he adds: “If proof be needed that
the ‘_saltonas_,’ another name—perhaps the Portuguese one—for these
wingless armies, march in one direction, it is abundantly found in the
experience of the screen and trap, or Cypriote system of destroying
locusts, which is based on this fact, and on this alone. This is
conclusive demonstration.”[21]
The distance that these footgangers—to translate, almost without
changing, the Dutch word—go in a day depends upon the amount of food
they find upon the road, but fluctuates, as a rule, between one mile and
two. They start about eight o’clock, when the sun begins to get hot; and
halt for the night a little before the sun sets. Dr. Munro describes the
way in which the female locust, before laying her eggs, drills a hole in
the hard ground with the disc-like extremity of her abdomen, but he
mentions nothing very peculiar in connection with the laying of the eggs
such as characterises the performance of that ceremony by the Australian
plague locust, as will be mentioned shortly.
------------------------------------------------------------------------
[Illustration: A PLAGUE OF LOCUSTS]
The dark cloud is entirely composed of locusts, which
sometimes fill the air from twenty feet to two or three
thousand feet above the ground. The poor people attempt in
vain, by shouts, by lighting fires, and waving branches, to
avert the attack.
The first appearance of these locusts is in enormous hosts, which may
sometimes be seen at a distance of from seven to ten miles, and then
appear as a black cloud in the clear and rarefied air of South Africa.
“It is impossible,” says Dr. Munro, “to estimate the number of locusts
in these clouds, but some idea may be formed from the fact that when
they are driven, as sometimes is the case in a storm, into the sea, so
many are washed ashore that they lie on the beach as a bank from three
to four feet thick and from fifty to one hundred miles in length, and
the stench from the corruption of their bodies, it is affirmed, is
sensibly perceived for a hundred and fifty miles inland.”[22] The aerial
movements of the locusts, when they fairly surround one, are described
as “curious, interesting, and pretty.” Distant vision (more especially
overhead) is impeded on account of their numbers. The effect when you
look on them in the sun’s rays resembles “snow falling thickly and
gently,” and the sun is only seen as though it were in eclipse. “Its
light is darkened and shadows cannot then be cast from it.”[23] The
height at which the swarm flies may be anything between forty feet and
two miles from the ground, but as a rule it is not greater than 400
feet, though from 500 to 800 is not uncommon. Sometimes they fly by
moonlight, but this is not their usual practice. As in their earlier
wingless state, they seem to act by one common impulse, which prevents
confusion. It is obvious, indeed, that with such myriads filling the
whole air, a leader could neither be perceived nor followed, and from my
own observations I am convinced that the same difficulty applies to this
way of explaining the movements of flocks of birds. I have never,
myself, seen any evidence of birds being led by one or more of their
number, but much to convince me that when banded together, in numbers,
their movements are governed by a totally different principle, viz. that
of thought transference or thought-unity—collective thinking, as I have
elsewhere called it—for that is what it most suggests. If this is not
the case with locusts, what, I would ask, is the alternative
explanation? If great hosts of men be neither led nor of one mind where
to go, they must fall into confusion, impeding one another’s movements,
and this is a law which has to do with numbers merely, without respect
to the species of which they are composed. It has often been noticed,
however, that large crowds seem liable to be swayed suddenly by some
common impulse.
Locusts may fly about a district all day doing but little harm, “and at
sundown,” says Dr. Munro, “the sight becomes interesting beyond
description, for the whole company then appear to vie with one another
in order to roost quickly.”[23] When all have found a resting-place,
“every twig, branch, bush, or separate stalk of the corn or wheat or
flax are completely covered, and sometimes they stick to each
other”[23]—three or four deep even. “As far as the eye can see, the
surface assumes a brownish-red hue. Pillars, posts, or the walls of
houses are all alike to them at the time of roosting for the night.”[23]
Such, then, is the Plague Locust of South Africa, which is, when at
maturity, about three inches long. Some years ago, however—the exact
date is not given—a larger and handsomer species made its appearance,
and is thus referred to in a letter which was sent by “A Disgusted
Farmer” of Grahamstown to one of the South African papers: “The new red
locust, which, during the last month, has spread from the Orange River
to the sea, coming apparently from the north as well as from Natal, is
doing terrible damage. Everywhere fruit-trees are being
destroyed—quince, apricot, fig, orange, lemon, naartje trees. Not only
are the leaves eaten, but young branches are all barked, so that they
are probably killed. A splendid crop of mealies, covering the whole of
Peddie, Lower Albany, Alexandria, and other districts, has been entirely
destroyed. Pumpkin plants are being eaten too. Vegetables of all
kinds—lucerne, cattle-cabbage, and kale—are also swept away. The locusts
are laying everywhere, and, no doubt, the plague will continue some
years. What is the agricultural farmer to do?”[23] I do not know, but
here, probably, were there locusts, he would pick out all such birds as
fed on them and try to get them taken off the list of protected species,
shooting them illegally all the while he was petitioning.
Dr. Munro’s work was published in 1900, and its principal object was to
induce the South African Government to adopt the system of dealing with
the locust plague which had been practised with such entire success in
the isle of Cyprus. Whether this has since been done, and with what
results, I am unable to say. In Cyprus, however, the locusts, which from
the year 1600, especially, have changed the country from a garden into a
wilderness, were in one season almost entirely swept away. The method by
which so great a result was effected is the invention of an Italian
gentleman—Signor Matthei by name—resident in the island, and is based
upon the inability of the immature locusts, the footgangers—probably the
grown ones too, but this is immaterial—to crawl up a smooth
perpendicular, still more an overhanging surface. Such a surface was
supplied by a long band of leather, glazed and polished, surmounting a
strip of calico, which was made about four feet high, but need not, as
it was afterwards found, have been more than two. This insurmountable
obstacle, supported at intervals by sticks set in the ground—not
upright, but slanting a little towards the path of the locusts—was set
up over a large area of country like a miniature Chinese Wall, and
proved even more insurmountable. At intervals along the inner side of
the barrier deep pits were dug, whilst at wider ones stood men provided
with brooms, spades, brushwood, and all else requisite. When the locusts
arrived at the Chinese Wall they climbed up the canvas part of it, but
being unable to pass the smooth band of leather they fell down in heaps,
and their ever-increasing multitudes soon filled the pits, in which they
were buried, burnt, stamped down, or otherwise provided for. Afterwards
their carcases were dug out and heaped on carts, and the pits, being
empty again, were ready for more. In this way two hundred million
quadrillion billions—or something of that sort—of locusts were
destroyed, and next year when everything was again ready for them hardly
any appeared. By this invention, as simple as it is ingenious and
inexpensive, the locust plague in Cyprus has become a thing of the past,
and if the conferrer of so great a benefit was ever not a man of large
fortune, let us hope that that has become a thing of the past, too, for
he must have saved several to the British Government. If the locusts,
after coming to the Chinese Wall and finding themselves unable to climb
it, had turned round and walked in another direction, this would have
made a capital instance of intelligence shown by insects—but they did
not do so.
With native labour, the above system, which has been so entirely
successful in Cyprus, could, Dr. Munro makes no doubt, be put in
operation in Africa; but Mr. W. W. Froggatt, the Government entomologist
of Australia, does not think it adapted for that country. Writing in
_The Agricultural Gazette_ of New South Wales (March, 1901), Mr.
Froggatt says, “Though they have been successfully dealt with in Cyprus,
Egypt, Algeria, and India by means of trenches, traps, and burning in
the hopper state, and digging up and destroying the eggs in the earlier
stage, in nearly all cases the areas infested were comparatively small;
the labour employed was so cheap that small armies of natives could be
employed at a small cost to destroy them, while in several instances an
autocratic government made the natives, whether they were inclined or
not, work at their plan of destruction.” In Australia, where, “whether
they were inclined or not,” the natives have been got rid of, very much
as though they were locusts—or some less stubborn insects—themselves,
this would not do.
It was in the summer of 1899 that Mr. Froggatt, in consequence of
reports received of the advent of locusts in various parts of the
country, left Sydney for Condobolin. On the way there many “mobs”—to use
the Australian word—were encountered, and numbers of locusts flew in at
the railway carriage windows. Upon alighting, Mr. Froggatt became the
witness of a very interesting spectacle—a ceremony, as it may well be
called, in which vast numbers of the insects were engaged—of which he
gives the following description:—
“In the open red soil we found them laying their eggs in thousands, and
the operation was very remarkable. The female set to work by pressing
the tip of her abdomen into the soil, and working the plates at the
apex, so that she gradually bored a regular circular shaft, slightly
over an inch in depth and under a quarter of an inch in diameter, the
segments of the abdomen extending and stretching as the work progressed.
But the most extraordinary part of the operation was that each female,
while boring the chamber to deposit the eggs, was attended by two males,
each of which rested his head against hers, with his antennas resting
over her head, and the inner foreleg clasped over the prothorax behind
the base of the head. Resting like this, with the tails of the two
attendant males pointing outwards, the three formed a three-rayed star.
Wherever the business of egg-laying was going on, each female and her
attendants were surrounded by a cluster of admiring males, averaging
from thirty to fifty in number, generally in bunches of fours or fives,
forming an irregular ring round them, but separated from her by a clear
space of three or four inches. In no instance were there ever more than
two males touching the female, though we examined thousands of them at
work.”[24]
What is the meaning of this odd performance?—this ceremony, as it
appears to me, though Mr. Froggatt takes a utilitarian view of it. “The
probable and only reason,” he remarks, “that I can see for the
attendance of the two males upon the egg-laying female is that it
enables her to get a firmer grip of the ground, and, in fact, holds her
in position till she completes her task.”[24] But why, then, should the
females of no other species of locust, as far as we are aware, require
this aid, and should not the soil of Africa be as hard as that of
Australia? “I can find,” says Mr. Froggatt, “no record of this habit in
any of our described species, which have the same habits.”[24] Again,
besides the two chief actors, we have the admiring ring of from thirty
to fifty males, who can be of no possible service, but whose conduct
shows that they take a strong interest in what the female is doing. What
is it, too, that regulates the number, or, at any rate, the personality
of the assistant males? If it is a matter of rendering assistance only,
and the two males who do so are bound to the female by no more special
tie than the crowd of interested spectators, why do not these, or some
of them, push forward? Why is there never any contention between them?
These considerations make me think that there is something of a formal
and ceremonious character about these queer proceedings, and that they
are governed by the same general law as are certain antics or set
figures amongst birds, wherein three individuals take a part. What one
requires to know is the courting and marital relations of the male and
female locust before the egg-laying takes place.
These little locusts—_Epacromia terminalis_ is the specific name—are
only about an inch in length, and the male, from the description, seems
a little brighter than the female, which may be due to sexual selection.
The female appears to lay nineteen eggs only, neither more nor less,
which is not so many as one would have expected from the Arabian legend.
With some other species, however, the number more conforms to the
statement said to have been made to Mahomet.
There is no vanity at all in my thinking that this has been an
interesting account of locusts, since I myself have had nothing to do
with it. In giving a general description, from general reading, of
things generally known, and that have been described scores of times
before, one is entitled to use one’s own language, and to think,
perhaps, that one stands at no particular disadvantage in doing so. But
when, in regard to something specially curious or interesting, the
graphic words of an eye-witness are before one, the best thing one can
do, in my opinion, is to copy them out. If it be suggested that this is
but a lazy way of writing a book, my reply is that a compiler best shows
his industry in the searching out of material. The late Professor
Romanes was alive to this fact, and has left us in consequence his
_Animal Intelligence_—one of the most interesting books that exist, in
my opinion—about one-eighth of which, or perhaps a little more, is
written by himself.
-----
Footnote 21:
Dr. Æneas Munro, The Locust Plague and its Suppression.
Footnote 22:
The Agricultural Gazette of New South Wales, March, 1900.
Footnote 23:
Dr. Æneas Munro, The Locust Plague and its Suppression.
Footnote 24:
The Agricultural Gazette of New South Wales, March, 1900.
------------------------------------------------------------------------
CHAPTER VIII
Locusts and _locustidæ_—The most musical grasshoppers—Katydid
concerts—A much-resembling note—Cricket thermometers—Cicadas
and sounding-boards—Admired musicians—An appreciative
audience.
LOCUSTS, as everybody knows, belong to the grasshopper family, but it
may surprise some who have read the grumblings of the learned over
popular names—white ants, hedge-sparrows, etc.—to find that
entomologists have so managed matters that they do not belong to the
_locustidæ_—which is one of the two groups into which all grasshoppers
are divided—but to the other group. There are long-horned grasshoppers
and short-horned grasshoppers. The long-horned ones, which are not
locusts, are all of them _locustidæ_, but none of the _locustidæ_ are
locusts, because locusts have short horns. Entomologists think it would
be absurd to alter this, after it has gone on so long, a view in which
ornithologists, with their _storm_-petrels and hedge-_accentors_, no
doubt agree with them. A mere popular name, with its roots in the Saxon
or Celtic, can be changed, and there an end, but scientific nonsense, in
Latin, and begun by Linnæus, as is generally the case, let no man
presume to meddle with.
It is amongst the _locustidæ_ that we find the most musical of the
grasshoppers, the Katydids—so well known and highly appreciated in the
United States—standing on a far higher level in this respect than the
comparatively unmusical locusts. Not that the _locustidæ_—however
musical—use their long horns for blowing purposes. Properly speaking,
these are only antennæ, and function as such, the musical apparatus
being situated elsewhere. The Katydids, for instance, rasp their fore
wings against each other, according to the general idea, three times in
succession, producing the three syllables, Ka—ty—did, which have given
the insect its name, but according to Mr. Scudder[25] only twice, which
makes either “Katy,” or “She did”; that is to say, as a general rule,
for he admits the three on occasions. The notes are uttered with great
emphasis, and at the rate of some two hundred in the minute, the
performance continuing, at least in the case of some species, all day
and all night long.
A number of grasshoppers go by the name of Katydids in America, but the
general type of the insect is a graceful, green, fragile-looking
creature, with very long, slender antennæ, and, in the female, a long
ovipositor at the other end, as if to balance matters. There are many
species, and all, or most of them, sing both by night and day, and what
is very remarkable, or, at least, very interesting, they have a
different note for either. Speaking of one—or, rather, of a long-horned
grasshopper nearly related to the Katydids, but not actually a member of
the sisterhood—which he had been watching in the sunshine, Mr. Scudder
says: “As a cloud passed over the sun he suddenly changed his note to
one with which I was already familiar, but without knowing to what
insect it belonged. At the same time, all the individuals around, whose
similar day-song I had heard, began to respond with the night-cry. The
cloud passed away, and the original note was resumed on all sides.”[26]
_Scudderia angustifolia_ is the name of this little musician, so called,
perhaps, because so sensitive to scudding clouds. But the Katydids do
more than merely play an individual tune, each on his own instrument.
They hold concerts, at which many join together to make an elaborate
musical display, a certain number commencing on one note, and others
joining in harmoniously on another. There are leaders, whose business it
is to hold the time-measure, and, by a steady insistence on the right
note, to draw back any who may happen for a moment to get out of tune.
The orchestra is divided into so many companies, who support and assist
one another, so that the whole makes a concerted harmony, in which there
are many different movements. As a rule the performance is most
creditable, though occasionally the effect is marred by a careless
player. Before commencing, the company always tunes up.
Possibly it may be thought that there is some mistake here—that things
cannot be quite like this. Personally I have no knowledge on the
subject—never having been to America—but here is what Dr. George M.
Gould says, writing in _Science_ for October or November, probably 1895,
since the number is referred to as “recent” in _Nature_ for December 5th
of that year. “As soon as the sun has set and twilight is advancing, the
Katydids in the trees begin to ‘tune up.’ The first notes are scattered,
awkward and without rhythm, but if no wind is blowing thousands soon
join in, and from time to time, until daylight breaks, there is no
intermission.... In order to make my description clearer, let us suppose
a thousand Katydids, scattered through the trees, to utter their several
notes all at once, and call them Company A. Another thousand—Company
B—at once answers them, and this swing-swong is kept up, as I say, all
night. Company A’s note is the emphatic or accented note, and is more
definitely and accurately a precise musical note, whilst the note of
Company B varies from one to five half-tones below, the most conspicuous
note being five. In the old-fashioned musical terms I learned as a boy,
Company A is, e.g., clearly and definitely _do_, while the note of
Company B is either _la_, or more certainly _sol_. Not only is Company
A’s note more unisonal and definite, but it is firmer, more accented,
and it seems to me that more insects join in this note than in the
second. Careful observation has convinced me that no insect of Company A
or Company B ever joins in the other company’s note. The rhythm is
usually perfect, unless there is a disturbance by a breeze. A sharp gust
upsets the whole orchestra, and confusion results, but the measured beat
is soon refound. In the instants of confusion one can detect the steady
see-saw of certain ones, as it were, ‘leaders,’ or first violinists, who
hold the time-measure, despite the wind, and who soon draw the lost
notes of the others once more into the regular measure or beat. I do not
mean to say that by diligent attention one may not at times detect
individuals sawing out of tune, stray fellows that are indifferent or
careless, but the vast majority, usually even without a single
exception, if there is no wind or rain, thus swing along, hour after
hour, in perfect time. I have counted the beats several times, and find
the number is always identical: thirty-four double beats, or sixty-eight
single ones, in sixty seconds. The effect of the rhythm upon the mind is
not unlike that of the woodman’s cross-cut saw, handled by two steady,
tireless pairs of hands, although the Katydids give a larger volume of
sound, and the _timbre_ is harsher.” Such is the account, and upon it
Dr. Gould asks two questions: “What function does the orchestration
subserve?” and “Is there anything comparable to it among other animals?”
In view of these performances of the Katydids one may perhaps question
the statement, often made, that crickets are _the_ most musical of all
insects. The Snowy Cricket, however, of the United States, and no doubt
elsewhere in America, is a very striking performer, especially at night,
when it emits sounds which Nathaniel Hawthorne has likened to “audible
stillness,” and of which he says: “If moonlight could be heard it would
sound like that.” Thoreau describes it as a “slumbrous breathing,” but
according to the State Entomologist of the United States, this
“slumbrous breathing,” or “audible stillness,” consists of “a shrill
re-teat, re-teat, re-teat,” which Mr. Leland Howard,[26] indeed, thinks
the best description, but is not quite my idea—nor probably
Hawthorne’s—of how moonlight would sound. Harrington—who I suppose is
another entomologist—does not interfere with any of these opinions, but
describes something which he has seen, and can find nothing about in
books. “While the male,” he says, “is energetically shuffling together
his wings, raised almost vertically, the female may be seen standing
just behind him, and with her head applied to the base of the wings,
evidently eager to get the full benefit of every note produced.”[26] No
doubt the female likes the notes—that, indeed, is the _rationale_ of
their utterance—but what they are really like it is impossible to make
out from these various descriptions, another of which, by the way, is “a
rhythmic beat.” Possibly they are no more extraordinary (at any rate,
“re-teat” is not) than those of our own, and cheerful, house-cricket,
which to my ear have always sounded very pretty, but which Cowper
evidently did not care about except as a matter of association, since he
thus alludes to them in the _Task_:—
“Sounds inharmonious in themselves and harsh,
Yet heard in scenes where peace for ever (sic) reigns,
And only there, please highly for their sake.”
No doubt there are associations, though these, belonging to the kitchen,
appear to me to be of another and blither description, but the “sounds”
themselves, in my opinion, are neither harsh nor inharmonious, as far as
any unpleasantness to the ear is conveyed by the last word.
One interesting point about the song of crickets is that the number of
notes uttered in any given space of time—per minute, say—varies
according to the temperature, the two rising together. Professor
Dolbeare was the first, as far as I know, to call attention to this
fact, and he is thus confirmed by a lady: “One cool evening a cricket
was caught and brought into a warm room. In a few minutes it began to
chirp nearly twice as rapidly as the out-of-door crickets. Its rate very
nearly conformed to the observed rate maintained on other evenings under
the same temperature conditions (as now indoors). From this series of
observations we found that the rate of chirping was, as Professor
Dolbeare says, very closely dependent on the temperature.”[27] So the
crickets are little thermometers—sixty-three degrees Fahrenheit to one
hundred chirps per minute.
As we have seen, the Katydids give concerts, and we may therefore infer
that they like their own music in a musically appreciative way; that
they listen to each other as critical connoisseurs, whether they have
other feelings or not, and that it is not a mere matter of the female
alone admiring the sounds made by the male, just because _he_ makes
them. In all this, however, the admiration is confined—at least, as far
as we know—to one species—that to which the musician belongs. Katydids
appreciate the performances of Katydids. But there is one group of
performers whose music gives satisfaction, not merely to individuals of
other species than their own, but to such as are not even included in
the same order with them, so that racial pride or family prejudice
cannot be the reason of it. Towards these stars we will now turn our
gaze.
All who have lived in the more southern parts of the world, including
the southern countries of Europe, must have made the acquaintance of the
cicadas, for in these regions they are large insects, conspicuous by
their appearance when once seen, and by their song long before they are
noticed. There is something very uncouth—one might almost say
grotesquely humorous—yet at the same time pleasing and lovable about the
broad flat heads and great goggle eyes of these insects, in the which it
is easy to imagine some quaint sort of expression that seems to mean or
suggest something for which the language supplies no word. Their wings,
both long and broad, which, when folded, project far beyond the
extremity of the abdomen, concealing everything save the great head and
the wide shield or boss of the thorax, help also in giving them a most
salient and characteristic appearance, and make them look more aerial
than they really are. Their legs, whilst they retain their ordinary
resting attitude, are entirely hidden, and so too are the organs of the
mouth, which combine to make a sharp-pointed beak. Thus their appearance
is typical of air and sunshine, and anything so gross as mere feeding or
terrestrial locomotion seems foreign to their nature. The ancients, who
loved and admired the cicadas extremely, thinking them the most
fortunate of creatures, supposed that they lived entirely on dew.
“Oh Tettix, drunk with sipping dew,
What musician equals you?”
sings Anacreon, or someone who imitated him and wrote very gracefully,
for Tettix was a common Greek name for the cicada. Really they live on
the sap of the trees on which they sit, and there may even be two
opinions about their music. To me it is pleasant enough—full of the joy
of the sunshine, as it were, and its loudness and the continuous way in
which it goes on excites one’s wonder. In regard to the way in which it
is produced, Darwin says, at page 351 of his immortal work, _The Descent
of Man_: “The sound, according to Laudois, who has recently studied the
subject, is produced by the vibration of the lips of the spiracles,
which are set in motion by a current of air emitted by the tracheæ. It
is increased by a wonderfully complex resounding apparatus, consisting
of two cavities covered with scales. Hence the sound may truly be called
a voice. In the female the musical apparatus is present, but very much
less developed than in the male, and is never used for producing sound.”
As the Greeks, who must have had their observers, used to say—
“Happy the cicadas’ lives,
Since they all have voiceless wives.”
This sounds all right—I mean the account of the apparatus—but according
to Dr. Powell, of New Zealand, it is all wrong. Writing in the
_Transactions of the New Zealand Institute_,[28] Dr. Powell, after
quoting the above passage, says, “I am, of course, ignorant of the
details of his description; but unless the cicada which he describes
differs essentially in the nature of its musical organs from those found
in New Zealand, and also from those described more or less correctly by
other authors, especially Réaumur, he is most certainly in error.” Dr.
Powell, then, after telling us that the stridulating organs of the
cicada are constructed on a principle unique in nature, viz. a vibrating
membrane, continues: “In the male, on the upper surface of the first
ring of the abdomen, on either side, may be seen a crescent-shaped
opening, and on examining this opening with a magnifying-glass it will
be seen to lead into a shallow cavity, closed in by a horny membrane.
This membrane is highly elastic, and the sound is produced by the
contraction of the muscle straightening out the folds of the membrane;
this produces a click and, on the muscle relaxing, the membrane, from
its elasticity, springs back with another click.” That this is really
the way in which the sounds are produced seems proved by the fact that
“if a live insect be caught, and these membranes be observed during the
act of stridulation, they will be seen to be vibrating rapidly in time
with the beats of the shrill sound.”
But what about the “wonderfully complex resounding apparatus, consisting
of two cavities covered with scales”? After a full examination and
various experiments, Dr. Powell arrives at the unexpected conclusion
that the sound is in no way dependent upon these “large transparent,
drum-like membranes,” as he calls the cavities in question. I was “much
surprised,” he says, “to find that the large drums seemed to take no
part in the production of the sound, and the idea occurred to me that
they might be hearing organs; but on examining the females, which are
dumb and do not possess the stridulating organs, I found that the drums
exist, indeed, but are quite rudimentary instead of being large, as we
should expect to find them, were they subservient to the sense of
hearing.” If, however, the drums did answer the purpose of a resounding
apparatus in the male, we should expect to find them exactly as they are
in the female, and so strong does the evidence of their suppression in
her appear to me, that I cannot help thinking that, in spite of all Dr.
Powell’s observations and experiments, he was somehow mistaken, and that
in nature they do act in this way.
As to the quality of the sound produced by the cicada—of its song, as we
may call it—this varies greatly in the different species, for there are
many cicadas. Speaking of that of the largest—the great _Pomponia
imperatoria_ of Borneo—as big as a mouse, one may almost say, Mr.
Annandale remarks, “The sound produced by this species is, at the
beginning of the song, like the winding up of a large clock, and ends by
being comparable to the notes of a penny whistle. Between these extremes
it rises in a series of trills, each of which concludes with a kind of
click. Each section of the song is faster, louder, and clearer than the
one which preceded it, until, almost five minutes after the cicada’s
settling, the noise suddenly comes to an end as the insect flies off to
another tree, where it commences again.”[29] This great pompous imperial
insect—to give it a free rendering of its Latin name—sits shrouded in
the mysteries of the deeper jungle, while smaller and less majestic
babblers haunt its skirtings and the village groves. “Another species,
commonly heard at night in the jungle, has a clear, loud, clarion-like
call, which can be heard for a great distance.”[29]
Of the three New Zealand species of cicada—or those found in
Canterbury—a large and small green, and a black one, the two first, Dr.
Powell tells us, say “crrrk-crrrk-crrrk,” the second “r-r-r-r-r-r,” and
the third “crrrk-rrrrr,” _ad infinitum_. “Many persons,” he adds, “are
totally unable to hear the voice of the small green cicada, or any very
acute sounds, and inasmuch as the entire range of the human ear is,
according to Helmholtz, eleven octaves, it has been justly remarked that
the air may be filled with shrill insect sounds, which may be perfectly
audible to the insects themselves, but absolutely inaudible to our
grosser senses.”[30]
It is in Natal—at least, the fact has been observed there—that the
cicadas, as they sing, are listened to by admiring groups of other
insects. These appear to be beautiful creatures, having wings of a
soft, gauzy texture, but iridescent, and shot with the colours of the
rainbow. A band of these radiant attendants, consisting sometimes of a
dozen or fifteen, fly to the tree where a cicada is sitting and
arrange themselves in a semicircle around it, facing its head. They
are “all ear” evidently, and, as the sweet sounds continue, one or
other of the listeners will advance and touch the antennæ or legs of
the object of its admiration. Such marks of appreciation, however,
though flattering in proportion to their undoubted sincerity, are not
to the taste of the cicada, who will sometimes, whilst in the midst of
its song, strike out vigorously with a foot or so—for, of course, it
has six—causing its too obtrusive admirers to retreat to a more
respectful distance, where they continue to listen with every sign of
being extremely pleased.[31] Some years ago we did not even know the
name of these musical-connoisseur-like, and withal very beautiful
insects, but now they have been identified by Mr. Kirby, at the
British Museum, as _Nothochrysa gigantea_, so we are all much the
wiser, and have a weight lifted from our minds.
-----
Footnote 25:
Leland O. Howard, The Insect Book. It has, however, been asserted, I
know not with what truth, that Mr. Scudder was mistaken in this
particular, and changed his opinion.
Footnote 26:
Leland O. Howard, The Insect Book.
Footnote 27:
The American Naturalist, April, 1898.
Footnote 28:
Transactions of the New Zealand Institute, vol. 5, p. 286.
Footnote 29:
Proceedings of the Zoological Society for 1900, pp. 837-69.
Footnote 30:
Transactions of the New Zealand Institute, vol. 5, p. 286.
Footnote 31:
Nature, vol. 44, p. 451.
------------------------------------------------------------------------
CHAPTER IX
A Greek mistake—Nature vindicated—Cicadas provided for—A
difficult feat—Perseverance rewarded—Cicadas in story—Dear
to Apollo—Men before the Muses—Plato and Socrates—Athenian
views—A mausoleum for pets—The Greek ploughman—Apollo’s
judgment—Hercules’ bad taste—Modern survivals—A beneficent
insect—Elementary education in Tuscany.
THE Greeks thought that the life of the cicadas was all joy, but modern
research has been successful in removing the reproach of inconsistency
from the general scheme of creation. All is in order, as it now appears:
the cicada’s case has been considered, and a very handsome wasp provided
for it. At least, I think it is handsome. It is large and strong, I
know, as is necessary for the part it has to perform, but I cannot quite
remember the colours it flies under; an expression which, though
metaphorical, may be pardoned, since flags have much to do with such
dramas as that now to be described. For as the joyous, sun-loving
creature sits in its accustomed place, chirupping forth those shrill yet
musical notes which I, at least, have never wearied of, the destroyer is
at hand, and settling on its broad back, curves its abdomen beneath that
of the poor blithe singer, and in a moment has done its work. As the
sting enters, the happy note that has been sounding regularly for the
last hour, perhaps, is changed to a discordant scream of pain, and with
a spasmodic spring or flutter—the last, or near the last, that it will
ever make—the cicada, with the wasp still clinging to it, falls to the
ground. This is awkward for the wasp, who doubtless considers herself
aggrieved in the matter, since the cicada is so bulky that, powerful as
she is, she can neither lift it from the ground in flight, nor is she
prepared to drag it all the way to her burrow. What, then, is she to do,
or of what use to her is the prize she has obtained with such
adroitness? But she has her plan, and though the captious behaviour of
the cicada has, for the moment, a little deranged it, it is not
permanently frustrated. Slowly, but with firm insistence, she drags her
victim to the tree on which a moment before it was so happily seated,
and then exerting all her force, begins to mount the trunk with it.
Often she has to pause and rest, often it seems as though the task would
be beyond her, but she continues the laborious ascent, sometimes for
upwards of an hour, until at last a height has been reached at which it
is possible for her to put her great project into execution. This is no
other than to fly down obliquely, with her victim clasped in her arms,
to the pleasant little sarcophagus which she has previously prepared for
it, for though flight upwards, or in a straight line, with such a
burden, is out of the question, her strength is equal to this. It is
necessary, however, that she should balance the body nicely, and make a
fair and uninterrupted start, in order not to be overweighted and again
fall. Her enterprise is “full of poise and difficult weight,” and cannot
be successfully carried out in face of the rude struggles of a tiresome
obstructive not “in tune with the infinite.” These struggles, however,
have now ceased; the cicada is in a comatose condition, and, having
adjusted it properly, and assumed the requisite attitude and position,
our wasp—whose scientific name, by the way, is _Sphecius
speciosus_—launches herself, with “the white man’s burden” she has
“taken up,” from her coign of vantage, and reaches home with it in
safety. How high she has previously ascended the tree I cannot say,
since my informant does not, but it would be interesting to ascertain
both this and the average distance which she has to fly to her nest, and
to compare the one with the other. Unless the latter is very much
greater than the former—and as the journey is constantly downwards it
cannot, one would think, be very far—then we must see in the wasp’s
choice of a toilsome ascent up a perpendicular tree-trunk, in preference
to a horizontal journey along the ground, a triumph of instinct over
intelligence, and it is, indeed, quite possible that, having always been
accustomed to fly back with her prize, which perhaps was not always so
heavy, she should go through as much labour to enable her to do this as,
differently directed, would attain the end for which it is employed.
------------------------------------------------------------------------
[Illustration: A WASP BEARING OFF A CICADA.]
After the wasp has killed the cicada, they both fall to the
ground. Strong as the wasp is it is not easy for her to
carry such a heavy insect to her nest. But she has her plan.
Slowly but persistently she drags her victim to a tree-trunk
and up it, though it may take her an hour to reach the
requisite height. Then she sails off for her nest on an
inclined plane, with wings extended, and her victim clasped
in her arms.
The burrow of this wasp consists, we are told, “of a gently sloping
entrance, extending for about six inches, when, ordinarily, a turn is
made at right angles, and the excavation is continued for six or eight
inches farther, ending in a globular cell an inch and a half in
diameter. Frequently a number of branches leave the main burrow at about
the same point, each terminating in a round cell.”[32] In each of these
cells either one or two cicadas are deposited, and it would seem that
when there are two, only one of these is provided with an egg, so that
some of the wasp-larvæ have double rations. As the female _speciosus_
(her arguments, I think, would need to be specious to make one in love
with a scheme in which she plays such a part) is very much larger than
the male, it seems more than probable that the female eggs are laid in
the chambers which contain two cicadæ, and the male ones in those which
accommodate a single one only. If so, then these solitary wasps must
have the same control over the sex of the eggs laid by them as the queen
bee has. The social ones, should this be the case, no doubt have, too,
but as the former must have preceded the latter, it would appear that
this power has not been developed to meet the needs of a complex state
of society—as has been generally supposed—but in accordance with much
more simple conditions. The fact, however, if it be one, has not yet
been demonstrated.
“The delicate white, elongate egg of the wasp is laid under the middle
leg of the cicada, and when it hatches, the larva protrudes its head and
begins at once to draw nourishment from between the segments of its
victim. The egg hatches in two or three days, and the larva attains full
growth in a week, or a little more. It feeds entirely from the outside,
and, when full-grown, spins a white silken cocoon (mixed with much
earth, however), which is finished at the expiration of two days. It
remains in the cocoon, unchanged, through the winter, transforming to
pupa only in the following spring, and shortly before the appearance of
the true insect. When the adult hatches it gnaws its way out of the
cocoon, and so on up through the burrow to the surface of the ground,
thus completing its life-round in a full year.”[32] How long, exactly,
the life of the cicada lasts after it has entered into hospitable
relations with the _speciosus_ I am unable to say.
Such, then, is the end of the cicada, in spite of the love of Apollo,
who, according to the Anacreontic ode, bestowed upon it its shrill song.
Thus it dies, though “cherished by the Muses, painless and fleshless,
almost equal to the gods.” Whether it be fleshless _speciosus_, in the
larval state, best knows (on the latter point there will have been no
means of comparison), that it is painless one can only hope. It is
something, however, to be so known to fame. Homer himself alludes to the
cicada in terms of respect, calling its shrill song “delicate music,”
whilst Hesiod tells of “the dark-winged Tettix, when he begins to sing
to men of the coming summer; he whose meat and drink is of the
refreshing dew, and who all day long and at break of day pours forth his
voice.”
There was no end, apparently, to the love of the ancients—especially the
Greeks—for the cicadas, or tettiges—for they were known by both names—or
to the graceful things they said of them. From poets and philosophers
down to ploughmen, all were equally fond of them. “We bless thee,
Tettix,” says a poet whose name has been merged in that of one who is
now a name only, though a great one—Anacreon, namely—“We bless thee for
that seated on the tree-tops, sipping the dew, thou singest royally....
Oh, sweetest of summer prophets! honoured by mortals, thou art cherished
by the Muses. Phœbus himself loves thee, and gave thee thy shrill song”;
and Plato tells us that “as music soothes the mind and dissipates
fatigue, so the ploughman loves and cherishes the cicada for its song.”
The Greek ploughman, apparently, was a less gross embodiment than the
one of the present day, after twenty-five centuries or so of
improvement. To Apollo the cicadas were sacred, because they
“everlastingly sang to the sun,”[33] and, for the Muses, they had once
supplied their place. “As the story goes,” says Plato, “before the Muses
lived the cicadas were men on earth, and so loved song and singing that,
to lose no time from it, they left off eating, and so died of that dear
delight. But, in death, they became cicadas, and this boon was granted
them by the Muses, lately born, that on earth they should eat no more,
but only sing until they died again, and that then they should return to
the Muses to tell them who, amongst mortals, loved and worshipped them
most.” “A lover of music like yourself,” says Socrates in the “Phædrus”
of Plato, addressing one of _his_ worshippers, “ought surely to have
heard this story of the cicadas, how they were once human beings, but
died through forgetting to eat. But now, dear to the Muses, they hunger
no more, thirst no more, but sing only, from their birth. And in heaven
they tell Terpsichore of the dancers, Erato of the lovers, Calliope,
eldest of the nine, and Urania, of those whose heart is in
philosophy—and thus they whisper to them all.”
So established were these and similar stories that, in Greece, a cicada
perched on a harp was often engraved upon gems as the symbol of the
Muses, and, were there a musical contest, one had only to settle on the
lyre or pipe of the competitor it favoured, for the prize to be
instantly adjudged to that one—since Apollo was then held to have
spoken. Only in the absence of such indication were other methods of
forming a conclusion resorted to. In common with other graceful
creatures, cicadas were often kept as pets by the Greeks, and that
mausoleums were sometimes raised to these favourites we know from the
following epigram of the poetess Anytie—written probably for the friend
it celebrates:—“For a grasshopper, a nightingale of the fields, and for
an oak-haunting cicada Myro has built one common tomb. There the maiden
sits and weeps for three pets, torn from her by unrelenting Hades.”
Amongst the Athenians the cicadas were looked upon as children of the
soil of Attica, and those only who, like them, had been born upon it,
were permitted to twist the golden tettix, or bodkin, amidst their
flowing locks, thus forming the knot in which they were accustomed to
wear them. This privileged bodkin received its name through being
surmounted with the head, in gold, of a cicada, or tettix, and the
wearers—or bearers—of these insignia—which were strictly forbidden to
strangers—were known for this reason as Tettigophori. They were most
proud of the distinction, and, indeed, as it showed them to be
Athenians, they had a somewhat better right to be than is common in such
cases. Yet, amidst all this praise, we meet, here and there, with a
dissentient note. Hercules, for instance, feeling inclined to sleep,
once, on the banks of the river, opposite where the town of Locris
stood, and not being able to, on account of the perpetual singing of the
cicadas, took it so seriously that he prayed to the gods to put a stop
to their disturbing him. The gods, with whom Hercules was always a
favourite, heard his prayer, and cicadas, from that time, ceased to sing
opposite Locris, though they swarmed all round about that town. Here it
seems just to be hinted that Hercules was not very fond of the cicadas’
song, and Virgil—but he was a Roman—has called it (_infandum!_) a
_creaking_ note. On the whole, however, when he mentions these insects,
he gives us a pleasing picture.
“_Sole sub ardenti, resonant arbusta cicadis_,”
he sings; a line which seems bathed in sunlight, and makes one see the
green lizards too. On the whole I cannot help thinking that Virgil loved
the cicadas.
It is interesting to find that in modern Italy, generally, but
especially in Tuscany, the old ideas and legends in regard to the
cicadas have not yet died out. Still, according to the Tuscan peasant,
they were maids—not men—before the Muses, till Apollo, as a mark of his
favour, promoted them into insects. Now, however, but little distinction
seems to be drawn between cicadas and crickets, or grasshoppers, and,
indeed, this was to some extent the case in classical times—the three
often figuring together on ancient coins or rings. Amongst all of
these—and together they supply a number of species—the greatest
favourite with the Tuscan peasant of to-day—as perhaps it was in days
long gone by—is a beautiful grey-green grasshopper, which the Americans
would call a Katydid, but is, here, the cavalletta. This insect is
looked upon as the special patron of children, upon whom it has the
power of conferring musical and poetic genius, as well as more general
mental endowments. To perform this properly, however, it must enter the
room where its little favourite lies asleep, and this it seems often to
do. The mother, should she see it, has her own part to play in the
matter, which she does by tying the beneficent insect, by a long thread,
to the bed-post, and chanting the following verses, with the idea,
probably, that “then the charm is firm and good.”
“Cavalletta, good and fair,
You bring good fortune everywhere,
Then since into this house you’ve come,
Oh, bring good fortune to our home,
Unto me and everyone,
But bring it mostly to my son.
Cavalletta, this I pray,
Bring, and do not take away.
In life you were a lady, full
Of talent, good, and beautiful,
Let me pray, as this is true,
You’ll give my child some talent too.
And when you fly from east to west,
May you, in turn, be truly blest,
For though an insect form you bear,
You’re still a spirit good and fair.”
------------------------------------------------------------------------
[Illustration: A LUCK-BRINGING GRASSHOPPER]
[Illustration]
In Tuscany, if this insect comes into a child’s room whilst
asleep, it is the mother’s duty to attach the grasshopper by
a thread to the child’s bed to bring good fortune. The
grasshopper is shown in the right-hand corner.
As the child grows older, and learns to talk, he is instructed in the
truth of the matter, and taught by heart the following verses, which he
must repeat whenever he sees a Cavalletta:—
“I am but little, as you see,
But yet I may a genius be;
And if, when grown, I shall be great
And make a name in Church and State,
I’ll not forget that one fine day,
As I in cradle sleeping lay,
A Cavalletta blessed me there,
In answer to my mother’s prayer.”[34]
We are not told what happens to the Cavalletta that has been tied up,
after “the charm’s wound up.” The proper thing for the mother to do
would certainly be to let it go, but I can’t help thinking that what she
really does do is to put her foot on it, under the idea that only that
can make the thing quite certain. That would be so like the peasantry—of
any country.
-----
Footnote 32:
Leland O. Howard, The Insect Book.
Footnote 33:
Plato.
Footnote 34:
The above account, with the translation of the verses, is from Mr.
Leland’s work on Etruria. I have, however, altered some lines, in
order to retain the Italian name _cavalletta_ instead of the American
Katydid, which jars horribly here.
------------------------------------------------------------------------
CHAPTER X
Cicadas in England—A blower of bubbles—The prolific Aphis—A
nice calculation—Scientific curiosity—Dragon-fly armies—The
son of the south-west wind.
IT is generally understood that there are no cicadas or tettixes in
England, and this—with a reservation in favour of a single species
residing in the New Forest—is roundly asserted in various entomological
works of authority. Since, however, Mr. George Bowdler Buckton, F.R.S.,
has written a monograph of the British _Cicadæ_, or _Tettigidæ_, in two
volumes, each of which has a number of plates giving figures of the
various species, all with their Latin names, there would seem to be a
conflict of learned opinion; and I, for my part—since one of these
species has relations with a nice little parasite which I should like to
describe—am of opinion, after profound investigation and impartial
weighing of the evidence on both sides, that Mr. Buckton is right. What
strikes one at first sight as curious is that numbers of creatures, as
large sometimes as humble bees, or larger, and of very striking
appearance—often quite brilliantly coloured—should for so long have
escaped observation; for certainly one has never seen them oneself, and,
on making inquiries, one soon finds that nobody else has. But there is
an explanation of this seeming miracle, and that of a not very
satisfactory nature. One may have noticed, whilst going through the
plates, that in the neighbourhood of each striking figure there are two
little irrelevant-looking black lines, drawn soft and fine, very
unobtrusive, looking as though they wished to elude observation; and
gradually it begins to dawn upon you that these lines represent the real
size in linear measurement of the very salient, _outré_-looking creature
you are looking at. This, then, is the key to the mystery. England is
full of cicadas, but they are all so small that nobody can see them—at
least without taking some trouble. So our poets have been silent, our
philosophers have made no reflections, and our ploughmen, to this day,
are without a proper objective for those appreciative perceptions of
life around them which, if it only existed, there might be some evidence
of their possessing. Our aristocracy too, or old county families, have
never been able to “think gold of themselves,” as the saying is, on
account of their golden tettix-pins, though the feeling itself has not
been entirely denied them. In a word, our national character has been
uninfluenced by cicadas, and, on this, two questions arise: first—for it
is no use to start on an assumption—whether faults exist in it, and
then, if they do, whether all or any of them are due to this cause. But
such matters are for the historian to deal with, and would be out of
place in the pages of a work like this.
Though cicadas are so small in England—whilst their voices, if they have
any, as there seems no particular reason to doubt, are too attenuated to
be audible to our human ears—yet they are not quite invisible. When
seen, however, they are known by some other name, such as frog-hoppers,
tree-hoppers, or the like. Some of these, in their larval stage, which
much resembles the adult, take a great deal of pains to conceal
themselves, though in this they have another reason than that of wishing
to elude observation. Our common cuckoo-spit is a good instance of this,
and also of how a wrong explanation of a common and easily observed
phenomenon may for a long time be given, not only in popular works, but
also in scientific text-books or monographs, or within the supposedly
up-to-date pages of various encyclopædias. The cuckoo-spit, as everyone
knows, sits in the midst of a little bower of froth (allied to that
other of bliss perhaps) which, on being examined, resolves itself into
an accumulation of bubbles, having a somewhat sticky consistency. We had
always been told—and still are now very often, though the contrary has
been well made out—that these bubbles proceeded from the insect itself,
after the manner of any other secretion. But this is not the case. The
secretion here is only a clear fluid, and into this the insect
afterwards blows bubbles by a mechanical process, and through the
addition of air. It is Professor E. S. Morse who, in the pages of
_Appleton’s Popular Scientific Monthly_,[35] has thus revolutionised all
our ideas on this subject. His account is as follows: “The so-called
frog-spittle or cuckoo-spit appears as little flecks of froth on grass,
buttercups, and many other plants during the early summer. Immersed in
this froth is found a little green insect, sometimes two or three of
them concealed by the same moist covering. This little creature
represents the early stage of an insect which, in its full growth, still
lives upon grass, and is easily recognised by its triangular shape and
its ability of jumping like a grasshopper.”
“If the insect is cleared from the mass of froth it will crawl quite
rapidly along the stem of the plant, stopping, at times, to pierce the
stem for the purpose of sucking the juices within, and finally settling
down in earnest, clutching the stem with its legs. After sucking for
some time, a clear fluid is seen to exude from the end of the abdomen,
flowing over the body first, and gradually filling up the spaces between
the legs and the lower part of the body and the stem upon which it
rests. During all this time not a trace of an air-bubble appears; simply
a clear, slightly viscid fluid is exuded, and this is the only matter
that escapes from the insect. This state of partial immersion continues
for an hour or more. During this time, and even when walking, the
posterior segments of the insect’s abdomen are extended at intervals,
the abdomen turning upwards at the same time. It is a kind of
reaching-up movement, but whether this action accompanies a discharge of
fluid, or is an attempt at reaching for air, I have not ascertained.
