The family of Wasps whose name I inscribe at the head of this chapter
has not hitherto, so far as I know, made much noise in the world. Its
annals are limited to methodical classifications, which make very poor
reading. The happy nations, men say, are those which have no history.
I accept this, but I also admit that it is possible to have a history
without ceasing to be happy. In the conviction that I shall not disturb
its prosperity, I will try to substitute the living, moving insect for
the insect impaled in a cork-bottomed box.
It has been adorned with a learned name, derived from the Greek
Tachytes, meaning rapidity, suddenness, speed. The creature's godfather,
as we see, had a smattering of Greek; its denomination is none the
less unfortunate: intended to instruct us by means of a characteristic
feature, the name leads us astray. Why is speed mentioned in this
connection? Why a label which prepares the mind for an exceptional
velocity and announces a race of peerless coursers? Nimble diggers of
burrows and eager hunters the Tachytes are, to be sure, but they are no
better than a host of rivals. Not the Sphex, nor the Ammophila, nor the
Bembex, nor many another would admit herself beaten in either flying
or running. At the nesting-season, all this tiny world of huntresses is
filled with astounding activity. The quality of a speedy worker being
common to all, none can boast of it to the exclusion of the rest.
Had I had a vote when the Tachytes was christened, I should have
suggested a short, harmonious, well-sounding name, meaning nothing else
than the thing meant. What better, for example, than the term Sphex? The
ear is satisfied and the mind is not corrupted by a prejudice, a
source of error to the beginner. I have not nearly as much liking for
Ammophila, which represents as a lover of the sands an animal whose
establishments call for compact soil. In short, if I had been forced, at
all costs, to concoct a barbarous appellation out of Latin or Greek in
order to recall the creature's leading characteristic, I should have
attempted to say, a passionate lover of the Locust.
Love of the Locust, in the broader sense of the Orthopteron, an
exclusive, intolerant love, handed down from mother to daughter with
a fidelity which the centuries fail to impair, this, yes, this indeed
depicts the Tachytes with greater accuracy than a name smacking of
the race-course. The Englishman has his roast-beef; the German his
sauerkraut; the Russian his caviare; the Neapolitan his macaroni; the
Piedmontese his polenta; the man of Carpentras his tian. The Tachytes
has her Locust. Her national dish is also that of the Sphex, with whom I
boldly associate her. The methodical classifier, who works in cemeteries
and seems to fly the living cities, keeps the two families far removed
from each other because of considerations and attaching to the nervures
of the wings and the joints of the palpi. At the risk of passing for a
heretic, I bring them together at the suggestion of the menu-card.
To my own knowledge, my part of the country possesses five species, one
and all addicted to a diet of Orthoptera. Panzer's Tachytes (T. Panzeri,
VAN DER LIND), girdled with red at the base of the abdomen, must be
pretty rare. I surprise her from time to time working on the hard
roadside banks and the trodden edges of the footpaths. There, to a depth
of an inch at most, she digs her burrows, each isolated from the
rest. Her prey is an adult, medium-sized Acridian (Locust or
Grasshopper.--Translator's Note.), such as the White-banded Sphex
pursues. The captive of the one would not be despised by the other.
Gripped by the antennae, according to the ritual of the Sphex, the
victim is trailed along on foot and laid beside the nest, with the head
pointing towards the opening. The pit, prepared in advance, is closed
for the time being with a tiny flagstone and some bits of gravel, in
order to avoid either the invasion of a passer-by or obstruction by
landslips during the huntress' absence. A like precaution is taken by
the White-banded Sphex. Both observe the same diet and the same customs.
The Tachytes clears the entrance to the home and goes in alone. She
returns, puts out her head and, seizing her prey by the antennae,
warehouses it by dragging backwards. I have repeated, at her expense,
the tricks which I used to play on the Sphex. (For the author's
experiments with the Languedocian, the Yellow-winged and the White-edged
Sphex, cf. "The Hunting Wasps": chapter 11.--Translator's Note.) While
the Tachytes is underground, I move the game away. The insect comes up
again and sees nothing at its door; it comes out and goes to fetch its
Locust, whom it places in position as before. This done, it goes in
again by itself. In its absence I once more pull back the prey. Fresh
emergence of the Wasp, who puts things to rights and persists in going
down again, still by herself, however often I repeat the experiment.