Suddenly the insect begins to make bubbles by turning its tail out of
the fluid, opening the posterior segment, and grasping, as with a pair
of claspers, a moiety of air, then turning the tail down into the fluid,
again, and instantly allowing the enclosed air to escape. These
movements go on at the rate of seventy or eighty times a minute. The
tail is moved alternately to the right and left in perfect rhythm, so
that the bubbles are distributed on both sides of the body, and these
are crowded towards the head, till the entire fluid is filled with
bubbles, and the froth thus made runs over the back and around the stem.
In half a minute some thirty or forty bubbles are made in this way—a
bulk of air two or three times exceeding that of the body—without the
slightest diminution in the size of the body.”
It seems clear, therefore, that the air which is put to this purpose is
abstracted directly from the atmosphere, and that neither it nor the
bubbles manufactured through it have ever been within the body of the
insect. Moreover, if the little bubble-maker be thoroughly dried—which,
according to Professor Morse, is a matter of difficulty—it will continue
to secrete such spare fluid as it still has, but not the tiniest bubble
is seen to issue with this. If set in a drop of water it struggles to
the surface, and then goes through the same process of blowing bubbles
as it has done when immersed in fluid of its own distilling. The result,
however, is not the same, for the water will not hold the bubbles, which
constantly disappear. Such, then, is the manner in which the frothy pool
is made. What purposes does it answer? That of a pond, apparently, for
it would appear that in their larval state these little frog-, or
tree-hoppers, are to some extent aquatic insects. If kept dry and not
allowed to renew their supply of fluid, their body shrivels, and before
long they die. This is not through suffocation, since they can breathe
air, by means of spiracles, in the ordinary way. If, however, they are
examined closely, certain leaf-like appendages may be detected upon each
side of the seventh and eighth segments of the abdomen, and Professor
Morse suggests that these may be of the nature of branchiæ, or gills,
enabling the insect to breathe, also, in water or fluid, by abstracting
the air from it, after the manner of a fish, as some other aquatic larvæ
do. “As many of these,” he says, “respire in two ways, either inhaling
air through the spiracles, or by means of branchial leaflets, so
_Aphrophora_ (for that is the classic name of our insect) may likewise
utilise its branchial tufts for the same purpose. Thus we may see the
reason for this bubble-blowing, since each fresh bubble added to the
mass may aerate the fluid, so to speak, and thus secure at intervals a
fresh supply of oxygen.”[36]
In early spring, if one examines the leaf-buds of rose trees, which now
begin to swell, one may often see tiny little black specks, like grains
of gunpowder, scattered over their surface, especially within any fold
or crevice which it presents. These are the eggs of the Aphides, insects
which, if not cicadas, are not so very far removed from them, and which,
looked at from various points of view, are extremely interesting little
creatures. One of these points of view, which we may conveniently start
from, is their extraordinary rate of increase, which exceeds even that
of the Chinese. “A single insect,” says Mr. Buckton, “hatched from one
of these shining black ova may be the mother of many billions of young,
even during her lifetime. Réaumur calculated that one Aphis may be the
mother of the enormous number of 5,904,900,000 individuals during the
month or six weeks of her existence. But neither Tongard nor Morren is
satisfied with this estimate, both declaring that quintillions are
within the capabilities of a single mother’s efforts. Professor Huxley
(who, by the way, was not interested in the alleged phenomena of
spiritualism, _even if true_) makes a curious calculation which, at any
rate, affords some approximate idea of what a quintillion of Aphides
might mean. Assuming that an Aphis weighs as little as one-thousandth of
a grain (which is less than I should ever have thought), and that it
requires a man to be very stout to weigh more than two million grains,
he shows that the tenth brood of Aphides alone, without adding the
product of all the generations which precede the tenth, if all the
members survive the perils to which they are exposed, contains more
ponderable substance than 500,000,000 of stout men: that is, more than
the whole population of China.”[37] This, it appears, is an
under-estimate, which is rather annoying, for one would like to call it
a gross exaggeration. But facts are facts—in whatever degree they may
interest one—and it is impossible not to feel respect for an insect like
this, especially in these days, when the diminished returns of the
census are beginning to cause alarm as to the future destinies even of
our own once proudly fecund race. It is a wonderful record for a single
individual—to have weighed down China—and when Mr. Buckton remarks that
facts like these regarding the prolific nature of Aphides “afford
sufficient explanation of the occurrence of the extraordinary swarms so
often noticed by authors,”[37] nobody is likely to disagree with him.
With billions a certainty, and quintillions in the air, swarms seem
amply accounted for.
One of the authors here alluded to is our homely immortal, White of
Selborne. “I shall here mention,” he says, “an emigration of small
Aphides, which was observed in the village of Selborne no longer ago
than August 1st, 1785. At about three o’clock in the afternoon of that
day, which was very hot, the people of this village were surprised by a
shower of Aphides, or smother-flies, which fell in these parts. Those
that were walking in the streets at that juncture found themselves
covered with these insects, which settled, also, on the hedges and
gardens, blackening all the vegetables where they alighted. My annuals
were discoloured with them, and the stalks of a bed of onions were quite
coated over for six days after. These armies were then, no doubt, in a
state of emigration and shifting their quarters; and might have come, as
far as we know, from the great hop-plantations of Kent or Sussex, the
wind being, all that day, in the easterly quarter. They were observed,
at the same time, in great clouds about Farnham, and all along the vale
from Farnham to Alton.”[38]
Other great migrations of Aphides have at various times been observed.
In the autumn of 1834 the city of Gand was invaded, and, one may almost
say, taken by a vast army of them, and at Bruges and Antwerp the same
swarm is said to have darkened the sun,[39] a result of such gatherings
more noticeable elsewhere than in England, since our sun usually is
darkened. Insects, though their movements are not so regular, nor, as a
rule, so noticeable as those of birds, yet often migrate—how often or
how regularly it is difficult to say. Locusts are, of course, the stock
example as well as the most terrific one, but perhaps dragon-flies, were
they as destructive, would have been as much noted in this connexion.
Their migrations seem to be tolerably frequent, and a record of them
between 1494 and 1868 has been published by Koppen, a German
entomologist. In 1881 a great flight of them took place in Illinois.
“The air,” we are told, “for miles around seemed literally alive with
these dragon-flies, from a foot above ground to as far as eye could
reach, all flying in the same direction, a south-westerly course, and
the few that would occasionally cross the track of the majority could
all the more easily be noticed from the very regular and swift course
they generally pursued; but even these few stray ones would soon fall in
with the rest again. Very few were seen alighting and all carefully
avoided any movable obstacles.”[40] This migration took place during a
very dry season, and may have been caused by it owing to the drying up
of swamps, ponds, etc., in which the insects would otherwise have laid
their eggs, obliging them to seek other suitable places.
In the spring of 1900 a great migration of dragon-flies was observed in
Belgium. “All the observers agree that the insects flew rather low, with
astonishing regularity, and without resting; that they kept close to the
earth, where there were no obstacles, but that they mounted to a height
of 10 to 12 mètres when houses or trees were in the way. They did not go
round obstacles in their line of route, but surmounted them, and
descended on the other side. According to some observers, their flight
was very slow, others again asserting that it was very swift. When the
velocity could be estimated, however, it was found to be at 5 mètres per
second or 18 kilometres (11¼ miles) per hour (so that the slows have
it). In general they went in groups, more or less isolated, and more or
less dense.” The writer of the above account—a Belgian—concludes thus:
“All the facts point to the following conclusions: The dragon-flies of
the 5th came from regions situated to the east of the country, which
they entered in several columns, flying at a great altitude: between 7
and 8 a.m. they descended towards the earth, continuing their route
towards the west. But we remain in ignorance of their point of
departure. The swarm probably quitted its usual habitation early in the
morning, and immediately flew to a great height. It was only on arriving
near the earth that they flew against the wind”[41] (which, however,
they then continued to do).
What Mr. Hudson calls “dragon-fly storms” are a special phenomenon of
the Pampas. In this case the cause of the migration—for such movements
seem to come under this heading—is a special wind called the _pampero_,
that blows south-west from the interior of the Pampas. It is very
violent, cold, and dry, and the dragon-flies evidently fear it. The
“storm” is thus described by Mr. Hudson: “It is in summer and autumn
that the large dragon-flies appear; not _with_ the wind, but—and this is
the most curious part of the matter—in advance of it; and inasmuch as
these insects are not seen in the country at other times, and frequently
appear in seasons of prolonged drought, when all the marshes and
watercourses for many hundreds of miles are dry, they must, of course,
traverse immense distances, flying before the wind at a speed of 70 or
80 miles an hour. On some occasions they appear almost simultaneously
with the wind, going by like a flash, and instantly disappearing from
sight. You have scarcely time to see them before the wind strikes you.
As a rule, however, they make their appearance from 5 to 15 minutes
before the wind strikes; and when they are in great numbers, the air, to
a height of 10 or 12 feet above the surface of the ground, is all at
once seen to be full of them, rushing past with extraordinary velocity
in a north-easterly direction. In very oppressive weather, and when the
swiftly advancing _pampero_ brings no moving mountains of mingled cloud
and dust, and is, consequently, not expected, the sudden apparition of
the dragon-fly is a most welcome one, for then an immediate burst of
cold wind is confidently looked for. In the expressive vernacular of the
gauchos the large dragon-fly is called ‘_hijo del pampero_,’ son of the
south-west wind.”[42]
-----
Footnote 35:
Vol. 57.
Footnote 36:
Appleton’s Popular Scientific Monthly, vol. v.
Footnote 37:
Buckton, Monograph of the British Cicadæ or Tettigidæ.
Footnote 38:
White’s Natural History of Selborne, Letter liii. p. 283 (stereotyped
edition).
Footnote 39:
Buckton, Monograph of the British Cicadæ or Tettigidæ.
Footnote 40:
Leland O. Howard, The Insect Book.
Footnote 41:
The Entomologist’s Monthly Magazine, October, 1900.
Footnote 42:
Hudson, The Naturalist in La Plata, pp. 131, 32.
------------------------------------------------------------------------
CHAPTER XI
Aphides and their enemies—Curious interrelations—The biter
bit—Altruistic development—Bread and beer protectors—Saved
by ladybirds.
WITH prolific powers which have been successful in arousing the interest
even of the late Professor Huxley, it is a comfort to think that the
numbers of the Aphides are always being kept down by the operation of
certain well-contrived causes, most of which take the shape of various
insect enemies. Were all of these, or perhaps were any one of them,
entirely removed, the whole world apparently might find itself deep
buried beneath a “star-y-pointing pyramid” of insect organisms, for what
cannot quintillions, in the hands of a competent mathematician, achieve?
The wonder certainly seems that any kind of check should be sufficient.
We owe our safety, in part, as might have been surmised, to a small
Ichneumon Fly, the traces of whose work may generally be seen in a
number of brown lifeless corpses, which are dotted about like so many
skeletons at the feast, amongst any collection of living Aphides. These,
if examined more closely, are seen to be mere empty sacs, each one
having at some part of it a quite circular aperture, through which the
issuing guest has escaped. But the amount of the good thus effected is
not to be estimated by the number of these shells, these nests from
which the bird has flown. Such are only in the last stage of things,
whilst almost all, including the healthiest-looking of the living
Aphides, are probably travelling along the same road, to arrive at the
same goal. All, or almost all, have within them a guest whose energies
are unceasingly devoted to absorbing the whole of their interior
arrangements into itself, and gradually taking their place. “In June,”
says Mr. Buckton, “during the hot weather, I have seen, at the same
time, as many as three of these flies on one rose sprig, each poised on
the back of an Aphis, which throws itself into many contortions for the
purpose of throwing off its enemy. The Ichneumon, however, remains fixed
on the back for ten or more minutes (as though enjoying the situation)
before the ovipositor is thrust under the skin of the victim and the egg
is laid. The Aphis appears to suffer at first but little, since it soon
resumes its occupation of pumping up the sap. A worm-like, or more
commonly, a maggot-like creature, according to the species of the
parasite, hatches from this egg, which revels in the organised
nutritious fluid elaborated by the Aphis. The greater part of the
abdomen is occupied by this maggot when it becomes full fed, and then it
may often be seen through the transparent integument, as a grub curled
into a semicircle. Finally, the Aphis dies, the grub ceases to feed, and
after a certain period of rest cuts out of the roof of its prison a
circular plate, like a trap-door, as regular in form as if a carpenter’s
centre-bit had been used. The emerging fly has four wings, long antennæ
composed of numerous joints, a wasp-like body and legs, and is in every
way suited for its marauding expeditions.”[43]
Other and more interesting dramas can take place within the body of an
Aphis; wheels within wheels, one masterpiece of economic contrivance
enclosing another, perfection more perfected. Along what path, indeed,
can the beauty and wisdom of Nature—those endless steps from endless
seeming halting-places that become, when reached, but so many points of
fresh departure—be run to earth, so to speak? The brain becomes, at
last, almost weary in the pursuit of wisdom’s ways, and even the
delighted spirit would fain cry, “Hold! Enough!” Thoughts like these are
powerfully excited by the following picture.
It is spring, early spring, and already the young Aphides have begun,
with gladness born of the opening year, to absorb the sweet sap from the
stems of the immature wheat-crop. Later, however, when July’s sun shines
brightly behind its cooling screen of clouds—for in England all climatic
extremes are tempered—they ascend in “numbers numberless” to attack the
ear itself. What, then, can save the hope of the husbandman? What but
_Ephedrus plagiator_, a small black-winged Ichneumon Fly that even now
is at work? As each individual Aphis clings to the wheat, it becomes, in
spite of its efforts to fill itself, hollower and hollower; its appetite
flags, and ere it can fatally affect the plant on which man’s life and
the machinations of the protectionist depend, it has become a mere brown
pupa-case for a body other than its own to develop in. A day or two, and
almost on every grain of the wheat hangs an insect, lifeless, but—oh,
floweret springing from the tomb!—life-filled. Hardly a living Aphis is
to be seen feeding amongst them. The wheat-crop has been saved. But the
march of events, thus unfolded, does not end here. Another drama has to
be played out ere the full life issues from the once living cradle whose
contents it has absorbed and become, nor will it bear the image of that
particular Ichneumon Fly that laid its little egg, some weeks ago, in
the body that seemed so designed for it. Like the Aphis, the Ichneumon,
too, must learn to live for others, thus rising through selfishness to a
purer and higher embodiment. If we pass a little later through the same
cornfield, another insect, differing from, yet of the same general type
as the prior parasite, may be seen running to and fro over the
wheat-ears, tapping each tenanted abode with tremulously quivering
antennæ, which, as well as the whole body, seem to vibrate with
excitement. It is looking for lodgings, but not every house so touched
can be utilised, for _Ceraphrus Carpenteri_—such is the new tenant’s
name—must first be satisfied that none of its own species have already
taken possession. Once assured on this point, however, its duty lies
plain before it, and bending its antennæ against the wheat-ear, so as to
form a fulcrum, it turns the tip of its abdomen towards that of the dead
Aphis, and with its ovipositor commences to saw through the skin. As
much as ten minutes may be occupied in the accomplishment of this task,
for the sarcophagus that has thus to be pierced is hard, and the
ovipositor, though short, is not stout, but slenderly formed. But there
is no flagging of energy, and at length, when efforts steadily continued
have been crowned with success, the same deft instrument is again
employed to pierce the sleeping _ephedrus_, and a second egg is
deposited in this second cradle. To this new tenant the former one must
now yield up the juices of its body, even as those of the Aphis were
freely rendered unto it. It must die in its turn, but by its death
another lives, and thus the physical act of aggression, which we call
selfishness, becomes the seed-bed, as it were, or forcing-house—the
food-plant, to use an entomological simile—of a moral altruism. True,
the Aphis may at first struggle, the maggot, pierced by the ovipositor,
may flinch for a moment, but after that there is complete passivity,
without which there can be no complete acquiescence. Self-absorption,
that is the moral of it all; for the true self of the Aphis, which is
not represented by the outer husk, is absorbed into the Ichneumon, and
so in regard to the latter. Thus, throughout the animal kingdom we must
look to the inner, and not to the outer, significance. What matters it,
though Nature be “red in tooth and claw,” if the fierce rendings of the
outer integuments are but as the first gropings towards interior rest
and calm? And should we not, in the lower walks of life, look to the
soul through the body, and see in processes which, with ourselves, might
seem to represent the flesh only, a blending which but anticipates the
more complete separation? Thus, and thus only, as it appears to me, can
we impart beauty to a scheme which, without this key, must appear
selfish and unsatisfactory. The key may be hard to find, but when we
once hold it we need no longer repine.
Besides the Wheat Aphis, which but for such arrangements as have here
been glanced at, would almost deprive us of bread, we have the Hop
Aphis, a species the dread of which is still more strongly disseminated
amongst the masses of this country, inasmuch as its interference would
be with the supply of beer. No wonder, then, that the little ladybird is
beloved by all, since, but for its efforts, many a poor man might have
to live in a state of enforced sobriety, which, in its turn, must
deleteriously affect that position of respect and esteem which many
illustrious and highly placed individuals now hold in the hearts of the
people, so that a general disturbal of habits and ideas, amounting
almost to moral chaos, would attend any serious diminution in the
numbers of this insect, England’s true guardian angel. But it were
unjust to claim an undue share in the merit of recognising work like
this. Appreciation of such services is, as one might expect, widely
spread, and is expressed in such popular names as, for instance, in
Lombardy “Bestioline del Signore,” in Tuscany “Madonnine” or
“Marioline,” in France “Bête” or “Vache à Dieu,” and in Germany
“Sonnenkäfer.” The first-named countries, indeed, are not, or used not
to be, beer-drinking, so that unless this little madonna is a patroness
of the vine too, they are not so easy to understand. It may, however, be
incidentally mentioned that the ladybirds are good friends to the
orchards, and destroy many thousands of apple- or plum-eating Aphides.
Aphides, in fact, of some kind or other, are what they have come into
the world to destroy. It is their mission, their epos.
The following account of the habits of these beneficent creatures,
principally in the above connection, is given by Mr. Buckton, a profound
student of insect life-histories: “The food of Coccinella (the ladybird)
consists almost exclusively of Aphides. Their marvellous voracity is
shown equally in their larval and their winged condition. The former
stage may be commonly seen throughout early summer as slaty-grey or
brown six-footed creatures, covered with tufted tubercles, and provided
with mandibles efficient both for holding and sucking out the juices of
their victims. In some years the imagos (or grown insects) are
wonderfully numerous, and when they take wing form vast swarms which
travel great distances. In the year 1869 such a cloud passed over a
large part of Kent, Sussex, and Surrey,” and their effect (of the same
genial nature as that of Bacchus wandering through the earth) was soon
seen in the good hop crop of the following year. “Although the
Coccinella is not restricted to the Hop Aphis for its food, it
frequently follows its migrations, and travels on the same winds. Whilst
feeding, the Aphis is held and manipulated by the jaws or palpi of the
Coccinella, and the devouring operation proceeds amidst the struggles of
the victims from the apex of the abdomen to the thorax, which parts,
together with the head and legs, are finally rejected.”[43] This
process—which is by no means confined to insect life, but extends
upwards from it even into the highly organised mammalia—does not seem to
be a pleasant one to witness, for Mr. Buckton remarks upon it: “We may
express some hope, in sympathy with the Aphis, that the automatic theory
of animal life may here find some place, and that reflex action may
explain the fact that, under the microscope, the mutilated remains of
the Aphis, without stomach and without internal organs, have been seen
to walk away and live after the operation for a considerable time!
Automatically the Coccinella furbishes up its jaws and antennæ in
readiness for another meal. From thirty to forty Aphides may thus be
consumed in one hour.”[43]
Automatically perhaps—that is to say, between the lines—we may gather
Mr. Buckton’s opinion of the automatic theory. There are some theories
which seem held, like dykes or barriers, to prevent the sea from getting
in. One doesn’t want the sea to get in, because it would swamp such a
lot of things, which, although quite artificial, one is not prepared to
part with, but one doesn’t believe in the barrier except for that
particular purpose to which it is applied. The automatic theory in
regard to animals is a case in point. Scientific men make use of it in
order to keep out another, which they don’t want to have to admit,
though they do, as a fact, believe in it. This, again, one can read
between the lines whenever they give any account of their observations
on this or that animal, whether it be dog or elephant, ants or something
much lower down in the scale—rotifers, for instance, or amœba in the
ocean of a watch-glass. One sees what they really mean very well then,
though they may not themselves be aware of it, but they are never in the
least _convincing_ when they air their automatic theory. Aphides, as may
have been gathered incidentally, feed wholly upon the juices or sap of
plants. Active _ab ovo_ (which means from the egg), “their occupation,”
says Mr. Buckton, “is to grow as fast as possible,” and with a view to
this end the rostrum or beak, with its enclosed sucking or pumping
apparatus, is fully developed from the very commencement, “often,
indeed, to such an abnormal extent that it forms an awkward appendage,
trailing behind the body whilst walking.”[43] The insect does not,
however, walk much, but, settling itself down on the twig or stem where,
perhaps, it first saw the light, pierces the bark with the instrument
thus provided for it, and commences to suck up the sap into its mouth.
This is not a process which can be indulged in with impunity to the
plant, especially since Aphides reside in great societies upon the same
one, and turn their attention to every part of it, not even excepting
the roots. Troops of small Aphides, in fact, have sometimes been found
in the pips of large codling apples. In consequence of this excessive
drain upon their fluids, which is as though our own blood were to be
sucked, plants thus invaded by Aphides become greatly weakened, and
their young shoots and leaves have a distorted appearance in
consequence. Others, either through this cause alone, or in consequence
of some poison or acid injected by the Aphis, have gall-like excresences
produced upon them. These have a hollow interior, into which the Aphides
penetrate, and there take up their residence. Such swellings thus become
their houses, and therefore, since it is a great advantage to the
Aphides to be sheltered in this way, it is possible that some special
instinct through the exercise of which the tree is thus affected, may
have been implanted in them by the action of natural selection.
Aphides are often spoken of by entomologists as if a very high degree of
interest attached to them, and, no doubt, in many respects this is the
case. As we have seen, they exhibit certain phenomena of _corporealism_
(which _did_ interest Professor Huxley) to a greater extent perhaps than
any other creature, though of this I am not at all sure; but after all
one soon gets over the wonder of that, especially since there is no
realising it, and then it does not seem to raise a creature to a very
high level of interest. Again, to quote authority, “there is a most
curious alternation of broods in these insects, some forms being winged
and with separate sexes, and others wingless or apterous and capable of
producing their kind for an indefinite number of generations before a
sexual brood is again developed. In fact, the anomalies of members of
this family are endless, and it would require volumes to epitomise even
the comparatively little which has already been discovered with
reference to their habits and transformations.”[44] Still, for all this,
it is difficult to look long at an Aphis, or a collection of Aphides
upon a rose tree or any other of the plants they affect, without getting
heartily tired of them, and for me, as perhaps for most people, the
principal interest about these sluggish creatures lies in the relations
which have become established, without any intelligent efforts on their
own part, between them and ants—but it will be best to reserve the
discussion of this subject for the following chapter.
-----
Footnote 43:
Buckton, Monograph of the British Aphides, vol. i
Footnote 44:
The Concise Knowledge Library, Natural History, pp. 601, 602.
------------------------------------------------------------------------
CHAPTER XII
Ants and their honey-cows—A mutual benefit—Unity of motive—The
end and the means—Two ways of getting honey—Insect
cattle—Wasps as cow-milkers—A cow-keeping bee—Ant
cow-sheds—Aphides in ants’ nests—Children of light and
darkness—Forethought extraordinary.
A drop of honey, or something like it, is the connecting bond between
the ant and the Aphis. It is exuded by the latter through certain
tubercles which are situated at the end of the abdomen, and is, of
course, the product of the endless quantities of sap, which, so long as
it lasts, these insects are for ever pumping up from the plant they
inhabit, and swallowing. This honey, or honey-dew, to use the more
special name bestowed on it, the ants want, but they are not content
with drinking it whenever it issues from its manufacturers, in natural
course. This is not sufficient, and they have learned to increase the
flow of so valued a beverage by their own efforts—in other words, they
milk the Aphides, which thus become their cows. To do this they tap them
with their antennæ, softly and gently, on the sides of the abdomen—a
quick little shower of touches. Under the influence of this probably
pleasant sensation the Aphis becomes willing to part, and, raising the
abdomen, “teems her refreshing dew” in a drop from the tip of it. This
action of the ants cannot, in Europe, be successfully imitated, at least
it has not been, and if an ant is not forthcoming the fluid is contained
in the body of the Aphis until necessity compels its being ejected.
Probably the ants, if delayed in their visits, are missed by the
Aphides, as a cow misses her milker, and long before they do excrete, as
the process is called, they would perhaps have done so had they felt
able. The sensation no doubt of the ant’s antennæ on the abdomen has
become, through usage, the almost necessary stimulus to the act produced
by it.
The above remarks are best illustrated by a quotation from Darwin,
which, in my opinion, should always be given in any general account of
the relations of ants and Aphides. “I removed,” says Darwin, “all the
ants from a group of about a dozen Aphides on a dock plant, and
prevented their attendance during several hours. After this interval I
felt sure that the Aphides would want to excrete. I watched them for
some time through a lens, but not one excreted. I then tickled and
stroked them with a hair in the same manner, as well as I could, as the
ants do with their antennæ; but not one excreted. Afterwards I allowed
an ant to visit them, and it immediately seemed, by its eager way of
running about, to be well aware what a rich flock it had discovered; it
then began to play with its antennæ on the abdomen first of one Aphis
and then of another; and each, as soon as it felt the antennæ, lifted up
its abdomen and excreted a limpid drop of sweet juice, which was eagerly
devoured by the ant. Even the quite young Aphides behaved in this
manner, showing that the action was instinctive, and not the result of
experience. It is certain, from the observations of Huber, that the
Aphides show no dislike to the ants: if the latter be not present, they
are at last compelled to eject their excretion. But, as the excretion is
extremely viscid it is no doubt a convenience to the Aphides to have it
removed; therefore, probably, they do not excrete solely for the good of
the ants.”[45]
If the reverse of this were the case, if the Aphides did excrete for the
sole benefit of the ants, then, in Darwin’s own opinion, the case for
natural selection would be broken down, and with this there would be
some better ground of reason for those who would see in relations of
this sort a set-off, as it were, against the never-ending bloodshed and
rapine, accompanied with suffering in varied—often in an intense—degree,
which is the very stuff out of which Nature has woven her mantle. But
there can be no essential difference where the principle at work is
precisely the same. So long as a creature does benefit itself, the way
in which it does it, and the incidental effects of its doing so, are of
no consequence; it is the motive power that the philosopher has to
consider, and there is little comfort—if comfort be needed—in knowing
that an animal, to do itself good, is doing good to some other, when one
also knows that, governed by the same incentive, it would as cheerfully
prey upon that other’s eye. As Hamlet says, in such a case “the
readiness is all.”
As an illustration of this truth here is another picture of how ants
procure honey from a weaker creature that may happen to have swallowed
it, when it is not to be obtained by the soft methods of persuasion.
“Once upon a time,” says Dr. Lincecum, “there dwelt in my yard a
flourishing colony of the very smallest species of black ant,” and
having described how these Lilliputians found and ate some syrup
belonging to the household, and were in consequence attacked by a larger
and stronger species, he continues, “They”—that is the attacking
party—“grabbed up the heavily burdened little fellows, doubled them, and
biting open the abdomen, drew out the full sac, and seemed to swallow
it. Then, casting the lacerated carcase aside, they furiously sprung
upon another of the panic-stricken crowd and repeated the horrid
operation.”[46] Clearly, then, Nature, so long as she can attain her
end, cares not by what means she attains it.
Independently of any feeling of comfort which the Aphides may experience
in being milked by the ants, observation at once shows that they benefit
largely, in a general way, by the attentions of the latter. It is not
enough for the ants to milk their cows when they happen to meet them.
They go very much farther than this, and cow-keeping is of as much
importance with them as with us. Lucky the Aphis who has a guard of ants
round it, fiery warriors prepared to defend their property against all
foes. None need be feared now. Let but an Ichneumon buzz, and a dozen
stalwarts start to the rescue.
“I dare thee but to breathe upon my love.”
“Fear not, sweet wench, they shall not touch thee, Kate,
I’ll buckler thee against a million.”
And so they do indeed, or against any reasonable number. But there is no
combination amongst these banditti. Each comes but to eat his own Aphis,
and no one thinks of helping a friend. All therefore are powerless
before the organised attack of so fierce a bodyguard. Whilst the ants
are with them the Aphides are quite safe, and they are often permanently
guarded in this way. Other ants take even more elaborate precautions for
the safety of their property, placing them in stalls, where they stand,
by plastering earth, etc., about the plant on which they are feeding.
Lastly, others still conduct them into their own nest, where they keep
them, sometimes, in a chamber specially prepared for their reception,
every necessary measure being taken for their proper nourishment, and,
as one may say, comfort. Nay, the very eggs of the Aphides are tended by
the ants, and hatch out in their own nurseries. Nor is it little for
which they do all this, since, taking their size into consideration, the
yield of these ant-cows each day must be much greater than that of our
own—at least, I should imagine so.
It is not all ants who do these things, nor do any do all of them, but
where there are Aphides and also ants, it would seem to be the exception
rather than the rule for the latter to neglect them.
But Aphides, though the principal ant-cows of Europe, are not the only
ones even there, whilst elsewhere various other species that have this
honey-excreting property become their substitutes. “In the tropics,”
says Belt, in his much-observing work, “their place is taken in a great
measure by species of _coccidæ_ and genera of _Homoptera_, such as
_Membracis_ and its allies. My pineapples were greatly subject to the
attacks of a small, soft-bodied, brown coccus, that was always guarded
by a little black stinging ant (_Solenopsis_). This ant took great care
of the scale-insects, and attacked savagely any one interfering with
them, as I often found to my cost when trying to clear my pines by being
stung severely by them. Not content with watching over their cattle, the
ants brought up grains of damp earth, and built domed galleries over
them, in which, under the vigilant guard of their savage little
attendants, the scale insects must, I think, have been secure from the
attacks of all enemies.”[47] And again, the same naturalist tells us,
“The pawpaw trees growing in my garden were infested by a small brown
species of _Membracis_—one of the leaf-hoppers that laid its eggs in a
cottony nest on the under part of the leaves. The hopper would stand
covering the nest until the young were hatched. These were little
soft-bodied, dark-coloured insects, looking like Aphides, but more
robust, and with the hind segments turned up. From the end of these the
little larvæ exuded drops of honey, and were assiduously attended by
small ants belonging to two species of the genus _Pheidole_. A third
ant—a species of _Hypoclinea_—which I have mentioned before as a
cowardly species, whenever it found any young hoppers unattended, would
relieve them of their honey, but would scamper away on the approach of
any of the _Pheidole_. The latter do not sting, but they attack and bite
the hand if the young hoppers are interfered with.”[47] The latter “are,
when young, so soft-bodied and sluggish in their movements, and there
are so many enemies ready to prey upon them, that I imagine that in the
tropics many species would be exterminated if it were not for the
protection of the ants.”[47]
But these leaf-hoppers had not only ants, but wasps to protect them, and
there were constant skirmishes and bickerings on their account between
the two. The wasp obtained the honey just in the same way as the
ants—namely, by stroking the hoppers with its antennæ, and its
possession of wings, more than its greater size, gave it a clear
advantage over its rival. It did not grapple with the latter, even when
there was only a single one to dispute its right, but, rising on the
wing, and hovering about till a good opportunity presented itself, it
would dart down suddenly on the impertinent little dwarf, and strike it
from the leaf or stem. So quick was this action that Mr. Belt could not
determine whether it was with the feet or the mandibles that the wasp
delivered its blow, but he thinks it was with the former; that is to
say, the front pair of them. But in spite of its superiority in single
combat, the wasp could not prevail against the numbers of the ants. If,
indeed, it was first in the field, there was not much difficulty, for
though the leaf would before long be found by some or other of the ants,
yet the first arrivals were only pioneers, and when once they were
knocked off it it had to be found again, only for a similar fate to
befall the new discoverers. Often, however, the wasp would try to clear
a leaf already in possession of the ants, and the way to which was
known. But in this it was never successful, for though many fell,
streams of others came rushing up, so that the wasp had no time to enjoy
the fruits of its labours, but was obliged to keep constantly fighting,
and before long was tired out. Though a giant amongst pigmies, and
having wings—a sort of flying-dragon contending with an army of
knights—yet it did not despise its small enemies, and evidently dreaded
lest any of them should succeed in fastening on it. No doubt it
knew—from inheritance, or experience, or both—that an ant clinging to a
leg was a difficult thing to get rid of, and to avoid being placed in
this position it never fought upon the ground—that is, the leaf—but only
on the wing, in the manner described. Had it used its mandibles to bite
with, the ants would have seized them, and some might have got on its
body. Its sting played no part, doubtless because the small size and
hard bodies of the ants would have rendered it ineffective.
We see from the above account that ants are not the only insects that
can make discreet use of honey-yielding creatures, though they excel all
others in this respect. Wasps have also learnt to milk, if not to stall,
their kine, and to wasps, it would seem, must be added—which need not
surprise us—at least one species of bee. A correspondent, whose name and
date of communication I cannot now remember, says, writing to _Nature_:
“Fritz Muller has observed in Brazil a larva of a leaf-hopper—_Umbonia
indicator_—which is used, like the Aphides by the ants, as milch cattle
by a species of stingless bee—_Trigonia Cagafogo_. This bee is fond of
oily matters, and feeds on carrion, old stinking cheese, and oil
secreted by various plants. Although stingless, it possesses a very
intense venom, which causes a most lively irritation of the skin.” I
wish I could give the details of a fact so interesting, but have not had
the opportunity of reading the original account from which this bald
statement is taken. The ants, therefore, have rivals in this industry,
and possibly such rivalry may exist to an extent hitherto unsuspected.
Though the protection of these insects by the ants architecturally—by
moist earth placed round them, that is to say—is mentioned in the above
account, it is not dwelt upon, and seems to play but a small part in the
general drama. Some ants, however, rely solely on this method. Mr.
Gaudie, writing in the _Victorian Naturalist_,[48] gives the following
account of one of these: “A small species of ant, commonly distributed
in the Mallee, has a curious habit of keeping in close confinement a
rather large mealy Aphis, which feeds on the stems of young eucalyptus
gum trees. Round and over these Aphides the ants construct a domed
covering of particles of bark, grass, etc., which serves the double
purpose of imprisoning the aphides and excluding other ants. Some of
these coverings appear to be entirely closed, whilst others have an
opening left in the edges. This doorway is, however, constantly guarded
by a pair of ants, which continually move about in the open space, and
seem much impressed with the importance of the duty assigned to them.
Each enclosure contains generally from three to a dozen Aphides, and
about the same number of ants. Upon making a breach in some of these
structures for the purpose of observation, I have noticed that many of
the live stock were immediately seized by the ants and forcibly removed
to a place of safety. The ant under notice is about a quarter of an inch
in length, and is of a uniform dark, reddish-brown colour, and forms its
ordinary habitation under logs, or in old rotten stumps, and sometimes
in the ground. Several other species of ants are very assiduous in their
attendance on the various aphides, _tettigonidæ_, and coccids, but the
above is the only kind I have noticed that uses such extraordinary means
to secure a monopoly of the much-prized ‘honey-dew.’”
For ants that keep and rear Aphides in their nests we need not go
farther than our own little yellow one—_Lasius flavus_. They guard and
look after the eggs of their protégés, which form little black shiny
clusters, with the same care that they bestow on their own, and when
they are hatched set about providing food for the young aphides. This,
it would appear, does not consist of the roots of various plants
penetrating the nest itself, for Sir John Lubbock found that the first
business of the ants, after the young aphides had appeared, was to
conduct or carry them out of the nest, evidently in order that they
should find their natural food. None being at hand under these
artificial conditions, and the plants required not being known, the poor
aphides all died, and this happened again the following year. In the
year succeeding to this, however, Sir John was more fortunate, and this
is the account he gives of his interesting discovery: “The eggs
commenced to hatch the first week in March. Near one of my nests of
_Lasius flavus_, in which I had placed some of the eggs in question, was
a glass containing living specimens of several species of plants
commonly found on or around ants’ nests. To this some of the aphides
were brought by the ants. Shortly afterwards I observed on a plant of
daisy, in the axils of the leaves, some small aphides very much
resembling those from my nest, though we had not actually traced them
continuously. They seemed thriving, and remained stationary on the
daisy. Moreover, whether they had sprung from the black eggs or not, the
ants evidently valued them, for they built up a wall of earth round and
over them. So things remained throughout the summer, but on the 9th of
October I found that the aphides had laid some eggs exactly resembling
those found in the ants’ nests; and on examining daisy-plants from
outside I found on many of them similar aphides and more or less of the
same eggs.”[49]
As the young aphides had been brought by the ants to the daisies, and as
they had subsequently laid their eggs there, it would certainly seem
that the ants are accustomed to collect these eggs from without, and
that the aphides do not lay them in the nest. When they are hatched the
young aphides, as we have seen, are taken out to feed and lay, and these
new eggs laid by them are, in their turn, brought in and tended by the
ants. This, as Sir John Lubbock remarks, is a much more remarkable thing
than if the aphides, living in the nest with the ants, simply laid their
eggs there. In that case they would probably hatch out whether they were
tended or not, and it could not be long before the ants would become
aware of their value. Here, however, we see this knowledge—how first
obtained we know not—exhibited in a more striking manner, and also a
great degree of foresight displayed, since as the eggs, except for
accidents, would hatch where they were, it can only be with the idea of
providing against these that the ants bring them into their nest. There
they are safe from many dangers which threaten them above ground, and
are not exposed to the rigours of winter or other climatic vicissitudes.
What are we to say of this act? I think there might be one or two things
to say, but Sir John Lubbock says this: “Our ants may not, perhaps, lay
up food for the winter; but they do more, for they keep, during six
months, the eggs which will enable them to procure food during the
following summer—a case of prudence unexampled in the animal
kingdom.”[49] There is a slight national note here which should,
perhaps, make us suspicious. At least, I am always suspicious when a
Frenchman praises anything French, an Englishman anything English—even
ants or the climate—a Tierra del Fuegian anything in Tierra del Fuego,
and so on. No doubt if prudence really induces the act, it is very
great, but if we could imagine any other cause through which the habit
might have begun, natural selection would have brought about the rest,
since those ants which stored aphides’ eggs would have had more aphides,
and consequently more honey-dew to nourish them than those which did
not. Now the eggs might at first have been eaten, and so carried down,
as provisions, or aphides, brought into the nest, might have laid before
they got out again. However the act originated, it is probably a
prudential one now, but if the growth of prudence has been aided by that
of an inherited habit, having nothing to do with this, it is not quite
so remarkable. But what, exactly, does “our” in the above passage mean?
_Lasius flavus_ is not confined to England—at least, I suppose not—and
if other countries have a claim on its mental powers, our cue should
rather be to undervalue them—at least, the note of national vanity
should be held in check by the all as powerful one of national
prejudice.
Besides these particular aphides, which leave the nest directly after
leaving the egg, there are four or five other species which live in it
altogether, and feed on the roots of various growing plants. Some nests
which I had contained a few, but under natural conditions they are to be
found, I believe, in abundance. Special chambers, it would seem, are
given up to them, and in Kirby’s _Marvels of Ant Life_ there is a
picture of such a “subterranean cow-house.” The question arises, where
do these aphides lay their eggs, and, if in the nest, does not it
largely discount the intelligence, or prudence, attributed to _Lasius
flavus_ in bringing the other ones into it? In that case, since the eggs
of the various species probably resemble one another, any found outside
would be brought in by the ants, just as their own larvæ or pupæ would
be—or anything else which they value—nor need we ascribe greater
foresight to the one act than to the other.
Ants, however, do more wonderful things in relation to aphides than this
that Sir John Lubbock has recorded, and if that act is unexampled, as an
exhibition of prudence, elsewhere in the animal kingdom, it is not, I
think, in this particular branch of it. First it must be remarked that
amongst the aphides we have what is called the “alternation of
generations,” that is to say a light-loving generation that feeds on the
stems and leaves of upper earth, produces one that loves darkness, whose
food is only the underground roots of the plants their parents lived on.
This brood in its turn gives birth to another, which forthwith seeks the
sun, and so the round goes on. There is this difference in the two
broods, that the light-lovers, nevertheless, seek out darkness when the
time comes to lay their eggs, whilst the children of darkness lay theirs
in the caves where they have, all their lives, lived. That ants should
be aware of all this, and habitually adapt their cow-keeping economy to
circumstances so recondite, seems very extraordinary, but it would
certainly appear to be the case. Thus when _Lasius fuliginosus_ (another
Franco-Britannico, etc., species) sees _Schizoneura venusta_—its
particular Aphis—seated on a grass stem, and evidently wishing to lay
her eggs, it knows at once what to do. Soft and large, with voluminous
wings, such an insect is not well fitted for burrowing. She could hardly
do it, in fact, so the ants, recognising this, begin to do it for her,
and soon drive a tunnel leading down to the roots of the grass, through
which they lead her, first, however, having clipped off her wings, which
are now but a useless encumbrance.
Arrived at the terminus, the ants make a proper apartment for their cow
Aphis, and here, in the midst of warm sympathisers, and with every
comfort and luxury about her, she no longer hesitates to lay her eggs.
In due time they hatch, producing wingless aphides, and from the brood
thus raised the ants obtain their honey. When, however, this crawling
generation have in turn produced another winged one, the ants, far from
seeking to detain these in a place where they would only die, again set
to work to make tunnels, through which they conduct them successively to
the upper air. One tunnel, one would think, would be sufficient for the
purpose; but Lichtenstein, who observed these facts in the south of
France,[50] states that each Aphis, as it issues from the egg, has a
separate one made for it by the ants. Having reached the surface, these
cave-born Ariels spread their wings and fly away. Where they will settle
no ant knows, but to the community that has freed them they are lost,
probably—they and their eggs—for ever. Do the ants know this? If they
do, they do not repine at it, for they know also that the perpetuation
of the species, through which alone they can hope for fresh honey, has
been provided for. This seems to me altogether to outdo the prudential
feat of _Lasius flavus_, and since _Lasius fuliginosus_ is distributed
probably throughout the greater part of Europe, all the nations that do
honour to that portion of the earth’s surface are at equal liberty to
think of it with patriotic complacency as “_our_ ant.” For my part, I
will only say this, that, whether it is or not, I think it deserves to
be a Japanese ant—or that the Japanese, nowadays, much more deserve to
have it than we do: that perhaps is the better way of putting it.
-----
Footnote 45:
Darwin, Origin of Species, pp. 207, 208.
Footnote 46:
“Letter to the Smithsonian Institute,” The American Naturalist,
September, 1874, p. 565.
Footnote 47:
Belt, The Naturalist in Nicaragua, 1874, p. 226.
Footnote 48:
February, 1898, vol. 14.
Footnote 49:
Lubbock, Ants, Bees, and Wasps, p. 72.
Footnote 50:
Kirby, Text-book of Entomology, p. 113.
------------------------------------------------------------------------
CHAPTER XIII
Cow caterpillars—The adventures of Theophrastus—Cave-born
Ariels—Led to the sky—A strange attraction—Ant slaves and
slave-holders—Slave-making raids—Feeble masters—An ant
mystery—Effects of slavery—The decadent’s reply.
AS we have seen, both in this chapter and a former one, aphides are not
the only insects which yield the ants honey—or something honey-sweet—and
are cherished by them in consequence. There are, for instance, the
coccidæ, or scale insects, as mentioned by Belt; but whilst some of this
family are milked in the same way as the aphides, to which, indeed, they
bear a strong resemblance, others are simply eaten, as though they were
sweets. To them might be said in warning, “Make yourself all honey, and
the _ants_ will swallow you,” but who can modify the nature of his own
juices? Then there are the ants’-nest beetles, many of which have a
sweet downiness which the ants enjoy licking, and are for this reason
carried about with them when they move from one place to another. Not
that they are always carried, for one little beetle, at any rate, whose
name—it must be a diminutive—is _Formicoxenus nitidulus_, is accustomed
to ride on the backs of its protectors, like the little cockroaches
discovered by Professor Wheeler.
But perhaps the most interesting parallel to the aphides, as cows, is to
be found in certain caterpillars, which are as soft and defenceless as
they are, and represent a class of creatures which ants habitually prey
upon. A certain family of butterflies, however, commonly known as the
Blues, but entitled to the scholarly name of _Lycænidæ_, produce
caterpillars which bear, upon the twelfth segment of the body, a certain
honey-holding reservoir which, when full or nearly so, may be made to
yield its contents through the same treatment which is so effectual in
the case of the aphides. The ants tap or titillate the body of the
caterpillar, near where the gland is situated, with their antennæ, and
the caterpillars, charmed with such affability, overflow in return. This
interesting fact has been observed in various parts of the Old World,
and also in North America; but the most detailed account which we have
of it comes from India. In this case, as in all the others, the
caterpillar is a quite small one, and feeds on the leaves of a certain
tree, bearing both “an astringent yellow fruit” and the name of
_Zizyphus jujuba_, though, by the way, jujubes are not, as a rule,
astringent. The name of this little caterpillar—it would scorn to be
behind the tree it feeds on in such a matter—is _Tarucus theophrastus_,
so now we have something to fix it in the memory. The ant that
patronises it is a large black one—_its_ name I cannot give—and here,
too, as in the case of the aphidean relations, we have, in the most
noteworthy of the actions recorded, a very remarkable instance of what
looks like foresight, and foresight, too, of a very large and general
kind. In the first place, the ants make a nest at the foot of the trees
in which the caterpillars reside, and here, during the period of their
growth and nourishment, they avail themselves of their services. But
when this period is over, and the caterpillars are about to change into
chrysalids, then a strange scene takes place. All over the tree, ants
are now to be seen running about in a state of the greatest excitement,
and whenever they meet a caterpillar descending, or preparing to
descend, the trunk, in order to burrow into the earth at its base, and
there pass its pupal stage of existence, they conduct it down themselves
and relieve it from the labour of digging, just in the same way as our
English ants do with the aphides.
Still stranger is the scene which reveals itself if the earth at the
base of the tree be removed, for then it is seen that chrysalids, and
caterpillars that are about to turn into chrysalids, are clinging all
round the trunk, whilst all amongst them are the ants, helping to place
this one or that one in position. The band thus formed round the tree
may be several inches broad, and it is always remarkably even, as though
arranged on æsthetic principles. As the light shines in, the ants become
agitated, and seizing hold of their property—for in this light they
consider the caterpillars—begin to rebury them, so that in time, if the
annoyance continues, they will form a fresh circle of bodies lower down
the tree. Here, then, is an ants’ nest, described as temporary by Mrs.
Wyllie, from whose interesting account[51] the above facts are taken,
full of butterfly chrysalids, and in about a week it becomes full of
butterflies themselves, and amidst the rough, black bodies of hosts of
earth-working Calibans, colours born of the rainbow gleam and flash from
the fairy wings of delicate insect Ariels. Each one of these was helped
from its cradle, thus strangely situated, by a little group of these
gnomes, who then assisted it to unfold its wings, and guided its
uncertain steps. Later, when strength has come to it, and something—it
knows not what—like an upward desire, these same gnomes will lead it to
the portals of their gloomy Hades, where it will spread its wings and
fly to meet the light. In so strange a way, led by such uncouth guides,
does Ariel find the sky. Yet, as though the place of their new
birth—gloomy though it be and opposed to their light-loving natures—had
yet some nameless attraction for them, crowds of these butterflies may
be seen, for some time after their exodus, hovering over the nest,
before they leave it for ever to dwell in the courts of the sun.
Just as in the case of the aphides released by _Lasius fuliginosus_,
these ants will never see their butterflies again, nor will they gain
any after advantage that can with certainty be traced to the particular
individuals thus set free. But they gain in such a manner as, if the
reflection really occurred to them, would make ants not much below men.
The process of reasoning would be this: “Though we may very likely not
get any caterpillars from the eggs which these butterflies will lay, yet
we ought not to kill them, because then there would be so many
butterflies less in the world, to lay eggs, and if we did this every
year, and other ants too, caterpillars, as well as butterflies, would
become scarce, and at last we should not get enough.” For myself I doubt
if ants really do reason like this, but by what steps this habit of
releasing butterflies so as to ensure the perpetuation of the species
has come about, I don’t quite see. In the case of the aphides, perhaps
it has been through actual observation of their habits, and here, too,
this hypothesis may not be excluded, since the butterflies might well be
seen laying their eggs, nor is it unlikely that these are watched, and
the issuing caterpillars tended from the beginning. For the purposes of
the ants, indeed, all aphides, and every theophrastus, would be the
same, and they might very well think that those which they found laying,
or about to lay their eggs, were the very ones previously liberated by
them from the nest. Thus the difficulty involved in supposing that they
must reason in a general and not merely in a particular way does not
really exist.
Some of these black caterpillar-tending ants of India are not always so
lucky as to secure stock. They may live far from a _jujube_ tree, and so
never meet the right species; but if ever they do, even though it be in
the most unexpected manner, they are not taken by surprise,
notwithstanding that other caterpillars are habitually devoured by them.
Mrs. Wyllie proved this by an experiment. “I took Theophrastus,” she
tells us, “from a tree, and introduced him on the pathway of another
company of the same species of ant, which lived in our verandah, but
kept no farm, and it was odd to see the ants come tumbling out headlong
to fight the intruder, and the sudden way in which they cooled down on
investigation of the foe. None attempted to harm him, and he was
politely escorted across the boundary, the ants running alongside and
feeling him all over with their antennæ. This must have been
instinctive, as they could have had no former knowledge of him as a
‘milk-giver.’” Mrs. Wyllie adds that “the dead chrysalids in an ants’
nest are carefully removed and thrown away outside; the ants also
distinguish between the dead and the living.”
Anyone observing or reading about ants might exclaim, on finding that
they utilised the natural product of other insects and kept them in
captivity in order to do so, “Where will this end? May they not, then,
also keep slaves?” And in very fact, as all the world now knows, we do
find what is called slavery amongst ants, though to me it hardly seems
the right word, since there is perfect willingness on the part of the
slave, and no power of punishment lies with the master. There is
equality, moreover, since this is not a matter of the kind of things
which one class of a community does and another does not do, but of the
spirit in which each does them. With the ants we have the Japanese
spirit—or rather the Japanese seem getting nearer to the ants—and so
there is real equality. However, the first act which makes these
creatures slaves—for I will use terms as I find them—is one of violent
and deadly hostility, and through it they are, of set purpose, taken
possession of and carried off to the nest. At that period, however, they
are yet in the cradle, have yet to be born into their last and most
perfect state of life. From the moment they are so born they grow up as
a part, and indeed the most important part, of the body politic, and of
such pleasure and consideration as obtains in ant-life they have their
full share.
From the above it may be gathered that these ant-slaves are ants
themselves, and this, indeed, is the case. One species of ant raids the
nest of another, overpowers the able-bodied inhabitants, slays or
incapacitates a certain number, and carries away with it to its own nest
as many of the helpless pupæ as it is able to. For a great many
years—thousands probably—these combats and carrying off of spoil had
been observed, but it had always been imagined that the pupæ—or ants’
eggs, as they are commonly called—were taken as provisions, merely to be
stored in the nest of the victor, and there eaten at leisure. The
discovery of the real truth was an era in the study of ant-history, and
it was made by a Frenchman—Pierre Huber—a man of whom Darwin says that
he was a “better observer even than his celebrated father,” for Pierre
was the son of François Huber, the blind man, who yet found out all
about bees. I hardly see how he can have been _better_ myself; but the
son was not blind, and, of course, eyesight is an advantage in
observation.
The particular species of ant concerning which this discovery was made
is _Formica rufescens_, or _Polyergus rufescens_—the reader may take his
choice—and Darwin, who impresses the facts of ant-slavery upon the mind
better than a dozen books specially devoted to ants or insects, says of
it: “This ant is absolutely dependent on its slaves, and without their
aid the species would certainly become extinct in a single year. The
males and fertile females do no work of any kind, and the workers, or
sterile females, though most energetic and courageous in capturing
slaves, do no other work. They are incapable of making their own nests
or of feeding their own larvæ. When the old nest is found inconvenient,
and they have to migrate, it is the slaves which determine the
migration, and actually carry their masters (one might just as well call
_them their_ slaves) in their jaws. So utterly helpless are the masters,
that when Huber shut up thirty of them without a slave, but with plenty
of the food which they like best, and with their own larvæ and pupæ to
stimulate them to work, they did nothing; they could not even feed
themselves, and many perished of hunger. Huber then introduced a single
slave, and she instantly set to work, fed and saved the survivors, made
some cells, and tended the larvæ, and put all to rights. What can be
more extraordinary than these well-ascertained facts?”[52] The slave-ant
in this case is _Formica fusca_, and it is also held in bondage by
another species of slave-maker, viz. _Formica sanguinea_—or the
Blood-red Ant—as was likewise a discovery of Pierre Huber. This last
species is found in the south of England, and its slave-making habits
have been observed by Darwin, who opened fourteen nests and found a few
slaves in all of them. “The slaves,” he tells us, “are black, and not
above half the size of their red masters, so that the contrast in their
appearance is great.”[52] The black ants were not often seen by Darwin
to leave the nest, and others who have observed their habits in England
have considered them as “strictly household slaves.”[52] Huber, however,
whose observations were carried on in Switzerland, says that “their
chief office is to search for aphides,”[52] and this would take them far
afield. In Switzerland, however, slaves seem to be more numerous in the
nests of the Blood-red Ant, and Darwin attributes the difference in
their habits to this account. Huber also tells us that the Swiss slaves
“habitually work with their masters in making the nest, and they alone
open and close the doors in the morning and evening.”[52] This is done,
I suppose, by placing pellets of earth in the mouth of the
entrance-tunnel and removing them again; but there is one species of ant
which would have only to place or remove itself, for this purpose, since
its large head, by being wedged into the passage, stops it up, and thus
fulfils the office of a front door. The ant that does this must be one
belonging to a certain caste of workers having very large heads, for the
heads of the other ones would not be large enough. The nest of this
species is made in decaying wood, and there is always some worker who
thus uses his large head as a stopper, removing it when a
fellow-townsman wishes to enter the nest, but presenting its smooth,
impenetrable surface, guarded with jaws, to all unauthorised intruders.
It is Forel, one of the best ant-observers of to-day, who tells us this,
and the ant apparently is _Lasius fuliginosus_, which is a British
species, and, according to an account which I have already referred to,
does not seem to be always a wood-borer. _Formica sanguinea_, however,
does things—or has things done for it—after a more ordinary fashion.
Darwin was the witness of a slave-raid on the part of _F. sanguinea_
which was not, in this instance, very successful. He says: “They
approached, and were vigorously repulsed by an independent community of
the slave-species (_F. fusca_), sometimes as many as three of these ants
clinging to the legs of the slave-making _sanguinea_. The latter
ruthlessly killed their small opponents, and carried their dead bodies
as food to their nest, twenty-nine yards distant; but they were
prevented from getting any pupæ to rear as slaves. I then dug up a small
parcel of the pupæ of _Formica fusca_ from another nest, and put them
down on a bare spot near the place of combat; they were eagerly seized
and carried off by the tyrants, who perhaps fancied that, after all,
they had been victorious in their late combat.”[52] In his work, _Ants
and their Ways_,[53] the Rev. Farren White describes a similar raid
which was—or rather which had been, for it was nearly over when he
arrived on the scene—wholly successful. Here, however, the oppressed
species seems to have made a very poor resistance, though very likely it
had been more vigorous in the earlier stages of the raid. “I watched a
_fusca_,” says Mr. White, “carrying off a pupa from behind the entrance
whence the _sanguineæ_ were issuing forth. Immediately it saw one of the
enemy approaching, it dropped its charge and left it to its fate. The
_sanguinea_ then gave it a push, and drove it off in double-quick time”;
and, again, “I noticed a _sanguinea_ coming up out of the nest with a
pupa, and a _fusca_, observing it, went up a fern-frond with the utmost
expedition.”[53] Other observations of a similar nature were made, and
the conclusion arrived at by Mr. White is “that between the _fuscæ_ and
the _sanguineæ_ there is a well-defined and clearly pronounced
antagonism. In presence of the _sanguineæ_ the _fuscæ_ were
terror-stricken. In fact the depredators had it all their own way, and
were able in this instance, at least, to carry out their marvellous
instincts without destroying a single life.”[53] It will be seen how ill
this accords with the account given by Darwin. My own way of accounting
for the discrepancy is that, in the first instance, the little _fuscæ_
were flushed with success, and, in the second, demoralised through
defeat. The same effects would follow the same causes in all but the
most splendid human armies.
The raids made by the first-mentioned species, _Polyergus rufescens_,
or, as Huber calls them, the Amazon ants, are of an even more determined
description, for none are braver, or perhaps so brave. If one of these
should find herself alone and in the midst of enemies, she makes no
effort to escape, as many, though not all, other species would, but
fights on to the end, making constant agile leaps to this side or that,
at every one of which she transfixes an enemy, and dies at last biting
hard. To fight, indeed, is the whole end, aim, and business of life for
an Amazon, and we have already seen how they do no work, and are washed,
fed, and carried by their servants. It is not quite true, however, that
they cannot feed themselves, as Pierre Huber thought, and had good
reason to think, for a well-known living observer—Herr Wasmann—has
discovered that their mandibles are so constructed as to enable them “to
absorb nourishment from eggs or pupæ.” Possibly the mandibles are
hollow, and communicate thus with the mouth, as is the case with some
other insects, but I have not Wasmann’s account at hand, and his
exponent says only this. Wasmann tells us also that these Amazons will
“absorb nourishment,” however they do it, even from the eggs of their
own species. They cannot, however, feed on liquid food, and as they had
no other when shut up without servants, that is why they died, or would
have died, had these not been brought them in time. So too, though their
slaves wash and brush them, yet they are always brushing themselves and
attending generally to their own toilette, and this they do even amidst
“All the currents of a heady fight,”
so that Wasmann has compared them to the Spartans combing their long
hair before the battle of Thermopylæ, though we are not told that they
combed it after the fight had begun.
Still, it seems plain that the habit of keeping slaves has exercised a
degrading influence on these ants, and this tendency is much more
markedly apparent in several other species. One of these with a really
dreadful name, _Strongylognathus_—we might call them Strong Ants, but
they seem to be weak ones—is described by Forel as “_une triste
caricature_” of the Amazons, and the extraordinary thing is that,
though themselves feeble and enervated, they manage to make, or by
some means obtain as slaves, the workers of a much more robust
species—_Tetramorium_, to wit; workers, by the way, are the only class
of ants ever enslaved. These weak ants fight in the same way as the
Amazons themselves; but, though spirited enough, they are so much
inferior in bodily vigour to the _Tetramoriums_, “a courageous species
living in large communities, that in a battle between the two,
artificially instigated by Forel, almost all the slave-holders were
killed, without being able to avenge their deaths even on a single one
of those whom they aspired to rule.” Yet they won the day, or rather
the already enslaved _Tetramoriums_, who marched to do battle for
them, won it for the few survivors in their ranks. From this we can
see how, when these decadents once have slaves, they may get more. The
difficulty is how they are obtained in the first instance—when a nest
is first founded by a queen of the slave-making species, for example.
It might be supposed, finding two kinds of ants living together, one
weaker and much more helpless than the other, that the former lived a
parasitic existence in the nest of the latter, and was not a
slave-owner at all; but this theory is disproved by the fact that no
males or females of the _Tetramoriums_ are ever to be found, showing
that it is not they but the others who are the true founders of the
nest.
A still more extraordinary instance of a slave-holding species of ant
than the one just mentioned is _Anergates atratulus_, for in this there
are no workers at all, only kings and queens, who are waited on, and
their eggs and larvæ fed and tended, by the slave species—_Tetramorium_,
in this case also—just as though these latter were their true-born
subjects. Here too the slave species is only represented by workers.
These male and female _Anergates_—a worker of the species has never been
known—are both few in number and weak in themselves. When a pair of them
(or a fertilised queen) go off to found a new colony, how do they, or
how do their few weak descendants, impress a strong fierce species into
their service, by whom the nest is built, and every other service
performed? The question remains unanswered. Nobody knows. Several
theories have been advanced, one by Sir John Lubbock, who supposes that
the king and queen of _Anergates_ assassinate the queen of _Tetramorium_
and reign in her stead,[54] and another, more recently, by Wasmann,
whose idea is that fertile queens of _Anergates_ are sometimes adopted
by a colony of _Tetramoriums_ who have lost their own queen. This last
is the newest suggestion, and is considered just at present, perhaps for
that reason, the most probable. To me Sir John Lubbock’s view seems
likelier to be correct, since it is more usual in nature for the weak to
prey, as parasites, upon the strong, than for the strong to seek
assistance of the weak. True, I can form no idea as to how the
assassination of the rightful queen takes place, but Nature is full of
resources, and will do much to promote a really worthy end.
I will conclude this chapter by quoting some remarks of Sir John Lubbock
as to the ill effects which the institution of slavery exercises, with
ants as with men, upon the character of the slave-holder. “These four
genera,” he says, “offer us every gradation from lawless violence to
contemptible parasitism. _Formica sanguinea_, which may be assumed to
have comparatively recently taken to slave-making, has not, as yet, been
materially affected. _Polyergus_, on the contrary, already illustrates
the lowering tendency of slavery. They have lost their knowledge of art
and their natural affection for their young! They are, however, bold and
powerful marauders. In _Strongylognathus_ the enervating influence of
slavery has gone further, and told even on the bodily strength. They are
no longer able to capture their slaves in fair and open warfare. Still,
they retain a semblance of authority, and, when roused, will fight
bravely, though in vain. In _Anergates_, finally, we come to the last
scene of this sad history. We may safely conclude that in distant times
their ancestors lived, as so many ants do now, partly by hunting, partly
on honey; that by degrees they became bold marauders, and gradually took
to keeping slaves; that for a time they maintained their strength and
agility, though losing, by degrees, their real independence, their arts,
and even many of their instincts; that gradually even their bodily force
dwindled away under the enervating influence to which they had subjected
themselves, until they sank to their present degraded condition—weak in
body and mind, few in numbers, and, apparently, nearly extinct, the
miserable representatives of far superior ancestors, maintaining a
precarious existence as contemptible parasites of their former
slaves.”[55]
Since, however, in all these cases the masters are still truly served by
their slaves, who make them comfortable, and have no more sense of their
degradation than they themselves have, an answer might be made to these
moralisings. However various the masks behind which true motives lie
hid, happiness, diversely conceived of, is the one end and aim of all.
Does it, then, really much matter by what means it is attained? Till we
can show that these slave-holding ants have become less and less happy,
we are only tilting at shadows, and an _Anergates_ might very well say,
in regard to the above view, “Tut, prut, drop your heroics. I am very
comfortable; these strong fellows work for me. I like not working, and
what I am I wish to be.”
-----
Footnote 51:
It appeared, I think, originally in the _Bombay Journal_ and is
reproduced in one of the leading entomological magazines.
Footnote 52:
Darwin, Origin of Species, pp. 216, 217, 218.
Footnote 53:
Rev. Farren White, Ants and their Ways, pp. 177-9.
Footnote 54:
Lubbock, Ants, Bees, and Wasps, pp. 87-9.
Footnote 55:
Rev. Farren White, Ants and their Ways, pp. 177-9.
------------------------------------------------------------------------
CHAPTER XIV
Ant partnerships—How some ants feed—Persuasive methods—An
_imperium in imperio_—Amusement by instinct—Begging
the question—Nest within nest—Ant errors v. human
perfection—Distorted arguments—How partnerships
begin—Housing an enemy—Ant ogres.
THE relation of slave and slave-master—to use the received
terminology—is not the only one of a social and friendly nature in
which ants of different species stand towards one another; for as will
have been gathered in the previous chapter, slavery amongst ants is a
quite friendly institution, conducted, in fact, upon the
“liberty-equality-fraternity” principle. Some species of ants,
however, inhabit the nests of other species, or build their own amidst
theirs in such a way as almost to make them one, and thus they live as
perpetual guests, not only without paying for such accommodation by
rendering their hosts any services, but often forcing these latter to
be of service to them in other ways also. Thus, a small species of
Texan ant whose first or Christian name is _Leptothorax_, but whose
surname has not yet been fixed upon, lives on these terms in the nests
of a larger one, the celebrated _Myrmica brevinodis_. Whether
Professor Wheeler was the discoverer of the little ant I am not quite
sure, but he was the first, I think, to observe its relations with the
big one and those of the big one with it, and his account of them is
excessively interesting. “A small dish,” he says, “containing a syrup
of sugar and water was placed near the nest (an artificial one under
close observation). This was soon found by two of the _Myrmica_
workers, which at once gorged themselves with the liquid and returned
into the nest.”[56] Soon afterwards a _Leptothorax_ worker entered it
also, and having run or tracked down one of the two honey-gorged
creatures, forthwith got up on to its back, and, seated there, began
to lick its head, an attention which it supplemented with a soft,
persuasive titillation with its antennæ, whilst at the same time
communicating a motion to its abdomen, which Professor Wheeler is so
convinced must have been accompanied with certain sounds—known to the
learned as stridulations—that he does not hesitate to affirm that it
was thrown “into stridulatory oscillation.” Nor was the _Myrmica_ deaf
to such an appeal. It slackened its pace, hesitated, then paused, and
as though unable longer to resist the influence, folded its antennæ
and appeared to give itself up to the full pleasure of the thing. The
tempter, now, still making soft play with the antennæ, lowered its own
head, and began to lick the _Myrmica_ first on one cheek and then the
other, including also the mandibles and parts adjoining. Thus
fostered, a dewy moisture, drawn evidently from the reservoir of
lately swallowed nectar, began to glisten on the lips of the large
ant, and, increasing rapidly to a droplet, was re-imbibed by the
expectant little one. “The latter,” says Professor Wheeler, “then
dismounted, ran to another _Myrmica_, climbed on its back, and
repeated the very same performance. Again it took toll, and passed on
to still another _Myrmica_.”[56] Up to the present the attention of
Professor Wheeler had been concentrated on the doings of this one
individual, but now, turning his attention to other parts of the nest,
he “observed that nearly all the _Leptothorax_ workers were similarly
employed. In one corner a number of _Myrmica_ workers had formed a
circle about a few of their small larvæ, which they were cleansing and
feeding. A _Leptothorax_ soon found its way to this cluster, and
stepped from the back of one ant to that of another, lavishing a
shampoo on each in turn, and apparently filling its crop with the
liquid contributions thus solicited.”
The above method of obtaining food appears to be peculiar to these ant
parasites. Beetles, for example, solicit it either by taps or touches
with the antennæ—which is a similar one indeed, but does not go so far
nor involve a ride—or else by stroking the face of their host with their
fore-feet. Other species of ants, when soliciting food from one another
or demanding it from their slaves, employ a more or less similar method,
whilst the _Lepismid_ that we have before spoken of is a thief pure and
simple. Licking seems to be the personal discovery of _Leptothorax_, and
being licked the peculiar privilege of _Myrmica brevinodis_. That it is
a valued one is clear, but the price asked for it is not always
forthcoming, possibly because there is not always anything to forthcome.
On such barren occasions _Leptothorax_ makes the best of a bad job, and
dismounting from its first love, runs about looking for another.
Sometimes, after having licked the head and face of its patron, the poor
petitioner turns round and proceeds to do the same by its abdomen. This,
perhaps, is a last effort of persuasion, but Professor Wheeler rather
supposes the surface of _Myrmica’s_ body to be “covered with some
agreeable secretion.” Queen _Myrmicas_, however, seem to be very rarely
treated to any sort of licking, and males apparently never. The reason
of this, probably, is that both queens and males are themselves
accustomed to receive their food from the workers by a similar process
of regurgitation, and are probably therefore not in the habit of
regurgitating it. They are therefore neglected by the little parasites,
who console themselves by being all the more insistent with those who
have something to give. These—that is to say, the workers—are waylaid
whenever they enter the nest, as having presumably found something to
eat outside it, and, in order to be on the spot, at once their
importunate lickers, who seem to live in a perpetual state of crying,
“Give! give!” keep in the more or less immediate proximity of the
entrance, or entrances, should there be more than one. Professor
Wheeler, indeed, doubts if the _Leptos_ ever feed themselves in the
ordinary way, but inasmuch as they were on one occasion seen by him to
do so, such doubt appears to me to be uncalled for.
These little ants make, in regard to the big ones within whose nest they
live, a sort of _imperium in imperio_. In a small chamber surrounded by
the large galleries of the _Myrmicas_, and communicating with these by a
passage too narrow for the latter to pass through, lives the queen with
a small number of workers; eight of them in the nest observed by
Professor Wheeler, together with a few larvæ, almost filling the cavity.
They appear to be on affectionate terms with one another, the workers
feeding their queen in the most assiduous manner, and she often playing
with them like a cat with her kittens, throwing them on to their backs,
and then “hugging and kissing them” (as Professor Wheeler describes it)
_con amore_. Not that the Professor himself takes this view of it, for
after hesitating whether to ascribe such behaviour to maternal
affection, “the play instinct,” or hunger, he decides for the latter—on
what grounds, since there was a continual passage of viands from one ant
to another, the queen especially being “assiduously fed,” I am unable to
see. What, too, is “the play instinct,” except a mere term made use of
in order to suggest the idea of automatism in regard to an act which
hardly seems to admit of such an interpretation? Instincts represent
imperious necessities which, if not attended to, the species must fail
or perish. Such, at any rate, are the grounds on which they must be
supposed to have been originally built up. But what creature has had to
play in order to survive? Not ants, surely, who work so hard that they
cannot stand in need of more exercise than their daily life affords
them. Nor, it would seem, is such an instinct developed amongst other
insects, which again seems to show that it cannot be of any great
importance. When, therefore, we find that ants, the most wonderful of
all insects, do play, this strongly suggests their possession of an
intelligence analogous to that of the higher animals. Instinct, however,
is largely independent of intelligence, such as we understand it, and
therefore, to allude to “the play instinct” in ants before the
instinctive character of the act has been made out, is to prejudge the
question whether ants are automatic or reasoning beings.
The smallness of the passages leading from the interior chamber of
_Leptothorax_ to the broad galleries of the _Myrmicas_ suggests that the
latter were not intended to pass through them; but we cannot really draw
this inference, since an ant in tunnelling would allow for the size of
its own body, but not for that of another species. Certain it is that
the big ants constantly force their way through the narrow passages,
thus partly breaking down the wall, and that they are then received by
the little ones in a quite friendly manner, and persuaded to part with
some of their interior stores. Still, when this has been effected, their
friends seem mildly desirous that they should go, and, as soon as they
have gone, set to work to repair the breaches made by their entrance. No
sooner has this been done, however, than they are broken down again, and
so it may continue, apparently, for an indefinite period, at any rate in
nests constructed for observational purposes, and where the conditions
are, therefore, more or less artificial. Whether it is so to anything
like the same extent under nature may well be doubted, for that any
creature should live in a state of never-ending useless labour does not
seem likely; and, moreover, unless the one ant could have made itself
comfortable within the nest of the other, why should it have become
established there at all? But whatever it may be outside the study, this
is Professor Wheeler’s account of what fell under his observation: “At
one p.m.,” he tells us, “the _Myrmica_ workers discovered the
hiding-place of their little companions, and two of them, in single
file, shouldered their way through the narrow passage, enlarging it as
they proceeded. As soon as the head of the first _Myrmica_ appeared in
the chamber, the _Leptothoraxes_ which had been attending to their
morning toilet and that of their larvæ, and to the careful arrangement
of their eggs, turned to meet the intruders.”
“Now dreadful deeds
Might have ensued,”
and for such an upshot, indeed, upon the first occasion, Professor
Wheeler was prepared. “For an instant,” he says, “I fully expected to
see a fierce battle, but I had misjudged the _Leptothorax_ character. To
my surprise the _Myrmicas_ on entering were received with a profusion of
shampooing, and, though sadly crowding the occupants of the little
chamber, they let themselves down comfortably, and appeared to
experience all the sensuous satisfaction of a couple of _roués_ who have
dropped into a Turkish bath for the night. Yet the little _Leptos_,
though behaving in this friendly manner” (their conduct indeed was not
more disinterested than upon other occasions), “seemed to have some dim
desire to remove the _Myrmicas_ from their nest, for from time to time
one was seen to pull with her mandibles at the fore leg or antenna of
one of the intruders, as if to remind her that there are limits to
polite hospitality.” Professor Wheeler adds that “this was the only act
even approaching hostility witnessed between the two species. The
_Myrmicas_ never showed the slightest irritation towards the _Leptos_,
never seized them in their mandibles or even menaced them. They seemed
rather to look upon the little creatures with gentle benevolence, much
as human adults regard little children. They never passed their little
guests without the antennal greeting, and the _Leptos_ shampooed their
hosts with comical zeal.”[56] The continued breaking down and repair of
the dividing wall is then described, with the conclusion that “in their
natural environment the _Leptothoraxes_ would not be cramped for space,
and would probably dig their cell where they would not so frequently be
disturbed by their inquisitive hosts.”
As regards the possible effects upon the _Myrmicas_ of having thus
frequently to render up food swallowed for their own nourishment, it
must be remembered that amongst most ants this is a thing of custom;
and, again, it seems probable that there would be an internal sense on
the part of the regurgitating individual as to concessions of this
nature having gone as far as it was healthy that they should go. As we
have seen, they are not infrequently refused. Professor Wheeler,
however, came to the conclusion that _Myrmica_ colonies suffer very
considerably from this cause, and on this he makes the following
comment: “If I have correctly estimated the influences which may tend to
diminish the fecundity and prosperity of the _Myrmicas_, we have in this
double nest another striking demonstration of the complete absence in
ants of any faculty of reason. For if the _Myrmicas_ possessed a glimmer
of this faculty they could easily annihilate the gluttonous little
nest-mates that are for ever roaming about their galleries like so many
animated stomach-pumps.”[56] Yes, truly a _most_ “striking
demonstration,” seeing that we human ants can annihilate, all in a
moment, any evil that has insensibly gained a footing amongst us, and
with which we have been familiarised from birth. Custom, growing
gradually from unnoticed beginnings, plays no part at all amongst
us—never affects our views in the very slightest degree. In Europe we
hang up all the brewers and distillers; whilst mobs of infuriated
Chinamen rend in pieces the vendors of opium and crushers of their
women’s feet. There is no such thing in _human_ nature as tolerating an
evil for the pleasure that lives in it; no _man_ ruins his health, and
sinks into an early grave, through being a slave to sensual pleasures.
Nor can what is manifestly wrong seem right to _us_; there is no
pernicious, obstinate, wilful shutting of _our_ eyes. What a contrast
does all this present with such a state of affairs as we are here
considering! And how plain it is that there can be no reasoning power in
the ant, since reason and right conduct are synonymous with man!
What is the origin of these strange co-partnerships—for there are
others—which we find existing between ants of two different species
living in the same or in one double nest? As we know, the different
species of ants are commonly very hostile to one another; and for any to
enter the nest of some other one is to court destruction, if they be not
the stronger party. Nay, they dare not even enter a strange nest of
their own species. It seems probable, therefore—this, at least, is my
own view of it—that such friendly cohabitation has come about through
the channel, not of peace, but of war—through successful encroachments
which, from being unavoidable, have come gradually to be less and less
resented, till the two parties, mingling freely, have learnt to live on
other terms. Now there are ants which live, like ogres, in the nests of
other species, preying upon their eggs and young. Such a one is
_Solenopsis fugax_—to whom we will come presently—but it is perhaps even
more interesting to find in species between whom relations of a similar
nature to those which we have been considering exist, occasional slight
traces of a mutual hostility. As between the _Leptos_ and _Myrmicas_
indeed this has only as yet been noticed, very faintly, on the part of
the former; but in regard to another pair who live together—our great
wood-ant, namely, _Formica rufa_ and tiny little _Formicoxenus
nitidulus_—Professor Wheeler remarks: “On one occasion in one of my
artificial nests, in which the ants had previously lived on good terms
with one another, I saw a _Formica_ touching a _Formicoxenus_ with her
antennæ and menacing her with her mandibles, but she departed without
even attempting to seize her. In the same nest I found a _Formicoxenus_
which had seized the leg of a _Formica_ in its mandibles and had died in
this position.”[57] Other observers, too, have from time to time—but
only very occasionally—noticed facts of the same sort. Through such
exceptional slight indications we may perhaps see, “as in a glass
darkly,” what things were at the beginning.
Let us now look at the beginning. _Solenopsis fugax_, Sir John Lubbock
tells us, “makes its chambers and galleries in the walls of the nests of
larger species, and is the bitter enemy of its hosts. The latter cannot
get at them because they are too large to enter the galleries. The
little _Solenopses_, therefore, are quite safe, and, as it appears, make
incursions into the nurseries of the larger ant and carry off the larvæ
as food. It is as if we had small dwarfs about eighteen inches to two
feet long harbouring in the walls of our houses and every now and then
carrying off some of our children into their horrid dens.”[58] This is
the general proposition. Monsieur Janet can add a few particulars. “The
_Solenopsis_,” he says, “may establish itself near almost any other ants
of our country, and is found especially with....” Here follows a list
all in Latin, but our common Wood-ant—the large one that makes those
great heaps of pine-needles—and the Amazon, or slave-making ant, are
contained in it.[59] “The _Solenopsis_ nest,” continues M. Janet, “may
partially surround that of its neighbour’s, or it may even be partly
excavated in the masses of earth which separate the galleries of the
latter. In each case—and probably, too, when, as is frequent, there is
not such close contiguity—fine connecting galleries enable the
_Solenopsis_ to make incursions into the nests of their neighbours,
where, as we shall see, they find an abundance of food. The actual nest
consists of a number of small circular chambers about 8-20 mm. in
diameter and only 6-8 mm. in height. Most of these chambers are
separated from one another by several centimetres, and are connected by
slender galleries, often less than two millimetres in diameter, entering
the chambers at their walls, ceilings, or floors, which latter are
remarkably clean, smooth, and hard.”[59]
The food of which these horrid little ants find such an abundance is, of
course, the cocoons and larvæ of their unfortunate neighbours, and M.
Janet gives the following account of the way in which they dispose of
them: “From ten to thirty of them,” he says, “climb up on to a cocoon
and cover it with little perforations which, finally, becoming
confluent, enable them to reach its contents. If it contains a pupa, the
legs and antennæ fall an easy prey to the mandibles of the _Solenopses_.
In this case the victim is cut into, sucked, and torn into very small
pieces, which the ants hasten to carry away into the interior of the
nest. The operation is much more difficult in the case of a larva which
has just spun its cocoon. Such a one I have seen the _Solenopses_ drag
into the interior of the nest and keep working at for twenty-four hours.
At the expiration of this period the larva began to look flaccid (as may
be believed), and was covered with little black dots which were,
sometimes, double, corresponding with the little wounds made by the
mandibles of its assassins. Numbers of the latter were busy lapping up
the liquid which exuded from the wounds, but it was not until thirty-six
hours had elapsed that the larva was entirely devoured.”[59] This is
certainly not a pleasant picture, yet, if our surmise is correct, the
remote descendants of these murderous _Solenopses_ may become as
harmless and as pretty in their ways as the little _Leptos_, a
reflection which goes far to discount any uncomfortable feelings we
might otherwise have been inclined to have in regard to the general plan
or scheme of things. Thus, in nature, though occasionally a slight
shadow may seem to rest upon the landscape, the next moment the very
memory of it is lost in a blaze of sunlight glory.
Forel believes that when a _Solenopsis_, and one of the larger species
of ants that it plagues, meet, the latter are unable to see it on
account of its small size, so that, practically, it is invisible. This
seems a strange doctrine, since the same ants can see smaller things;
and yet, from their behaviour under such circumstances, M. Janet is
inclined to think so too. It can hardly be that they shun combat, though
the _Solenopses_, in spite of their small size, are able, even here, by
virtue of their numbers, and being armed with stings, to meet their
victims, as one may almost call them, upon equal terms. M. Janet,
indeed, once saw so strong and warlike a species as the slave-making
_Formica sanguinea_ killed by some half-dozen _Solenopses_, but he adds
that on such occasions a considerable number of the latter were,
generally, killed also. This, however, is not sufficient to abate the
evil, so perhaps the molested species, finding that fighting is of no
use, accustomed to see _Solenopses_ from their birth, recognising, too,
as a part of their own atmosphere, the distinctive smell which they, no
doubt, possess, accept them like some disagreeable part of their lives,
and try to make the best of it.
-----
Footnote 56:
The American Naturalist, vol. 35, No. 419.
Footnote 57:
The American Naturalist, July, 1901.
Footnote 58:
Lubbock, Ants, Bees, and Wasps, pp. 78, 79.
Footnote 59:
Janet, Etudes sur les Fourmis.
------------------------------------------------------------------------
CHAPTER XV
Ant wonders—Leaves cut for mushroom-growing—How ants plant
mushrooms—A nest in a mushroom-bed—“Psychic plasticity”—Two
opinions—Ant stupidity—Unfair comparisons—The ant and
the servant-maid—Mushroom-growing beetles—Choked by
ambrosia—Intelligent uselessness—Automatic phraseology—A
curious insect.
ANTS, as everybody knows, have a special faculty for doing extraordinary
things. Only a few of these have been mentioned in the last and
preceding chapters, and only a few more can be touched upon in this. To
do the subject anything like justice, a whole large book would be
required, not a few chapters merely of a quite small one. What ants do,
indeed, reminds me of the refrain, constantly repeated, of a certain old
ballad lately brought to my notice, viz.—
“Wonders, notable wonders! never the like was heard.”
For instance, they grow mushrooms (rice, or some cereals, they used to
grow and reap, but lately they have not been allowed to); they use their
own larvæ as an implement to sew or stick things together with, thus
making little shuttles of them; they make bridges of their own bodies,
by which they pass over rivers—even wide ones, it would seem, at least
for them—which otherwise would be impassable; they allow themselves to
be made into honey-pots and kept full for the good of the general
community, who take a little of them when they want it; they have
cemeteries, and would appear even to feel something like awe or respect
in the presence of their own dead; they cause certain plants to grow and
come to maturity, which would otherwise die, in order to make a house in
them, and so on and so on, many other wonders equally notable, to say
nothing of those which have already been recounted.
To take the first on the list—I hardly believe in a classification of
wonders—Belt, who was an engineer, but ought to have given up his whole
life to observations of this sort, was the first, I believe, to find out
that ants were mushroom-growers. Like others, when he came to Nicaragua
he saw the leaf-cutting ants passing in long, double columns backwards
and forwards between their nests and the trees, the homeward-bound
column laden with their little crescent-shaped bits of green leaf, the
outgoing one empty-handed. “The first acquaintance a stranger generally
makes with them,” says Belt, “is on encountering their paths on the
outskirts of the forest crowded with the ants; one lot carrying off the
pieces of leaves, each piece about the size of a sixpence, and held up
vertically between the jaws of the ant; another lot hurrying along in an
opposite direction empty-handed, but eager to get loaded with their
leafy burdens. If he follows this last division, it will lead him to
some young trees or shrubs, up which the ants mount; and where each one,
stationing itself on the edge of a leaf, commences to make a circular
cut, with its scissor-like jaws, from the edge, its hinder feet being
the centre on which it turns. When the piece is nearly cut off it is
still stationed upon it, and it looks as though it would fall to the
ground with it, but on being finally detached the ant is generally found
to have hold of the leaf with one foot, and soon righting itself, and
arranging its burden to its satisfaction, it sets off at once on its
return. Following it again, it is seen to join a throng of others, each
laden like itself, and, without a moment’s delay, it hurries along the
well-worn path. As it proceeds, other paths, each thronged with busy
workers, come in from the sides, until the main road often gets to be
seven or eight inches broad, and more thronged than the streets of the
city of London. Standing near the mounds, one sees from every point of
the compass ant-paths leading to them, all thronged with the busy
workers carrying their leafy burdens. As far as the eye can distinguish
their tiny forms, troops upon troops of leaves are moving up towards the
central point and disappearing down the numerous tunnelled passages. The
outgoing empty-handed hosts are partly concealed amongst the bulky
burdens of the incomers, and can only be distinguished by looking
closely amongst them.”[60]
It used to be supposed that these leaves themselves, in a decaying
state, were the food of the ants, whilst another theory was that they
were used to make a sort of underground roof to the nest with. Belt’s
discovery took everybody—including himself—completely by surprise. “I
believe,” he says, “the real use they make of them is as a manure, on
which grows a minute species of fungus, on which they feed: that they
are in reality mushroom growers and eaters”;[60] and he thus narrates
the circumstances which led him to this conclusion:—
“When I first began my warfare against the ants that attacked my garden,
I dug down deeply into some of their nests. In our mining operations we
also, on two occasions, carried our excavations from below up through
very large formicariums, so that all their underground workings were
exposed to observation. I found their nests below to consist of numerous
rounded chambers, about as large as a man’s head, connected together by
tunnelled passages leading from one chamber to another. Notwithstanding
that many columns of the ants were continually carrying in the cut
leaves, I could never find any quantity of these in the burrows, and it
was evident that they were used up in some way immediately they were
brought in. The chambers were always about three-parts filled with a
speckled brown flocculent, spongy-looking mass of a light and loosely
connected substance. This mass, which I have called the ant-food, proved
on examination to be composed of minutely subdivided pieces of leaves,
withered to a brown colour and overgrown and lightly connected together
by a minute white fungus that ramified in every direction throughout
it.”[60] Belt assured himself in many ways, but not through actually
seeing them do so, that this fungus was what the ants fed on, and he
adds, “that they do not eat the leaves themselves I convinced myself;
for I found near the tenanted chambers deserted ones filled with the
refuse particles of leaves that had been exhausted as manure for the
fungus, and were now left, and served as food for larvæ of
_Staphylinidæ_ and other beetles.”[60]
Belt’s conclusions have been since amply verified, and the actual
process of preparing the leaves and laying down the mushroom-beds, as
well as the clipping and—if I mistake not—eating of the mushrooms, has
been observed. Herr Möller—a German observer who resided for some years
in tropical America—is usually referred to in this connection; but such
extracts from his writings as I have come across are to me less
_convincing_ than the following account of Mr. Edward Tanner, which is
contained in the _Journal of the Trinidad Field Club_.[61] The
observations were made with ants in confinement, as were Herr Möller’s
also, I believe. “Each forager,” says Mr. Tanner, “drops her portion of
leaf in the nest, which is taken up as required by the small workers,
and carried to a clear space in the nest to be cleaned. This is done
with their mandibles, and if considered too large, it is cut into
smaller pieces. It is then taken in hand by the larger workers, who lick
it with their tongues. Then comes the most important part, which is
almost always done by the larger workers, who manipulate it between
their mandibles, the ant using her palpi, tongue, three of her legs, and
her antennæ while doing so. It now becomes a small, almost black ball,
varying in size from a mustard-seed to the finest dust-shot, according
to the size of the piece of leaf that has been manipulated, which varies
from ⅛ by ⅛ to ¼ by ¼ of an inch. These balls, really pulp, are then
built on to an edge of the fungus-bed by the larger workers, and are
slightly smoothed down as the work proceeds. The new surface is then
planted by the smaller workers with slips of the fungus brought from the
older part of the nest. Each plant is planted separately, and they know
exactly how far apart the plants should be. It sometimes looks as if the
plants had been put in too scantily in places, yet in about forty hours,
if the humidity is regulated, it is all evenly covered with a mantle as
if of very fine snow. It is this fungus they eat, and with small
portions of it the workers feed the larvæ.”
The statement herein contained that the ants plant the new portion of
their mushroom-bed with slips or plants taken from the already growing
fungus is, as far as I know, new. I do not remember it in Herr Möller’s
paper,[62] who speaks of the _hyphæ_ of the fungus growing through and
round the little leaf-balls within a few hours, but without reference to
their being planted, nor is it alluded to by Professor Wheeler, who has
studied the mushroom-growing ant—whether the same or a similar species I
know not—in Texas. Forel, again, speaking of an allied form in Colombia,
says, “The largest workers triturate the leaves”; and again, “the
medium-sized workers of the minim caste are for ever clipping the
threads of the fungus, which then develops the ‘Kohlrabi’ (the little
round swellings, that is to say), on which the ants feed.”[62] Possibly
this last may allude to the planting, but if so, it is the reverse of
clearly put. Professor Wheeler also alludes to this constant clipping of
the fungus, and sees in it the probable cause of the mutilation of the
antennæ of the little blind cockroaches that live with these ants and
take toll of their mushrooms.[63] But as these constitute the sole food
of their insect cultivators, it is natural that the latter should
frequently clip in order to eat them, and the clipping would, no doubt,
stimulate their growth. All this, however, is different from the actual
deliberate planting of the fungus on newly laid-down portions of the
bed—an act which would imply a very clear intention, and make the ants
farmers in the same way that we are. This, however, need not be the case
if they only lay down the beds, for these at one time probably
constituted their actual food, the crop of fungus being merely
incidental. But if the ants deliberately plant the fungus, then, indeed,
they must know precisely, in a human way, what they are about.
As we have seen, the leaves, from which, in their state of pulp, the
mushrooms spring, are stored up by the ants in large underground
chambers; but these mushroom-beds, or gardens, as they are often called,
are themselves a sort of nest, containing tunnels and chambers, and not
merely unformed heaps. It is in one or other of these chambers that the
queen ant of the nest resides, a majestic creature, almost an inch long,
but inflated both with pride and eggs to a disproportionate extent. Her
sons and virgin daughters, who will some day be queens themselves, keep
her company, whilst all about in the galleries and all over the broad,
flat surface of the garden, which resembles a large flattened sponge,
walk the different castes of workers, some large, some small, some
medium-sized, with a few big-headed soldiers here and there amongst
them, as though to keep the crowd in order. Whether they have really any
such duty assigned them we do not know, but they do not appear to do any
work, whilst the others are all busy at something, and the smaller
workers particularly keep threading the stalks and filaments of the
fungus in order to weed out any extraneous useless growth from amongst
it.[63]
It is a sad reflection—thus sighs Professor Wheeler—that so much ordered
energy, such apparent intelligence, should all be really due to—_what_
he does not seem to be quite certain about, not automatism entirely
perhaps, but if not, then semi- or demi-semi-automatism, tempered with
“psychic plasticity.” Against this view of the matter we have that of
Belt, who, after giving two instances, which came under his own
observation, of intelligent adaptation, on the part of ants, to meet
particular circumstances, exclaims, “Can it be contended that such
insects are not able to determine by reasoning powers which is the best
way of doing a thing, or that their actions are not guided by thought
and reflection?”[64] But then Belt was not provided with the term
“psychic plasticity,” and without it he could only infer intelligence
from any intelligent act.