Yet it would be very easy for her to put an end to my teasing: she would
only have to descend straightway with her game, instead of leaving it
for a moment on her doorstep. But, faithful to the usages of her race,
she behaves as her ancestors behaved before her, even though the ancient
custom happen to be unprofitable. Like the Yellow-winged Sphex, whom I
have teased so often during her cellaring-operations, she is a narrow
conservative, learning nothing and forgetting nothing.
Let us leave her to do her work in peace. The Locust disappears
underground and the egg is laid upon the breast of the paralysed insect.
That is all: one carcase for each cell, no more. The entrance is stopped
at last, first with stones, which will prevent the trickling of the
embankment into the chamber; next with sweepings of dust, under which
every vestige of the subterranean house disappears. It is now done:
the Tachytes will come here no more. Other burrows will occupy her,
distributed at the whim of her vagabond humour.
A cell provisioned before my eyes on the 22nd of August, in one of the
walls in the harmas, contained the finished cocoon a week later. (The
harmas was the piece of enclosed waste land in which the author used to
study his insects in their natural state. Cf. "The Life of the Fly,"
by J. Henri Fabre, translated by Alexander Teixeira de Mattos: chapter
1.--Translator's Note.) I have not noted many examples of so rapid a
development. This cocoon recalls, in its shape and texture, that of the
Bembex-wasps. It is hard and mineralized, this is to say, the warp and
woof of silk are hidden by a thick encrustation of sand. This composite
structure seems to me characteristic of the family; at all events I find
it in the three species whose cocoons I know. If the Tachytes are nearly
related to the Spheges in diet, they are far removed from them in the
industry of their larvae. The first are workers in mosaic, encrusting a
network of silk and sand; the second weave pure silk.
Of smaller size and clad in black with trimmings of silvery down on the
edge of the abdominal segments, the Tarsal Tachytes frequents the
ledges of soft limestone in fairly populous colonies. (T. tarsina, LEP.)
(According to M. J. Perez, to whom I submitted the Wasp of which I am
about to speak, this Tachytes might well be a new species, if it is not
Lepelletier's T. tarsina or its equivalent, Panzer's T. unicolor. Any
one wishing to clear up this point will always recognize the quarrelsome
insect by its behaviour. A minute description seems useless to me in the
type of investigation which I am pursuing.--Author's Note.) August and
September are the season of her labours. Her burrows, very close to
one another when an easily-worked vein presents itself, afford an ample
harvest of cocoons once the site is discovered. In a certain gravel-pit
in the neighbourhood, with vertical walls visited by the sun, I have
been able within a short space of time to collect enough to fill the
hollow of my hand completely. They differ from the cocoons of the
preceding species only in their smaller size. The provisions consist of
young Acridians, varying from about a quarter to half an inch in length.
The adult insect does not appear in the assorted bags of game, being
no doubt too tough for the feeble grub. All the carcases consist of
Locust-larvae, whose budding wings leave the back uncovered and put one
in mind of the short skirts of a skimpy jacket. Small so that it may be
tender, the game is numerous so that it may suffice all needs. I
count from two to four carcases to a cell. When the time comes we will
discover the reason for these differences in the rations served.
The Mantis-killing Tachytes wears a red scarf, like her kinswoman,
Panzer's Tachytes. (The Mantis-hunting Tachytes was submitted to
examination by M. J. Perez, who failed to recognize her. This species
may well be new to our fauna. I confine myself to calling her the
Mantis-killing Tachytes and leave to the specialists the task of
adorning her with a Latin name, if it be really the fact that the Wasp
is not yet catalogued. I will be brief in my delineation. To my thinking
the best description is this: mantis-hunter. With this information it
is impossible to mistake the insect, in my district of course. I may add
that it is black, with the first two abdominal segments, the legs and
the tarsi a rusty red. Clad in the same livery and much smaller than the
female, the male is remarkable for his eyes, which are of a beautiful
lemon-yellow when he is alive. The length is nearly half an inch for the
female and a little more than half this for the male.--Author's Note.)