Still it cannot be denied that a great many instances have been
given—noticeably in the case of “_our_ ants” by Sir John Lubbock[65]—in
which these paragons of insects have behaved very stupidly, or shall we
say—for why should a creature that cannot be intelligent be stupid
either?—with great “psychic _rigidity_”? Certainly such contradictions
are very puzzling, but I would suggest one way of trying to estimate
better the rigid type of ant intellect, which I believe to be absolutely
new, and that is to compare it not with one’s own brain—or Darwin’s—but
with that of a rigid type of person. It is wonderful what a difference
this might make in our conclusions. An ant, for instance, that is
unable, under some special circumstances, to get a thing down into its
nest, because it persists in holding or pulling it, in the way it has
always been accustomed to, or another that would rather be blown into
the water along a known road than leave it for a new one, makes a poor
figure in presence of the seven sages, or amidst a circle of senior
wranglers mentally called up for its confusion; but we should think,
rather, of some pin-headed servant-maid, setting an article of furniture
each morning in the place that, with evident intention, you have removed
it from overnight, or making up a larger and larger fire as the weather
gets warmer and warmer. One should think of the obstinacy with which
many people cling to old habits which changed times have made useless,
or even harmful, and of how numbers not only prefer inferior things they
are used to, to the most decisive improvements, but hate and revile such
improvements as though they were undeniable evils. Instances will occur
to everyone. I would rather not mention any for fear of alienating nine
out of every ten of my readers. We should think, also, of savages or
primitive, slow-moving peoples. What a great unadaptability, for
instance, did the Matabele show in their methods of encountering our
countrymen during the war, and throughout the rising; as also in that
rising itself, since it was against all those well-known blessings which
our empire confers upon savages.[66] It is to these less exalted levels
of human faculty that we should look when we seek to compare an ant’s
mind—when out of its usual set track—with our own, if we wish to do the
ant any justice. That we pursue an opposite plan is my own explanation
of many a partial verdict. To every experimenter in these directions
(who should happen to ask my advice) I would say, first, “Do you know,
or have you ever known, a really silly person?” and on his beginning, at
once, with “Yes, Mrs.” or “Miss” (as the case may be), I would strike in
peremptorily thus: “Then keep _her_—not Newton—in your mind as a
standard of comparison.”
That ants should intentionally cultivate mushrooms will appear wonderful
to everybody, and some will see in it the high-water mark of their
mental development, by whatever path it has been arrived at. It seems
natural to connect such doings with the fact that “in ants the cerebral
ganglia are of extraordinary dimensions, and in all the Hymenoptera
these ganglia are many times larger than in the less intelligent orders,
such as beetles.”[67] Yet the brain of an ant—“one of the most
marvellous atoms of matter in the world, perhaps more so than the brain
of a man”—is “not so large as the quarter of a small pin’s head.”[67] Of
what size, then, can a beetle’s be?—especially that family of beetles
which grow and cultivate mushrooms, just in the same way that ants do.
It would be suggestive—though I hardly know of what—should it be found
that, comparatively speaking, _they_ have no brain at all.
The beetles alluded to have been named, with reference to the particular
kind of mushrooms they grow, ambrosia beetles, though in what the great
superiority of these over those raised by the ants lies I do not know,
for no one appears to have tasted them. It has been agreed, however, to
call them ambrosia. “One of the most remarkable facts,” says Mr.
Froggatt, “is that each group of these beetles is associated with a
certain kind of ambrosia or fungus, notwithstanding that they are found
in different timbers. This substance is actually cultivated by the
mother beetle upon a carefully prepared layer or bed of wood-débris,
generally at the end of the gallery; but in others the ambrosia is grown
only in certain brood chambers of peculiar construction, whilst in
others again it is propagated in beds near the cradles of the
larvæ!”[68] When the latter hatch, they find a supply of celestial food
awaiting them, and can walk about the various galleries, feeding upon it
to their hearts’ content.
In other cases, however—that is to say, with other species—social
development has gone further, and, besides boring galleries, the
mother-beetle excavates a number of cells in their walls, like rows of
bedrooms opening out of either side of a passage. She does not, however,
quite finish her bedrooms, but, whilst they are still incomplete, lays
an egg in each, and when this hatches, the young beetle, then in its
larval state, takes up the task where she left off, and in time
completes it. All the while they are growing up the mother feeds the
young ones, and, between the intervals of doing so, stops up the
entrance to the cell with a “plug”—such is the word employed; “to what
base uses we may return, Horatio!”—of ambrosia. In time, when they have
acquired the full imago form, each female beetle flies away to make a
burrow and rear a family of her own, and in some species she is
accompanied in this marriage flight, as it may be called, by the male.
In others, however, the males are wingless, and remain in the burrow,
till, when their appointed time comes, they die. Whether the male, when
winged, assists the female in her mining operations I am not quite sure,
inasmuch as that point seems to be avoided in the accounts which I have
been able to consult, but the wingless male would not be able to do so,
as he would be left behind in the burrow when the female flew away to
found another colony.
The fungus, when it has once commenced to grow, increases very rapidly,
so that if the number of beetles in the nest is much diminished, as,
say, by some accident, the rest cannot eat enough to keep it down, and
so, it would appear, are suffocated. It is asserted, however, that when
the wingless males are deserted by the females, and would otherwise
perish in this way, they all collect together in a few of the galleries
and feast on the ambrosia there growing. By this means, we are told,
they “prolong for a time their useless existence”—an ungrateful way of
putting it, so it seems to me, as the poor things have already been
useful in a very indispensable manner, so that their existence as a
whole is anything but useless, and to separate a part of it from the
rest and carp at that is silly as well as ill-natured. But it is the
fashion to speak in this harsh way of the male insect, beginning with
the drone bee; whereas when the female has done all that _she_ can
do—which is often just to lay her eggs—nobody talks of _her_ useless
existence. Fashion is a curious thing, and ants, even if they be
automatons, are not the only creatures that do things automatically.
It is certainly very curious, if it be true, that the wingless male
beetles should, by thus congregating together in this way, and so saving
their lives, show more intelligence than the winged females, who, under
similar circumstances, are choked with their ambrosia, as the Duke of
Clarence was with his nectar in a malmsey-butt. It is true that with the
males the thing happens every year, whereas with the females it is only
accidental; but, in the particular circumstances, it is difficult to see
how inheritance can have had anything to do with it. Here, then, are a
particular family of beetles who live the same sort of social life that
ants and bees do, which discovery appears to have been made by a Mr.
Hubbard not so many years ago, and from whose paper on the subject all
the above particulars have been taken, though only through the medium of
various magazines, since even at the British Museum I was unable to get
the paper itself. So long ago, however, as 1844 a certain Herr Theo
Hartig “published an article on the ambrosia of _Xyleborno (Bostrichus)
dispar_, in which he showed that it was a fungus growth (_pilzrasen_),
and he named the fungus _Monilia candida_.” This statement is made by
Mr. Hubbard in his much more recent account. Not feeling perfectly
certain from it whether the origin, as well as the nature, of the
strange-named substance was not also divined by the German investigator,
I quote the reference in order not to do him a possible injustice, for
to me it seems that there have been few more interesting discoveries
than this of these ant-like, ambrosia-growing beetles. But why the ants
only grow mushrooms, thus allowing themselves to be enormously outdone
by an inferior insect, is more than I can understand.
And now a word of justice to these beetles. It might be supposed that,
by burrowing into trees, they caused the death of the latter, but this
is not really the case. Writing in _The Agricultural Gazette_ of New
South Wales for August, 1900, Mr. Froggatt, the Government Entomologist,
makes the following statement absolving _Xleborus_: “This curious little
beetle (_X. solidus_) is rather plentiful about Sydney, and is
frequently sent to us taken out of the trunks of fruit trees, which it
is supposed to have killed; but in all cases that have come under my
notice it has had nothing to do with the tree dying, but is attracted to
the tree as soon as it becomes sick, the bark begins to wither, and the
first symptoms of decay set in.” Mr. Froggatt adds: “The instinct that
leads these and other wood-boring beetles to a tree as soon as it is
sick is something marvellous; in the tropics I have collected many fine,
rare species upon the freshly cut tent-poles in our camp, attracted to
the wood, but otherwise seldom found in the bush.” This instinct would
seem to be a remarkably developed scent, though why a severed branch
should smell differently from the tree of which it but a moment before
made a part it is not easy to imagine. However, we cannot, without
evidence, attribute clairvoyance to beetles, and perhaps it is the cut
from which the scent emanates.
Another example of an insect which is neither an ant, bee, wasp, nor
white ant, but which yet may be said to live a true social life, is the
little creature which, under the name of _Psocus venosus_ and as
belonging to the order _Carrodentia_, will be familiar to everyone. It
is nearly related to the so-called book-lice, but lives in the open air,
“being seen,” says Mr. Leland Howard, “upon the trunks of trees, in
flocks numbering from twelve to forty or fifty individuals.”[69] These
browse together like a herd of miniature cattle on the various lichens
that embrace the bark, and these they nibble so closely that wherever
they move they leave a bare track behind them. Sometimes one family and
sometimes several are included in the herd, all ages and stages being
represented, from the wingless but free-moving larvæ to the winged imago
form. The latter, however, though they be thus provided, will not
readily forsake their young, but the whole of them, when alarmed, first
run all together, and then, if the cause of disquietude continue,
suddenly scatter as though in panic, and run hither and thither, in all
and every direction. When the danger seems over, they close up their
ranks again, and go on browsing as before.
The female _Psocus_ lays her eggs in little clusters of from fifteen to
twenty, and protects each cluster under a sort of dome or shield of
gnawed wood which she presses upon them so that they stick to it. She is
said to brood over the eggs, but this does not appear to mean that she
actually incubates them. Rather, she remains about, keeping watchful
guard till they are hatched, and then takes the young to find pasture,
walking at their head like a hen in front of her chickens. From such
beginnings as these it seems possible that the social life of ants has
been, in the course of ages, evolved and developed.
-----
Footnote 60:
Belt, The Naturalist in Nicaragua, pp. 72, 73, 79-81.
Footnote 61:
Journal of the Trinidad Field Club, No. 3.
Footnote 62:
As quoted in The American Naturalist for November, 1900.
Footnote 63:
The American Naturalist, November, 1900.
Footnote 64:
Belt, The Naturalist in Nicaragua, pp. 27, 28.
Footnote 65:
Lubbock, Ants, Bees, and Wasps.
Footnote 66:
The greatest being speedy extinction.
Footnote 67:
Darwin, The Descent of Man, p. 54.
Footnote 68:
The Agricultural Gazette of New South Wales, March, 1900.
Footnote 69:
Leland O. Howard, The Insect Book.
------------------------------------------------------------------------
CHAPTER XVI
From wood to ambrosia—Wood-boring beetles—Rival claimants—Stag
and other beetles—Metempsychosis—Flies with horns—Comical
combatants—Female encouragement—The sacred Scarabæus—A
beetle with a profession—Table companions—Old and new
fallacies—From theft to partnership.
IT is, no doubt, through feeding on wood that the beetles we have been
considering came in time to feed on ambrosia. The particular fungus,
that is to say, which for some unaccountable reason has received this
name, appeared as a natural growth upon the walls of their tunnels, and
in time it came to be thought necessary, and its coming was arranged
for. By similar steps, probably, the leaves once carried as food to
their nests by the sauba ants, or cooshies, have become the soil merely
on which that food is grown; and so I have no doubt myself that even if
the present agricultural ants of Texas do not purposely sow and
afterwards reap the rice that springs up around the circular mound of
their domicile, their descendants will do so. Indeed, it seems rather
curious that, with such facilities for a gradual development, the habit
has not yet been acquired; and this is the chief reason which inclines
me to suspend judgment on the question, and wait for further
observations. Far from thinking the thing too wonderful, I wonder if it
be not the case. Such wonder, however, is for ants and not for beetles,
except, indeed, ambrosia beetles, who certainly merit it, though in an
opposite way. No other wood-borers of the order are anything but
wood-eaters, or, at any rate, if a few feed on fungus, as would not be
improbable, should it happen to appear, they have nothing to do with the
cultivation of it. The words “as far as we know,” however, must be added
to the foregoing statement. Numbers of beetles pass the larval and pupal
stage of their existence within the trunk of a decaying or even of a
perfectly sound tree, from which they issue after the final
metamorphosis has been made. Amongst these is our own stag-beetle, in
whom, that is to say in whose caterpillar, some suppose themselves to
see the _Cossus_ of the ancient Romans, which was as much appreciated by
them, and, no doubt, justly, as are earthworms by the Chinese. Others,
however, believe this to have been the large red meaty-looking
caterpillar of the goat-moth; and as the one conjecture is quite as
plausible as the other, the only, or, at any rate, the best way of
arriving at a conclusion would be to try them both—a simple plan which,
as far as I know, has not yet been adopted.
The stag-beetle—when of maximum size, that is to say, for it varies
amazingly in this respect—is much the largest beetle which this our
island possesses, but though, with its huge, antler-like jaws, it makes
a good perennial illustration for all books of popular entomology, its
merits seem to end there, for either there is nothing or nothing has yet
been observed particularly interesting about it. No doubt, if we look at
the matter from an absolute rather than a relative point of view, the
second of these two explanations is the correct one, for a creature has
only to be studied in order to become interesting; but as compared with
ants, bees, wasps, and many other insects, beetles, or, at any rate, the
vast majority of them, are not so very entertaining in their habits, and
the stag-beetle has no superiority in this respect to correspond with
its size and uncommon appearance. This appearance, however, is confined
to the male, who alone possesses the great branching mandibles on which
its greater size also is largely dependent. It would be natural to
suppose that these formidable weapons, as they certainly appear, stood
in relation to the combats of the males for the possession of the
females, yet it is often stated that the short, sharp pincers of the
latter, which can be made, it would seem—anyone who doubts may try—to
meet in the flesh, are really the more efficient of the two. Be this as
it may, it is not improbable that the stag-beetle’s jaws, since they are
very handsome, may have been developed less as weapons than as
ornaments, under the laws of sexual selection. Darwin, if I remember,
was doubtfully of this opinion, and he attributes many strange
projections and processes on the head or thorax of other beetles—as
notably that huge one with a snout like a weaver’s beam, called the
Hercules beetle—to the same agency. No use for this extraordinary trunk,
as one may term it, has as yet been discovered, but as the under portion
is covered with a thick matting of soft brown hairs, it would seem as
though it had some office to perform, unless indeed we suppose this
_chevelure_ to be likewise admired. A lesser, though still tremendous,
projection, starting from the head, as the other one does from the
thorax, is likewise unaccounted for, for though the two together make in
appearance a pair of uncouth and irregular pincers, they neither are,
nor apparently can be used in this way. Nothing appears to be known of
this strange creature’s habits, and the same may be said in regard to
most of the more remarkable-looking beetles of the world, as well as
those which are not so extraordinary in their appearance. The ways of
beetles, in fact, have been but little studied, and it is perhaps not
too much to say that if for every thousand that fill the show-cases in
museums we could know the life-history of one, we might with infinite
advantage, in exchange for this knowledge, throw the whole pin-forest of
them into the sea. In what light this fact, if true, exhibits the
labours of those naturalists—as the world calls them—who, living for
years amidst the life-teeming regions of the earth, have spent their
whole time in constantly killing and killing, coming home, at last, with
an acre of carcasses, to write a book containing hardly anything of
first-hand observation—the soul of natural history—I will not pause to
inquire.
------------------------------------------------------------------------
[Illustration: THE HERCULES BEETLE.
The enormous beetle from which this illustration was drawn, though not a
particularly large specimen, is six inches long, and the upper jaw
measures three inches and a half.]
There are many other species of beetles, the males of which are
ornamented about the head and thorax with all sorts of knobs and
projections, so that, with some, one might think that a one-horned or
two-horned rhinoceros had undergone metempsychosis, as it is called,
that its soul, that is to say, had transmigrated into the body of an
insect, which latter had been fashioned so as fancifully to resemble its
old one. However, as this would be a downward journey, it is more
satisfactory to imagine that certain beetles have been “translated” into
rhinoceroses. As to these kinds of excrescences, Darwin believed them to
be of the nature of adornments, and since their owners—the males—have
not been seen to use them in warfare, and indeed do not appear to fight,
it is difficult to imagine any other _raison d’être_ for them. This
seems all the more likely because certain flies found in the Malay
Archipelago have likewise excrescences, which we have to call horns, and
these too are confined to the males, though it is hardly to be imagined
that they would fight in a manner to make them of service. These flies
must be most extraordinary creatures to look at. They have long legs,
which they draw together underneath them, so as to stand very high, and
their horns are not only conspicuous by their size and shape, but also
by being brightly coloured. Thus in one species they are a beautiful
pink with a light stripe down the centre, and bordered on each side with
black. In another the colours are yellow, black, and brown, and though
_Elaphomia cervicornis_ has to be contented with black, and pale tips,
yet his are the finest pair of all, being nearly as long as his body,
and branched so as to look like a pair of slender and delicate stag’s
horns. The other pairs are not like this, one of them being rather
club-shaped, and therefore less horn-like, whilst another has an
extraordinary resemblance to the antlers of an elk, which are broad and
palmated, so that _it_ is the _Elaphomia alcicornis_. Here, therefore,
are both horned beetles and horned flies who yet do not fight with their
horns, so that unless they serve as ornaments it would be a puzzle to
say what they do serve as; for as the male beetles do not fight, which
is the principal way in which male creatures, including man, show their
vigour, why should we suppose them to be more vigorous than the females?
In some other beetles, which do fight, the sexes do not differ
conspicuously, nor do their facial or other peculiarities appear to bear
any special relation to warfare. Thus “those curious little beetles, the
_Brenthidæ_” of the Malay Archipelago, have an extraordinarily long
snout—or rostrum, to talk entomologically—at the end of which come the
jaws and antennæ, and this rostrum is used by the female to bore holes
in decaying wood, where she afterwards deposits her eggs. The males,
however, do what they can with them as weapons, and Dr. Wallace has seen
two of them fighting together in a very comic manner. “Each,” he tells
us, “had a fore-leg laid across the neck of the other, and the rostrum
bent quite in an attitude of defiance, and looking most ridiculous.”[70]
On another occasion “two were fighting for a female, who stood close by
busy at her boring. They pushed at each other with their rostra, and
clawed and thumped, apparently in the greatest rage, although their
coats of mail must have saved both from injury. The small one, however,
soon ran away, acknowledging himself vanquished.”[70] _Lethrus
cephalotes_ is another fighting beetle, and here the males, instead of
horns or anything extraordinary, have merely somewhat larger mandibles
than the females. “The two sexes,” says Darwin, “inhabit the same
burrow. If, during the breeding season, a strange male attempts to enter
the burrow he is attacked; the female does not remain passive, but
closes the mouth of the burrow and encourages her mate by continually
pushing him on from behind; and the battle lasts until the aggressor is
killed or runs away.”[71]
Of yet another species, the _Ateuchus cicatricosus_, the sexes “live in
pairs, and seem much attached to each other; the male excites the female
to roll the balls of dung in which the ova are deposited, and if she is
removed he becomes much agitated. If the male is removed the female
ceases all work, and, as M. Brulerie believes, would remain on the same
spot until she died.”[72] But M. Brulerie was reckoning apparently
without M. Fabre, since whose investigations in this last department it
may be said that “_nous avons changé tout cela_.” For this _Ateuchus_ is
none other than the celebrated Scarabæus, or sacred beetle, and, in the
first place, M. Fabre has shown that the balls of dung, which are rolled
about by them with so much perseverance and energy, do not contain the
ova, as it was always thought that they did, but are merely provender
and nothing more, and though sometimes they are rolled by two beetles
together, these are not the male and female, or, at any rate, they need
not be. They are just as likely to be two males or two females, and in
any case, though the two may be of opposite sexes, they do not represent
a mated pair. Simply when the two—if, as is by no means always the case,
more than one take part in the rolling—have pulled and pushed the ball
to a suitable place, they make a hole in the ground, into which they
drag it, and, having closed the aperture, sit and feast at their
leisure.
According to Fabre the vital principle contained in the egg would be
destroyed were it rolled about in this fashion, so when the mother
Scarabæus, who, it would appear, works in this matter alone, is ready to
lay her eggs, she first makes an excavation, and then brings the dung
down into it in pellets, till there is a heap of it, which fills the
whole concern. Then “the first thing to do is to select very carefully,
taking what is most delicate for the inner layers, upon which the larva
will feed, and the coarser for the outer ones, which merely serve as a
protecting shell. There around a central hollow which receives the egg
the materials must be arranged layer after layer, according to their
decreasing fineness and nutritive value; the strata must be made
consistent, and adhere one to another; and finally the bits of fibre in
the outside crust, which has to protect the whole thing, must be felted
together.”[73]
Thus, when the grub first issues from the egg, it finds light digestible
food ready to hand, which becomes coarser and more fibrous with its
growth and increased capacity of assimilating such stronger diet. As
more and more is eaten, the ball, which is about the size of an ordinary
apple, becomes hollower and hollower, till at last, when only the outer
crust remains, the grub is ready to enter upon that wonderful series of
changes—called its metamorphoses—which will bring it forth into this
larger ball of dirt, a complete beetle, with a useful profession, that
of scavenger, immediately open to it.
Thus a fallacy which, according to Fabre, dates from the time of the
Pharaohs, viz. that every ball of dung which one might at any time see a
Scarabæus beetle rolling and trundling along contained its egg, has been
finally disposed of, nor is this the only one. It used to be thought,
not only that any two beetles rolling a ball between them were male and
female, but also that any single one that happened to be in difficulties
would immediately fly off and summon a comrade or two to its aid. Fabre
denies this altogether, and maintains that in this rolling away of
provisions each individual beetle is purely a self-seeker. It is true,
as we have seen, that the _bonne bouche_ will often be eaten by two
Scarabæi—never more—in the cavern prepared beforehand for its reception,
but, according to Fabre, this is only because it is to the mutual
interest of both to act in this way, since neither can succeed in
appropriating the ball to itself, in spite of efforts—which in other
cases, however, may be successful—to do so.
In all such cases the one beetle is the real owner of the ball, whilst
the other is only there with the intention of stealing it if he can.
Thus the thief will often let himself be pushed along by the honest
worker, lying flat on the ball, and doing no work whatever, though at
other times, when a rise in the ground makes it difficult for a single
beetle to roll it, he will assist with all his power. Again, whilst the
one Scarabæus is hollowing out a cave for the approaching banquet to
take place in, the other, left with the ball, will, after some time,
begin to go off with it alone, and unless pursued by the owner before he
has gone too far, he accomplishes his purpose, and eats it all himself.
Thus he has associated himself to the maker of the ball with the
distinct idea of stealing it if he can. He has this plot in his mind, to
pretend partnership, to even give real assistance, but to watch his
opportunity and decamp when it occurs. That, at least, is the view
suggested for our adoption, but I cannot say that it recommends itself
to me. Fabre, in my opinion, has disposed of one error only to fall into
another of precisely the same kind. He says very justly in regard to the
idea that one beetle would deliberately fly away and summon others to
its assistance, “It is no slight thing to admit that an insect has a
truly surprising grasp of the situation, and a facility for
communicating its ideas to others of its kind more surprising still. Are
we to suppose that a Scarabæus in distress conceives the idea of begging
for help, flies off, explores the country round, etc.?” Very true; but
if we are not to suppose this, I certainly will not suppose, either,
that this same Scarabæus can conceive the idea of pretending to assist
another in order to rob him of his property. This would be as deep a
laid scheme as the other, and the facts of the case, as given by Fabre
himself, do not appear to me to lend themselves to such an explanation.
The point of these interesting relations has been, in my opinion,
entirely missed. What we really see in them, or what, at least, is there
for us to see, is the beginnings of order and social polity, evolving
themselves out of lawlessness and the strong hand. Further, it has
already gone some little way, for the fact that two Scarabæi do, as a
matter of fact, assist each other very materially in rolling the ball,
and that they do sit and eat it together in the same chamber, are not to
be got over by any such amusing fancy picture as this brilliant writer,
as well as keen observer, has given us. It is no use fixing our eyes
upon that part of the conduct of the beetle which we are invited to call
the thief, in contradistinction to the owner—I doubt myself if Fabre has
always kept the two distinct from beginning to end—if we pass over the
other and much more interesting parts of it. Why does this beetle help
to get the ball up a hill, and why does he sit for some considerable
time with it outside the cave that the other is making, before he begins
to go off with it? Does he say to himself, in the first case, “If we
don’t get it to the right place, to begin with, he’ll never dig a hole
and leave me outside with it,” and, in the second, “I’ll wait till he
has come out and found it all right, several times, so that his
suspicions may be put to sleep”? This would be scheming with a
vengeance; but _serviteur Monsieur Fabre_, I must refer you to your own
incredulity in another matter. I will never accept such an explanation,
and the view which I take of the whole affair is this. The beetle which
Fabre calls the thief is under the sway probably of precisely the same
feeling as the other one—the rightful owner. He has seized a piece of
dung, and as he seizes it, whether another has it at the time or not, it
appears to be his, that being the only idea of rightful ownership which
is not too large for his comprehension. Finding, however, that another
beetle has exactly the same idea as himself, he is forced, willy
nilly—and the experience is being constantly repeated—to accommodate
himself to this circumstance and make the best of it. The ball—this is
the one great advantage—will continue to roll even if he does not push
it. Therefore he can afford to be lazy sometimes, and be pushed along
with it. The ball stops: in that case he must push it, and, even without
this incentive, it would appear from Fabre’s account that the two often
work together. Thus, from the very necessities of the case, it is
evident that a sense of partnership—at least a feeling of doing work in
combination with another—has begun to dawn in the mind of the Scarabæus.
The fact that when the one beetle is left alone with the ball, whilst
the other excavates, it does not immediately go off, but stays a little,
as though waiting to be rejoined, suggests to my mind that this feeling,
fostered by custom, has already gone some way, though it is not
wonderful that, after a time, the primitive individualistic tendency
should again assert itself. But when the fugitive is overtaken, it
assists the other to roll the ball back, and the end of it all is a meal
shared peacefully between the two, in one common apartment. If we
suppose that the instinct, or capacity, of working together for some
common end has had any beginning, surely we might expect to find it in
some such state of affairs as this. The result of primitive conceptions
is that two Scarabæi are often obliged to roll one ball between them,
and if there be any advantage in this arrangement, natural selection
will no doubt do the rest. That it has already begun to do it is, I
think, very probable; but Fabre was not an evolutionist.
-----
Footnote 70:
The Malay Archipelago.
Footnote 71:
Darwin, The Descent of Man, p. 300.
Footnote 72:
The Malay Archipelago.
Footnote 73:
Souvenirs Entomologiques.
------------------------------------------------------------------------
CHAPTER XVII
Do ants sow and reap?—Rival observers—The Texan _v._
Macaulay’s schoolboy—More evidence wanted—How ants cross
rivers—Tubular bridges—Ant armies—A world in flight—Living
nests—Ants and plants—Mutual dependence—Nests in thorns and
tubers—Ant honey-pots—Business humanity—Burial customs—A
strange observation—Two views of ants.
MUSHROOM-GROWING, especially if the ants plant the mushrooms in the way
stated by Mr. Tanner, is just as extraordinary, I think, as their habit
of planting a field with ant-rice and reaping it at the proper time
would be, did they really practise it. Up to a little while ago it
certainly seemed as though they did, for there was Dr. Lincecum’s
definite statement based upon twelve years’ observation, and this, if
not confirmed by Mr. McCook, was, at any rate, not contradicted by him.
On the contrary, McCook mentioned a good many facts pointing in the
direction of Lincecum’s assertion, and though he did not consider them
decisive, he could see no reason why the ants should not act in this
way, as indeed there is none: so that as he had only stayed a few months
where Lincecum had lived for twelve years, he seemed like a weaker
witness supporting, according to his opportunities of observation, a
much stronger one. Now, however, comes another witness, whose
opportunities have also been great, and in a somewhat heavy-handed way,
in a spirit of myth-slaying and irrelevant reference to supposed
schoolboy knowledge, hardly required in face of all that ants are known
to do, denies the whole thing.
First, however, let us have the assertion as originally made by
Lincecum, which is, that on the summit of the mound of their nests, from
which they carefully clear away all other vegetation, the harvesting
ants sow the seed of a certain plant called ant-rice for the purpose of
subsequently reaping a harvest of the grain. It is sown in time for the
autumnal rains to bring up, and at the beginning of November a green row
or ring of ant-rice, about four inches wide, is seen springing up round
the circumference of the _disk_ (as the circular top of the mound is,
for some reason, always called). In the vicinity of this circular ring
the ants do not permit a single spire of any other grass or weed to
remain a day, but leave the aristida or ant-rice untouched until it
ripens, which occurs in June of the next year. After the maturing and
harvesting of the seed, the dry stubble is cut away and removed from the
disk, which is thus left unencumbered until the ensuing autumn, when the
same species of grass again appears as before, and so on.[74] After
stating in a letter to Darwin that he has seen all this taking place
year after year, Dr. Lincecum adds:—“There can be no doubt of the fact
that the particular species of grain-bearing grass mentioned above is
intentionally planted. In farmer-like manner the ground upon which it
stands is carefully divested of all other grasses and weeds during the
time it is growing. When it is ripe the grain is taken care of, the dry
stubble cut away and carried off, the paved area being left unencumbered
until the ensuing autumn, when the same ant-rice reappears within the
same circle and receives the same agricultural attention as was bestowed
upon the previous crop, and so on year after year, as I _know_ to be the
case in all situations where the ants’ settlements are protected from
graminivorous animals.”[75] Lincecum also believed that the ants were
able in some way to prevent the seed stored in their nests from
germinating. This same fact has been asserted, and apparently proved, by
Moggridge, in regard to the harvesting ant of southern Europe, and he
also states that, if in spite of the precaution any seeds begin to
sprout, the ants by gnawing off the tips of the radicles would prevent
the germination from proceeding.
This, then, is the case _for_ the harvesting ant, as we may say; for if
these things be true they are certainly much to its credit, whereas, if
not, the scandal is so great that it ought to change its name. Let us
now hear the case against, as stated by Professor Wheeler, after which
readers may make up their minds, if they can, for I have not quite done
so yet. I quote in full, so that the two statements may be balanced
against each other, and this, I hope, will be more interesting than the
usual “Mr. So and So, however, disputes this and thinks, etc.”—another
line or two in which the contrary proposition of the one before is
stated at about the same length. This is what Professor Wheeler, who
“speaks home—you may relish him more (or at least as much) in the
soldier as the scholar”—has to say: “It may not be altogether out of
place in this paper to record a few other observations on _Pogonomyrmex
molifacieus_, inasmuch as this form has been singled out among all the
known members of the genus as presenting certain remarkable instincts.
Lincecum is responsible for the myth that this _Pogonomyrmex_ sows a
certain species of grass, the ‘ant-rice’ (_Aristida oligantha_),
protects it from harm and frees it from weeds while it is growing, for
the purpose of reaping the grain. This notion, which even the Texan
schoolboy (not Macaulay’s, who probably knew as much about it) has come
to regard as a joke, has been widely cited, largely because the great
Darwin stood sponsor for its publication in the Journal of the Linnean
Society. McCook, after spending a few weeks in Texas observing the ant
in question and recording his observations in a book of 310 pages,
failed to obtain any evidence either for or against the Lincecum myth
and merely succeeded in extending its vogue by admitting its
plausibility. Two years of nearly continuous observation enable me to
suggest the probable source of Lincecum’s and McCook’s misconceptions.
In either case the observer has started with a few facts, and has then
stopped short to draw inferences before gathering more facts. If the
nests of _Molifacieus_ be studied during the cool winter months—and this
is the only time to study them leisurely and comfortably, since the cold
subdues the fiery stings of their inhabitants—the seeds which the ants
have garnered in many of their chambers will often be found to have
sprouted. It is, therefore, certain that these ants are not able to
prevent the seed from germinating, as Moggridge claims for the European
species of Messar, except by conveying them to drier chambers; and in
protracted spells of wet weather even this precaution seems to be of no
avail. On sunny days the ants may often be seen removing these seeds
when they have sprouted too far to be left for food, and carrying them
to the refuse heap, which is always at the extremity of the cleared
earthern disk or mound. In this place the seeds thus cast away as
inedible often take root, and, somewhat later, form an arc of tall grass
more or less closely approximating to a complete circle round the nest.
Since these ants feed largely, though by no means exclusively, on
grass-seeds, and since these particular seeds are a very common and
favourite article of food, it is easy to see how their grass should
often predominate in the circle. In reality, however, only a small
percentage of the nests, and only those situated in certain localities,
present such circles. Now to state that the ant, like a provident
farmer, sows this cereal, and guards and weeds it for the sake of
garnering its grain, is as absurd as to say that the family cook is
planting and maintaining an orchard when some of the peach-stones which
she has carelessly thrown into the backyard, with the other kitchen
refuse, chance to grow into peach trees.”[75] Certainly such a thing
should have been observed before the statement was made, and, if it has
not been, the facts seem more probably accounted for on the above
explanation.
Professor Wheeler goes on to say that “there are several other facts
which show that the special ring of grass about the nest is an
unintentional and inconstant result of the activities of the ant colony.
For instance, one often finds very flourishing ant-colonies that have
existed for years in the midst of much-travelled roads, or in stone
side-walls, often a hundred or more feet from any vegetation whatever
(without any ant-rice on their mounds therefore). Again, it is very
evident that even a complete circle of grass like those described by
Lincecum and McCook would be entirely inadequate to supply more than a
very small fraction of the grain necessary for the support of a
flourishing colony of these ants. Hence they are always obliged to make
long trips into the surrounding vegetation, and thereby wear out regular
paths, which radiate in different directions, often to a distance of
forty to sixty feet from the entrance of the nest. The existence of
these paths, which are often found in connection with grass-encircled
nests, is alone sufficient to disprove Lincecum’s statements.”[75] It
certainly seems easier to suppose that Lincecum misinterpreted certain
facts, not themselves in dispute, than that an explanation on which so
many considerations seem to throw doubt is the correct one. One thing,
at least, seems certain—if some of these ant communities grow grain of
set purpose, all of them do not. This may be possible, but more proof of
it than Lincecum has brought is demanded. If the ants really sow and
reap the grain that grows upon their mounds, and, more especially, if
they carefully keep the patch clear, it ought not to be difficult to see
them doing so. This last would be decisive, whereas the other two are by
no means so.
That ants should use their own larvæ like a shuttle, and for the same
purpose, seems as strange a thing as one can well imagine, but there is
no doubt at all about it, the act having been witnessed on various
occasions by competent observers, whose evidence is mutually
corroborated. The species in question is common in Eastern Asia, and is
accustomed to make little houses or arbours for itself by bending leaves
round so that the edges meet, and then fixing them together, as some
caterpillars do. Now the larva can do something which the grown ant
cannot, which is to spin a cocoon from a sort of gummy, thread-like
substance which issues from the mouth. Whilst one group of ants
therefore join to keep the leaf bent in the proper position, another
take each a larva in their jaws, and pass it from edge to edge of the
leaf, applying its mouth to each edge, until the two are bound firmly
together.[76] Whether this is a more or less remarkable habit than
growing mushrooms it would be difficult, perhaps, to decide, nor is
there any need to try, since such questions are more interesting left
uncertain.
It is well known, or at least credibly asserted, that ants cross rivers
by clinging one to another from the branch of a tree overhanging the
water, till the end of this living chain, as it becomes longer and
longer, is carried by the force of the current to the opposite bank,
where a bridge is formed, over which the main body marches.[77]
According to Du Chaillu the ants in Africa make, not only a bridge, but
a tunnel—“a high, safe tubular bridge through which the whole vast
regiment marches in regular order.”[78] These are the celebrated driver
or bashikouay ants, who, when upon their terrible marauding marches, put
every living creature, including man, to flight, though for many flight
is in vain. Size and strength are here no protection. “The elephant and
gorilla fly before them; the black men run for their lives.” So says Du
Chaillu, and, sure enough, when the skins of some of the poor gorillas
he shot arrived in England, several of these ants were found amongst the
hair.[79] In the forests of equatorial Africa, abounding—if they have
not all been shot by this time—with large animals, these hunting-raids
must give rise to some stirring scenes. What crashings through the trees
and undergrowth! What uncouth sounds, perhaps, of mingled pain and rage!
How a bitten gorilla would express himself! What a subject for a picture
if a herd of elephants, a few families of gorillas, a score or so of
lions, with a few leopards, and baboons, perhaps a rhinoceros, and any
number of antelopes, were all to come rushing down together to where an
artist stood ready for them! I should like to see the picture he would
draw.
------------------------------------------------------------------------
[Illustration: PURSUED BY DRIVER ANTS]
[Illustration]
The greatest beasts of the forest will fly before these terrible little
insects,
one of which is shown in the left-hand corner.
A more remarkable sight even than an ant-bridge is perhaps an ant-nest,
by which I mean, not an ants’ nest in the ordinary sense of the term,
but a nest made of ants. The following quotation from the
much-containing _Naturalist in Nicaragua_, page 25, will explain this
hard saying. “They make their temporary habitations in hollow trees, and
sometimes underneath large fallen trunks that offer suitable hollows. A
nest that I came across in the latter situation was open at one side.
The ants were clustered together in a dense mass like a great swarm of
bees hanging from the roof, but reaching to the ground below. Their
innumerable long legs looked like brown threads binding together the
mass, which must have been at least a cubic yard in bulk, and contained
hundreds of thousands of individuals, although many columns were
outside, some bringing in the pupæ of ants, others the legs and
dissected bodies of various insects. I was surprised to see in this
living nest tubular passages leading down to the centre of the mass,
kept open just as if it had been formed of inorganic materials. Down
these holes the ants who were bringing in booty passed with their prey.”
Of the many curiously constructed or strangely produced dwellings of
ants, this made out of their own bodies is amongst the most remarkable.
Many ants live in the interior of various plants. The plant generally
benefits as much as the insect by this arrangement, so that there is a
mutual dependence between the two, which in some cases is carried to
such an extent that the life of one or both seems a necessary part of
that of the other. In Borneo, for instance, a certain large tuber which
grows on the branches of aged trees is always found inhabited by a
certain red ant, of small size, but fierce disposition, which rushes out
and attacks anyone who ventures at all near its dwelling. The seed of
this tuber is disseminated in the same way as is our own mistletoe,
through the agency of birds, that is to say, the seed being surrounded
by a similar pulpy mass, which adheres to the branch on which it falls.
Soon after germination the tuber, which is shaped something like a
carrot, begins to develop, but whilst still quite small its growth
ceases and in this state it would remain, and before long, die, if it
should not happen to be found by the ants in question. If it should be,
however, its life is assured. They immediately bore a hole at the base
of the stem, upon which this enlarges to a great degree, so that soon
there is room for them to excavate galleries in the cellular tissue of
the interior, and to form a populous colony. The whole tuber is soon
perforated in all directions, and becomes a living and growing
formicarium, the great accretion of cellular tissue which has made this
possible having been caused by the poison—if we may call it so—of the
ant’s bite, in the same way as the sting of the gall-fly raises galls
upon the oak.[80] Of course, from the moment that the ants appear the
tuber is safe from any other insect, or small bird, or mammal that might
otherwise do it harm. The ants in defending their nest would defend it,
and it is on this principle of mutual advantage that such ant and plant
alliances have been brought about.
Thus the dry, arid plains, called savannahs, of tropical America support
a species of acacia of which the thorns, characteristic of the family,
grow in pairs and are shaped exactly like the horns of some oxen. Every
pair of these horns becomes in time an ants’ nest, and if the tree be
touched or shaken, the ants rush out full of fury in defence of their
habitations. Thus every tree is tenanted by a large army of retainers,
who almost more than the thorns themselves, which have been developed
for the same purpose, protect it against browsing quadrupeds. Its
thorns, however, would be no protection against the leaf-cutting ants in
search of materials for their mushroom-beds, whereas these are kept at
bay by a hostile species, smaller indeed, but armed with a powerful
sting. “For these services,” says Belt, “the ants are not only securely
housed by the plant, but are provided with a bountiful supply of food;
and to secure their attendance at the right time and place, this food is
so arranged and distributed as to effect that object with wonderful
perfection. The leaves are bi-pinnate (double, that is to say), and at
the base of each pair of leaflets, on the mid-rib, is a crater-formed
gland, which, when the leaves are young, secretes a honey-like liquid.
Of this the ants are very fond; and they are constantly running about
from one gland to another to sip up the honey as it is secreted. But
this is not all; there is a still more wonderful provision of solid
food. At the end of each of the small divisions of the compound leaflet
there is, when the leaf first unfolds, a little yellow, fruit-like body,
united to it by a point at its base. Examined through a microscope, this
little appendage looks like a golden pear. When the leaf first unfolds
the little pears are not quite ripe, and the ants are continually
employed going from one to another examining them. When an ant finds one
sufficiently advanced it bites the small point of attachment; then,
bending down the fruit-like body, it breaks it off and bears it away in
triumph to the nest. All the fruit-like bodies do not ripen at once, but
successively, so that the ants are kept about the young leaf for some
time after it unfolds. Thus the young leaves are always guarded by the
ants; and no caterpillar or larger animal could attempt to injure them
without being attacked by the little warriors.” Thus, as Mr. Belt very
aptly puts it, “the ants are really kept by the acacia as a standing
army to protect its leaves from the attacks of herbivorous mammals and
insects.”[81]
As for the honey or honey-pot ants, they were first heard of in America,
and various floating stories, which seemed more or less hard to credit,
having got into circulation about them, without there being any positive
knowledge to check them, Dr. McCook, to remove this grave reproach to
transatlantic entomology, started off one day to observe them. He soon
found that the main fact which had been stated was correct, viz. that a
certain sect or caste of these ants, disregarding the Italian warning,
were in the habit of making themselves all honey, to be swallowed in
consequence by the rest of the community. These are the so-called
honey-pots, and so well do they deserve their name, that when full the
abdomen becomes almost perfectly circular, like a glass globe, and so
enormously swollen that the body in proportion to it is like a grain of
wheat stuck into a cherry or gooseberry.[82] The legs dangle towards the
ground, but hardly, or only by a great effort, reach it, and in this
last state of distension the insect may find it impossible to get about,
though as a rule by dragging or pushing herself along sideways, she is
able to do so to a certain extent. These honey-jars have special
chambers for their accommodation, and here they hang in clusters from
the roof, awaiting the visit of any worker, who upon signifying his
wants—it would seem after climbing up to them—is fed, after the ordinary
ant manner, by regurgitation. In the same way the honey-bearers are
themselves filled, or more properly speaking, feed themselves, since the
mouth arrangement, in spite of the direction in which things seem
hastening, has not yet become so simple as in the case of a real jar.
The honey which the rotunds, as McCook calls them, receive from the
workers is gathered at night, and is obtained almost entirely from the
galls of oak trees, which, when pierced by the ant’s mandibles, exude a
white transparent liquid in minute globules. This is greedily licked up
by the ants and distributed by them after the return home, not only to
the rotunds, but to such of their fellow-workers as may not have taken
part in the expedition.[83] The honey thus obtained is pleasant to ant
and human taste alike, and the Indians of New Mexico, as no doubt
elsewhere, obtain it by the simple process of squeezing the
insect—breaking the honey-jar, as one may say. They also make from it a
fermented liquor having intoxicating powers, so that one need not wonder
that the idea of farming the honey-ant, like the honey-bee, has been
seriously discussed in the United States. McCook, however, has pointed
out that “the limited quantity of the product would prevent a profitable
industry,” and he adds: “Besides, the sentiment against the use of honey
thus taken from living insects, which is worthy of all respect, would
not be overcome.”[83] Personally I think it would be overcome, and
pretty quickly, too, as are most other sentiments that stand in the way
of pleasure or profit. Women would get it under first, as in the case of
birds, seals, etc., and the world would soon follow, with “woman’s
influence” upon its lips. But let me not be unjust. I do not believe in
sentiment as a working force in the case at all. If the ants are not to
be squeezed it will be on commercial considerations.
That the worker-ants—and for that matter the others also—are extremely
fond of the honey so curiously stored by them, will be easily believed,
and an unpleasant illustration of their greediness in this respect was
often observed by McCook when capturing a nest. The swollen bodies of
the rotunds, on these occasions, were sometimes unavoidably ruptured,
whereupon such workers as happened to be near these unfortunates,
forgetting their alarm, which had hitherto been great, and the ruin and
confusion all around them, paused in their flight, or aimless movements,
and greedily lapped up the overflowing honey.[84] It is all the more
interesting, therefore, to learn that when the “little life” of these
poor honey-pots is at length “rounded with a sleep,” their contained
treasure, though so easily obtainable, goes with them to the grave, the
idea of opening the full crop, and imbibing the contents, never seeming
to occur to any ant. This is all the more remarkable in that the
workers, when they recognise that life is extinct, carefully separate
the abdomen from the thorax by sawing through, with their mandibles, the
little connecting stalk called the petiole. The two parts are then
removed separately, that representing the head half being carried,
whilst the “golden bowl” of the body “unbroken,” though with “the spirit
fled for ever,” is rolled along the various chambers and galleries of
the nest, till it finally finds a resting-place in the cemetery just
beyond its precincts.[84] To what are we to attribute the
non-utilisation of the honey in the dead body? Even were it possible
that the ants could forget that it was there, they cannot be unconscious
of what must be smelt, as well as seen, through the semi-transparent
walls of the abdomen. Some feeling must restrain them—what, I am not
prepared to say in a work which does not aim at being scientific.
Here, then, we have one most suggestive illustration—“suggestive,” I
think, is a very useful word—of the funeral habits of ants. Many others
could be instanced, but I will end this chapter, and small account of
ant doings, generally, with the following extract from the _Proceedings
of the Linnæan Society_ (1861). The observer was a Mrs. Hutton, of
Sydney; and Romanes, who quotes her account in his _Animal
Intelligence_, remarks that though she is not a well-known observer the
facts reported were such as scarcely to admit of a mistake. Personally,
I attach no weight whatever to anybody’s not being known as an observer.
Want of leisure, or unpropitious circumstances generally, must prevent
large numbers of people from seeing what they would be very well able to
note accurately if they did, or from recording what they do see; whilst,
on the other hand, leisure, joined to taste in a certain direction,
makes many a quite average observer known as a good one. A good
observer, in fact, is rather one who is always keeping on, and does not
weary, than one who can see a single salient thing more plainly than
most other people; and, again, it is easy to set a fictitious value
merely on being before the public.
Having thus defended Mrs. Hutton, I proceed now to quote her account: “I
saw,” she says, “a large number of ants surrounding the dead ones”
(soldier ants which she had herself killed and left lying on the ground
some half-hour previously), “and determined to watch their proceedings
closely. I followed four or five that started off from the rest towards
a hillock a short distance off, in which was an ants’ nest. This they
entered, and in about five minutes they reappeared, followed by others.
All fell into rank, walking regularly and slowly, two by two, until they
arrived at the spot where lay the dead bodies of the soldier ants. In a
few minutes two of the ants advanced and took up the dead body of one of
their comrades; then two others, and so on, until all were ready to
march. First walked two ants bearing a body, then two without a burden;
then two others with another dead ant, and so on, until the line was
extended to about forty pairs, and the procession now moved slowly
onwards, followed by an irregular body of about two hundred ants.
Occasionally the two laden ants stopped, and laying down the dead one,
it was taken up by the two walking unburdened behind them, and thus, by
occasionally relieving each other, they arrived at a sandy spot near the
sea. The body of ants now commenced digging with their jaws a number of
holes in the ground, into each of which a dead ant was laid, where they
now laboured on until they had filled up the graves. This did not quite
finish the remarkable circumstances attending this funeral of the ants.
Some six or seven individuals had attempted to run off without
performing their share of the task of digging; these were caught and
brought back, when they were at once attacked by the body of ants and
killed upon the spot. A single grave was quickly dug, and they were all
dropped into it.”
“Prodigious!” as Dominie Sampson would have said, and certainly I think
this is one of the most remarkable observations upon ants that has ever
been made. As far as the burying is concerned, it has been corroborated
by the Rev. W. Farrar White, who, at the same time, corroborates Pliny;
but how strange are all the circumstances! What was it, one wonders,
that made just a few of the crowd shirk their share of the labour—for
this is not like ants. Some strange, uncanny feeling in connection with
the dead bodies may be suspected; but seeing that, as the Russian
proverb truly says, “Another man’s soul is darkness,” it is not very
likely that we shall ever know what ants feel.
One interesting question is suggested in this connection, though I have
never known it raised yet. Two views of what ants are, excluding
compromises, may be taken—the automatic one, tempered with “psychic
plasticity,” of Professor Wheeler, and that formed by Mr. Belt, who,
having fully satisfied himself—from the keenest observation, be it
remembered—of their reasoning powers and capacities, remarks, “When we
see these intelligent insects dwelling together in orderly communities
of many thousands of individuals, their social instincts developed to a
high degree of perfection, making their marches with the regularity of
disciplined troops, showing ingenuity in the crossing of difficult
places, assisting each other in danger, defending their nests at the
risk of their own lives, communicating information rapidly to a great
distance, making a regular division of work, the whole community taking
charge of the rearing of the young, and all imbued with the strongest
sense of industry, each individual labouring not for itself alone, but
for all its fellows, we may imagine that Sir Thomas More’s description
of Utopia might have been applied with greater justice to such a
community than to any human society.”[85] Now, if Belt’s view be the
correct one, or if the evidence in favour of it be at all strong, is it
not time for us to ask ourselves, merely as a moral problem, how far we,
in our clumsy and imperfect human state, have a right to kill ants and
tumble Utopia to pieces, simply for our amusement, intellectual or
otherwise? Ought we to do this? Or ought we, like a lady who lives in
America and writes to very scientific papers, to imprison queens who do
no harm, and make ourselves learned at the expense of one, or both of
their antennæ, during the term of their natural lives? However simply
and sweetly we may talk of this, however much true womanly feeling may
enter into the narrative, nay, even though we give the queens pet names,
is it really right?
-----
Footnote 74:
Romanes, Animal Intelligence, pp. 106-107.
Footnote 75:
The American Naturalist, February, 1902.
Footnote 76:
The Cambridge Natural History, vol. 6.
Footnote 77:
Du Chaillu, Adventures in Equatorial Africa, pp. 312, 313.
Footnote 78:
J. G. Wood, Homes Without Hands, p. 452.
Footnote 79:
W. F. Kirby, Marvels of Ant life, p. 73.
Footnote 80:
Dr. Beccari’s account, quoted in the _Popular Science Review_, 1875.
Footnote 81:
Belt, The Naturalist in Nicaragua, pp. 219, 220.
Footnote 82:
The ideal of what a short-billed tumbler pigeon’s head should be.
Footnote 83:
McCook, The Honey-Ant of the Garden of the Gods.
Footnote 84:
The American Naturalist, February, 1902.
Footnote 85:
Belt, The Naturalist in Nicaragua, pp. 28, 29.
------------------------------------------------------------------------
CHAPTER XVIII
Bees and wasps—A bee’s masonry—What happens to
caterpillars—Living food—Variations in instinct—A wasp’s
implement—Unreal distinctions—A cautious observer—Bees that
make tunnels—A wonderful instinct—Leaf-cutting bees—Nests
made of poppy-leaves—Born in the purple—Commercial
philosophy—The appreciative white man—Economy of labour—Bees
and rats—Busy shadows—A bee double.
THE consideration of ants naturally leads to that of bees, but of the
life and doings of the hive-bee—made common now in a hundred practical
treatises and bee-keeper’s manuals—it is not the design of this little
book to treat. Wasps are less written about, but even here, in a work
which can only deal with a very few insects out of a very great many, a
choice may be permitted one, so I will merely observe, in regard to the
common species, that in my opinion wasps are much less irascible than
bees—in fact, quite good-natured compared to them—but at the same time,
owing to their room-entering, table-pillaging propensities, much greater
nuisances, so that they deserve stern treatment, but a more charitable
estimate of their character. Hornets, again—which seldom offend in this
way—appear to me to be very peaceable insects, as though, wielding a
mighty weapon, they felt that they had no need to use it except on “a
striking emergency.” Such a definition would apply to the running of a
stage-coach, diligence, omnibus, waggon, etc.—in fact, any large
vehicle—into their nest on the highway, in which case the consequences,
one may well believe, would be appalling. Never having been in such a
position myself, and being without trustworthy information on the
subject, my powers of description are useless here, but there is a way
of dealing with this emergency also. This reminds me, however, of an
account which I have read somewhere or other of hornets having once
stopped a Roman army. This may seem surprising nowadays, but we must
remember that in classical times armies did not possess artillery. There
is therefore nothing invidious in the opinion which I here express, that
however much they may have stopped the Romans, they would never stop the
Japanese.
In both ants and bees we find solitary and social species, so as in ants
we have been considering the latter only, we will now reverse the
process with bees. There are many interesting species of solitary bees,
but it must be premised that the word “solitary” is to be understood
here in a special rather than in a general sense. As far as mere numbers
are concerned, there is often a large community of bees building their
cells in close proximity all at the same time, but each builds its cell
for itself alone, or rather for its family—no one thinks of helping its
neighbour. There is no co-operation, in fact, and that makes all the
difference. It would be all the same to every one of the bees that are
building so close together if all the rest went away and left it to work
alone. And yet we cannot even quite say this, because, in one case, at
any rate, though every individual bee makes its own cell and thinks only
of that and of its own family, yet, when all the cells are finished, the
whole community join in making one mud roof over the whole of them. By
this we see how difficult it is to find quite separate places for allied
animals, and how the habits of one are apt to slide gradually into those
of another. Still, we must do the best we can, and take words as we find
them, remembering that the locusts, as already explained, do _not_
belong to the _locustidæ_.
------------------------------------------------------------------------
[Illustration: DRIVEN OUT BY HORNETS.]
[Illustration]
Aelian, in his “Natural History,” says that a city in Crete
was attacked by such a plague of hornets that the
inhabitants were driven to abandon it, and build a new city
on another site. A hornet is shown to the right of this
inscription.
Amongst the best known of the solitary species of bees are the Carpenter
Bees, the Carding and Tapestry Bees, and the Mason Bees. Of the latter a
great French observer, who, though he lives now, belongs really to the
days of Réaumur and Swammerdam, has something to tell us. Speaking not
of Réaumur’s maison bee—that “splendid Hymenopteron with its dark violet
wings and costume of black velvet”[86]—but of a smaller
species—_Chalicodoma sicula_—he says: “You should see the active bee at
work when the road is dazzling white in the hot sunshine. Between the
neighbouring farm where she is building and the road where the mortar is
prepared there is a deep hum of the bees perpetually crossing each other
as they come and go. The air seems traversed by constant trails of
smoke, so rapid and direct is their flight. Those who go carry away a
pellet of mortar as big as small shot: those who come settle on the
hardest and driest spots. Their whole body vibrates as they scratch with
the tips of their mandibles and rake with their forefeet to extract
atoms of earth and grains of sand, which, being rolled between their
teeth, become moist with saliva, and unite. They work with such ardour
that they will let themselves be crushed under the foot of a passer-by
rather than move.”[86] Then comes the making of the actual nest, or
little collection of cells. “After choosing a boulder,” says Fabre, “she
comes with a pellet of mortar in her mandibles, and arranges it in a
ring on the surface of the pebble. The forefeet, and, above all, the
mandibles, which are her most important tools, work the material, which
is kept plastic by the gradually disgorged saliva. To consolidate the
unbaked clay, angular pieces of gravel as large as a small bean are
worked in singly on the outside of the still soft mass. This is the
foundation of the edifice. Other layers are added, until the cell has
the required height of three or four centimetres. The masonry is formed
by stones laid on one another and cemented with lime, and can stand
comparison with our own. Layers of mortar sparingly used hold them
together. The cell completed, the bee sets to work at once to store it.
The neighbouring flowers, especially those of _Genista scorpius_, which
in May turn the alluviums of the torrents golden, furnish sugared
liquids and pollen. She comes with her crop swelled with honey, and all
yellow underneath with pollen dust, and plunges head first into the
cell, where for some moments one may see her work her body in a way
which tells that she is disgorging honey. Her crop emptied, she comes
out, but only to go in again at once, this time backwards. With her two
hind feet she now frees herself from her load of pollen by brushing
herself underneath. Again she goes out, and returns head first. She must
stir the materials with her mandibles for a spoon, and mix all
thoroughly together. When the cell is half full it is stored; an egg
must be laid on the honey paste, and the door has to be closed. This is
all done without delay. The orifice is closed by a cover of undiluted
mortar, worked from the circumference to the centre. Two days, at most,
seem required for the whole work.”[86] Afterwards several more
cells—making a continuous group of from six to ten—are added, and when
all is completed, the mason bee “builds a thick cover over the whole
group, which, being of a material impermeable to water, and almost a
non-conductor, is at once a defence against heat and cold and damp. This
material is the usual mortar, made of earth and saliva, only with no
small stones in it. The nest is now a rude dome, about as big as half an
orange; one would take it for a clod of mud flung against a stone, where
it had dried. Nothing outside betrays its contents—no suggestion of
cells, none of labour. To the ordinary eye it is only a chance splash of
mud.”
Of course, when the eggs are hatched, the bee larvæ feed on the stored
pollen and honey, a pleasing picture which suggests another something
like it, though not altogether the same. I allude to certain species of
solitary wasps, which, urged by the same feelings of maternal
solicitude, choose a living caterpillar, grasshopper, spider, etc., for
the future sustenance of their young. Take, for instance, _Ammophila
urnaria_ of North America, whose habits in this respect have been
carefully studied. This wasp is about an inch long, with very long legs,
and a waist even exaggeratedly wasp-like. It is black in colour, but
with a red mark running round the fore part of the abdomen. At the
proper time she—for, of course, we are dealing with the female—may be
seen running about the ground, and eagerly searching the various plants
and grasses that come in her way. Occasionally, as though in lightness
both of heart and body, she gives a leap off the ground, and at other
times will fly up from it more deliberately, to make an examination of
some overhanging leaf. At last, as a result of these little aerial
excursions, let us say, she knocks down a certain green caterpillar of
the kind wanted, and with maternal devotion full upon her, at once sets
to work. The caterpillar, however, though taken by surprise, and
assaulted the instant it has touched the ground, resists strenuously, as
though instinctively knowing, and highly disapproving of, the fate in
store for it. It is larger and more bulky than the wasp, and its
contortions are so powerful that the latter is several times repulsed in
her assaults. She is not discouraged, however, but continues
perseveringly to fly at the caterpillar, till at last she takes it at a
disadvantage, possibly in a moment of weariness, and alighting with her
long legs on each side of the large, soft body, seizes it by the neck
with her mandibles, and holds it fast. Now the caterpillar, stimulated
doubtless by the painful, or at least unwelcome nip, struggles with
redoubled energy; but it is beneath its oppressor, who, straddling over
it and never relaxing her grasp, lifts it at last, with an effort, a
little from the ground, and inserting her curved abdomen like a fish
hook beneath it, strikes in a more effective and certain way than did
ever the most benevolently contemplative member of all the fishing
fraternity. The result is instantly apparent, for with the entry of that
deadly sting into its body, all struggles on the part of the caterpillar
cease, and it lies a living corpse at the feet of its cruel oppressor.
The latter, after remaining still for some moments as though to give her
victim time to realise and appreciate its situation, stings it again and
then again, each time choosing, as she has done before, for the locality
of the operation, the junction of two out of the dozen or so segments
into which the long length of the caterpillar is divided. Then she flies
up, but after circling a little above the scene of her triumph, she
descends again, and gives her victim, though now helpless and paralysed,
a taste or two more of her quality. The first part of her business is
now done, and well done. She has earned a rest, or rather she may
exchange one form of activity for another. Accordingly she proceeds to
indulge in the pleasures of the toilette, and it is not till this is
completely finished that she flies with, or drags, her victim to the
neat little burial-place, representing also her future nursery, which
she has already provided for it.[87]
The above illustration is taken from the account of a particular case
which fell under the keen observation of G. W. and E. G. Peckham, two
well-known American entomologists. On other occasions, however, this
wasp—that is to say, various individuals of the same species—besides
stinging the caterpillar, went through another and more curious process.
This consisted in biting and squeezing the anterior upper portion—the
neck as we may call it—of their victim.[87] The same operation was also
observed by Fabre when he watched his good mothers, but though I have
called it biting and squeezing, that is not the right term for a
_savant_ to employ. _He_ calls it malaxation, which, perhaps, means
doing both at the same time. Biting, however, would seem to imply no
less, but, perhaps in order to bite scientifically, it is necessary to
take a piece out, or at least to make the blood come, though in common
parlance this does not, or did not, hold good, since Sampson bit his
thumb at Abram and Balthasar, in the first scene of _Romeo and Juliet_,
but it cannot be supposed—nor does the context support such a view—that
he bit it so hard as that. Malaxation, however, let it be; but why such
a process on the part of the wasp should be necessary it is not easy to
see, since the mandibles are not poisonous like the sting, and the
latter is all in all sufficient to produce the paralysis required, as is
apparent in the instance already given, where the sting alone was
employed. To me it seems possible that this malaxation may be a
happiness to the wasp merely, as the shaking of a rat certainly is to a
terrier, whatever other advantages accrue from it. That insects, like
other animals, including man—who, indeed, is the crowning instance—take
a savage pleasure in overpowering and killing their prey, I have myself
very little doubt.
We have seen that this wasp stung the caterpillar between the segments
of its body, and, as we will assume—for the result seems to warrant the
inference—in the central part of it, so that the sting, entering the
great nervous cord or ganglion, which is situated in this region, with
little swellings at each of the segmental rings, produced the described
paralysis. It was Fabre’s view that this must always be the case, and he
thought likewise, in accordance with his own observation, that the
caterpillar received a sting at the junction of all or nearly all the
segments of its body. Otherwise it would be imperfectly stung, and in
consequence not sufficiently paralysed to prevent its struggling, and so
detaching the young larva, or perhaps the egg, which, as it would seem,
is laid on, and not inside, the body of its living provisions. On the
other hand, were the caterpillar stung too severely, so as to be killed
outright, the grub when hatched would only have putrid meat to feed
upon, and this again, it was assumed, would be fatal to its existence.
On these grounds Fabre concluded that we had here an instinct which must
have been perfect from the beginning, since as anything short of such
perfection would be followed by the death of the larva, those gradual
steps by which, on the theory of natural selection, all excellence
either of structure or instinct has been attained, could not in a case
like this have had any existence.
But all this has been exploded by subsequent observation. What Fabre saw
he knew, but in all that he inferred without seeing he was entirely
mistaken. As observed by the Peckhams, a caterpillar may be either stung
so slightly as to be quite lively, and yet not succeed in shaking off
the wasp larva hatched on its body, or so severely as to die almost
immediately, yet without detriment to the larva who feeds on its
discoloured and more or less putrified body, with the same gusto, and
apparent benefit, as though it were warm with life.[87] Thus the
question seems not so much to be, how can such perfection of instinct as
was observed by Fabre have been attained through the process of natural
selection, as why it should have been attained; or perhaps we may even
go further and ask if this supposed perfection exists at all, and
whether Fabre did not deceive himself. A wasp having secured a
caterpillar is, of course, at liberty to sting it as often as it
pleases. Why, then, should one wasp behave quite like another one in
this respect? Here, as elsewhere, there would be some amount—perhaps a
considerable amount—of variation in individual disposition, and wasps of
milder or less savage mood would sting less frequently than their
fiercer fellows. There might, therefore, as it appears to me, be a large
amount of fluctuation both in the number and degree of severity of the
stings—if indeed there is any regulation in this respect—and also in the
consequent injury to the caterpillar or other insect, without any
particular scope being offered for natural selection to play a part.
What room, indeed, for such a force can there be if it makes no
difference to the wasp-grub whether the caterpillar which is to be its
food, is stung badly or slightly, or whether it lives or dies?
That this is really the case seems to be implied in the following
paragraph which I quote from the same interesting work that I have
before referred to[87] “The conclusions that we draw from the study of
this genus differ in the most striking manner from those of Fabre. The
one pre-eminent, unmistakable, and ever-present fact” (the invariable
fact, as one might say) “is variability. Variability in every
particular—in the shape of the nest and the manner of digging it, in the
condition of the nest (whether closed or open) when left temporarily, in
the method of stinging the prey, in the degree of malaxation, in the
manner of carrying the victim, in the way of closing the nest, and last
and most important of all, in the condition produced in the victims of
the stinging, some of them dying and becoming ‘veritable cadavers,’ to
use an expressive term of Fabre’s, long before the larva is ready to
begin on them, while others live long past the time at which they would
have been attacked and destroyed if we had not interfered with the
natural course of events. And all this variability we get from the study
of nine wasps and fifteen caterpillars”![87] Fabre’s ideas therefore
seem totally disproved, but though natural selection—the counter-theory
to his own—has no doubt produced the _Sphex_ and _Ammophila_, with their
habit of stinging and storing caterpillars, to serve as food for their
young, it does not follow that it has done anything more than this; for
though variation be the stuff in which natural selection works, it need
not always work in it—any more than a tailor need always make clothes
because there is an abundance of cloth.
------------------------------------------------------------------------
[Illustration: SOLITARY WASPS]
In the upper part of the picture a solitary wasp is seen
attacking a caterpillar on a leaf. Beneath is another of the
same species busy pounding the entrance to its burrow with a
pebble.
In the digging and closing of her burrow—her nesting-habits, as we may
call them—our _Ammophila_ is almost as interesting to watch as in her
mode of proceeding with caterpillars, though here a certain well-known
stimulus to human enjoyment which I need not enlarge upon is wanting.
Having found a convenient spot for her nursery, she digs, with her
mandibles and front pair of legs, a little tunnel in the ground, to
about the length of her own body, and at the end of it hollows out a
round chamber or cavern just large enough to make comfortable quarters
for a pair of invalid caterpillars—a hospital for incurables, we may
call it to begin with, but soon to become their tomb. Having dug to
about her middle, the wasp backs out, with a little pellet of collected
earth held firmly in her mandibles. With this she flies to a little
distance and then, letting it drop, alights on the ground and takes a
little rest before returning to continue her work. She may either fly or
run back, for her legs are as highly developed as her wings—she is in
fact a very perfect athlete. The process of excavation is now continued,
there is more burrowing, more flying away with the earth dug out, and
before long the nursery-vault is completed. The next thing is to find
caterpillars for it, but before flying away to look for one, _Ammophila_
carefully conceals the entrance to her tunnel with pellets of earth,
which she often brings from a distance, and will not be satisfied with
unless they seem well adapted for their purpose. At last, when the
aperture is both blocked and hidden, she starts off upon the still more
important undertaking which has been already described, and after a
longer or shorter interval—if her quest is successful—returns with a
nicely stung caterpillar. As two are required there must be another
journey and another stopping up of the burrow, before the final one,
which is of a more solid nature, occupying, sometimes, as much as twenty
minutes. In thus bringing her labours to a conclusion, _Ammophila_ often
shows a wonderful degree of intelligent foresight—foresight we must term
it if we admit the intelligence; for sometimes she will drag a leaf over
the entrance to the tunnel, though now filled in, or taking a stone as
large as her head in her mandibles, will pound down the earth with it to
make it firm and compact.[87]
It used to be said—and may be still by that large class of people who
are for ever making false parallels and artificial distinctions—that man
was the only animal that made intelligent use of an instrument, but
Darwin instanced a monkey cracking a nut with a stone, and an elephant
breaking off a bough to fan itself with. Here, in an insect, we have a
case which is perhaps even more to the point—more extraordinary, that is
to say; for certainly the idea of flattening and pressing down earth
over a general surface, and of taking something to do it with, seems a
little less obvious than that of cracking a nut, in a similar manner,
and therefore to require more thought in the planner of such a process.
No wonder that the delighted witnesses of this interesting fact flung
themselves on the ground on each side of the unconscious inspirer of
their wonder, in order to have a better sight of it; but that a previous
observer of the same thing should have waited a year before publishing
what he had seen, because he feared such a statement would not be
believed,[87] is to my mind a display of prudence almost as wonderful,
though not nearly so edifying, as that of _Ammophila_ herself. If we are
not to make known what we see, because people who believe in their own
and nobody else’s eyesight are not likely to credit it, how is evidence
to accumulate for the benefit of the more intelligent part of the
community? It is only of this small minority that we should think, or,
rather, we should not think of anything but the truth, where truth is
concerned.
Returning to bees of the solitary kind, “the operations of the
wood-piercers,” says Bingley, “merit our careful attention.” They shall
have it for a moment, but space is against them. However, the female of
the species, _Xylocopa violacea_, which for some reason is disliked by
householders, bores in the springtime, by the aid of her strong
mandibles alone, neat little circular tunnels in such objects as
garden-seats, gates, front doors, arbours, window-shutters, rustic
tables, and the like. At first, it is stated, she “bores
perpendicularly, but when she has advanced about half an inch she
changes her direction, and then proceeds nearly parallel with its sides
for twelve or fifteen inches. If the wood of the seat, door, table,
etc., be sufficiently thick, she sometimes forms three or four of these
long holes in its interior, a labour which for a single insect seems
prodigious, and in the execution of it some weeks are sometimes
employed. On the ground, for about a foot from the place in which one of
these bees is working, little heaps of timber-dust are to be seen. These
heaps daily increase in size, and the particles that compose them are
almost as large as those produced by a hand-saw.”[88] When the tunnels
are finished, the mother bee divides them into some dozen little rooms
about an inch deep, making the divisions of wood-dust, which she cements
together by aid of a glutinous secretion with which she is furnished.
Before each cell is closed it is filled with a paste composed of the
farina of flowers, mixed with honey (it makes one envy the grub), and an
egg is deposited in it. As each cell takes some time to make and
provision, it is obvious that the egg in the lower one will hatch a
little sooner than the one above it, and so on right up to the top. If,
therefore, any one of the larvæ “were to force its way upwards, which it
could easily do, it would not only disturb, but would infallibly destroy
all those lodged in the superior cells.”[88] Here, however, natural
selection (called Providence in Bingley’s time) steps in, and “has
wisely prevented this devastation, for the head of the nymph
(chrysalis), and consequently of the emerging bee, is always placed in a
downward direction.”[88] Of course, therefore, the insect moves forward
in the direction towards which it looks at birth—its new birth, that is
to say; and, moreover—this is the really astonishing thing—“the mother
digs a hole at the bottom of the long tube, which makes a communication
between the undermost cell and the open air. By this contrivance, as all
the bees instinctively endeavour to cut their way downward, they find an
easy and convenient passage, for they have only to pierce the floor of
their cells in order to make their escape, and this they do with their
teeth very readily.” As regards this communicating passage, however, it
is presumably a mere continuation of the tunnel, and was probably once
occupied with cells, like the upper portion. Why the lower end of the
tunnel should have come in time to be left empty—what advantage, that is
to say, its being so represents—it is not easy to see, but possibly it
stood in danger of being reached by a bird’s beak, through what has now
become the exit of escape merely.
As there is a leaf-cutting ant, so, too, there is a leaf-cutting bee,
but here the resemblance ends, since no thought of food or fungus enters
the mind of the latter insect. Her more simple and direct object is to
make the severed leaves into cells, and this she does with wonderful
skill and ingenuity. The cells, which are made by rolling the pieces of
leaves round within a tunnel or gallery, previously excavated in the
earth, are separated from one another by a circular piece, which fits
into the tube with extreme nicety, making at once the ceiling of each
lower compartment and the floor of that above it. As each is finished
the bee, as in the other instances, fills it with a mixture of honey and
pollen, upon which she then lays an egg, and finally closes the mouth of
the tunnel. The leaf principally used for the manufacture of these
pretty cradles is the rose leaf, and the paste which fills them is of a
rose-red colour, owing to the pollen having been collected for the most
part from thistles.
The children of the leaf-cutting bee, therefore, are delicately housed,
but what are they, in this respect, to those of the poppy or tapestry
bee, who are born like the Byzantine princes in a “purple[89] chamber”
made of the rich leaves of poppies? Here they lie, or crawl, in state,
one to each royal apartment, which is filled, almost to the brim, with
the sweet food of bees. Yet when they come forth, at last, it is not as
gorgeous imperial creatures clothed in “purple and pall,” but only
little ordinary-looking black bees covered all over with dirty grey
hair. And their beautiful purple poppy chamber has been seen by no
one—not even by themselves probably—buried as it is full three inches
deep in the earth. Wallace, somewhere in his _Malay Archipelago_,
moralises over the beautiful little kingbird of paradise, sparkling out
its life amidst the forest solitudes of a remote island, unseen by human
eyes, save those of savages, till once or twice, perhaps, in a century,
some wandering white man, who alone is capable of appreciating its
beauty, comes to bang its life out and bear away its skin. The thought
of this dainty little crimson-tapestried bower lying in black darkness,
like a grave beneath one’s feet, rouses a similar train of reflection in
the mind, but perhaps it would do so more strongly were it associated in
the same degree with ideas of sport or profitable collecting.
The carding-bee is interesting, not so much for the nest which it makes,
as for the wonderful way in which it makes it—or, to express it more
justly, it is more especially interesting on this account. Having either
made or found a suitable cavity, these bees under-roof it with a thick
thatching of moss. To carry this, bit by bit, to the place, would take
them a very long time, so, instead of doing so, they stand one behind
another, with their backs toward the nest, in a line that reaches from
the moss to its entrance. The furthest bee then pulls out a piece with
her mandibles, cards it with her fore feet, and, with the others, passes
it on, beneath her body, to the second bee, who passes it to the third,
the third to the fourth, and so on, all down the line, the last bee
entering the nest with it. Thus these bees do with moss exactly what
rats have been seen to do with eggs, when transporting them to their
burrows. A most interesting anecdote of this is quoted by Romanes,[90]
from Jesse’s _Gleanings_, but it does not appear to be in my edition,
which I had thought was a complete one. All I can find is a bare
reference to their having been known to “convey” eggs from a box, in
this way—“convey the wise it call.” This is an annoying discovery, for I
detest all selections, not made by myself, from Palgrave’s _Golden
Treasury_ to any man’s “Hundred Rest Books.” But if my edition _is_ a
complete one, then the thing should be looked into, for the anecdote
quoted by Romanes is not there—at least it is untraceable through the
index.
Like ants, bees are subject to parasites, and as some belonging to the
former are ants themselves, so with bees we have the same thing, but
developed to a still more striking extent; for there is no ant that I
know of that lives with another which it so closely resembles that the
latter is unable to distinguish it from itself. Such bees, however,
there are. Some of our humble bees, for instance, go through life thus
attended by a double whose existence it never for one moment suspects.
The two, indeed, are linked in the closest bonds of social intimacy.
Together they leave the nest, together they fly from flower to flower,
together they re-enter it. Together, too, they seem to glow in
industry—to emulate each other’s toil. But all the while that the true
industrious bee is collecting pollen and nectar the double is only
pretending to do so—or rather, let us say, seeming—and whilst the former
bustles about, feeding the larvæ and making the cells, the latter only
bustles about, like the shadow of a busy person on the wall. But when
the true bee lays an egg, the double lays one too, almost at the same
moment, and in the very same cell. Both are then hatched, together, and
the two larvæ grow up in the same cradle, nourished by the same food,
make their transformation side by side, and so creep forth into the
nest. The two, as I say, are hardly to be distinguished one from
another, yet all the while one is a real true-hearted humble bee, and
the other a mere show, a stage make-up, an outer shell without any of
the proper qualities inside. And the best of the joke is, that,
probably, the false or cuckoo bee, as it is called, is as much deceived
as its foster relatives, and imagines itself a good honest sterling
member of the community. It is forced by nature to cheat, but the fraud
is unconscious, and the impostor is imposed on in its turn.
Thus in the insect world we have something which can only be brought
about, amongst ourselves, through a conscious disguise, by means of
wigs, false moustaches, etc.—what we call an impersonation—but here is a
life-long impersonation which costs the “born actor” no trouble. Why is
this? What is the meaning of it? Why should one bee—or any other insect
or creature—look just like another one, and yet have a Latin name of its
own, which the other has no right to? Why should the individuals of one
species be hardly more like each other than they are like the
individuals of another species, even though—as is often the case—these
two species are widely separated in the system of nature? Such are the
questions to which a consideration of these cuckoo-bees, as they are
called, give rise. They will be answered, if at all, in the following
chapter.
-----
Footnote 86:
Fabre, Insect Life, pp. 275-283.
Footnote 87:
Peckham, The Instincts and Habits of the Solitary Wasps.
Footnote 88:
Bingley, Animal Biography.
Footnote 89:
The real purple of the ancients was a rich red—crimson or vermilion.
Footnote 90:
Romanes, Animal Intelligence, pp. 361, 362.
------------------------------------------------------------------------
CHAPTER XIX
Natural selection—Protective resemblances—A locust’s
stratagem—Mock leaf-cutting ants—Flowery dissemblers—A Malay
explanation—Snake-suggesting caterpillars—A prudent
lizard—Inconclusive experiments—A bogus ant—Flies that live
with bees—A caterpillar that dresses up—A portrait-modelling
caterpillar.
EVERYBODY knows nowadays how all the different species of animals and
plants, living and extinct, have come into existence. It was quite
simple. All they had to do was to keep on varying. Some of them varied
in a way that was good for them, some in a way that was bad. The latter
died, but the others increased and multiplied, and as the process was
always going on, and it is impossible to vary long without becoming
changed, it happened that creatures which had started with a certain
appearance got in time to have quite another one, so that they would not
have been recognised by the people who used to know them, if these same
people had kept alive. However, as the process was so slow that it took
millions of years, and is still going on, awkward things of this sort
never happened, and so, as nobody had ever seen one species of animal
change into another before their eyes, they found it difficult to
believe that they ever had done so; for the ordinary person says
“seeing’s believing,” though he believes in all sorts of things that
neither he nor anyone else ever has seen, or is ever likely to. Still,
for all that, he thinks his own eyesight must be better than anyone
else’s.
This process of eternal change, with the changes for the better
surviving, and those for the worse dying out, is what is called natural
selection, and if we understand it—as there are few now who do not—we
can understand this, that if any kind of creature is so strong and
formidable that it would be an advantage for weaker creatures to be
mistaken for it, then it is not at all unlikely that some of these
weaker creatures will get more and more to resemble it, until at last
they are so mistaken. For instance, our common wasps, who are armed with
a formidable sting, and are very skilful in using it, are not attacked
by any other insect, excepting hornets, which are not common. Any fly or
moth, therefore, that resembles a wasp will be generally left alone, and
the more so the more it resembles it. Accordingly we do find flies and
moths that look very like wasps, and live safely in consequence. Still
more would it be of advantage to look like a hornet, and there is a moth
so like one that it is called the Hornet-clear-wing.
On this same principle of being mistaken for something that is safe from
attack or annoyance, all sorts of animals, and in a special degree
insects, have come to look like various objects around them, and amidst
which they live, such as stems of grass, pieces of moss or stick,
leaves, flowers, and so on—some of the resemblances being more special
and extraordinary. These are things which, though the eye may see, it
does not as a rule dwell upon, because there are so many others round
about. Who, for instance, would look at any particular blade of grass?
So a bird that would pounce down upon an insect that it saw moving
amongst the leaves of a tree, if there was no doubt that it was an
insect, would not take any pains to examine what only looked like one
leaf amongst many.
Thus, throughout nature we have these curious resemblances of certain
creatures to certain other creatures, or to the plants or inanimate
objects around them, but it is principally amongst insects that the
phenomenon is met with, probably because they increase and multiply so
quickly that there has been more time both for the laws of inheritance
and for the great controlling one of natural selection to have come into
play. Whatever is the reason, there is no doubt about the fact, which
will be best illustrated by one or two salient instances.
Ants, though they fall a prey to various animals larger than
themselves—such as birds or ant-eaters—yet in their relations with other
insects occupy a position of comparative safety, on account of their
weapons and pugnacity, and, still more, of their numbers. The driver
ants of equatorial Africa, and their South American representatives, the
_ecitons_, are indeed, when they set out on their foraging expeditions,
the terror, not only of insects, but of all animal life. “Wherever they
move,” says Bates, referring to the latter, “the whole animal world is
set in commotion, and every creature tries to get out of their way.”[91]
This, however, as they climb trees, and send out encircling columns
which enclose a considerable extent of ground, is difficult, or rather,
impossible, for all such as cannot fly some distance without alighting;
for if an ant or two once seize upon them all is over. An insect,
therefore, that cannot evade the onset of such an enemy is lucky if it
has some such means of ensuring its safety as has been above referred
to. One at least thus specially favoured inhabits Nicaragua. “I was much
surprised,” says Mr. Belt, “with the behaviour of a green leaf-like
locust. This insect stood immovably amongst a host of ants, many of
which ran over its legs, without ever discovering there was food within
their reach. So fixed was its instinctive knowledge that its safety
depended on its immovability, that it allowed me to pick it up and
replace it amongst the ants without making a single effort to escape. It
might easily have escaped from the ants by using its wings, but it would
only have fallen into as great a danger, for the numerous birds that
accompany the army of ants are ever on the outlook for any insect that
may fly up, and the heavy flying locusts, grasshoppers, and cockroaches
have no chance of escape.”[92] This locust resembled a green leaf which,
as we have seen, was a very protective resemblance indeed. It might,
however, had it been a smaller insect, have resembled one of the ants
themselves, and in that case could have run about with them, pretending
or appearing to forage, also with perfect impunity. Whether the _Eciton_
has such a double I know not, but various ants have. With some it is a
spider that assumes their form. With others, as we have seen to a
partial extent, a caterpillar, but the _Sauba_, or leaf-cutting
ant—which is also the mushroom-growing one—is understudied, leaf and
all, by an insect which, though the order to which it belongs has been
determined, has not yet apparently received a name. “An example,” says
Professor Poulton, “of protective mimicry, which I believe to be more
wonderful in its detail and complexity than any which has been hitherto
described, was observed and interpreted by my friend Mr. W. L. Sclater,
in 1886, during his investigations in British Guiana. Mr. Sclater and
his native servant had been collecting insects by shaking the branches
of a tree over a sheet. The servant, although described as a very acute
observer, saw an insect on the sheet which he mistook for one of the
abundant Cooshie ants (perhaps the native name), carrying its little
jagged segment of leaf over its back. Mr. Sclater looked more closely,
and saw that it was an entirely different insect belonging to the order
_Homoptera_. Its length was about that of an ant carrying its leaf. The
leaf was represented by the thin flattened body of the insect which in
its dorsal part is so compressed laterally that it is no thicker than a
leaf” (or as we would say, which along the back is no thicker than a
leaf), “and terminates in a sharp, jagged edge. The head and legs were
brown, and suggested the appearance of that part of an ant which is
uncovered by the piece of leaf. The jagged dorsal line, when seen in
profile, evidently corresponds to the roughly gnawed edge of the
fragment of leaf, for Mr. Sclater tells me that the contour of the
latter is generally shaped by the mandibles of the ant rather than due
to the natural margin.”[93]
The above-mentioned insect is a dweller in trees, and one might have
supposed that a general resemblance to the leaves among which it moves
would have been a sufficient protection for it. This probably was the
beginning of the deception, which became more complex as time went on.
In the leaf-like back of the insect we see probably the original
disguise, but as the eyes of birds became more acute they began to
pierce through it, more especially when the creature walked. Round about
the would-be leaf, however, the leaf-cutting ants—distasteful to the
birds that so affected it—were constantly moving and walking. If only it
could get to resemble one of these it might be as active as it pleased,
and especially if its motions, as well as its appearance, became ant- or
ant and leaf-like. And this, indeed, was what gradually began to take
place. Variation was always going on, and natural selection was always
at hand to mould and shape its results. The two insects were, to begin
with, of much the same size, and the general leaf-like appearance of the
one was a good basis on which the more particular resemblance to the cut
piece of leaf, carried by the other, might be founded. A few deeper
washes of brown, some not very profound modifications of contour, and an
ant-suggesting legs and body began to appear beneath it. Meanwhile,
however, hundreds of thousands—nay, millions—of bad or mediocre copies
were swept away, the species became rarer and rarer—trembled, perhaps,
on the verge of extinction; but just when it might have appeared to the
birds, who were no longer able to obtain a once much-enjoyed morsel,
that it really was extinct, it was saved; nature’s object had been
gained. A certain number of individuals were left, were close at hand
even; even now, at that very moment, one might be crawling on the same
twig where a despondent bird sat, only it was not to be distinguished
from a leaf-cutting ant. Such are the ways of nature, such the slaughter
that attends her victories.
In Borneo, and the Malay Archipelago generally, there is a pretty pink
flower known as the “Straits Rhododendron.” Once a gentleman was looking
at one of these flowers and admiring it, when all at once it turned
round and stared him in the face. It was not a flower, but a mantis; its
flattened legs—pink like them—made the petals; its abdomen, turned up
over the back and held thus motionless, resembled an opening bud. “When
I held the branch on which the insect had established itself in my hand
I could not tell exactly where animal tissue commenced and where flower
ended, so perfectly was the one assimilated to the other, both in colour
and surface-texture.”[94] When once established on a flower this mantis
would remain there quite motionless, if undisturbed, until it had
occasion to leave it; and of course, in nature, had any insect settled
on or near it, it would have instantly been seized. The ways of the
mantis are well known. “Under a most sanctimonious aspect,” says Fabre,
speaking of the little green one of Provence, “it hides the morals of a
cannibal”;[95] and, indeed, the female, which is larger and stronger
than the male, will often turn upon the latter and devour it in the very
midst of a love-passage. This it does, as in all other cases, by
suddenly launching forward one or both of its fore-arms—which have been
previously held in an attitude of prayer—and enclosing the body of the
victim between their first and second segments, each of which is toothed
along the edge like a saw. The double row of teeth meet in the body,
which, held aloft, and writhing on either side of the trap, is devoured
piecemeal by the mantis, who, with its sharp jaws, tears little
mouthfuls out of it as long as it, or its appetite, lasts. This process,
made more interesting by the way in which it was brought about, was
witnessed in the case of the above-mentioned species. Small flies
frequently settled upon it as it sat motionless, flower-like amidst
flowers. “These it made no attempt either to drive off or to capture;
its motions seeming rather to attract than repel them. After a short
time a larger _Dipteron_, as big as a common house-fly, alighted on the
inflorescence within reach of the predatory limbs. Then the mantis
became active immediately; the fly was seized, torn in pieces, and
devoured.”[96] Such are the real propensities of the seeming flower, and
such, too, it may be observed, are those of some actual flowers—to wit,
insectivorous ones.
To the Malays, however, whose minds are not yet open to the doctrines of
protective or aggressive resemblance, or to evolution generally, this
mantis _is_ a flower, they “know not seems.” The blossoms of “the
_sendudok_” have become alive, and perhaps some analogies suggested by
their own life-experience temper their surprise at such an apparent
change of disposition. They say, too, that few men ever see more than
one flower-mantis in the whole course of their lives, so rare a creature
is it. In this, no doubt, they are right; yet it would be possible,
perhaps, even for a Malay to see several without knowing anything about
it. Native eyes are almost always sharper and better than those of the
Europeans who come amongst them; but, on the other hand, no native goes
about like a modern entomologist, with his eyes specially open in one
direction and the possibilities of protective resemblance in his mind.
The same naturalist, during the same expedition, was singularly
delighted to secure a larva, whose resemblance to a snake was “so
startlingly accurate that I was, for a moment, completely deceived.”[96]
A description follows which, as it is of that kind which deals longly
and learnedly in details without producing any particular general
effect, may be left out. It would seem, however, that this caterpillar,
like many others, has the power of withdrawing its actual head into a
fold or two of its skin, which is here so marked that it performs the
office of a mask, obscuring and taking the place of the real head thus
obliterated. The mask is furnished with two spots, which at once become
the creature’s eyes, and both in colour, shape, and general appearance
bear a remarkable resemblance to those of a snake; whilst a wrinkled
fold, running back on either side from what appears to be the snout,
suggests the mouth, and the flattened head with its characteristic
arrangement of broad, flattened scales is also indicated by certain
markings and colours on the required part of the caterpillar’s body. An
apparent head like this, thrown suddenly up as though threatening to
dart forward with a hiss and distended jaws, might alarm anyone, and
such a mock demonstration is evidently required to give full effect to
the disguise. Thus we are told that “when the larva was moving about
with the anterior segments well expanded the resemblance to a snake was
not so startling; but directly it was touched the terrifying attitude
was assumed, the anterior segments being drawn in and the front of the
body turned towards the aggressor. When, at the same time, the hinder
part of the body was hidden by leaves the deception became complete, and
if effective enough to deceive, even temporarily, a human being, it must
surely be equally effective in deterring less highly organised and timid
foes.”
For the “timid” certainly, but for the “less highly organised” the
conclusion does not seem so plain. No sight is better than a bird’s,
and it is practice that makes perfect in any particular direction.
Still, unless we suppose the disguise to be accidental merely—and this
no one with a knowledge of the whole subject can do—the object of it
seems clearly apparent, and we may, therefore, assume that, on the
whole, it is successful—to the extent, at any rate, of keeping the
species in existence. In such matters, however, there is nothing like
practical experiments, if one has the chance of making them, as the
finder of the caterpillar in question must have had, since he says,
“Unfortunately I was unable to test the efficacy of the disguise, for
fear of losing the larva, which I was anxious to rear for the purpose
of identification.”[96] To me this appears a false judgment. Such a
test would have been much more interesting, surely, especially if
resulting in the way anticipated, than a dry pinned specimen and a
Latin name.
Another large snake-resembling caterpillar was found by Bates in the
forests of Brazil, and the likeness was sufficiently striking to alarm
several people to whom he showed it. But it is not necessary to go so
far afield, for here in England, according to Professor Poulton, we have
an excellent example of this kind of protective resemblance. This is no
other than the caterpillar of the elephant hawk-moth, which by
withdrawing its head into its body—just as does the Bornean
species—produces a similar false face, with a pair, or, indeed, two
pairs of fierce-looking eyes.[97] This caterpillar feeds on the great
willow herb, and when at rest keeps amongst the dead brown leaves at the
base of the stem. “As soon,” says Professor Poulton, “as the leaves are
rustled by an approaching enemy, the caterpillar swiftly draws its head
and the three first body-rings into the two next rings, bearing the
eye-like marks. These two rings are thus swollen, and look like the head
of the animal, upon which four enormous, terrible-looking eyes are
prominent. The effect is greatly heightened by the suddenness of the
transformation, which endows an innocent-looking and inconspicuous
animal with a terrifying and serpent-like appearance.”[98]
With this caterpillar, since naturalists know what to call it, and there
is no chance of its handing down any of their names in Latin to
posterity, it has been possible to make experiments, and on the whole
perhaps they have been in favour of the protective resemblance theory.
The most interesting one—that I have read, that is to say—was made by
Professor Poulton with a full-sized green lizard, and is thus described
by him: “The lizard was evidently suspicious, and yet afraid to attack
the caterpillar, which maintained the terrifying attitude in the most
complete manner throughout. The lizard kept boldly advancing, and then
retreating in fright; but at each advance it approached rather nearer to
the caterpillar. After this had taken place many times and nothing had
happened, the lizard grew bolder and ventured to gently bite what
appeared to be the head of the caterpillar; it then swiftly retired, but
finding that there was no retaliation it again advanced and gave it a
rather harder bite. After a few bites had been given in this cautious
manner, the lizard appeared satisfied that the whole thing was a fraud,
and devoured the caterpillar in the ordinary manner.”[98] Professor
Poulton has no doubt as to the lizard having been alarmed at first by
the appearance of the caterpillar, and adds that he has never seen one
act in the same way on any other occasion; other large hawk-moth
caterpillars being eaten at once with entire _sang-froid_. It may be
observed, however, that if every lizard were to act in the way recorded,
under natural conditions, the advantage to the caterpillar would be nil,
since though a species may survive through not being eaten, it certainly
will not through being eaten with hesitation. And why should a lizard be
more timid in the open air than in a box or a fern-case? Unless we
assume, therefore, that this particular one was bolder than most others
would be, the result of the experiment was not for, but against, the
theory it was designed to test; and since we have no business to assume,
the only thing to do is to get more caterpillars, and give them to more
lizards. Small birds, however—and this in a country like England is more
to the point—seem really to fear these pseudo-snakes to the extent of
flying away from them.[99] But would an ordinary large caterpillar of
the _Sphingidæ_—say, of a privet hawk or death’s-head moth—frighten them
in the same way? If so, then again we are nowhere.