I do not think that she is very widely distributed. I made her
acquaintance in the Serignan woods, where she inhabits, or rather used
to inhabit--for I fear that I have depopulated and even destroyed the
community by my repeated excavations--where she used to inhabit one of
those little mounds of sand which the wind heaps up against the rosemary
clumps. Outside this small community, I never saw her again. Her
history, rich in incident, will be given with all the detail which
it deserves. I will confine myself for the moment to mentioning her
rations, which consist of Mantis-larvae, those of the Praying Mantis
predominating. (Cf. "The Life of the Grasshopper": chapters 6 to
9.--Translator's Note.) My lists record from three to sixteen heads for
each cell. Once again we note a great inequality of rations, the reason
for which we must try to discover.
What shall I say of the Black Tachytes (T. nigra, VAN DER LIND) that I
have not already said in telling the story of the Yellow-winged Sphex?
("The Hunting Wasps": chapters 4 to 6.--Translator's Note.) I have there
described her contests with the Sphex, whose burrow she seems to me
to have usurped; I show her dragging along the ruts in the roads a
paralysed Cricket, seized by the hauling-ropes, his antennae; I speak of
her hesitations, which lead me to suspect her for a homeless vagabond,
and finally on her surrender of her game, with which she seems at once
satisfied and embarrassed. Save for the dispute with the Sphex, an
unique event in my records as observer, I have seen all the rest many
a time, but never anything more. The Black Tachytes, though the most
frequent of all in my neighbourhood, remains a riddle to me. I
know nothing of her dwelling, her larvae, her cocoons, her
family-arrangements. All that I can affirm, judging by the invariable
nature of the prey which one sees her dragging along, is that she must
feed her larvae on the same non-adult Cricket that the Yellow-winged
Sphex chooses for hers.
Is she a poacher, a pillager of other's property, or a genuine huntress?
My suspicions are persistent, though I know how chary a man should be of
suspicions. At one time I had my doubts about Panzer's Tachytes, whom
I grudged a prey to which the White-banded Sphex might have laid claim.
To-day I have no such doubts: she is an honest worker and her game is
really the result of her hunting. While waiting for the truth to be
revealed and my suspicions set aside, I will complete the little that I
know of her by noting that the Black Tachytes passes the winter in
the adult form and away from her cell. She hibernates, like the Hairy
Ammophila. In warm, sheltered places, with low, perpendicular, bare
banks, dear to the Wasps, I am certain of finding her at any time during
the winter, however briefly I investigate the earthen surface, riddled
with galleries. I find the Tachytes cowering singly in the hot oven
formed by the end of a tunnel. If the temperature be mild and the sky
clear, she emerges from her retreat in January and February and comes to
the surface of the bank to see whether spring is making progress.
When the shadows fall and the heat decreases, she reenters her
winter-quarters.
The Anathema Tachytes (T. anathema, VAN DER LIND), the giant of her
race, almost as large as the Languedocian Sphex and, like her, decorated
with a red scarf round the base of the abdomen, is rarer than any of
her congeners. I have come upon her only some four or five times, as an
isolated individual and always in circumstances which will tell us
of the nature of her game with a probability that comes very near to
certainty. She hunts underground, like the Scoliae. In September I see
her go down into the soil, which has been loosened by a recent light
shower; the movement of the earth turned over keeps me informed of her
subterranean progress. She is like the Mole, ploughing through a meadow
in pursuit of his White Worm. She comes out farther on, nearly a yard
from the spot at which she went in. This long journey underground has
taken her only a few minutes.