Perhaps a still more extraordinary instance of protective resemblance
than any of the foregoing is that of a caterpillar which pretends to be
an ant—one provided with an efficient sting, and of an irritable
disposition. Here, as in the snake cases, it is by one portion of the
body only that the fraud is perpetrated, but this, instead of being the
front, is the hind part, in which, perhaps, it offers a unique example
of the sort. The colour of the caterpillar is exactly that of the ant,
and whilst its extremity represents the latter’s head, two black spots
which are there situated bear an equally close resemblance to the eyes.
The jaws are represented by the last pair of false legs or claspers,
which are of disproportionate size, and can upon occasion be stretched
widely apart, whilst a number of thin, tentacle-like processes, attached
in pairs to the segments of the body, have all the appearance of an
ant’s legs and antennæ. Armed with these properties, which, however, in
a state of quiescence are not very recognisable, the caterpillar waits,
as one may say, to have its feelings ruffled, when, by flinging the
hinder part of its body into the air, each separate appurtenance begins
at once to act the part assigned it, and the whole becomes a startling
make-up. The head, with eyes, is jerked from side to side, the jaws
gape, the legs move, the antennæ quiver, and an angry, threatening ant
starts, as by magic, into being. “When,” says Mr. Annandale, “the
caterpillar is seen in an end-on position, or when the anterior
two-thirds of the body are hidden, the resemblance is positively
startling,” so that “it is difficult to imagine how a lizard or a frog
with a previous experience of the ant could fail to be deterred.”[100]
In the light of the above cases, that of the cuckoo-bees does not seem
so very wonderful, since both the species are bees, and all or most of
the members of any group or family of animals as a rule bear some
resemblance to one another, since they descend from a common and not
very remote ancestor. Many flies, however, have almost as close a
resemblance to various bees and wasps, whilst one of the latter is even
the model for a species of cricket, which would otherwise fall a victim
to it and others of its family. There is a beetle, too, so like a wasp,
not only in its appearance, but in the way in which it runs about and
moves its antennæ, that anyone almost would be taken in. Whether, under
this disguise, it enters wasps’ nests and preys upon the larvæ, as the
bee-like _Volucella_ flies enter the nests of the humble-bees they
imitate, I do not know, nor, I think, does anyone, but this might very
well be the case. These flies, however, now I come to think of it, do
not really injure the bees. It used to be the idea that they did, but
lately it has been discovered that they are only scavengers, feeding on
all the waste products of their hosts, and even on their dead bodies
should such opportunities arise.[101] The humble-bees, on their part,
seem to appreciate these services, though we are not entitled to say
that they admit the flies into their nests on this account, since they
probably do so owing to their likeness to themselves.
Of the walking-stick insects, which are hardly to be distinguished, even
with close attention, from the grass or twigs on which they cling,
everyone has heard or read, and the caterpillars, common enough in
England, which remain motionless, projecting like a twig from its stem,
and looking just the same as one, are almost as good instances of
unconscious deception. But neither these caterpillars, nor any of the
other insects that have been mentioned, do anything, except through the
attitudes they assume, to produce their wonderful disguises. They have
nothing to do with the cutting out of the material. They do not dress up
for the part themselves. That, however, is what some caterpillars do.
There is one, for instance, in Borneo, that has a number of spines
arranged in pairs down its back, and on each of these spines it fixes
several little buds of the plant on which it is feeding, such buds, and
not the leaves of the plant, being the actual food it eats. Consequently
the caterpillar, which is quite a small one, looks like a spray of tiny
buds itself, and can hardly, by possibility, be noticed amidst its
flowery chaplet. The buds are not impaled on the spines, as might be
supposed, but are attached to them with silk, which the caterpillar
weaves for the purpose, and the whole process of the thing has been
observed by the gentleman who gives the account, and who is no less
competent a person than the curator of the Sarawak Museum. This is what
he says: “A bud would be shorn off with the mandibles, then held in the
two front pairs of legs, and covered all over with silk issuing from the
mouth of the caterpillar. The caterpillar then twisted the front part of
its body round, and attached with silk the bud to one of the spinous
processes, and another bud would then be attached to this, and so on
until a sufficiently long string—generally three or four buds—was made,
when operations on another spine would be commenced. The caterpillar fed
on these buds, scooping out the interior, and when not hurried, using
the empty shells in preference to whole buds for its covering. When
irritated it curled up, and remained thus for fifteen or twenty minutes.
At other times it would sway about, looking like a branchlet blown by
the breeze.”[102]
In time this caterpillar made “a silk cocoon covered with buds,” but it
never turned into a butterfly, for ants attacked it, and its life was
nipped in the bud. It appears to be a very rare caterpillar, and nobody
knows what butterfly it belongs to, or what is its full Latin name.
Since it is a _Geometer_, however, why not _Geometer ignota_ under a
sketch (as given in _Nature_, June 25th, 1903), in the cabinet—which
would, in all cases, be the better plan?
I really do not know whether this or another caterpillar of South
America be the more extraordinary, for if the one makes itself like
something, the other makes something like itself. _Anæa_ (_sp?_)—I give
the name as I find it—is a little green caterpillar having a very funny
nondescript sort of shape—as much like a little piece of gnawed-out
leaf, left hanging to the midrib, as anything else. Such an object,
however, is not one of the common ones of nature, and if it stood alone
might be unrecognised or misinterpreted. The caterpillar, therefore,
feeding along the midrib of the leaf, gnaws out a number of such little
pieces, more or less like itself, and leaves them sticking upright along
it, attached by a point or two. All the rest of the leaf at that part of
the midrib, it apparently eats, or bites away, so that there remains
only the slender, bare stalk, with several bits of leaf upon it, one of
which is the caterpillar. To say which bit is he is now very difficult,
and it looks as if none of them were. This caterpillar is, of course,
green, like the leaf he feeds on, but he is not the same colour all
over. He is light above and dark below, and this exactly suits—I have it
on authority—the chiaroscuro of the situation, so that, both in light
and shadow, he looks for all the world like a little elongated bit of
green leaf attached to the midrib by a couple of stalks.[103] One would
say, “Some caterpillars must have been eating that leaf”; but one would
never think the caterpillar that had been eating it was still there.
-----
Footnote 91:
Bates, The Naturalist on the River Amazon (second edition, 1864), p.
420.
Footnote 92:
Belt, The Naturalist in Nicaragua, pp. 19, 20.
Footnote 93:
Proc. Zool. Society for 1891, pp. 462, 463.
Footnote 94:
Proc. Zool. Society for 1900, pp. 837-69.
Footnote 95:
Fabre, Insect Life, p. 165.
Footnote 96:
Proc. Zool. Society for 1900, pp. 837-69.
Footnote 97:
There are two British species of Elephant Hawk-Moth, the large and
small. The caterpillar of the former has four false eyes, that of the
latter only two.
Footnote 98:
Poulton, The Colour of Animals, pp. 258-61.
Footnote 99:
Leland O. Howard, The Insect Book.
Footnote 100:
Proc. Zool. Society for 1900, pp. 837-69.
Footnote 101:
Leland O. Howard, The Insect Book.
Footnote 102:
Nature, June 25th, 1903.
Footnote 103:
Poulton, The Colour of Animals, pp. 258-61.
------------------------------------------------------------------------
CHAPTER XX
Butterfly resemblances—A living leaf—How spiders trap
butterflies—Butterfly doubles—Suggested explanation—More
evidence wanted—Warning coloration—A theory on trust—A
straightforward test—Advice to naturalists—A strange
omission.
SOME of the most remarkable instances of protective resemblances amongst
insects are exhibited by butterflies, one, perhaps, being the most
perfect existing under nature; however, I only say perhaps. This is the
world-renowned leaf butterfly of Sumatra, and elsewhere in the Malay
Archipelago. Of the great purple emperor family, it is purple on the
upper surface, and gleams like a meteor as it shoots about in the rich,
sun-bathed atmosphere of the tropics, its conspicuousness being enhanced
by a sort of miniature, sharp-pointed swallow-tail, in which the hinder
pair of wings end, and a broad, orange bar, like a sash or scarf of
honour, running right across the anterior wings. It flies boldly and
strongly, and when it descends upon a bush or shrub it is as though a
little purple torch had shot through the foliage; but all at once, even
though you see it come down just in front of you, it has vanished
utterly—the torch has gone out. You may look and look, but unless you
know the trick, and have seen the settling, and never taken your eyes
off the exact spot, you will never find the butterfly, or see anything
more of it until, all at once, it gleams in the air again. For the under
part of the leaf butterfly’s lovely purple wings is like the leaf
indeed—“the sere, the yellow leaf”—with a midrib running down the centre
veinings on either side, a curled tip at the top, a stalk at the bottom,
and everything proper to leaves, but not as a rule to butterflies. All
four wings join in this effect, for being thrown up in the usual way
when the insect settles, the leaf-like shape is thus brought about,
one-half of the under surface being seen on each side in clear profile,
whilst the purple now lies hid within, like the pictures on a folded
screen. As for the body of the butterfly, that is hidden inside the
wings too; the legs are all but invisible, and the two little pointed
swallow-tails, just touching the plant’s stem with their mutual tip,
make the stalk of the leaf. Even on the wall of a room or a curtain it
would seem as though a dead leaf were sticking there; how much more
when, as is always the case, the butterfly flies into some bush or
thicket crowded with dry, brown leaves, and settles all amongst them. It
is not that you don’t see it there that makes you miss it, but that you
see it and scores of brown leaves all about it, every one of which looks
just the same as itself.
------------------------------------------------------------------------
[Illustration: PROTECTIVE MIMICRY]
The picture at the top shows birds pursuing butterflies, while
in the one below the same birds have lost their prey, as the
butterflies have alighted and show only the underside of
their wings, which are practically indistinguishable from
the neighbouring leaves.
To make the matter plainer, in case this is not a very accurate
description, here is the account of an eye-witness: “This species,” says
Dr. Wallace, “was not uncommon in dry woods and thickets, and I often
endeavoured to capture it without success, for after flying a short
distance it would enter a bush among dry or dead leaves, and however
carefully I crept up to the spot, I could never discover it till it
would suddenly dart out again, and then disappear in a similar place. At
length I was fortunate enough to see the exact spot where the butterfly
settled, and though I lost sight of it for some time, I at length
discovered that it was close before my eyes, but that in its position of
repose it so closely resembled a dead leaf attached to a twig as almost
certainly to deceive the eye, even when gazing full upon it.” Then
follows a minute explanation of the imposture. “The end of the upper
wings terminates in a fine point, just as the leaves of many tropical
shrubs and trees are pointed, while the lower wings are somewhat more
obtuse, and are lengthened out into a short, thick tail. Between these
two points there runs a dark, curved line exactly representing the
midrib of a leaf, and from this radiate on each side a few oblique
marks, which well imitate the lateral veins. The tint of the under
surface varies much, but it is always some ashy brown or reddish colour,
which matches with those of dead leaves. The habit of the species is
always to rest on a twig and among dead or dry leaves, and in this
position, with the wings closely pressed together, their outline is
exactly that of a moderately-sized leaf, slightly curved or shrivelled.
The tail of the hind wings forms a perfect stalk, and touches the stick,
while the insect is supported by the middle pair of legs, which are not
noticed among the twigs and fibres that surround it. The head and
antennæ are drawn back between the wings, so as to be quite concealed,
and there is a little notch hollowed out at the very base of the wings,
which allows the head to be retracted sufficiently. All these varied
details combine to produce a disguise that is so complete and marvellous
as to astonish everyone who observes it, and the habits of the insect
are such as to utilise all these peculiarities, and render them
available in such a manner as to remove all doubt of the purpose of this
singular case of mimicry, which is undoubtedly a protection to the
insect. Its strong and swift flight is sufficient to save it from its
enemies when on the wing, but if it were equally conspicuous when at
rest it could not long escape extinction, owing to the attacks of the
insectivorous birds and reptiles that abound in the tropical
forests.”[104]
Dr. Wallace then speaks of another closely allied species which is
common in India, on the under surface of whose wings there are
sometimes, to the boot of all that has been described, in the way of
disguise, “patches and spots formed of small black dots, so closely
resembling the way in which minute fungi grow on leaves that it is
almost impossible, at first, not to believe that fungi have grown on the
butterflies themselves.”[104] The minuteness of a resemblance like this
is really very surprising, for it seems as though the butterfly-hunting
bird or insect—some powerful wasp may represent the latter—was capable
of minutely examining the object in question, and saying to itself, as
it were, “I don’t think that can be a leaf, because there are no black
spots upon it,” or _vice versâ_. In reality, however, it is no doubt the
general effect, to which every detail contributes, that tells. What such
resemblances do seem to me to show—and this, I think, is a new idea—is
the accuracy and precision of some insects’ sight. How insects see
things has long been a question, and many, I suppose, think it quite
uncertain whether a leaf, for instance, throws the same picture on their
retina that it does on ours. But if, to deceive them, the copy must be
such that it also deceives us, is it not clear that it does? Otherwise
the effect of the original could probably be reproduced by a less
accurate copy. How little, after all, does the finest painting really
resemble nature! The effect alone does so, not the means by which it is
arrived at. Surely, then, if an insect, looking at a leaf or any other
object, received but a general impression of colour, with an outline
more or less blurred, or ill-defined, these copies of nature by
nature—made to deceive—would bear witness to the fact. A study of
protective resemblances is perhaps the best way of forming an idea as to
how creatures, other than ourselves, see the world. It is even possible
that such resemblances exist, which we, because we see things
differently, are totally incapable of detecting.
I do not know if any other striking case of resemblance to an inanimate
object (if plant life can be included under this term) is offered by the
butterfly world, though there are several more of the same kind, but I
cannot remember one just now. No doubt there are many which have not yet
been discovered. We have, however, various instances of concealment even
here in England, as, for instance, the peacock butterfly; but these, as
well as special resemblances, are, for the most part, more marked in
moths. The lappet moth, indeed, though it does not quite get the shape,
looks very like a dead brown leaf, whilst in the buff-tip moth we are
supposed to have a special resemblance to a piece of rotting wood,
clothed with moss or lichen, and broken at each end. Personally, I have
never received the impression of such a definite object, but only a
general one of rot and decay. Even here, however, I do not believe I
could ever be taken in, for the yellow head and tips of the wings, which
are supposed to offer a perfect resemblance to the two broken ends of
the piece of wood, are to me the tell-tale parts, and instantly cry out,
“Moth!” In fact, soft as is the colouring of the buff-tip, it still
seems to me a salient object, and I do not think very much of that
bird’s eyesight who fails to detect it under anything like favourable
circumstances.
Another moth that flies by day, and is not uncommon in the United
States, bears, when sitting on a leaf, a much stronger resemblance to a
bird-dropping, but in this not uncommon form of imitation moths, and all
other insects, are outdone by spiders, who use it aggressively against
them, and particularly, it would seem, against butterflies, as the
following instances will show. Mr. Forbes once, whilst travelling in
Java, saw a butterfly settled upon a bird-dropping. He watched it for
some time, and then, wondering at its long stay, approached cautiously,
and, slowly extending his hand, actually caught it by its wings, between
his finger and thumb—no mean feat, as it seemed, yet there was nothing
to boast of. As he lifted the butterfly only the wings came away, the
rest of it staying with the supposed bird-dropping, which was now seen
to be a spider, who, having caught the butterfly by means of this
shameful imposture, was quietly occupied in eating it. The disguise in
this case was of the most wonderful perfection. “Such excreta,” says Mr.
Forbes, who discovered this one, “consist of a central and denser
portion of a pure white, chalk-like colour, streaked here and there with
black, and surrounded by a thin border of the dried-up, more fluid
part.”[105] The appearance of each of these constituent parts was
successfully counterfeited by the spider in question, who, in its own
person, represented the more solid material, and spun the rest with its
web.
As I know from early experience, when a naturalist makes a prize, all at
once, of some interesting specimen, for some time afterwards he expects,
or, rather, feels as if he would see some other on every leaf or twig;
but time went by and no more of these “vain, delusive” spiders presented
themselves. At length, years afterwards, the same naturalist found
himself by the banks of the Moesi river, in Sumatra (which sounds much
more interesting than the Thames, for instance), and this was his second
experience. “I was,” he says, “rather dreamily looking on the shrubs
before me, when I became conscious of my eyes resting on a
bird-excreta-marked leaf. How strange, I thought, it is that I have
never got another specimen of that curious spider I found in Java, which
simulated a patch just like this! I plucked the leaf by the petiole
while so cogitating and looked at it half-listlessly for some moments,
mentally remarking how closely that other spider had copied nature,
when, to my delighted surprise, I discovered that I had actually secured
a second specimen, but the imitation was so exquisite that I really did
not perceive how matters stood for several moments. The spider never
moved while I was plucking or twirling the leaf, and it was only when I
placed the tip of my little finger on it that I observed that it was a
spider, when it, without any displacement of itself, flashed its falces
into my flesh.”[105] (He means it bit him.)
Not all butterflies are entrapped by the kind of simulacrum here
noticed. Nature can adapt herself to every taste, and in South Africa
there are spiders who make themselves attractive by appearing to be
flowers. Of some of these and their _modus operandi_ Mr. Rowland Trimen,
who was curator of the Cape Town Museum, gives the following interesting
account: “Many species of spiders,” he says, “are well adapted to
succeed by being coloured in resemblance to the flowers in or on which
they await the arrival of their victims. One that inhabits Cape Town is
of the exact rose-red of the flowers of the oleander, and, to more
effectually conceal it, the palpi, top of the cephalothorax, and four
lateral stripes on the abdomen, are white, according remarkably with the
irregular white markings so frequent on the petals of _Nerium_.”[106]
These, indeed, must be beautiful spiders, and one would like to hear a
little more of them, but Mr. Trimen goes at once from red to yellow. “I
was led,” he continues, “to notice a yellow spider of the same group in
consequence of seeing that two of a number of butterflies on the flowers
of _Senecio pulugera_ did not, on my approach, fly off with their
companions. Each of these unfortunates turned out to be in the clutches
of a spider, and when I released them I observed their captors very
narrowly, and I found that the latter’s close resemblance to the
_Senecio_ flowers was not one of colour alone, but due also to attitude.
This spider, holding on to the flower stalk by the two hinder pairs of
legs, extended the two long front pairs upward and laterally. In this
position it was scarcely possible to believe that it was not a flower
seen in profile, the rounded abdomen representing the central mass of
florets and the extended legs the ray florets, while to complete the
illusion the femora of the front pair of legs, adpressed to the thorax,
have each a longitudinal red stripe, which represents the ferruginous
stripe on the sepals of the flower.”[106]
Later on, Mr. Trimen was so fortunate as actually to see a butterfly
caught by another flowery impostor:—“The butterfly,” he tells us, “was
engaged in honey-sucking on a white flower-head of _Lantana_, and
explored each individual flower with its proboscis. While I was watching
it, the butterfly touched and partly walked over what looked like a
slightly folded or crumpled flower about the middle of the cluster. This
turned out to be a spider, which instantly seized the butterfly,
throwing forward its front legs, somewhat after the fashion of a mantis.
In this spider the effect of the little depressions on the limb of the
corolla was given by some depressed lines on the back of its smooth
white abdomen.”[106]
Other spiders resemble snail-shells, others ants, and one, at least, is
like a small scorpion, but we will return to the butterflies. As I have
said, except for that wonderful copy of a leaf, already described, I
cannot think of any very extraordinary resemblances amongst them,
belonging to that class, but there are others which form a little class
of their own. In the last chapter we have seen bees imitating bees, and
in this we will make the acquaintance of certain butterflies which, as
it were, pretend to be of a species which they do not really belong to.
Thus in Brazil, by the great River Amazons, a number of large showy
butterflies are found which belong to the family of the _Heliconea_, and
wherever these fly they are accompanied by various other butterflies,
belonging to quite different families, which are nevertheless so
extremely like them that even Mr. Bates, who, for eleven years, ran up
and down the Amazons with a butterfly-net in his hand, could never be
quite sure which kind it was that he was going to catch. Often, when he
thought he had got a _Heliconea_ he was perfectly thunderstruck to find
it was really a _Papilio_, _Pieris_, _Euterpe_, _Leptalis_,
_Protogonius_, _Ithoneis_, _Dioptis_, _Pericopis_, _Hyelosia_, or
something of that sort; or again, when it was one of these he was after,
and at last he thought he had it in the net, he would be petrified, on
looking more closely, to find that what he had really caught was a
_Heliconea_.
But now, as all these butterflies were alike or nearly alike, how could
Mr. Bates tell—or how had anybody been able to tell before him—that they
were really not all the same species—that a _Heliconea_ was not a
_Papilio_, or that a _Papilio_, _Pieris_, _Euterpe_, etc., were not all
of them _Heliconeas_? This, at first sight, seems a difficult question
to answer, but really it is not, because, in all these families of
butterflies, the various species composing them bear a kind of
generalised resemblance to one another: there is a family likeness, in
fact, and this is not only the case in regard to their outward
appearance—the shape and colour of their wings, etc.—but it applies, in
a still greater degree, to their structure and internal economy. Thus,
however strongly a _Pieris_, or one of those others, might resemble a
_Heliconea_, the trained eye of an entomologist could easily see that it
really was a member of another family, and since, in resembling the
_Heliconea_, it departed from the general type of pattern and colouring
exhibited by the family to which it belonged, whilst this one species of
_Heliconea_ it resembled was like the others, it might be inferred that
the latter was the imitated and not the imitating form. Again—and this
is still more decisive evidence in the cases where it applies—the
resemblance is often confined to one sex of the copying species, viz.
the female, so that whilst she is hardly to be distinguished from the
model on which she has founded herself, the male retains the appearance,
together with all the other characteristics, of the race to which both
he and she belong.
But now came a further question, the most puzzling or, at any rate, the
most important one of all, viz. Why should the one butterfly imitate, or
rather resemble the other, in such an extraordinary degree—a degree
seeming to preclude the possibility of mere chance having brought it
about? This question Mr. Bates is supposed to have been the first to
answer, though I cannot help thinking, myself, that he has only extended
an explanation, which, in some cases, was so obvious that no one had
thought of pointing it out, to these other cases where it was not nearly
so easy to see. For what can be plainer, as Mr. Bates himself remarks,
than that a moth, for instance, by closely resembling a hornet, would
escape the attacks of birds that might otherwise have devoured it? I
cannot think but that so patent an explanation had been in the minds of
many long before 1862, and though no one previous to that date may have
applied the principle of natural selection to such cases, it must be
remembered that natural selection had been established by Darwin some
ten or twelve years before.
Bates, however, besides making an ingenious application of the above
principle to a special case, gave a real reason for something which was
not at all obvious, viz. why one butterfly should be a gainer by closely
resembling another; and this no one had hitherto been able to do. His
surmise, which has since in many instances been confirmed, is as
follows. Having first pointed out that the _Heliconea_ butterflies are a
numerous, flourishing race, whilst those species that imitate them are
poor in numbers, he says, “What advantages the _Heliconidæ_ possess to
make them so flourishing a group, and, consequently, the object of so
much mimetic resemblance, it is not easy to discover. There is nothing
apparent in their structure or habits which could render them safe from
persecution by the numerous insectivorous animals which are constantly
on the watch in the same parts of the forest which they inhabit. It is
probable they are unpalatable to insect enemies. Some of them have
glands near the end of the abdomen which they protrude when roughly
handled; it is well known that similar organs in other families secrete
fetid liquids or gases and that these serve as a protection to the
species. They have all a peculiar smell. I never saw the flocks of
slow-flying _Heliconidæ_ in the woods persecuted by birds or
dragon-flies, to which they would have been easy prey; nor when at rest
on leaves did they appear to be molested by lizards, or the predaceous
flies which were very often seen pouncing on butterflies of other
families. If they owe their flourishing existence to this cause it would
be intelligible why species whose scanty number of individuals reveals a
less protected condition, should be disguised in their dress, and thus
share their immunity. Is it not probable, seeing the excessive abundance
of the one species and the fewness of individuals of the other, that the
_Heliconea_ is free from the persecution to which the _Leptalis_ is
subjected?”[107]
No sooner was this suggestion made than naturalists all over the world
began to test it, or rather to say that it ought to be tested. Some
experiments have been made, but they have not been very numerous, and it
can hardly be said that they entirely support Bates’s view. Sometimes
they do and sometimes they do not, so as there is no reason to suppose
that every butterfly is relished by every kind of insect-eating
creature, this is not conclusive, till the same tests are employed in
regard to butterflies that are not imitated in this way; for if the
latter have not been imitated on that account, it need not be on that
account that others have been imitated. Thus Belt says, as the result of
his observations, “The _Heliconidæ_ are distasteful to most animals; I
have seen even spiders drop them out of their webs again; and small
monkeys, which are extremely fond of insects, will not eat them, as I
have proved over and over again.”[108] He also “observed a pair of birds
that were bringing butterflies and dragon-flies to their young, and
although the _Heliconidæ_ swarmed in the neighbourhood, and are of weak
flight so as to be easily caught, the birds never brought one to their
nest.”[109] This seems very good evidence of the truth of Bates’s
theory, but then, as against it, we learn from the same observer that
“another spider that frequented flowers seemed to be fond of these very
same butterflies,” and as to the spiders which were seen to drop them
out of their webs, they may resolve themselves into one, since farther
on Belt says, “A large species of spider also used to drop them out of
its web when I put them into it.”[109] Then we are told that “there is,
however, a yellow and black-banded wasp that catches them to store his
nest with”; and which, having done so, “would quietly bite off its
wings, roll it up into a ball, and fly off with it.”[110] Professor
Poulton calls these cases “interesting exceptions,” and easily accounts
for them. But might not further observation keep adding to the number of
exceptions, until at last, they become so numerous that all one could
say would be this: “There is a great choice of insects in tropical
America, and some creatures may prefer one kind and some another, to
whatever species they belong.” In India, again, where there is another
family of butterflies having doubles, or understudies, only one species
was refused by all the mantids which a French naturalist gave them to.
Others were eaten by all of them.
Has any man tried eating one of these butterflies? That was what
Professor Wheeler did to test another supposed case of the same sort.
Here the insect was a large and very conspicuously coloured day-flying
moth. This moth has not an understudy, as far as is known, but it was
supposed, then, to be an example of what is called “warning coloration,”
that is to say, its bright colours were believed to be flourished in the
face of any and every animal it might meet with, in order to warn them
that it was not good to eat. Otherwise some bird, or lizard, or other
creature might kill it before it had time to find out that it wasn’t.
For instance, had it been just a brown moth—there are so many of these
and most of them good to eat—how was it to be distinguished from others?
But such a get-up as _that_—black and white wings and a black and orange
body—once seen it was not to be forgotten. It was like the red flag at a
rifle range, warning one off, and this is the theory of warning
coloration. So Professor Wheeler, as he rode through the deserts of
Wyoming, with the moths all about him, resolved to test this theory
which had lived for a long time, and still goes on living a good deal on
trust. “He dismounted from his horse and proceeded to masticate the body
of one of the moths. To his astonishment the little flavour that it
contained was mild and pleasant, one may almost say nut-like.”[111]
Perhaps it may be thought that, on the “_de gustibus_” principle, what
is pleasant to a human being might be disagreeable to a bird or a
lizard; but Professor Wheeler tried another experiment. “Another
day-flying moth, common in our eastern States, has deep black wings,
each adorned with a pair of large yellow spots, and there is a dash of
orange on its legs. It certainly cannot be a mimetic species (if it
were, of course, one would not expect it to be nasty) as there is no
other day-flying moth which could serve as its model. Several of these
moths were given to some lizards that had previously been well fed on
house-flies and could not, therefore, be very hungry. The moths were
seized at once, and devoured, with evident signs of relish.”[111]
As a result of these experiments Professor Wheeler concludes that
“naturalists should be more careful in imputing nauseous or disagreeable
qualities to some conspicuously coloured animals,” and he suggests that
“if every field entomologist could only bring himself to repeat the
writer’s experiment on one of many cases of ‘flaunted nauseousness’ and
place his taste impressions on record, we should in the course of time
have a really valuable body of evidence, for we can hardly assume that
beasts, birds, and reptiles can find things ‘nauseous’ which are quite
tasteless, or even pleasant, to the human palate.”[111] “_Il n’y a pas
de réplique à cela_,” and how it is that so simple a plan did not occur
to Mr. Bates during all the eleven years he was on the Amazon it is not
very easy to imagine. On the whole, perhaps, it may be said that the
reason why certain butterflies are imitated by other butterflies has not
been so satisfactorily settled as the fact that they are so imitated.
But, on the other hand, there is some—perhaps much—evidence of the truth
of Bates’s theory, and, moreover, that theory is in itself so plausible
that it seems to require a good deal of evidence to overthrow it.
It is not only in South America that butterflies dress up like one
another. Instances similar to those here given occur also in Africa and
the Malay Archipelago, as well as in other parts of the world. There is
even one doubtful case in England, both the copy and original being
moths. Moths, especially the day-flying ones, are represented in these
phenomena as well as butterflies, which are sometimes imitated by them.
-----
Footnote 104:
Wallace, The Malay Archipelago, pp. 100-2.
Footnote 105:
Forbes, A Naturalist’s Wanderings in the Eastern Archipelago.
Footnote 106:
Trimen, Protective Resemblance and Mimicry in Animals.
Footnote 107:
“Contributions to an Insect Fauna of the Amazon Valley,” in
_Transactions of the Linnean Society_, vol. 23, p. 495.
Footnote 108:
Belt, The Naturalist in Nicaragua, p. 109.
Footnote 109:
Ibid., pp. 316, 317.
Footnote 110:
Ibid., p. 109.
Footnote 111:
“Impostors among Animals,” in the _Century Magazine_, July, 1901.
------------------------------------------------------------------------
CHAPTER XXI
Sights of the forest—A butterfly bridge—Bird-winged
butterflies—“What’s in a name?”—Scientific
sensibility—Resemblance _v._ mimicry—A convenient wrong
word—Beauty in nature—Nuptial display—Strange
counter-theory—_Lucus a non lucendo_—Reasoning by
contraries—True in Topsy-turvydom—Butterfly courtship—Form
and colour—A curious suggestion—Powers of defective
eyesight.
THOUGH the principle of protective resemblance, as explained in the last
chapter, will account for the colours and markings of those butterflies
which imitate the _Heliconidæ_, it does not explain how the _Heliconidæ_
themselves came to be as they are; for in nature every mark and line and
shade has a meaning, and has come into existence by virtue of some law
or another. Beauty itself, independently of any _arrière pensée_, as we
may call it—remembering those flower-resembling spiders—requires to be
explained.
Nor are the _Heliconidæ_ themselves, though gaudily dressed showy
butterflies, anything like so beautiful as many others; for instance, as
the _Morphos_, those giants of their kind, who sweep like stars through
the tropical forests on wings whose whole broad surface is blue, but a
blue that flashes like a drawn sword and has a hundred glints and
gleamings of ever-varying light. High-fliers they are for the most part,
keeping to the tops of the trees, but every morning, and always at the
same time, they make a descent into the glades and alleys of the forest,
where for a little they flap lazily backwards and forwards, now in
eclipse, now flashing forth into sunlight, as though to flaunt their
beauties in the face of the lower world. Such openings in the primeval
forest are often made by the fall of great trees—for even where the axe
is not there is death in the midst of life—and as these majestic insects
sail high above them in a world of air and light, their shadows fall
upon the place beneath, and trace their course along the ground. When
the sun’s rays strike into them, such clearings become the gathering
grounds of various butterflies. Besides the great _Morphos_, the
flashing of whose wings in the sunlight can be seen sometimes a quarter
of a mile away,[112] various species of _Heliconeas_—the one we have
just been reading about—whose black wings are in some species spotted
with scarlet, in others with white or blue, waltz about the bushes or
undergrowth, “dancing in the chequered shade”; fritillaries somewhat
like our own, but of larger size and more effective colouring, fly
higher up, about the tree-trunks, whilst over the ground itself,
carpeted as it often is with flowers fallen from the leafy world above,
and scenting the air, ghost-like butterflies, whose clear, transparent
wings are without any colouring matter, ceaselessly hover and flit.
Wherever there is a river, many-coloured armies, bivouacked amidst its
various shoals and reefs, sit sucking water through, the moist particles
of the sand, whilst others, in even greater numbers, pass and repass
from one bank to another, making, however wide the waterway, an aerial
fluttering bridge. Other butterflies, also denizens of the great
Brazilian or Central American forests, have broad white wings, shot with
a satiny lustre, whilst those of yet another are like glass, with one
opaque spot of violet and blue, in the midst of each of them. In flight
this spot is the only part that can be seen, and it looks, Bates tells
us, “like the wandering petal of a flower.”[113] There are
swallow-tailed butterflies, too, whose livery of deep, soft green, and
deeper velvet black, set off with roseate hues, is amongst the richest
of all—“rich, not gaudy,” so at least I should term it, for I have seen
it, putting flowers to shame, on the lower slopes of the Himalayas. Here
these butterflies—double the size of our _Machaon_, and of another
shape, with racquet-rather than swallow-tails, flew on the open
hillside, courting the sun, but in Brazil they keep to the forest
depths, where, like Una, they “make a sunshine in the shady place.”
The butterflies of South America are almost rivalled—quite they cannot
be—by those of the Malay Archipelago. Here we have the great Bird-winged
Butterfly, discovered by Dr. Wallace, who calls it “elegant,” and
bestows upon it a name (_Ornithoptera Brookeana_) which is not quite
that.[114] However, “What’s in a name? That which we call a
_Brookeana_,” etc.—we must reverse the proposition. There is no
describing such a creature—at least, not convincingly. Suffice it to say
that its wings “almost resemble those of a sphinx moth in shape,” and
are deep, velvety black, but lit up with a band of green feather-like
markings, so brilliant and lovely that they reminded its discoverer “of
the wing-coverts of the Mexican trogon laid upon velvet”[114]—and that
for anyone who has seen a trogon, even stuffed and dried, is to say
enough. Besides this adornment the great _Brookeana_ has “a broad
neck-collar of vivid crimson and a few delicate white touches on the
outer margins of the hind wings.”[114] Another _Ornithoptera_ without
the _Brookeana_ is “the largest, the most perfect, and the most
beautiful of butterflies.” The two last, however, are matter of opinion,
and I should think myself that a _Morpho_ with its azure wings,
sometimes seven inches across, and flashing a quarter of a mile away,
would run—or fly—it hard. Then there is a yet more gorgeous species of
“Bird-winged Butterfly,” with wings equalling or even exceeding the
_Morpho’s_ in expanse, whose ample surface is divided between flame-like
orange and a black so deep, rich, and velvety that it seems to glow—“the
pride of the Eastern tropics, one of the most gorgeously coloured
butterflies in the world.”[115]
This was the butterfly that gave Dr. Wallace a headache, “so great was
the excitement produced by what will appear to most people a very
inadequate cause.”[115] Surely not; for the cause here alluded to was
not the insect’s beauty—which had been seen before, free and
untrammelled, without any such ill-consequence—but its capture and
anticipated transference to the cyanide bottle. It was not mere æsthetic
emotion, therefore, that produced the headache, but scientific
enthusiasm, of which no man need feel ashamed. It is easy for us on such
occasions to mistake our feelings, but the clue to them, I think, is
this, that however beautiful a creature may be, and however appreciative
we may think ourselves of such beauty, yet if we resolve, in the true
interests of science, to take that creature’s life, then the scientific
spirit must be far stronger in us than mere admiration of its beauty.
This test I would apply to another account which Dr. Wallace gives us of
the capture of “one of the most magnificent insects that the world
contains.” “I trembled,” he says, “with excitement as I saw it coming
majestically towards me, and could hardly believe I had really succeeded
in my stroke till I had taken it out of the net and was gazing, lost in
admiration, at the velvet black and brilliant green of its wings—seven
inches across—its golden body, and crimson breast. It is true I had seen
similar insects in cabinets at home, but it is quite another thing to
capture such oneself—to feel it struggling between one’s fingers, and to
gaze upon its fresh and living beauty, a bright gem shining out amid the
silent gloom of a dark and tangled forest. The village of Dobbo held
that evening at least one contented man.”[116] When we consider that the
“fresh and living beauty” was caught for the very sake of being made
dead and mouldy, and that the “bright gem” which would otherwise have
continued to flash in the forest was about to become one of those very
same specimens that had been looked at with such an inferior degree of
interest, we must admit, I think, that the higher of two passions was
predominant here, and that the author, in dwelling only upon the other
and lower one—mere delight of the eye—has done himself less than
justice.
Mr. Bates, without headaches, has given us some very pleasing pictures
of butterfly-life in the tropics, and in doing so he has instinctively,
as it were, kept the killing and capturing in the background. “The
number and variety of gaily-tinted butterflies,” he tells us, “sporting
about in this grove on sunny days, were so great that the bright moving
flakes of colour gave quite a character to the physiognomy of the place.
It was impossible to walk far without disturbing flocks of them from the
damp sand at the edge of the water, where they congregate to imbibe the
moisture. They were of almost all colours, sizes, and shapes. I noticed
here altogether eighty species belonging to twenty-two different genera.
It is a singular fact that, with very few exceptions, all the
individuals of these various species thus sporting in sunny places were
of the male sex; their partners, which are much more soberly dressed and
immensely less numerous than the males, being confined to the shades of
the woods. Every afternoon, as the sun was getting low, I used to notice
these gaudy, sunshine-loving swains trooping off to the forest, where I
suppose they would find their sweethearts and wives.”[117] What a
delightful scene! Here, “next to the very common sulphur-yellow and
orange-coloured kinds, the most abundant were about a dozen species of
_Eunica_, of large size, conspicuous from their liveries of glossy dark
blue and purple. A superbly adorned creature, the _Callithea Markii_,
having wings of a thick texture, coloured sapphire blue and orange, was
only an occasional visitor. On certain days, when the weather was very
calm, two small gilded green species literally swarmed on the sands,
their glittering wings lying wide open on the flat surface.”[117]
Such, then, are the colours of butterflies, and, as may be imagined,
comparatively few of these gorgeous liveries have been acquired through
the principle of protective resemblance—using the term in its widest
sense, to include those cases where one species becomes, as it were, the
double or wraith of another. Mimicry is the word which, by a ludicrous
process of false reasoning, naturalists have convinced themselves it is
right to apply to this particular kind of resemblance, and no other one;
though why a butterfly should _mimic_ another butterfly and only
_resemble_ a leaf, “_quien sabe?_” as the Spaniards say. The principal
reason adduced for this misuse of language, viz. that the wrong word is
more convenient than any right one, providing us with the useful series,
_mimic_, _mimicry_, _mimetic_, _mimicker_, _mimicked_, _mimicking_,
obviously applies to the one case as well as the other, and if it is an
advantage to be absurd in one way, surely it is a double one to be
absurd in two. On these grounds I would suggest to naturalists that,
having broken down the proper and natural confinements of the word in
question, they should rather extend its use than limit it, to the extent
even of calling their children “mimetic forms,” should they happen to
resemble them, and thinking twice before punishing a son for merely
“mimicking” his father.
But, leaving this, how—to take the jargon as one finds it—are the
glorious colours of butterflies to be explained when they are due
neither to protective resemblance, which is not mimicry, though it very
much resembles it, nor to mimicry, which is distinct from protective
resemblance, though mimicking it exactly? Certainly neither of these
will do to account for uncopied hues and patterns, which are like
nothing in the world but their own loveliness, unless, indeed, it be the
rival glories of the most resplendent birds. Still less will aggressive
resemblance—though, as we see, it can make spiders look like
flowers—explain them. The great governing cause which produces such
effects as these, as well as most others in nature, is natural
selection; but we must look beyond natural selection even, if we wish to
understand all the beauty that we see in the animal world, and
especially the higher developments of it.
Darwin, as we know, was the great demonstrator—though not the first
conceiver—of the law of natural selection,[118] and on this he might
have cried “_Nunc dimittis_” and retired, so to speak, leaving someone
else to find out the other law; but instead of that he went on and
demonstrated that too. This other law, the evidence for which is really
overwhelming, and has never been met by anything better than a conceited
over-estimation of human superiority, wrapped up in a cloud of wrong
reasoning, is that of sexual selection, which implies that, in the
choice of their mates, animals, like ourselves, are guided by some sort
of preference; and as this with them—again like ourselves—is usually
determined by the element of beauty, the most beautiful partners are
being constantly selected, and species in consequence become more and
more beautiful. This process, however, is usually confined to the males,
they being the eager wooers, whilst the females only wait to be courted,
and then shyly and modestly choose—such, at least, is the supposition.
This masculine beauty is often inherited by that sex only to which it is
so useful, but in other cases it is transmitted to the female also.
Thus, to take birds, where the results of the law of sexual selection
are on the whole most pronounced, we have, on the one hand, the
pheasants and birds of paradise, where the male alone is resplendent,
whilst in the trogons, parrots, and many other species the beauty is
common to both the sexes. As is well known, the males of various highly
ornate birds are accustomed to make the most extraordinary display of
their beauty before the females, making the most of the parts most
richly decorated, assuming just such attitudes as are required in order
to give these their full advantage, and, in fact, taking pains and
trouble in a high degree and of a very special and peculiar kind, which
must either be directed to an end which seems perfectly plain and
apparent, or else so much waste of time—due to no special cause and
without any particular meaning—an alternative which the opponents of
sexual selection do not in the least mind accepting.
To give one instance of what is called nuptial display in birds—for it
will serve to illustrate what Darwin supposes to take place with some
insects also, as well as forming a basis of comparison with what has
been more carefully observed in the case of spiders—Belt in his often
quoted work gives us the following pretty picture of humming-bird
courtship. Speaking of a beautiful blue, green, and white species
(_Florisuga mellivora_), he says: “I have seen the female sitting
quietly on a branch, and two males displaying their charms in front of
her. One would shoot up like a rocket, then suddenly expanding the
snow-white tail like an inverted parachute, slowly descend in front of
her, turning round gradually to show off both back and front. The effect
was heightened by the wings being invisible from a distance of a few
yards, both from their great velocity of movement and from not having
the metallic lustre of the rest of the body. The expanded white tail
covered more space than all the rest of the bird, and was evidently the
grand feature in the performance. Whilst one was descending, the other
would shoot up and come slowly down expanded. The entertainment would
end in a fight between the two performers; but whether the most
beautiful or the most pugnacious was the accepted suitor I know
not.”[119]
Here the display, as well as the intention, seems evident enough, and it
is not a whit more so than in hundreds of other cases collected by
Darwin during his lifetime, and which have been largely added to since
his death. As the hen is constantly present during these performances,
and as she has been known on various occasions to show a strong
partiality, or the reverse, to this or that male bird, we have here a
solid basis of observed fact on which to raise an hypothesis. On what
facts the counter one rests, as propounded by Dr. Wallace, viz. that
colour and antics are produced by superior vigour resident in the male,
it is less easy to see, unless, indeed, such as point in a quite
opposite direction may, on a sort of _lucus a non lucendo_ principle, be
held to support it. If this be conceded, then, indeed, we have a
plentiful crop, nor need we any longer feel sceptical because the eagle,
say—that bird of fierce energy—does not flash out like all the crown
jewels together as it descends on its prey, or because the swift, whose
vital force is, perhaps, even greater, leaves no train of jewelled light
to die all day, behind it, on the air. Nor need we wonder that the
trogons, though as resplendent as the swifts, swallows[120] and eagles
are dull-coloured, should be as lazy and sluggish as these are
energetic: nor that, whereas the females of some humming-birds are
sober-suited, those of others, though their vigour would seem to be in
no way superior, are as gem-like as their mates: or that the males as
well as the females of some wholly dull-coloured ones, and of many other
plain birds, seem bursting with vigour, and indulge in all sorts of
strange antics and dances: that a cock partridge, for instance, seems as
vigorous as a cock pheasant, and that bright colours and pugnacity are
dissociated in such tremendous fighters as the ruff, the coot, and the
blackcock. Multiply such instances by the score or the hundred—as can
easily be done—and if only the above-stated principle be granted, we get
more and more proof of the correctness of a theory to which facts, if
dealt with in the more usual way, would be almost instantly fatal. After
all, this would be a more satisfactory mode of procedure than that of
tolerating a travesty on the strength of a high reputation. There is
such a principle in nature as the _lucus a non lucendo_ one, so, as we
admit the word mimicry in a false sense—because it is convenient—why not
admit that? It would be not one whit less convenient—for the theory.
But, handling facts in another way, can we explain the beautiful colours
of butterflies as we explain the brilliant plumage of birds—by sexual
selection, that is to say? Of this there is not so much direct evidence
as could be wished, for butterfly courtship is a long affair, and, for
various reasons, is not so easy to watch under natural conditions, as in
the case of birds, though this, too, is often beset with difficulties.
We know, however, that the male is often much more beautiful than the
female, that he pirouettes around her, and that she remains often “icy
insensible”—in fact refuses him—which certainly implies a power of
choice. Rival males, too, will “whirl round each other with the greatest
rapidity, and appear to be incited by the greatest ferocity.”[121] That
butterflies, like bees, perceive and are attracted by colours is well
known, and it would be strange, indeed, if they were not alive to the
many very beautiful and complex patterns on their own wings, when these
cannot have been evolved through any principle of protection—since they
resemble or suggest nothing—when, in fact, if not beauty, it is
difficult to see the object aimed at. Yet the strange suggestion has
been made that, though butterflies see colours, they cannot see form,
that their sight is defective in some peculiar kind of way. But if form
is outline—and if not, what is it?—where is the distinction, seeing that
the beginning and leaving off of a colour or of two or more colours must
make an outline, and therefore a form? If we see the colours of a
pattern where the one ends and the other begins, we see that pattern,
and on the other hand, if we could not distinguish one colour from
another, or colour from something uncoloured—as, say, the air—we should
be blind to colour, as well as to form. Form can hardly be called a
thing of itself. It is rather the line of demarcation between two or
more things, so that, if each of these is clearly perceived, the form or
outline which their juxtaposition makes must be also perceived. Assuming
that butterflies see the beautiful arrangements of colour—eyes, spots,
bands, lines, etc.—in such a way as can alone account for their being
there to see—as well as we do, that is to say—then it is absurd to
imagine that they have no perception of form.
On what is this assertion based? Mr. Scudder relies on the following
facts: “Christy,” he tells us, “observed in Manitoba one of the
swallow-tails fluttering over the bushes, evidently in search of
flowers. As he watched it, it settled momentarily, and exactly as if it
had mistaken it for a yellow flower, on a twig of _Betula glandulosa_,
bearing withered leaves of a bright yellow colour.”[122] But might not
the association of ideas raised by a familiar colour in an insect’s mind
overpower for a moment its judgment? Might it not do so in the case of a
man also? And should we think a person very stupid who, for a moment,
mistaking a yellow leaf for a yellow flower, stretched out his hand to
pick it? Pooh! once again,[123] let us think of people who do foolish
things—kings, generals, cabinet ministers, servant-maids, etc.—not of
infallible persons. We should not be too severe—not “break a butterfly
on a wheel.”
Again—this is Mr. Scudder’s second instance: “Albert Müller records
seeing the blue Alexis of Europe fly towards a very small bit of pale
blue paper lying upon the grass, and stop within an inch or two of it,
as if to settle, doubtless mistaking it for another of its own
kind.”[124] Surely this is rather in favour of the butterfly’s sight
than otherwise, since it discovered its mistake and did not settle. Who,
too, can tell the precise moment at which the mistake was discovered,
since the piece of blue paper might have puzzled the butterfly—piqued
its curiosity to know what it was—even after it knew what it was not?
Thirdly, “Plateau has observed the small tortoise-shell butterfly fly
rapidly towards a cluster of artificial flowers.”[124] And who cannot be
taken in by artificial flowers? “Such examples as these,” says Mr.
Scudder, “seem to indicate that butterflies may perceive colour in mass,
but in no case indicate any further visual powers.”[124] To me they
indicate that butterflies can make mistakes. Mistakes rarely show one’s
perfections, but other indications of further visual powers are not
wanting. For instance, Mr. Scudder himself says: “One of my favourite
modes of showing this characteristic (inquisitiveness) to unbelieving
friends has been to toss my cap high in the air, when these butterflies
will often dart, dash at, and play around it as it begins again to
descend.”[124] How do they play around this moving object in the air if
it represents to them only “colour in mass,” and not a defined shape and
outline? Were it otherwise, they would fly right into it, and be carried
down with it sometimes on top of them. But if they see all parts of the
colour so that they can nicely avoid it, and sport about its periphery,
then they see the shape of the cap. Then, again, Mr. Scudder tells us:
“Many kinds are of a lively and even pugnacious disposition, and perch
themselves upon the tip of a twig, or on a stone, or some such outlook,
and dash at the first butterfly that passes, _especially if it be one of
their own species_;[125] then the two advance and retreat, forwards and
backwards, time and again, circle round each other with amazing
celerity, all the while, perchance, mounting skywards, until suddenly
they part, dash to the ground, and the now quiet pursuer again stations
himself on the very spot he quitted for the fray.”[126] How does he do
_that_ without accurate eyesight, with good defining power?—to which,
indeed, the whole performance bears witness. Elsewhere, too, this
pronounced characteristic of returning to the exact spot, left some
little time ago, is dwelt upon. To me it seems a complete upsettal of
the defective eyesight theory, or, since good eyesight could do no more,
what does such defectiveness matter?
The following description also, which Bates gives us, of butterfly-life
by the Amazons, does not suggest that any of these bright-day-lovers,
these children of the sun, need write an “_Apologia pro oculis suis_.”
“The fine showy _Heliconii_,” he says, “often assemble in small parties,
or by twos and threes, apparently to sport together or perform a kind of
dance” (my “dancing in the chequered shade,” therefore, was no inapt
quotation). “I believe the parties are composed chiefly of males. The
sport begins generally between a single pair. They advance, retire,
glide right and left in face of each other, wheel round to a
considerable distance, again approach, and so on; a third joins in, then
a fourth, or more. _They never touch_;[127] when too many are
congregated a general flutter takes place, and they all fly off, to fall
in again by pairs shortly afterwards.”[128] Lastly, Belt tells us this:
“Here a large spider built strong, yellow, silken webs joined one on to
the other, so as to make a complete curtain of web, in which were
entangled many large butterflies, generally forest species, caught when
flying across the clearing. I was at first surprised to find that the
kinds that frequent open places were not caught, although they abounded
on low white-flowered shrubs close to the webs; but on getting behind
them and trying to frighten them within the silken curtain, their
instinct taught them to avoid it, for, although startled, they threaded
their way through open spaces and between the webs with the greatest
ease.”[129] If a butterfly with defective eyesight can thread its way
between spiders’ webs, so as never to be caught, “with the greatest
ease,” “why, then, say an old man can do somewhat”—but it must be
without spectacles.
-----
Footnote 112:
Bates, The Naturalist on the River Amazon.
Footnote 113:
Ibid. (1864), p. 63.
Footnote 114:
Wallace, The Malay Archipelago, p. 29.
Footnote 115:
Ibid., pp. 257, 258.
Footnote 116:
Ibid., pp. 328, 329.
Footnote 117:
Bates, The Naturalist on the River Amazon (1864), p. 333.
Footnote 118:
In 1813 Dr. Wells, first amongst the moderns, conceived, or at least
formulated in writing, the idea of natural selection; but Aristotle,
as is usual in such cases, had anticipated him as well as Darwin,
Wallace, and one or two others, and that in a very unmistakable
sentence (see footnote on first page of the “Historical Sketch” in
_The Origin of Species_). It would seem, however, that no one of these
conceptions was influenced by any previous one. Of sexual selection
Darwin seems to have been the discoverer as well as, in the opinion of
many, the demonstrator.
Footnote 119:
Belt, The Naturalist in Nicaragua, pp. 108-12.
Footnote 120:
Swallows have the highest temperature known amongst birds, viz. 111¼.
Footnote 121:
C. Collingwood, Rambles of a Naturalist in the China Seas, p. 183.
Footnote 122:
Scudder, Frail Children of the Air.
Footnote 123:
See pp. 179-181.
Footnote 124:
Scudder, Frail Children of the Air.
Footnote 125:
My own italics.
Footnote 126:
Scudder, Frail Children of the Air.
Footnote 127:
My own italics.
Footnote 128:
“Contributions to an Insect Fauna of the Amazon Valley,” in _Trans.
Linn. Soc._, vol. xxiii, p. 495.
Footnote 129:
Belt, The Naturalist in Nicaragua, pp. 108-12.
------------------------------------------------------------------------
CHAPTER XXII
Beautiful spiders—The “Peckham paper”—Spider courtship—Male
antics and love-dances—Occasional accidents—Strength of the
evidence—The one explanation—Darwin’s last words—His theory
established.
SPIDERS, as we have seen, may attain beauty by getting more and more
like flowers, but beauty is not the attribute with which they are
principally connected in our minds. Rather they are a synonym of
something uncouth and horrid-looking, as well as of skill and
persevering industry. For those of us, however, who have lived in the
tropics they have other associations, for here, side by side with the
most hideous of monsters, huge, dark, and hairy, are found others, small
and gem-like, flashing indeed with beauty, the representatives in their
order of the humming-birds, those “living sunbeams” of the Indians,
amongst birds. These lovely little spiders belong to a particular
family, the _Attidæ_, which has been placed by common consent at the
head of all the others, since, whilst structurally, and in other
respects, it is inferior to none, “it contains among its 1,500 species
the greatest amount of sexual differentiation and the highest
development of ornamentation.” Dr. Wallace, after noticing “their
immense numbers, variety, and beauty,” in tropical South America, says,
“Many of them are so exquisitely coloured as to resemble jewels rather
than spiders”;[130] and again, in his work on the Malay Archipelago, he
alludes to them as “perfect gems of beauty.”[131]
These little radiant spiders live amongst flowers and foliage, and here
they chase such small insects as their size allows them to cope with.
Besides running, they make little leaps into the air, and so, if they
can manage it, come down on their prey, for which reason they are often
called “jumping spiders.” This is a very different mode of action from
that of remaining perfectly still till a butterfly or other insect
happens to settle on one, and it is accordingly instructive to find
that, great as is the beauty of these flower-haunting spiders, yet it
does not resemble that of the flowers amongst which it is displayed. The
iridescent flashes and sparkles more resemble those of the mineral than
of the vegetable world—where, indeed, they hardly exist—and must serve,
as well as their active movements, to point them out to their enemies
even amidst a background of flowers. It is not upon principles of
protection, therefore, or to acquire a dissembling resemblance that such
bright brilliancy has been developed in these little creatures.
Since, therefore, these spiders could not have become beautiful on any
principle of protective or aggressive resemblance, nor yet of warning
coloration, for which there would here be no opening, and had yet become
beautiful in a high degree, they seemed to Professor and Mrs. Peckham to
offer a good subject for the testing of the theory of sexual selection,
and deciding as to whether Darwin or Wallace was right in that matter.
After several months of careful, and often very laborious
observation—rewarded, however, by the most interesting results—they have
given their answer, and this answer, resting as it does on the most
irrefragable evidence, should be decisive for all time. It may safely be
asserted that anyone who, after reading the “Peckham paper,” as it may
well be called, is not convinced both that the male spiders of this
beautiful family woo the females by displaying their beauty before them,
and that the females carefully watch the display, accepting only such as
please them sufficiently and rejecting the others, never will be
convinced, since only by the spiders actually speaking, which is not
likely to happen, could the evidence be bettered. If, indeed, the female
had been heard to say “Pretty i’ faith,” or “You are a fine young man,”
just before her actions gave clear, or still clearer indication that
this was in her mind, had she murmured “Take me” as she let herself be
taken, and had the male asked, after the way common in novels, “Was it
my abdomen or the stripes on my palpi that made you first fall in love
with me?” then, perhaps, even those who believe that the higher
spiritual love is for man alone would have been converted—and yet I know
not, since assertions so unlikely in themselves might have flung doubt
on the whole paper.
But, however this may be, the evidence now offered us in favour of
Darwin’s views can never be strengthened except in this way, so that, as
far as proof is possible in such a matter, sexual selection as a law and
principal agent of beauty in nature is now proved, though, at the same
time, several more facts are added to those upon which the counter
hypothesis seems based, and which would certainly prove it in
Topsy-turvydom. To take these first, the authors of the paper in
question have sought to apply to spiders “the hypothesis that the
brighter colour of the male is due to his greater activity and vital
force.” “Beginning,” they say, “with the most brilliant family—the
_Attidæ_—we find that the females are, with few exceptions, larger,
stronger, and more pugnacious than the males. Thus we placed two females
of _Phidippus morsitans_ together in a glass jar. No sooner did they
observe each other than both prepared for battle. Eyeing each other with
a firm glance, they slowly advanced, and in a moment were locked in
deadly combat. Within a few seconds the cephalothorax of one was pierced
by the fang of the other, and with a convulsive tremor it relaxed its
hold and fell dead. We placed together eight pairs in all, and in each
instance the fight was short and even to the death. Subsequently we put
in a well-developed male, which, though smaller, was compactly built and
apparently strong enough to bring the virago to terms, but to our
surprise he seemed alarmed and retreated, trying to avoid her. She,
however, followed him up and finally killed him.”[132]
So much for _Phidippus morsitans_. Coming to _Dendryphantes elegans_,
the authors, who kept a number together in a large box, “were much
struck by the greater quarrelsomeness of the females. They would
frequently go out of their way to chase each other, and they were much
more circumspect in approaching each other than were the males.”[133]
Again they say, “Valkenaer, Menge, Hentz, and others give numerous
instances where the male meets his death through the fierceness of his
mate. In fact the danger is so imminent that after a successful
courtship it is the habit in several genera (e.g. _Epeira_ and
_Tegnaria_) for the male to retire with precipitation from the web of
the female as a reasonable precaution; yet the rule is for the male to
be more ‘beautified’ than the female.”[133]
Coming now to the actual courtship of these brilliant spiders, the
authors placed pairs of several species in square wooden boxes, having a
cloth bottom, on which they could easily move about. One of the species
experimented on was _Dendryphantes elegans_ mentioned only a moment
ago—such a name is not to be forgotten—whose beauty is thus described:
“The male is covered with iridescent scales, his general colour being
green. In the female the colouring is dark but iridescent, and in
certain lights has lovely rosy tints. In the sunlight both shine with
the metallic splendour of humming-birds. The male alone has a
superciliary fringe of hairs on either side of his head, his first legs
being also larger and more adorned than those of his mate.”[133]
Yet the extra vigour from which this special growth is supposed to have
sprung has not, as we shall see, affected his growth in general. “The
female is much larger, and her loveliness is accompanied by an extreme
irritability of temper, which the male seems to regard as a constant
menace to his safety; but his eagerness being great and his manner
devoted and tender, he gradually overcomes her opposition. Her change of
mood is only brought about after much patient courting on his
part”.[133] And now comes the minutely interesting description of this
iridescent, _couleur de rose_ courtship. “While from three to five
inches distant from her he begins to wave his plumy legs in a way that
reminds one of a windmill. She eyes him fiercely, and he keeps at the
proper distance for a long time. If he comes close she dashes at him and
he quickly retreats. Sometimes he becomes bolder, and when within an
inch pauses with the first legs outstretched before him, not raised, as
is common in other species; the palpi also (in insects it would be the
antennæ) are held stiffly out in front, with the points together. Again
she drives him off, and so the play continues. Now the male grows
excited, as he approaches her, and while still several inches away
whirls completely around and around; pausing, he runs closer, and begins
to make his abdomen quiver as he stands on tiptoe in front of her.
Prancing from side to side, he grows bolder and bolder, while she seems
less fierce, and yielding to the excitement, lifts up her magnificently
coloured abdomen, holding it at one time vertically and at another
sideways to him. She no longer rushes at him, but retreats a little as
he approaches. At last he comes close to her, lying flat, with his first
legs stretched out and quivering. With the tips of his front legs he
gently pats her; this seems to arouse the old demon of resistance, and
she drives him back. Again and again he pats her, with a caressing
movement, gradually creeping nearer and nearer, which she now permits
without resistance,”[133] and so on,
“Till the happy ‘yes’ falters from her mouth,”
almost as exciting, though not quite so detailed, as the climax scene of
a latter-day novel.
------------------------------------------------------------------------
[Illustration: 1. A solitary spider dancing before its mate.]
------------------------------------------------------------------------
[Illustration: 2. A cockroach attacking an astonished scorpion. Its
weapons are the spines on its powerful hind legs.]
Of the courtship of another species—_Habrocestum splendens_—we have the
following account: “The male, a magnificent fellow when we first caught
him, displayed for a long time before the female. He began by advancing
a few inches before her, and then backing off again, this being repeated
many times. After a while he settled down under a little web in the
corner. The female, troubled by this indifferent treatment, advanced
towards him; he came out and she fell back. This play was kept up for
some time, but at length the male began his courting in earnest. When
within a few inches of her he began a rapid dance from side to side,
raising the whole body high on the tips of the legs, the first pair
being directed forward and the palpi clasped together, with the abdomen
turned to one side and lifted up. After a short dance he stood
motionless, striking an attitude and remaining quiet for half a minute.
Then he turned his back on her, moving irregularly about, with his legs
forward and his palpi vibrating. Again he dances sideways before her,
strutting and showing off like a peacock, or whirling around and
around.”[133]
On such occasions the female would “commonly move nearer to him and
appear much excited herself. We at first supposed that this turning
around was accidental, but it happened so regularly at a certain stage
of the courtship that we concluded it was an important part of the
display, serving to better show off his brilliant abdomen.”[133] Of this
there can hardly be a doubt, since on every occasion the male spider,
whatever his species, assumed such attitudes as displayed his best
points to the best advantage—a fact which recalls the following passage
in one of Darwin’s letters: “I am very glad to hear of your cases of the
two sets of _Hesperiadæ_ (a butterfly), which display their wings
differently, according to which surface is coloured. I cannot believe
that such display is accidental or purposeless.”
How glad, and more than glad, would Darwin have been to have read the
tale of these spiders! It is, indeed, one of those ironies of fate, of
which the world is so full, that he did not live to see this
demonstration—for it is no less—of the truth of his most original and
elevating views; elevating they may be well called, since they allow to
the animal world an æsthetic faculty, the power, once thought
exclusively human, of appreciating beauty. It is curious how willing
many are to exalt humanity at the expense of all other beings. The
higher faculties they like, and perception of the beautiful they like,
and spirituality—especially in love—they like very much indeed; but they
only like these things in their own species. That is to say, conceit
lies at the bottom of all this exaltation. Such man-worshippers would
not have more of a good thing in the world, but less, so that they may
have all there is of it. On such grounds the war against evolution was
waged, and its last struggles are against sexual selection. The body has
been given up, but the spirit, which touches us yet more nearly, is
still fiercely defended.
In _Hasarius Hoyi_ “the sexes are very different, the male being the
more conspicuous of the two. In his dances, the male has several
movements. Most commonly he goes from side to side, with his first legs
obliquely up. At other times he twists the abdomen to one side, and,
bending low on the other, goes first in one direction for about two
inches, and then, reversing, circles to the opposite point. The females
are very savage, especially with each other, and even the members of the
sterner sex are not always free from danger when paying their
preparatory addresses. Once we saw a female eagerly watching a prancing
male, and, as he slowly approached her, she raised her legs as if to
strike him, but he, nothing daunted by her unkindly reception of his
attentions, advanced even nearer, when she seized him and seemed to hold
him by the head for a minute—he struggling. At last he freed himself and
ran away.”[133] Yet “this same male, after a time, courted her
successfully.” That so much savagery has to be overcome in the female,
and finally is overcome by these dances, shows how powerfully she must
be affected by them. Of another and previously undescribed species, “a
dozen or more males, and about half as many females,” were found by the
authors “assembled together” under natural conditions. “The males were
rushing hither and thither, dancing opposite now one female and now
another. Often two males met each other, when a short passage of arms
followed. The males were very quarrelsome, and had frequent fights, but
we never found that they were injured. Indeed, after having watched
hundreds of seemingly terrible battles between the males of this and
other species, the conclusion has been forced upon us that they are all
sham affairs, gotten up for the purpose of displaying before the
females, who commonly stand by, interested spectators.”[133]
Then there is a small ant-like species, who, “unlike most of the _Attid_
males, keeps all his feet on the ground during his courtship. Raising
himself on the tips of the posterior six, he slightly inclines his head
downwards by bending his front legs, their convex surface being always
turned forward. His abdomen is lifted vertically, so that it is at a
right angle to the rest of his body. In this position he sways from side
to side. After a moment he drops the abdomen, runs a few steps nearer
the female, and then tips his body and begins to sway again. Now he runs
in one direction, now in another, pausing every few moments to rock from
side to side and to bend his brilliant legs, so that she may look full
at them.”[133] What can be clearer than this? And here, indeed, the
authors remark: “We were much impressed by the fact that the attitude
taken by the males served perfectly to show off their fine points to the
female. We had never known the male of this species until the day that
we caught this one and put him into the mating-box, and it was while
studying his courtship that we noticed how he differed from the female
in his iridescent first legs. He could not have chosen a better position
than the one he took to make a display.”[133]
Elsewhere, in another experiment with the same species, the authors,
after remarking that if these specially modified front legs were held in
any other way the effect of the flattened and iridescent surface would
be lost, go on to say: “This is a good example of what we have again and
again observed in the courtship of the _Attidæ_: that whatever fine
points of colour or structure the male possesses, his actions before the
female display them to the very best advantage. In whatever part the
special merit may lie, he sedulously strives to bring it to the notice
and impress its beauty upon the mind of the female to whom he is paying
his addresses.”[133] As for the female, she is throughout described as
watching the male eagerly and with the greatest interest, and that this
interest is not always felt from the first, but is aroused by degrees,
becoming, at last, so strong as to suspend for a time the natural
inclination to assault and eat the wooer, is all the more significant.
That there are dangers in these courtships there has been some
indication, “but worse remains behind.” _Phidippus rufus_ was caught
once and eaten in an unguarded moment, and whilst _Phidippus morsitans_
was waving his particularly handsome first pair of legs, “thickly
adorned with white hairs,” precisely the same thing happened to him.
Still, on the whole, such incidents are exceptional.
Particularly interesting is the account given of the courtship of
_Saitis pulex_, a male of which species was introduced into a box
already occupied by a female. “He saw her as she stood perfectly still,
twelve inches away; the glance seemed to excite him, and he moved
towards her; when some four inches from her he stood still, and then
began the most remarkable performances that an amorous male could offer
to an admiring female. She eyed him eagerly, changing her position from
time to time, so that he might be always in view. He, raising his whole
body on one side, by straightening out the legs, and lowering it on the
other by folding the first two pairs of legs up and under, leant so far
over as to be in danger of losing his balance, which he only maintained
by sidling rapidly towards the lowered side. The palpus, too, on this
side, was turned back to correspond to the direction of the legs nearest
it. He moved in a semicircle for about two inches, and then instantly
reversed the position of the legs and circled in the opposite direction,
gradually approaching nearer and nearer to the female. Now she dashes
towards him, while he, raising his first pair of legs, extends them
upward and forward as if to hold her off, but withal slowly retreats.
Again and again he circles from side to side, she gazing towards him in
a softer mood, evidently admiring the grace of his antics. This is
repeated until we have counted one hundred and eleven circles made by
the ardent little male. Now he approaches nearer and nearer, and when
almost within reach, whirls madly around and around her, she joining and
whirling with him in a giddy maze. Again he falls back and resumes his
semicircular motions with his body tilted over; she, all excitement,
lowers her head and raises her body so that it is almost vertical; both
draw nearer”[133]—and the male, now, for some short period is in no
danger of being eaten.
Lastly—for this must be the last example—we have a species—_Astia
vittata_—in which the male is represented by two differing forms, each
of which dances before the female in its own particular way. One of
these forms is red, like the female, which he resembles in other
respects, so that this must be taken as the original specific type. The
other, which has evidently been developed from it, in deference to the
æsthetic preferences of the female, is black, with the special adornment
of three tufts of hair on his head, or thereabouts, that part of a
spider which is termed the cephalothorax. These tufts stick bolt
upright, rising together, but separating about half-way up, and give to
their fortunate possessor—for, as we shall see, he is fortunate—a very
spruce and dapper appearance. Looked at dispassionately, if one can do
that, they are certainly as handsome as moustaches, and there is no
reason in the nature of things why they should not be admired as much.
So, indeed, they are, and that the admiration bestowed upon each is of
an equally high nature I, at any rate, see no reason to doubt.
The following description will show what a spider with moustaches can
achieve: “The _vittata_ form, which is quite like the female, when he
approaches her raises his first legs either so that they point forward
or upward, keeping his palpi stiffly outstretched, while the tip of his
abdomen is bent to the ground. This position he commonly takes when
three or four inches away. While he retains this attitude he keeps
curving and waving his legs in a very curious manner. Frequently he
raises only one of the legs of the first pair, running all the time from
side to side. As he draws nearer to the female he lowers his body to the
ground, and, dropping his legs also, places the two anterior pairs so
that the tips touch in front, the proximal joints being turned almost at
a right angle to the body. Now he glides in a semicircle before the
female, sometimes advancing, sometimes receding, until at last she
accepts his addresses. The _niger_ form, evidently a later development,
is much the more lively of the two, and whenever the two varieties were
seen to compete for a female the black one was successful.”[133]
Here, surely, is a final answer to those assertions as to indifference
on the part of the female, which, though made in the teeth of
probability, are often, on account of the difficulties of observation,
almost impossible to disprove. Here are two kinds of males, one lively
and with moustaches, the other not so lively and without them; as the
first is always, or even, say, generally chosen, his appearance must be
preferred. Were it only his liveliness, as Dr. Wallace has suggested,
why should he have acquired another dress as well as another dance? or,
if the female can have a choice as between liveliness and slowness, as
between a jig and a minuet, why, in Heaven’s name, should she not have
one as between one get-up and another? Sexual selection might, I think,
be put to the test in this one species with its two male forms. Let but
a sufficient number of courtships be observed and reported on, and if
_niger_, in a large percentage of them, wins the day, choice on the part
of the female—the only link in the chain of evidence which it is at all
possible to deny—is a proved thing.
But to continue: “He—_niger_—is bolder in his manners (no wonder he
prevails), and we have never seen him assume the prone position, as the
red form did, when close to the female. He always held one or both of
the first legs high in the air, waving them wildly to and fro; or when
the female became excited, he stood perfectly motionless before her,
sometimes for a whole minute, seeming to fascinate her by the power of
his glance”[133]—greatly aided probably by the three tufts of hair
showing through the archway of the uplifted legs. Here, again, too, as
in some of the other species—perhaps all—“although the males were
continually waving their first legs at each other, their quarrels were
harmless. It was quite otherwise with the females, since they not only
kept the other sex in awe of them, but not infrequently in their battles
killed each other.”[133] As the males cannot win the females by
fighting, what have they to contend with effectively except these
curious, elaborate, and most interesting displays, the purpose of which
is so excessively obvious? On the other hand, the fact that the females
yield, almost against their nature, to these displays, that they are
slowly and gradually won through their means, is proof positive that
they like them, and if so, how is it possible that they should not like
one more or less than another? What, in fact, is choice but a greater or
less reaction to this stimulus or to that? The initial absurdity of
laying claim to a monopoly of such a capacity as this, either in our
matrimonial affairs, or any other matter in which animals participate,
has not been sufficiently dwelt upon.
Professor Poulton, in considering this case of _Astra vittata_ with its
two male forms, one of which is always chosen by the female in
preference to the other, remarks (with his own italics), “It must be
admitted that these facts afford the _strongest support_ to the theory
of Sexual Selection.”[134] He thus endorses—as anyone, I think, not
hard-set the other way, must endorse—the opinion of the authors of the
paper that “in the _Attidæ_ we have conclusive evidence that the females
pay close attention to the love dances of the males, and also that they
have not only the power, but the will, to exercise a choice among the
suitors for their favour,”[135] to which he adds this rider:
“Remembering that this conclusion has only been reached in the _Attidæ_
by the closest study, I think we may safely explain the smaller
confidence with which we can speak of other animals by the want of
sufficiently careful and systematic investigation.”
The process of the narrative having led, in the last chapter or two, to
a discussion of some of the ways in which insects become shaped and
coloured through natural selection, sexual selection seemed marked out
as the subject for this one. The reason why I have filled it with
extracts from a certain very interesting paper has been a better one
than that of saving myself trouble. That paper—the most important one
perhaps that has ever been written on the subject—is a wonderful
confirmation of Darwin’s views, but Darwin, as it appears to me, has not
benefited by it in the way that he ought to do in the popular mind.
There is no work that I know of, written upon merely popular lines, that
brings these facts forward, and yet I feel sure that to large numbers of
people, who yet do not care to read books avowedly scientific, they must
be extremely interesting, not only in themselves, but as allowing them
both to form a judgment on the subject, and on the correctness or
otherwise of Darwin’s views—for Darwin is an interesting and picturesque
figure far beyond the close borough of science.
Now the general more intelligent public who read, perhaps, widely, but
not very deeply or very specially, know that Darwin believed in two
forces—natural and sexual selection—by the joint action of which,
species, as he held, had been gradually modified and evolved, and they
know that the former of these two has been accepted by science, but that
to the latter there has been much more opposition, and that it is not—or
is not supposed to be—established like the other. Many, perhaps, may
have read Dr. Wallace’s _Darwinism_, a work in which Darwin’s most
distinctive and original view—that one whose conception, apparently, he
shared with nobody and on which he based much of the argument contained
in his _Descent of Man_—is considered and rejected in a way which makes
the title of the book misleading, surely, if not a somewhat comically
ludicrous misnomer. All those who have read it, as well as many who have
not, will be interested—they cannot fail to be—in the wonderful record
of spider courtships contained in these extracts, and having reflected
on them, they will, if I mistake not, be much more impressed with the
arguments _for_ this part of Darwinism than they were with those brought
against it in the book of that name.
All these latter arguments, by the way—the languor of swallows as
against the vitality of parrots, trogons, etc.—were well known to Darwin
himself; and as no one was, at the same time, more impartial in
considering, and more capable of correctly estimating, facts hostile to
his own theories, or which, at first sight, might seem to be so, it may
not be out of place to end this chapter with a reference to what he
thought of them. This we may gather from a statement contained in a
paper—the last, presumably, ever written by him—which was read before
the Zoological Society but a few hours before his death, and which is as
follows: “I may, perhaps, be here permitted to say that, after having
carefully weighed, to the best of my ability, the various arguments
which have been advanced against the principle of sexual selection, I
remain firmly convinced of its truth.”
-----
Footnote 130:
Tropical Nature, p. 97.
Footnote 131:
Malay Archipelago (1898), p. 331.
Footnote 132:
Observations on Sexual Selection in Spiders.
Footnote 133:
Occasional Papers of the Natural History Society of Wisconsin, vol.
i., Nos. 1, 2, and 3.
Footnote 134:
The Colours of Animals.
Footnote 135:
Occasional Papers of the Natural History Society of Wisconsin, vol.
i., Nos. 1, 2, and 3.
------------------------------------------------------------------------
CHAPTER XXIII
Web making spiders—Dangerous wooings—An unkind
lady-love—Lizard-eating spiders—Enlightened curiosity—Rival
entomologists—Instinct of resignation—A worm-eating
spider—Alternative explanation—The dangers of
patriotism—Trap-door spiders—Web-flying spiders—Spiders that
nearly fly—Spider navigators—The raft and the diving-bell.
NONE of the spiders mentioned in the last chapter are web-makers. These
latter are not dancers; that is to say, the males do not dance before
the females when they wish to recommend themselves as husbands. Instead,
they pull at the strands of the web, whilst stationed at its
circumference, in a manner which has a distinct meaning for the female,
who sits in the centre, and who replies by other twitches. These may be
either of an encouraging or repellent nature, and it is only in the
former case that the lover ventures to approach. This, however, he must
do with extreme caution, and prepared at any moment to drop and hang
suspended by a thread should the object of his attentions, who greatly
exceeds him in size, change her mind or conceive some cause of
displeasure against him. Should he not be sufficiently quick on such
occasions, he is liable to be spun up between the long legs of his
lady-love as though he were a fly, and disposed of accordingly. This was
observed in 1798 by Raymond Maria de Termayer, who remarks upon it:
“Perhaps overpowering hunger compelled her to do it, but the act was
very ferocious.”
The most curious thing in these _webepathic_ courtships, as one may call
them, is that the female spider seems to know the particular jerk or
twitch of any strand of the web which is made by a male, and to
distinguish it, perfectly, from the vibrations set in motion by a fly or
other insect that enters it, for upon these occasions, though her back
may be turned towards her admirer, she does not trouble to look round,
whereas in the latter case she would not only do so, but come rushing
down to secure her victim—if she were hungry, perhaps it should be
added. On the other hand, as has been already mentioned, the male can
interpret the wishes of the female from the movement she imparts to the
thread, and regulates his conduct accordingly. Webepathy, therefore,
does not seem a name ill-chosen to describe this system of
intercommunication of ideas.
The spider mentioned above as devouring her lover was the common garden
or geometric one, as it is sometimes called, which in England is the
largest example of a web-spinner. In other parts of the world, however,
web-spinning spiders attain to a much larger size, and their webs, of
course, are in proportion. The largest, perhaps, are found in
Madagascar, and the gigantic fabrics which many of these weave are
curiously utilised by smaller spiders of a parasitic disposition, who
spin their own little webs between the thick strands of those of their
hosts. Here they live in perfect amity with the latter, in whose
presence they find a protection against the attacks of small birds—for
these, it would seem, stand in awe of these huge spiders, in whose toils
they are sometimes accidentally caught, and by whom they are then
devoured. So, at least, Vinson, the historian of the spiders of
Madagascar, would seem to imply, if he does not actually make the
statement, of which I will not be quite sure.[136] That the great
_Mygale_ of South America eats birds is now an established fact, Bates
having given an account of it in his well-known work, _The Naturalist on
the River Amazon_.[137] In this case also the birds—for there were two
of them—were caught in a web, but it was not a geometric one, in which
the spider sat, but a much denser and more closely woven fabric
stretched across a crevice, or irregularity, in the trunk of a tree, the
spider—which was of much larger size than the largest _Epeira_—keeping
watch behind it in the recess.
------------------------------------------------------------------------
[Illustration: A BIRD-CATCHING SPIDER’S WEB.]
This enormous Madagascar spider spins webs so strong that
birds are caught and held in them. In one of the large
meshes will be seen a small parasitic spider’s web for
catching flies and other insects. The smaller spider is not
only permitted to do this, but is protected by its host from
the attacks of the smaller birds.
Other spiders—as doubtless the _Mygale_ if he can get them—will eat
lizards, as the following account by Mr. Frederick Pollock will show:
“Having procured from the Deserta Grande some fine specimens of this
large and handsome spider (_Lycosa_—a kind of tarantula) in the early
part of this year, and having provided suitable cages with glass lids
for them, I was anxious to ascertain how large an animal the largest
spider would take; and for this purpose I obtained some lizards about
three inches long, including the tail. Three of these lizards were
killed and devoured by one spider during the time I kept it. They were
eaten bones and head and claws and all, the only remnant of the feast
being a small ball about a quarter of an inch in diameter, which was
cast aside at the bottom of the cage.”[138] But why were not some larger
lizards tried, since there was no difficulty about three inches? Every
inch would have increased the fun—I mean have added to the scientific
interest. But perhaps there were none larger.
Mr. Pollock goes on to say that “the islands of Madeira, Porto Santo,
and Deserta Grande all lie within an area about fifty miles across. They
have each its own peculiar large _Lycosa_, no two being alike; and it is
a very remarkable fact that these _Lycosæ_ vary in size inversely with
the magnitude of the island on which they are found—Madeira, the largest
island, having the smallest _Lycosa_, and Deserta Grande, the smallest
island, having by far the largest spider. The mode of defence of all
these varieties of _Lycosæ_ is precisely the same. They elevate the
thorax, raise the first pair of legs high up, and opening wide asunder
their falces, strike at and seize any object, such as the end of a
pencil” (or the tail of a lizard) “in a most formidable manner.”[138]
There is another lizard-eating spider, or at least a spider that will
eat lizards when formally introduced to them, and that in a very
scientifically interesting manner, the lizard showing such a lively
sense of its situation, and the jaws of the spider working in a way
which is very curious. These jaws, it appears, are double, also
“cheliform,” “denticulate,” and several other things, from which I
gather that there are two pairs, each pair working something like the
claws of a crab, but with a sawing action, adapted to their toothed
surface. By an extremely beautiful adjustment, when the spider in
question seizes its prey, one pair of jaws holds on to it, whilst the
other saws into it, and then the pair which has been sawing, holds, and
the pair which has been holding, saws, and so on alternately, a
division, and yet, at the same time, a combination of labour.
“Like to a double cherry, seeming parted,
But yet an union in partition.”
The efficacy of the arrangement was well tested by an Anglo-Indian
scientist upon a lizard three inches long, _exclusive_ this time of the
tail. “The spider sprang upon it, and made a seizure immediately behind
the shoulder. The poor lizard struggled violently at first, rolling over
and over in its agony, but the spider kept firm hold, and gradually
sawed away with its double jaws into the very entrails of its
victim.”[139] There was an interesting variation between this case and
the last, where, it will be remembered, the lizards were eaten “bones
and head and claws and all,” whereas here “the only parts _uneaten_ were
the jaws and part of the skin.” This lizard, however, was “at least five
inches long from nose to extremity of tail”; but then, again, the spider
must have been larger too, though clearly its meal was something in the
nature of a feat, since after it “it remained gorged and motionless for
about a fortnight, being much swollen and distended.”[139] There is no
mention of this in the other case, which would seem to imply that the
result was different. If so, we have here a fact of great interest—what
fact, scientifically elicited, is not?—but in order to establish it upon
a really firm basis, further experiments should be made, and, once more,
as the limit of size has evidently not yet been reached, I would
recommend a lizard of six inches long.
This spider, however, now I come to remember, is not really one, but a
_solpugid_, and a _solpugid_ is a creature so like a spider that it used
to be thought one some years ago, but now belongs, not only to a family,
but to an order of its own, which comes somewhere between the scorpions
and the true spiders. They are large creatures, and their bite is very
severe, though it does not appear to be poisonous. Some of the species
are nocturnal, as is the case with the one above mentioned, which was
christened _Galeodes vorax_ by its discoverer, Captain Hutton, if he
indeed discovered it. Captain Hutton, being a great entomologist—to
attain which title one has only to put pins through insects—used to lay
a sheet on the ground at night, and stand a lantern upon it. Numerous
insects were attracted to the light, and this brought _Galeodes_—who is
a great entomologist too, though without the pins—upon the _tapis_ or
_draps_.[139]
Often there would be fights between two rivals, and of these, or,
rather, of the general fighting, and one may also say yielding, habits
of the species, Captain Hutton gives the following somewhat curious
account. “They plant their true feet” (for these _Galeodes_ have a pair
which look exactly like feet, but are really their palpi) “firmly on the
ground, the body at the same time being elevated and the two pairs of
palpi held out in front, to ward off the attack. In this attitude they
advance and retire, according as either gains a slight advantage,
endeavouring to throw each other to one side, so as to expose some
vulnerable part or form an opening for attack; and when this is once
effected the fortunate wrestler instantly takes advantage of it, and
rushing in, seizes his adversary behind the thorax, and the combat is
ended, the vanquished victim yielding himself, without further struggle,
to his inevitable fate.” Similarly, “if, in their efforts to get away,
they are brought into contact, the one instantly seizes the other and
devours him, the victim making no struggle whatever; but if they meet
face to face they both enter into a wrestling match for life or death.”
This habit of yielding as soon as there is no more use in struggling
seems a very strange one, since it is opposed to the primary instinct of
self-preservation, and it is not easy to see how the species can benefit
by certain individuals dying in a passive manner, unless, indeed, by
refusing to do so they might injure the victor, who, by dying
afterwards, would add to the tribal mortality. If this be really the
explanation, we are reminded of Huber’s statement as to two queen bees,
when each has it in its power to sting the other, being seized with a
sort of horror, under the influence of which they separate, thus
avoiding the catastrophe of leaving the hive queenless.
Though, as we have seen, there are some spiders which eat birds, and
others which eat lizards, yet both these interesting things take place
abroad. Here, however, in England, it would seem that we have a spider
which eats worms, catching them at the end of a long woven bag which
descends into the earth, and into which the worm somehow manages to get.
How it does so, however, is not at all clear, since the bag, which is
sometimes a foot long, is described as having no opening at either end,
the spider living enclosed in it, apparently a permanent prisoner. Still
a sac like this would seem as difficult of entry for flies as for worms,
and the spider, which is three-quarters of an inch in length, and armed
with very large mandibles, or falces—to use the approved word—must, it
is plain, live on something. As a matter of fact, it was living on a
worm when found by Mr. Brown, who gives the following account of the
matter. “On drawing out one of the sacs,” he says, “I observed a worm at
the lower end, partially within the sac and partially outside, and it
was evident that the spider had been eating a considerable portion of
its anterior extremity.” One would have thought that a careful
examination of the way in which the worm had got into the sac would have
thrown light on the problem, but of this we hear nothing more.
When taken out of the ground the sac was limp and flaccid, but
afterwards the spider inflated it, and it was then seen to have some
minute valves—“openings,” that is to say, “protected or covered by a
little valve or door.” They were not, however, to be detected in every
nest—possibly on account of their very small size. That the object of
these valvular openings is to admit air seems obvious, for spiders
breathe through lungs and require a good supply of oxygen. It was now
concluded, both by Mr. Brown and Mr. Newman—a well-known
entomologist—that this particular spider lived on worms and resided
permanently in a long subterranean sac or bag, which it had the power of
inflating with air. A different view, however, was propounded by Mr.
Meade—an authority on spiders—who suggested that the worm had only got
into the sac by accident, and that the spider, like other subterranean
nest-makers, probably came out at night and fed abroad, returning to
rest at home during the daytime. To do this it would, indeed, have to
unweave one end of its sac—probably the upper one—and then do it up
again, but there was no reason, in Mr. Meade’s opinion, why it should
not act in this way. To me, however, it seems unlikely that the minute
valves, made with such care, should be destroyed in this manner and made
afresh every day; and moreover, when Mr. Brown looked again at the sac,
in order to test this theory, he could find no evidence of its having
been dealt with in this Penelopean manner. There were no traces of fresh
silk. The evidence, therefore, seems to be more in favour of _Attipus
sulzeri_—for that is its name—being a genuine worm-eating spider. If so,
it is worthy of all respect as a curiously aberrant form.[140]
These spiders are of a deep brown colour, with a very soft abdomen and a
generally half-baked appearance, but with hard, black, shining
mandibles. There was only a single individual—evidently the female—in
the sacs taken by Mr. Brown, but I myself was the finder of one such
sac—for I feel sure it must have been the same—in the New Forest, and in
this a pair were amicably settled, one being about twice the size of the
other. This, if I mistake not, was in May, but I also remember, or seem
to, that the bag was quite open at one end. Thus, then, stand the facts.
Upon them I think we are justified in believing that there is a
worm-eating spider in England, but of course it would be a very high
honour for any country to have such a creature, so that there is a
danger of letting one’s patriotic feelings run away with one.
In these sac-making spiders we see, perhaps, the ancestors of, or rather
travellers towards, those which crown a silk-lined perpendicular tunnel
with a skilfully made trap-door. The latter is furnished with a hinge,
and should it be discovered, the spider, seizing it from within,
endeavours with might and main to prevent its being raised. As is well
known, the upper surface of these trap-doors, or, as we may call them,
lids, are covered by the spider with such materials—leaves, grass, moss,
etc.—as surround the site of its nest, so that when shut down they are
indistinguishable from the general surface of the ground.
Another use to which the webs of spiders are put is that of a parachute,
on which the little creature—for small species alone may enjoy this
luxury—sails delicately through the air. This, however is not the
nearest approach made by any of the tribe to actual flight, though in
practice it almost surpasses that power, even as possessed by many
winged insects, who do indeed cleave the air, but cannot ride upon it in
a filmy chariot, twinkling in the rays of the sun. Still there is one
spider that, though it has not yet achieved wings, is in process of
developing them. This little semi-Ariel—but the subject will be best
done justice to in the glowing language of the Rev. O. P. Cambridge:
“Adult male, length rather above two lines. The abdomen is of an
elongated oval form, and rather flattened; its upper side is furnished
with an epidermis, which is continued, laterally, on either side to an
extent considerably exceeding the width of the abdomen, and of a
semi-oval or elliptical form; the outer portion of this epidermis, on
either side, is capable of being depressed and folded round the abdomen,
or elevated and expanded to its full width, after the manner of wings.
Mr. H. H. B. Bradley, of Sydney, New South Wales, to whom I am indebted
for examples of this exceedingly interesting and remarkable spider,
tells me that he has observed them elevating and depressing the flaps,
and also actually using them as wings or supporters to sustain the
length of their leaps. That this, as with an analogous appendage in the
flying squirrel, should be intended for such sustentation one could have
but little doubt, after examining it even in the preserved specimens.
The three examples were all found on one spot near Sydney, in the month
of October, running and jumping on low plants and flowers.”[141]
It is delightful to think of a little delicate spider-body like this,
rising gracefully from the petal of one flower, expanding its thin,
filmy fringes, and descending in a long slanting line through the air,
like a flying squirrel or a galeopithecus, onto the petal of another.
Even were its appearance no more than elegant, this would be a most
pleasing sight. But it is much more than this. Various hues meet in its
diminutive body, and so harmonious and pleasing is the general effect
produced by them that the first captor of so much loveliness was
enraptured as he gazed on his prize, whilst even Mr. Cambridge, with
only dried specimens to fire his imagination, yet cannot choose but
exclaim: “It is difficult to describe adequately the great beauty of the
colouring of this spider.”[141]
Spiders, then, either through gossamer or their own structural
modification, seem engaged in the conquest of the air. There remains but
the water, and this element also they have partly subdued. There are
raft-spiders and diving-bell spiders. The first, having woven a few
dried leaves, stalks, grasses, etc., launches out as courageously from
the shore as the first navigator, whose heart, according to Horace, was
thrice bound in brass, but who probably was timid and cautious. Our
spider, however, has no fears, nor need it to have any, since no sort of
capsizal can affect a structure which answers its purpose as well one
side up as another; whilst even if it were to sink—though that hardly
lies in its nature—there is always the water to run on. The raft, in
fact, is only like the nest or web ashore—a place to have a comfortable
meal in. The prey—some aquatic insect—is caught generally on the surface
of the stream, and the spider, after each successful raid, skims back
with her booty to the little self-guiding boat which it has temporarily
left. There, when no longer hungry, she sits and scuds about, careless
and pleasure-loving, like another little Phædria in her “flitt barck”
over the waters of the Idle Lake.[142]
“Thus,” says Büchner, “everywhere in nature are battle, craft, and
ingenuity, all following the merciless law of egoism, in order to
maintain their own lives and to destroy those of others.” In man,
indeed, there is some counterpoise to all this in the mind and _façon de
parler_; but the lower animals do not think so much, and, having no
proper language, cannot even talk altruistically.
Lastly, we have the water-spider, whose little spun nest, against the
submerged stem of some aquatic plant, is open at the bottom like a
diving-bell, and filled with air which its owner carries down from the
surface in successive bubbles, each one looking “like a globe of
quicksilver.” To collect them she swims on her back, and, in some
manner, entangles them amongst the numerous hairs with which her abdomen
is covered, where they cling safely all through the journey,
“Proud of that delicate lodgment.”
There may be other bubbles as pretty, perhaps, but few, by bursting, do
such good to those who have cherished them. In winter, it would seem,
the spider closes the entrance to the diving-bell, and sleeps, dry and
soft, in a well-aired bed, in spite of the damp situation.
-----
Footnote 136:
Vinson, Aranéides des Iles de la Réunion, Maurice, et Madagascar, pp.
268, 269.
Footnote 137:
Bates, The Naturalist on the River Amazon (1864), p. 96.
Footnote 138:
Annals and Magazine of Natural History, vol. x. (1872), pp. 273, 274.
Footnote 139:
Captain Thomas Hutton, “Observations on the Habits of a Large Species
of _Galeodes_,” Journal of the Asiatic Society. Reprinted in Annals
and Magazine of Natural History, August, 1873, No. 75.
Footnote 140:
The above facts are quite reliable, but having made my notes, I forgot
to mention their source—one of the established entomological
organs—and so cannot now refer to it.
Footnote 141:
Annals and Magazine of Natural History, September, 1874.
Footnote 142:
The Faerie Queene, book 2, canto vi.
------------------------------------------------------------------------
CHAPTER XXIV
Aquatic insects—Lyonnet’s water-beetle—A floating cradle—Larva
and pupa—An ingenious contrivance—Nothing useless—The
imaginary philosopher—How the cradle is made—The mysterious
“mast”—Later observation—The giant water-bug—An oppressed
husband.
SPIDERS having brought us to the water, it may be as well, or even
better, in view of the title of this work, to say something about
water-insects. Of these, so long as the water be fresh, and not salt,
there are many, and the largest, perhaps, if he exceeds some of the
dragon-fly larvæ and the Giant Water-Bug of America, must be the Great
Water-Beetle—_Hydrophilus piceus_—which is larger even than the much
commoner one—_Dytiscus_—which everybody knows, and which is _the_
water-beetle to most people.
It is the fate of some animals to become associated for all time in our
minds with the name of some particular man, as, for instance, the bee is
with that of Huber, and the ephemera with that of Swammerdam. Again, the
fame of Lyonnet, though he was skilled in eight languages, and became
cypher secretary and confidential translator to the United Provinces of
Holland, is principally bound up with a certain caterpillar, viz. that
of the goat moth, of which creature, though only an amateur in such
matters, he made dissections and executed plates, which have never yet
been surpassed, and are supposed to be entirely unsurpassable. In a
lesser degree his memory is associated with this particular
water-beetle—the great one, into the heart of whose mystery he was the
first to pierce: “In the beginning of July,” he tells us, “I had noticed
in the ditches a kind of cocoon which I did not recognise. It was
whitish, of the size of the end of the finger, nearly spherical, but
rather oval and flattened. The surface, which looked like tow, was not
quite smooth. One of the two ends was flatter than the other, and
furnished with a raised rim. From the space within this rim projected a
sort of little tapering mast about as long as the cocoon.”[143]
These cocoons, when opened, were found to contain about a hundred eggs.
Lyonnet kept them in water till the eggs hatched. “The larvæ,” he says,
when this had taken place, “remained one day enclosed in the cocoon
before escaping. Then they made an oval aperture in the lower part of
the flattened end of the cocoon, and escaped through this into the
water.”[143] Here they fed upon snails, their manner of eating which is
thus described: “The larva seizes the snail with its mandibles, then
bends its body backwards and rests the snail upon the broad back, which
serves as a table (as with the larva of the grain-eating ant of Texas).
In this position, holding the snail in its legs, the larva breaks the
shell, and devours it.”[143]
When full-fed the larvæ left the water, and one of them was placed by
Lyonnet in a box full of moistened earth. This it entered, and, some
days afterwards, changed into a large white pupa or chrysalis, about
which there was one curious feature, viz. that “on each side of the
head”—or, as an entomologist would say nowadays, “on the fore part of
the prothorax—were three brown, strong hooks. Two others of the same
kind were found at the hinder end of the body.”[143] These hooks were
solid, so that they could contain no part of the perfect insect, and
Lyonnet points to them as good examples of _apparently_ useless
structures. Their office, indeed, he himself knows, but he does not
reveal it till the usual philosopher has been imagined who denies that
they can have any. Then, of course, comes the anticipated discomfiture
of this unwary person—so frequent in the eighteenth century—who,
unwarned by experience, has walked quietly into the trap. “In the damp
earth which the pupa requires the above-described hooks fulfil a
purpose, unexpected by us, but, at the same time, of great importance.
The skin of the pupa is very delicate. Lying on damp earth, it could
hardly escape injury, and the weight of the body might easily give it a
distorted shape. But (_Monsieur le Philosophe_) the pupa protects itself
from these dangers by assuming an unusual attitude. It extends itself
back downwards in a horizontal position, and supports the weight of its
body by the three sets of hooks, as upon a tripod. In this attitude,
though surrounded on all sides by moist earth, it keeps its body from
actual contact with any object until it has assumed its final shape.
Thus,” continues Lyonnet, turning full upon the stupefied philosopher,
“we see how necessary are those hooks, which at first sight appeared so
useless. To decide that this or that structure is superfluous because we
cannot guess its use is truly ridiculous in beings whose information is
so limited as ours.”[143] Applauding shouts (“_Mais certainement!_”
“_C’est vrai cela!_”) rend the air, and the imaginary philosopher goes
out in a state of painful confusion.
The above facts, first made known by Lyonnet, have been confirmed by
subsequent observers, such as Miger, and the pupa of another and much
smaller water-beetle is now known to support itself in the same manner,
or, rather, on the same principle, since the place of hooks at either
extremity is taken by spiny projections, with which the back is covered.
Lyonnet now turned his attention to the mature beetle, and especially to
the female, whom he was anxious to see make her cocoon. Having put a few
in a large wooden trough and supplied them with some floating weed, “I
had,” he says, “before long, the pleasure of seeing the female
_Hydrophilus_ betake herself to work under my eyes. I found, to my
surprise, that, like the spider, she had her spinneret at the hinder end
of the body. Two small brown prominences enclosed each a delicate
conical tube, from each of which a separate thread proceeded, and with
these the cocoon was woven in the following way. At first, lying
upside-down near the surface of the water, the beetle buried the hinder
part of her body, and the two hindermost pairs of legs, in the weed,
whilst with the first pair, which were free, she drew and pressed the
weed around the end of her body, moulding it to its shape. She then
began to weave what seemed the under half of her cocoon, but having
finished this part she turned over with it so that it became the upper
half, and then wove the real under one. The two curved surfaces were
then woven together, and in about an hour and a quarter the body of the
cocoon was finished. For about two hours after this the beetle remained
still, her back being uppermost. At first her body was buried in the
cocoon up to the thorax, but one could see that she was gradually
withdrawing it. During these two hours of apparent rest she laid her
eggs, not at hazard, but in regular order, side by side, the pointed
ends uppermost. This work accomplished, she closed the mouth of the
cocoon, and then began to spin the little mast, which gradually rose
above the surface of the water till it had attained the requisite
height, and the cocoon was then finished.”[143]
Lyonnet was unable to discover the use of the so-called mast, and it
remains a mystery to this day, so that the imaginary philosopher might
have a better chance here, were it not his _métier_ to be put to
confusion. It is hollow, and as the cocoon contains air, with which the
beetle supplies it—just as the water-spider does her diving-bell—Miger,
whose observations were made in 1807, some fifty years after those of
Lyonnet, supposed it might serve as the channel of entry. But, although
hollow, it has no orifice, but is closed at the end, and this does not
seem to accord with the above view. Mr. G. A. Laker, a modern observer,
does not think that the spike can serve as a balance to the cocoon,
since this is usually attached to some weed, or other supporting
substance. He, however, cut the spike off two of the cocoons, and the
eggs in both of these remained unhatched. Moreover, these cocoons
subsequently sank, whereas in their normal state they “are so
constructed that when floating loose the spike retains its proper
position, and even if the cocoon be held so that the spike is parallel
with the water and then suddenly released, it immediately rights
itself.”[144] The balance theory, therefore, certainly seems to have
something in its favour. Lyonnet’s own conjecture was that the mast, as
he calls it—a designation against which Miger protests—might merely
represent the waste silk which the beetle felt impelled to get rid of.
The time taken by the beetle in making the whole cocoon is about five
hours, whilst the mast, spike, or turned-up point, as Miger severely
calls it, takes it half an hour. It is curious that whereas Lyonnet’s
cocoons held “about a hundred” eggs, Mr. Laker gives the number as
“usually between fifty and sixty.”[144]
As space has its exigencies—and long may it continue to have—I will here
merely mention such names as _Gyrinus_, _Dytiscus_, _Hydrobius_,
_Donacia_, etc., “and let _them_ speak for me,” but having paid some
attention to the great water-beetle, silence in regard to the giant
water-bug would be hardly gracious, and might be ill taken. This
terrific creature is like a monstrous exaggeration of our own
water-scorpion, to which it bears a distorted, but real resemblance,
minus, however, the long ovipositor—the so-called tail behind. Its
appearance is not to be described. Like other bugs, and as are the
aphides and cicadas for less cruel purposes, it is armed with a long,
sharp-pointed beak, through which, having plunged it into the body of
its prey, on whose back it has previously leaped, it sucks the
life-juices, holding on, all the while, with its two curved, claw-like
front legs. Its strength is in accordance with its size, and both are
such that it finds no one in its own circle, so to speak, at all capable
of contending with it. “It is the facile master of the ponds and
estuaries of the tidal creeks and rivers of the Atlantic States,” says
Uhler. “Developing in the quiet pools, secreting itself beneath stones
or rubbish, it watches the approach of a _Pomotis_, mud-minnow, frog, or
other small-sized tenant of the water, when it darts with sudden
rapidity upon its unprepared victim, grasps the creature with its
strong, clasping fore-legs, plunges its deadly beak deep into the flesh,
and proceeds with the utmost coolness to leisurely suck its blood. A
copious supply of saliva is poured into the wound, and no doubt aids in
producing the paralysis which so speedily follows its puncture in small
creatures.”[145]
Another American water-bug of similar build, but much smaller size, has
the same general habits, to which it adds the more special one of
carrying about its eggs on its back, where, in time, they are hatched,
but do not, it would appear—though this seems somewhat out of harmony
with the practical spirit of nature—proceed at once to suck their
parent’s blood, an omission which, as it would be a most moving instance
of unselfish surrender on the part of the latter, is, perhaps, to be
regretted. Possibly the reason is that the eggs are not fixed upon the
right back, so that even were this _dénouement_ to take place, we should
not have an instance of maternal, but only of paternal affection. This,
for some reason, is not so effective as the other, and therefore Nature,
who, as we know, is a consummate artist, may not care to waste her
materials on an inferior situation.
Be this as it may, the fact that the domestic economy of these
water-bugs did not proceed, throughout, upon the lines that might have
been expected may first have led a German observer—Schmidt—to suspect
something unusual, in consequence of which misgiving he looked more
closely into the matter, and found—what had not before been
imagined—that the male and not the female was the egg-bearer. He was
not, however, able to determine how this arrangement was brought about,
or with what feelings the male received and bore his burden. This was
left for Miss Slater, who found that the females in her aquarium
insisted upon laying their eggs on the backs of the males, that the
latter objected to their doing so, which led to a struggle between the
two, often lasting for two or three hours, but ending invariably in the
victory of the female. The male has, then, to bow to necessity, but he
does not do so in a cheerful spirit, nor even without some further
efforts to escape his destiny. “That he chafes under the burden,” says
Miss Slater, “is unmistakable; in fact my suspicions as to the sex of
the egg-carrier were first aroused by watching one in an aquarium which
was trying to free itself from its load of eggs, an exhibition of a lack
of maternal interest not to be expected in a female carrying her own
eggs. Generally the _Zaithas_ are very active, darting about with great
rapidity, but an egg-bearer remains quietly clinging to a leaf, with the
end of the abdomen just out of the water. If attacked he meekly receives
the blows, seemingly preferring death (which, in several cases, was the
result) to the indignity of carrying and caring for the eggs.”[145] This
last, however, is not very explicit, so that, the whole account not
being to hand, I cannot say what precisely happened.
It is curious that the male should be so spiritless, after receiving the
eggs, for this would seem to nullify such advantages as the arrangement
might otherwise offer. The eggs must be laid somewhere, and might be
supposed safer on the back of the male than elsewhere—in which fact,
perhaps, we may see the origin of the instinct. But if the male, sinking
under his burden, is able neither to defend himself nor it, this
advantage seems nullified.
Estuaries and tidal creeks, which, as we have seen, are included in the
habitat of these water-bugs—at least, of the giant one—bring us
gradually to the sea. That there are marine insects we know, but they do
not appear to extend beyond the tidal beach, on the sands of which they
expatiate, when the sea is out, and burrow into them on its return. All
are small, and still smaller is the amount said about them, even in such
works as are precisely those where all that is known on the subject
ought to be stated—systematic works of natural history, for instance,
which take “_Arthropoda_ (Insects, etc.)” in their due order, but do not
so much as tell you whether marine ones exist or not. Yet the date of
such works is after 1895. For these reasons, and another which has been
once or twice before alluded to, I have but one remark to make about
marine insects, and I will make that in the next chapter.
-----
Footnote 143:
Mémoires du Muséum, vols. 18-20.
Footnote 144:
Entomologist, vol. 14 (1881), p. 82.
Footnote 145:
Quoted in The Insect Book, by Leland O. Howard.
------------------------------------------------------------------------
CHAPTER XXV
One remark—Phosphorescent insects—Glow-worms and
fire-flies—Fiery courtship—A beetle with three
lamps—Travelling by beetle-light—The great lantern-fly
controversy—Is it luminous?—Madame Merian’s
statement—Contradictory evidence—A Chinese edict—Suggested
use of the “lantern”—Confirmation required—Luminous
centipedes.
NO marine insect—this is the remark—is phosphorescent—that is to say, as
far as I know, which is a very saving clause indeed. This seems curious,
because, as everyone knows, other sea-dwelling creatures are, producing
most wonderful and beautiful effects, and, moreover, the luminous
property is active in many terrestrial insects. Of these the glow-worm
is a familiar and, though, perhaps, the humblest, a very beautiful
example. At any rate, there are insects of the glow-worm family whose
fires are far less “ineffectual,” or, to speak more truly, far outglow
those of our own species. What, for instance, can be more gorgeous than
the green or orange lights—for they differ in colour according to the
sexes—with which the nights and the rich vegetation of the West Indies
are brilliantly, yet softly, lit up? Nothing, surely, if it be not the
name of the creature producing such splendour, which is _Pygolampis
xanthophotis_[146]—not one syllable less.
Whether it is the male or the female that gives out the green or the
orange light, I do not know, nor in my opinion do various monographists
in various encyclopædias and text-books, though they make no such
avowal, but content themselves with not saying. However, it is not a
matter of importance except to the insect producing it, in whose breast
the one or the other colour arouses very different sensations—rivalry or
love. For there is no doubt now that these lovely illuminations, as well
as those of our own glow-worm and of every other light-bearing creature,
have relation to the needs and wants of their producers, to whose
æsthetic sense, and not to ours, they are intended to appeal. That they
appeal also to our own is a mere irrelevant side-issue, not considered,
so to speak, by the force under whose pressure these beauties were
called forth, and not of the smallest consequence. It was not always
thought so, and were the pride of man reachable by such considerations
it might humiliate us to reflect that displays, which in real beauty
immeasurably surpass our clumsy illuminations and fireworks, are made
nightly, not for our eyes, but for those of a beetle.
------------------------------------------------------------------------
[Illustration: INSECTS THAT CARRY LAMPS
The glow-worms in this picture are rather larger than life. The male
insects have wings; it is the females chiefly, if not solely, that emit
the soft, beautiful light.]
Gilbert White, however, in the eighteenth century, exclaims amidst some
very pleasing verses:
“For see, the glow-worm lights her amorous fire!”[148]
on which one of his editors of the nineteenth remarks: “This is still
the generally received notion, but the fact is that both sexes of the
glow-worm are phosphorescent, not only in the perfect insect, but also
in the larva and even pupa state.”[147] But this does not affect White’s
statement, which is the simple fact, as well as “the generally received
notion,” and, moreover, though our own male glow-worm is phosphorescent,
it is not so brilliantly so as the female. Indeed, in the ninth edition
of the _Encyclopædia Britannica_—which is later than this editorial
note—it is stated not to be so at all, so that even if White believed
this—which is not very clear—he has been supported by learned authority
for a very long time.
In other species the male is the more brilliant, or the sexes do not
differ greatly in this respect, each one lighting its “amorous fire” in
the degree that nature allows it to—as no doubt our own male does too.
Of this fact, which, in the light of Darwinism, might have been boldly
assumed, there is no longer any doubt after Professor Emery’s
interesting observations[149] on the Italian species _Luciola Italica_.
These were made in the meadows around Bologna, where, having caught some
females, the Professor imprisoned them in glass tubes and laid them down
amidst the grass. In this situation, though smell as an attractive agent
was excluded, males would come flashing to the glass, and, on the other
hand, as soon as the lamp of any of these became visible, the female
would kindle her own, if it had previously been unlighted. Arrived on
the spot, the male would dash madly about the unapproachable female, who
continued to light her lamp at him till another, and then others,
arrived, when it is to be supposed that her favours were distributed. In
the end there would sometimes be a dozen fiery rivals glowing and
flashing round the tube. But though the female shot out her attractive
beams with evident intent to please, it does not appear that she was the
seeker in the business, since we hear only of males flying to the
imprisoned females, and not of females pursuing these males. To such
modest merit, therefore, as a nice distinction between different ways of
attaining the same end may entitle her, the female glow-worm also is
entitled.
The light of the two sexes in the Italian glow-worm is described by
Professor Emery as being the same in colour and intensity, but differing
in some other respects. The flashes of the male, for instance, are more
quickly recurrent, whilst those of the female gleam out at longer
intervals, but last for a longer time. They are, also, more tremulous,
as well as more restricted, though what is meant by this last
expression, since the brightness is said to be equal, is not quite
apparent. Possibly it may imply that the light proceeds from a lesser
area of the body, but, if so, this should be clearly stated, even in a
_résumé_. I can find no reference to such a fact, if it be one, in the
text-books.
From the above it is evident that the glow-worm’s fires are anything but
“uneffectual” from the point of view of the insect, but Shakespeare was
no doubt thinking of something very different—their paling, namely,
before the light of dawn. According to Gilbert White, however, they
should have been out long ago—the glow-worm being too wise to afford
opportunities of comparison in this respect. Thus subtly does the
naturalist of Selborne impugn the accuracy of the Bard of Avon: “By
observing,” he says, “two glow-worms which were brought from the field
to the bank in the garden, it appeared to us that these little creatures
put out their lamps between eleven and twelve, and shine no more for the
rest of the night.”[149] The intention here, though cleverly disguised,
is not sufficiently so to escape detection. It was possibly seen through
by the late Charles and Mary Cowden Clarke, who in one of the million or
so notes to their edition of Shakespeare, say, without distinct
reference to the passage in question:—“_Uneffectual._ There is double
signification included in this word; it means the glow-worm’s light,
which shines without giving heat, and which no longer shows when morning
appears.”[150] Thus whilst not committing themselves to White’s opinion
they provide a safe refuge for their author, in case it should prove in
time to be correct; according to the sound principle contained in a
Russian proverb which says, “Had he known where he was going to fall, he
would have laid down straw.”
In tropical countries fire-flies take the place of glow-worms with us,
and though the light which these give out is not so soft and poetic as
the lovely green or golden green one of the latter, yet it is more
effectively beautiful, owing to the way in which it wanders through the
night, appearing and disappearing in successive brilliant flashes. For
here the beetle that carries the lamp is a flier, and flashes it about
at pleasure through the air, having the power, it would seem, either of
showing or concealing its light. The effect of a number of these points
of brilliancy, gleaming out, now here, now there, on the soft night air
of the tropics, is inexpressibly beautiful, as though, in a smaller
firmament, innumerable miniature stars had ceaseless birth and death.
Women, who like to emphasise their own beauty, or the want of it, by
placing themselves in juxtaposition with every lovely thing in nature,
and care not if a thousand deaths go to help one smile or glance, have
not forgotten the fire-flies. They put them in their hair, or wire them
onto their dresses, threading them together, sometimes, in long bands,
which they wind about their fair—or otherwise—persons; they do this,
more especially, when going out to parties, fancy-dress balls, or other
social entertainments. The advantages are obvious, for the homeliest
features may be thus lighted up, and the dullest woman become brilliant.
No wonder that in some South American cities—Vera Cruz for example—these
fire-fly beetles form quite an important article of trade, all for
toilette purposes.[151] The natives catch them by waving sticks with
burning coals tied to their ends through the air, by the light of which
they are attracted, and so come within reach of a long-handled butterfly
net. When caught, they are put into a box covered with a little netting
of wire, and there kept till wanted. They are fed upon sugar-cane, and
twice a day must be bathed in tepid water.[151]
What is done with the poor beetles after they have contributed to the
night’s amusement we are never told—whether those that have been all
wired together are unwired and let go, or pulled off in two or more
pieces to save trouble, as seems more likely. It is likelier still
perhaps, in the houses of the rich, that the whole thing is flung aside,
and the poor living lamps left to struggle till they die—unprovided with
sugar-cane. But such details are not thought worth mentioning. The
charming effect is the one thing dwelt upon, and charming it may very
well be, though to gain it through a mass of even insect discomfort is,
to my mind, a contemptible thing. Fancy fifty or a hundred
uncomfortable, writhing, struggling things on the dress that a lady is
dancing in, every one of which, if let go, would make a wandering star
in the air more really worth looking at than the whole ball-room
together! By substituting flowers for women, however, effects far more
beautiful are gained through less reprehensible means. The
fire-beetles—why should they be called flies?—are in this case confined
in small globes of delicate glass, set amidst clusters of flowers, or
flowering shrubs, and thus they softly illuminate the garden. Give them
some sugar-cane whilst the party is in progress, and let them go next
morning, and they will have had very little to complain of—a strange
experience for any lower creature that gets into the clutches of the
highest one.
The most wonderful of all the fire-beetles is the large one of near two
inches long—quite, or more, if we count the antennæ—that inhabits
Mexico, where in ancient times it was used as a lantern by the Aztecs in
their night-journeys, as it still is by their modern descendants. It is
wonderful, not by reason of its size merely, or, in any special degree,
of the light it emits—though this is brilliant in proportion to it—but
because it carries three separate lamps: two above, situated on either
side of the thorax, and one on the under side, just in front of the
abdomen. Thus, as it turns or varies in its flight, one flash of the
most intense brilliancy follows another, like the revolving light of a
lighthouse. The colour of the light is described as a rich
green—richest, however, or at least brightest, on the under
surface.[151] The beauty and dazzling effect of this upon a dark night
can be imagined, and is thus described by Dr. Kidder: “Before retracing
my steps I stood for a few moments looking down into the Cimmerian
blackness of the gulf before me; and while thus gazing a luminous mass
seemed to start from the very centre. I watched it as it floated up,
revealing in its slow flight the long leaves of the palm _Euterpe
edulis_, and the minuter foliage of other trees. It came directly
towards me, lighting up the gloom around with its three luminosities,
which I could distinctly see.”[151] There is something wonderfully
poetical in the thought of winged beings like this pursuing each other
through the night, by the light of these glorious flashes—the “light of
their own loveliness,” it may well be called, since it is, indeed, their
beauty. If seems curious and a waste that where there is the greatest
capacity of poetic imagination we should find the least, or almost the
least, realisation of it in habit and structure.
We know from Oviedo that the Mexican Indians, when they travelled at
night, were accustomed to fasten these great refulgent beetles on their
hands and feet, and thus pass flaming through the country. They danced,
too, by their light, and even wove or painted by it. Why, therefore,
could not lamps of great power, as well as beauty, be evolved from such
insects by bringing the selective agency of man to bear upon them? The
phosphorescent principle in living nature has not perhaps been made the
most of by us. Was more made of it by the Aztecs? and did they turn
their attention to the systematic rearing of these living lamps?—for,
from hearing so little about them one would not think that these insects
were so useful now, as, from the above account and what other
contemporary Spanish writers tell us, it would seem that they were, at
the time of this old and cruelly destroyed civilisation.
Holder, in his work on phosphorescent animals, either quotes or refers
to Prescott as saying that “when the Spaniards visited the country”—that
is, Mexico, “the air was filled with the _cucujo_, a species of large
beetle which emits an intense phosphoric light from its body strong
enough to enable one to read by. These wandering flies, seen in the
darkness of the night, were converted by the excited imagination of the
besieged into an army of matchlocks.” Surely, from such a foundation,
something as superior to it as are our cultivated fruits, or domestic
breeds, to the wild stocks from which they sprung, might in no long time
be produced, since it is not to be supposed but that some individuals of
the _Pyrophorus_ give a stronger light than others. The above passage,
by the way, if it be from the _Conquest of Mexico_, as one might suppose
it to be, is most carefully concealed in the index, which, however, it
might very well be, and yet exist, as I know from much teasing
experience. As to the matchlocks, would to Heaven the old Mexicans, as
well as the Peruvians, had had them, or, still better, 11-inch
Howitzers. I might then have something more to say about these wonderful
beetles. All I can add now is that the light appears to be used by the
insect as a guide to its own movements, since when the celebrated Dr.
Dubois covered one of the side ones with wax, this caused the individual
so treated to walk in a curve, and when “both spots were covered it soon
stopped, and then moved in an uncertain manner, carefully feeling the
ground with its antennæ.”[151] But I do not know if “both” here means
all three of the lamps, or only the two upper ones.
If there be any luminous insect that eclipses the _Pyrophorus_ it must
be the great lantern-fly—also of South America—provided only that the
great lantern-fly _is_ luminous. That is a most essential point, and it
does not appear yet to have been satisfactorily made out. The principal
evidence on the affirmative side is that of Madame Merian, who was right
about the _Mygale_—the great bird-killing spider—and who here speaks as
an actual eye-witness. Her account is as follows: “The Indians,” she
says, “once brought me, before I knew that they shone at night, a large
number of these lantern-flies, which I shut up in a large wooden box. In
the night they made such a noise that I awoke in a fright, and ordered a
light to be brought, not knowing from whence the noise proceeded. As
soon as we found that it came from the box we opened it, but were still
more alarmed, and let it fall to the ground in a fright at seeing a
flame of fire come out of it; and as many animals as came out, so many
flames of fire appeared. When we found this to be the case we recovered
from our fright, and again collected the insects, highly admiring their
splendid appearance.”[151]
Here, then, is a definite statement, from which all possibility of
mistake seems excluded, if, as I suppose is the case, there is no doubt
as to the specific identity of the insect which was the subject of it,
and which is thus described by Mr. Holder in the work already mentioned:
“The _Fulgora lanternaria_ of South America,” he tells us, “is nearly
three and a half inches long from tip of head to extremity of tail (i.e.
abdomen), and almost five and a half inches broad with its wings
expanded.” Truly a goodly insect, of right portly dimensions, and if it
be not really luminous—upon occasions, at any rate, for it certainly is
not so generally—it is so much the greater pity. But to continue: “The
body is of a lengthened oval shape, while the head is distinguished by a
singular prolongation, which sometimes equals the rest of the body in
size.” This is a most remarkable appendage, if it may be called so,
hollow and with a blown-up, inflated sort of look. It does, indeed, to
some extent resemble a Chinese lantern, and seems made to be lighted up.
The colour, too, suggests this, since it is striped longitudinally with
red and yellow, presenting quite a gala appearance. Accordingly, it is
said to be here that the luminous property of this strange insect
exists. This is its lantern, and, by reason of it, it has received its
name of lantern-fly.
And yet, since that night when Madame Merian had her interesting
experience, we meet with no one, apparently, who can unequivocally say
that he has seen the Great Lantern-Fly with its lantern alight. On the
other hand, we have some second-hand statements which have almost the
value of first, such as that of M. Westmael, who “assures us that a
friend of his observed the luminosity”;[151] whilst “John C. Branner,
PH.D., states that when in South America he was often informed that it
was luminous, but never could find anyone who had personally seen the
light.”[151] The curious thing is that there are other lantern-flies
belonging to other parts of the world, and in regard to them too we have
the same doubt and discrepancy, the same assurances and general belief,
the same categorical denials. Thus a distinguished authority on the
subject of phosphorescence— Dr. Phipson—in referring to the smaller
Chinese species, _Fulgora candelaria_—the candle-fly—says: “It is from
these appendages, the sides of which are transparent, that the
phosphoric light appears.” And again: “It is said also that the trunk of
a tree covered with numerous individuals of _Fulgora candelaria_, some
in movement, others in repose, presents a very grand spectacle,
impossible to describe, but which may be witnessed sometimes in
China.”[151] It would seem, too, that there exists a Chinese edict which
forbids young women to keep these candle-flies; and if this is not with
the idea of preventing their use as signals, or of checking vanity, it
is difficult to see what the object of such an enactment can be.
Lastly, we are told by Packard, in his _Guide to Insects_, that “Mr.
Caleb Cooke, of Salem, who resided several years in Zanzibar, Africa,
told me that the lantern-fly is said by the native to be luminous. They
state that the long snout lights up in the night, and in describing it
say its head is like a lamp (_keetchwa kand-tah_).”
All this evidence appears to me to point in one way, and one way only—I
mean, of course, in its entirety, since otherwise it points in two ways.
But even if it is possible that in one country alone an insect—well
known and conspicuous—can have got the reputation of being luminous
without really being so, at least occasionally, this can hardly have
come about in regard to the same, or some allied insect, in three or
four countries. Added to this we have Madame Merian’s direct evidence,
but, on the other hand, it is perfectly clear that these insects are not
always, or even generally, luminous. The conclusion, then, seems
irresistible that they occasionally are so, that, for some reason or
other, the phosphorescent principle is active in them only at certain
times or seasons. Why this should be so we do not know, but there is
nothing inconceivable in it; and some other animals—for instance,
centipedes—would seem to be luminous at some times and not at others.
The so-called lantern or snout being a very remarkable organ, for which
some use must be assumed, the likelihood of its sometimes becoming a
lamp would be increased considerably, if, so far as we knew, it
performed no other office. This was how the case stood till lately; but
in 1899 there was the Skeat Expedition for scientific purposes to the
Malay Archipelago, and on its return Mr. Nelson Annandale propounded a
theory in regard to the more ordinary use, at least, of the organ in
question, which was based on his own observation. His account is as
follows: “The curious anterior prolongation of the head in many genera
of the _Fulgoridæ_ has long puzzled entomologists. At Biserat, in Jalor,
I was fortunate enough to observe the real use of this peculiar
structural modification. On the morning of May 30th I noticed a specimen
of _Hotinus spinola_ seated on the trunk of a Durian tree in the
village, and incautiously attempted to catch it in my hand. The insect
remained almost still, merely drawing in its legs towards its body and
pressing the claws firmly against the bark, until I had almost touched
it. Then it lowered its head with very great rapidity, flew up into the
air without spreading its wings, and alighted on the roof of a house six
feet behind a tree, and considerably higher than its position on the
trunk had been. At the time I did not notice anything peculiar in the
way in which this _Fulgorid_ jumped, for there are many large species of
the same family which, without being provided with long noses, can leap
for a considerable distance by means of their legs only; but as I was
examining my specimen (a dead one) I was struck by an indentation or
crease that ran across the central region of the nose at right angles to
its main axis. Then I discovered that at this point, and at this point
only, it was flexible, and that if the tip of the nose and the dorsal
surface of the abdomen were pressed together between the finger and
thumb, and then suddenly released, the insect would not fall straight to
the ground, but would be propelled for some distance through the air
before doing so, just as would be the case if a piece of whalebone were
treated in like manner.”[152]
Mr. Annandale then goes on to show, or to suggest, that the
_Fulgorid_—as he calls it—by pressing its snout—or lantern—against the
tree-trunk, and at the same time pushing itself off from it with its
legs, “would fly into the air at a tangent,” and he continues: “I have
no doubt that this is substantially what occurs in the case of
_Hotinus_; but in the living insect the action is far too rapid for the
eye to discriminate its details, and dead specimens cannot be made to
leap in this way because it is impossible to force the legs to perform
their part of the action.”[152] Such, then, is the theory, but as other
members of the family jump in much the same way, to all appearance,
without any such apparatus, and since the bending of the head, at such a
moment, might be correlated with the movements requisite to produce such
a leap as this, it certainly wants confirmation.
Some of the finest displays of luminosity have been observed in
centipedes, which although not insects, may be counted such for the
purpose of this volume. Thus M. Audouin, noticing one night a light
proceeding from one of his chicory-fields, “ordered his man to turn up
the earth, when the scene that followed is described as truly
magnificent. The soil appeared as if it had been sprinkled with molten
gold, the display being intensified if the insects were trodden upon or
rubbed. In the latter case streaks of light appeared, as if a bit of
phosphorus had been placed upon the hands, the light being distinctly
visible for twenty seconds.”[153]
Mr. Brodhurst, again, referring to another species—_Geophilus
electricus_—about an inch and a half in length, and in the daytime
inconspicuous enough, says: “The light looked like moonlight, so bright
was it through the trees. It was a dark night, warm and sultry. Taking a
letter, I could read it. It resembled an electric light, and proceeded
from two centipedes and their trails. The light illuminated the entire
body of the animal, and seemed to increase its diameter three times. It
flashed along both sides of the creature in sections, there being about
six, from head to tail, between which the light played, moving, as it
were, perpetually in two streams. The trail extended one and a half feet
from each centipede over the grass and gravel walk, and it had the
appearance of illuminated mucus. On securing one of the creatures for
examination, I found on touching it the light was instantly
extinguished.”[153] The display is, therefore, voluntary, nor could Mr.
Brodhurst ever get his centipedes to shine in captivity.
-----
Footnote 146:
Chambers’s Encyclopædia.
Footnote 147:
White, Natural History of Selborne (stereotyped edition), p. 84.
Footnote 148:
Ibid., p. 353.
Footnote 149:
Bull. Soc. Entomolog. Ital., 1885-7.
Footnote 150:
Cassell’s Illustrated Shakespeare, “Hamlet,” Act i., Scene 5, Note
137.
Footnote 151:
C. F. Holder, Living Lights.
Footnote 152:
Proceedings of the Zoological Society for 1900.
Footnote 153:
C. F. Holder, Living Lights.
------------------------------------------------------------------------
CHAPTER XXVI
Scorpions and suicide—The act proved—Intention
probable—Conflicting evidence—Scorpions and
cockroaches—Concentrating backwards—Economy of
poison—Decorous feeding.
THE assertion that scorpions are occasionally luminous—if indeed it has
ever been seriously made—does not appear to have received confirmation.
Of fire, indeed, these creatures have a horror, but that probably
relates to its property—heat—to which they are extremely sensitive. The
popular belief is, that, if surrounded by fire, a scorpion will
deliberately sting itself to death. Of the fact, or, at least, of the
fact of the self-inflicted sting, there can be little doubt, but in
regard to the motive there is room for difference of opinion. Mr. Pocock
says, truly enough, that it is _à priori_ improbable that the scorpion
has any intention of killing itself.[154] But what, then, is its
intention in stinging itself, supposing that it deliberately does so?
Nor must it be forgotten that the idea of death—of destruction—must be
indissolubly associated in the scorpion’s mind with the use of its
sting, since it uses it with that purpose only, and that is the result
which constantly attends its use. Is it, then, really so improbable that
it stings itself with the same intention as that with which it stings
other creatures?—or, rather, with what other possible intention can it
do so, assuming the act to be a voluntary one?
Nor would it be necessary to prove the intention that the sting, thus
delivered, should be fatal in its effects, and, in regard to this, Mr.
Bourne has satisfied himself by experiments with some Indian scorpions
that a self-inflicted wound, or even wounds inflicted by individuals of
the same species on one another, have no effect. On the other hand, he
found that a moderately high temperature was fatal to his scorpions, and
so concludes that this has been the real cause of death in all such
cases as we are here considering.[154]
The above theory, however, hardly accords with the experience of Mr. W.
G. Bidie, also of India, and that very part of it where Mr. Bourne’s
experiments were made—viz. Madras. Writing to _Nature_, he says: “One
morning a servant brought me a large specimen of this scorpion (the
common black one of Southern India), which, having stayed out too long
in its nocturnal rambles, had apparently got bewildered at daybreak and
been unable to find its way home. To keep it safe the creature was at
once put into a glazed entomological case. Having a few leisure minutes
in the course of the forenoon, I thought I would see how my prisoner was
getting on, and to have a better view of it, the case was placed in a
window in the rays of the hot sun. The light and heat seemed to irritate
it very much, and this recalled to my mind a story which I had read
somewhere that a scorpion on being surrounded with fire had committed
suicide. I hesitated about subjecting my pet to such a terrible ordeal,
but taking a common botanical lens, I focussed the rays of the sun on
its back” (so that Apollo may have flayed Marsyas as a mild
alternative). “The moment this was done it began to run hurriedly about
the case, hissing and spitting in a very fierce way. This experiment was
repeated some four or five times with like results, but on trying it
once again the scorpion turned up its tail and plunged the sting, quick
as lightning, into its own back. The infliction of the wound was
followed by a sudden escape of fluid, and a friend, standing by me,
called out, ‘See! it has stung itself: it is dead.’ And sure enough in
less than half a minute life was quite extinct.”
This seems plain enough. The scorpion had not died of the heat, up to
the moment at which it stung itself—an act which would require some
vital energy. It did sting itself, and in less than half a minute
afterwards it was dead. Moreover, as the experiments with the lens were
intermittent, there seems no more reason why the last one should have
been fatal than the other four or five. It is, perhaps, possible to
imagine that the scorpion was almost dead before, that the last heating
caused it to expire, and that in the moment of doing so it stung itself
by involuntary muscular action. There is nothing, however, in the
narrative to suggest this, but quite the contrary.
Supposing the sting to have been a voluntary act, what could the
scorpion have intended except to injure itself? Had it ever in its life
used its sting with any other purpose than that of doing injury? Mr.
Bidie adds: “I have written this brief note to show (1) that animals may
commit suicide; (2) that the poison of certain animals may be
destructive to themselves.”[155]
Writing several years later, also to _Nature_, Dr. Allen Thomson,
F.R.S., gives the following account, not, indeed, of his own experience,
but that of an eye-witness in whom he feels full confidence. He says:
“While residing, many years ago, during the summer months, at the baths
of Sulla, in Italy, in a somewhat damp locality, my informant, together
with the rest of the family, was much annoyed by the frequent intrusion
of small black scorpions into the house, and their being secreted among
the bedclothes, in shoes, and other articles of dress. It thus became
necessary to be constantly on the watch for these troublesome creatures,
and to take means for their removal and destruction. Having been
informed by the natives of the place that the scorpion would destroy
itself if exposed to a sudden light, my informant and her friends soon
became adepts in catching the scorpions and disposing of them in the
manner suggested. This consisted in confining the animal under an
inverted drinking-glass or tumbler, below which a card was inserted, and
then, waiting till dark, suddenly bringing the light of a candle near to
the glass in which the animal was confined. No sooner was this done than
the scorpion invariably showed signs of great excitement, running round
and round the interior of the tumbler with reckless velocity for a
number of times. This state having lasted for a minute or more, the
animal suddenly became quiet, and, turning its tail on the hinder part
of its body over its back, brought its recurved sting down upon the
middle of the head, and, piercing it forcibly, in a few seconds became
quite motionless, and, in fact, quite dead. This observation was
repeated very frequently.”[156]
Here, again, it is difficult to see how a mistake in observation can
have occurred, and admitting the facts to be true, they go far beyond
Mr. Bourne’s theory to account for these phenomena, which, however, has
been adopted by Mr. Pocock, as the result of his own experiments. In the
first place, it is not here the heat—unless by association of ideas—but
the actual sight of the flame that terrifies the scorpion, and death,
apparently, is inflicted as the result of that. Again, there can be no
doubt as to the self-inflicted stinging, and from the manner of it, as
well as its invariability, it seems to have been deliberate. Whether
death was the result of it or not, we have the act, and the act, if a
voluntary one, must have implied a destructive intention. It hardly
seems possible, however, that the light of a candle, outside a tumbler,
though held near it, can in so short a time have made the interior so
hot as to kill the scorpion, whilst, on the other hand, the poison from
the creature’s sting must have pierced its brain, and a few seconds
afterwards it was dead.
If, then, we decide to disbelieve in the story of scorpions committing
suicide when unable to escape from fire, we must explain away these two
accounts, which we can do by supposing the narrators to be either
dishonest or stupid. There is no other way that I can see, so if neither
of these do, we ought to believe the story. However, there is plenty of
evidence which points in the opposite direction, and the advantage of
this is that we can take our choice.
Scorpions are interesting animals to keep in captivity, and their habits
under these conditions have been carefully studied by Mr. Pocock.[154]
When supplied with sand they dig pits in it, in which they lie during
the greater part of the day. The second and third pairs of legs are used
for this purpose, the scorpion raising itself upon the other two pairs,
as well as, to a certain extent, upon the claws and the end of the tail.
In this position it kicks the sand backwards from under it, and then
when the excavation is sufficiently deep, sweeps away the accumulated
heap, with its tail, so that the edge of its lurking-place is on a level
with the surrounding surface. It can thus, as it lies there, obtain an
uninterrupted view, which the better enables it to receive with proper
attention any creature of the requisite size and quality that approaches
its portals. Such creatures are principally insects, spiders,
centipedes, wood-lice, and the like—but here we may remember one little
spider that imitates a scorpion, and may therefore approach with
impunity, at least if the disparity in size be not too great, for whilst
some scorpions are quite small, others attain a length of eight or nine
inches, with a bulk more than in proportion to their length.
In captivity, and, no doubt, under nature too, when they happen to come
across them, scorpions will eat cockroaches, but a cockroach is not
altogether a defenceless creature, and sometimes a large one will give
battle, and even with success. The weapons upon which, in these cases,
it relies are its powerful hind legs armed, as they are, with spines
which project backwards. Backwards accordingly it advances upon the
scorpion, and increasing its pace suddenly, when at the requisite
distance salutes the astonished enemy with a shower of kicks. So
unexpected is this mode of assault that it is sometimes effective, even
against so redoubtable an opponent as a scorpion, whilst a tarantula
spider has been known to fly, panic-stricken, before or rather behind a
large cockroach. But such efforts, however heroic, can have only a
transient success, where the conditions are so unequal. Jaws and sting
must prevail against soft bodies armed only with spiny legs. “_Alla
stoccata_ carries it away.” Generally the poor cockroach is
seized—sometimes, in the first instance, by the antennæ—as it comes
inadvertently too near to the scorpion, or even trespasses upon its
back. At once the tail is bent above it, and the fatal sting enters its
body. Paralysis ensues, and would no doubt be quickly followed by death,
even were the scorpion, thereupon, to retire. As it is, however, it is
difficult to say whether the victim dies more of the sting or of being
eaten.
From the latter process, at any rate, there is no recovery, as may be
seen in the case of smaller cockroaches, upon whom the scorpion, from
motives of economy, does not always waste its poison. It merely, when
thus provident, holds the contemptible creature in its claws, whilst
bringing to bear upon it its two pairs of chelæ or real jaws, which act
upon the same principle as those of _Galeodes vorax_, if the reader
remember. It feeds in a leisurely manner, the impatience of the
cockroach not affecting it in the least. Two hours for a good-sized
one—a _pièce de résistance_—is not considered too long by the scorpion.
Scorpions, it appears, use their stings in a very careful, deliberate
manner. It is not a mere random thrust with them, lunged in anywhere,
just as the body of an insect happens to come. On the contrary, they
feel about this body, most anxiously, with their tail, till they have
found a soft spot in it, and then introduce their sting in a careful
manner. In fact, they sting an insect in much the way that Isaak Walton
impaled a frog upon the hook—“tenderly as if they loved him”—and for the
same class of reason, viz. to make a workmanlike job of it, and not
break their stings against the harder parts of its body, for the point
of this weapon is delicate and might get chipped against the hard shards
of a beetle, or other such resisting surface.
For the same prudent reason the tail is carried aloft, over the
scorpion’s back, when it walks, so that the whole organ, but especially
the point of it, which is curled round again underneath, is preserved
from contact with the outer world. The sting, or rather the sides of the
poison vesicle just above it, are clothed with hairs, which are, no
doubt, delicately tactile, and the same may be said of the tail and
various other parts of the body. Touch, indeed, is the principal sense
which conveys impressions to the soul of the scorpion. Sight is
defective, and hearing does not seem to exist.
* * * * *
WILLIAM BRENDON AND SON, LTD., PRINTERS, PLYMOUTH
-----
Footnote 154:
Nature, June 1st, 1893.
Footnote 155:
Ibid., vol. xi.
Footnote 156:
Ibid., vol. xx. p. 577.
------------------------------------------------------------------------
Transcriber’s Notes
Title page - Added missing period
Pg. 42 - Changed ‘free-booter’ > ‘freebooter’ in caption to match
illustration index and rest of text
Pg. 106 - “Unto to me” > “Unto me”
Pg. 140 - “Tierra del Fuega” > “Tierra del Fuego”
Pg. 203 - ‘plausibilty’ > ‘plausibility’
Pg. 137 & 142 - ‘aphis’ > ‘Aphis’ to match other instances
Pg. 145 - Corrected typo: ‘Sycænidæ’ > ‘Lycænidæ’
Pg. 187 - Corrected typo: ‘Bell’ > ‘Belt’
Pg. 217 - Corrected typo: “312, 33” > “312, 313” - Source checked
Pg. 222 - Added missing close-quote w/reference to source
Pg. 222 - Corrected typo: ‘Amophila’ > ‘Ammophila’
Pg. 253 - Corrected typo: ‘caterpilllar’ > ‘caterpillar’
Pg. 270 - Corrected typo: ‘replique’ > ‘réplique’
Pg. 290 - Corrected typo: ‘exisit’ > ‘exist’
Pg. 334 - Corrected typo: ‘especally’ > ‘especially’
Except for the above, inconsistent hyphenation, as well as archaic and
non-standard spelling and has been retained.
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