Is this due to extraordinary powers of excavation on her part? By no
means: the Anathema Tachytes is an energetic tunneller, no doubt, but,
after all, is incapable of performing so great a labour in so short
a time. If the underground worker is so swift in her progress, it is
because the track followed has already been covered by another. The
trail is ready prepared. We will describe it, for it is clearly defined
before the intervention of the Wasp.
On the surface of the ground, for a length of two paces at most, runs
a sinuous line, a beading of crumbled soil, roughly the width of my
finger. From this line of ramifications (others) shoot out to left and
right, much shorter and irregularly distributed. One need not be a great
entomological scholar to recognize, at the first glance, in these pads
of raised earth, the trail of a Mole-cricket, the Mole among insects. It
is the Mole-cricket who, seeking for a root to suit her, has excavated
the winding tunnel, with investigation-galleries grafted to either side
of the main road. The passage is free therefore, or at most blocked by a
few landslips, of which the Tachytes will easily dispose. This explains
her rapid journey underground.
But what does she do there? For she is always there, in the few
observations which chance affords me. A subterranean excursion would not
attract the Wasp if it had no object. And its object is certainly the
search for some sort of game for her larvae. The inference becomes
inevitable: the Anathema Tachytes, who explores the Mole-cricket's
galleries, gives her larvae this same Mole-cricket as their food. Very
probably the specimen selected is a young one, for the adult insect
would be too big. Besides, to this consideration of quantity is added
that of quality. Young and tender flesh is highly appreciated, as
witness the Tarsal Tachytes, the Black Tachytes and the Mantis-killing
Tachytes, who all three select game that is not yet made tough by age.
It goes without saying that the moment the huntress emerged from the
ground I proceeded to dig up the track. The Mole-cricket was no longer
there. The Tachytes had come too late; and so had I.
Well, how right was I to define the Tachytes as a Locust lover! What
constancy in the gastronomic rules of the race! And what tact in varying
the game, while keeping within the order of the Orthoptera! What have
the Locust, the Cricket, the Praying Mantis and the Mole-cricket in
common, as regards their general appearance? Why, absolutely nothing!
None of us, if he were unfamiliar with the delicate associations
dictated by anatomy, would think of classing them together. The
Tachytes, on the other hand, makes no mistake. Guided by her instinct,
which rivals the science of a Latreille, she groups them all
together. (Pierre Andre Latreille (1762-1833), one of the founders of
entomological science, a professor at the Musee d'histoire naturelle and
member of the Academie des sciences.--Translator's Note.)
This instinctive taxonomy becomes more surprising still if we consider
the variety of the game stored in a single burrow. The Mantis-killing
Tachytes, for instance, preys indiscriminately upon all the Mantides
that occur in her neighbourhood. I see her warehousing three of them,
the only varieties, in fact, that I know in my district. They are the
following: the Praying Mantis (M. religiosa, LIN.), the Grey Mantis
(Ameles decolor, CHARP. (Cf. "The Life of the Grasshopper": chapter
10.--Translator's Note.)) and the Empusa (E. pauperata, LATR. (Cf. idem:
chapter 9.--Translator's Note.)). The numerical predominance in the
Tachytes' cells belongs to the Praying Mantis; and the Grey Mantis
occupies second place. The Empusa, who is comparatively rare on the
brushwood in the neighbourhood, is also rare in the store-houses of the
Wasp; nevertheless her presence is repeated often enough to show that
the huntress appreciates the value of this prey when she comes across
it. The three sorts of game are in the larval state, with rudimentary
wings. Their dimensions, which vary a good deal, fluctuate between
two-fifths and four-fifths of an inch in length.
The Praying Mantis is a bright green; she boasts an elongated prothorax
and an alert gait. The other Mantis is ash-grey. Her prothorax is short
and her movements heavy. The coloration therefore is no guide to the
huntress, any more than the gait. The green and the grey, the swift
and the slow are unable to baffle her perspicacity. To her, despite the
great difference in appearance, the two victims are Mantes. And she is
right.
But what are we to say of the Empusa? The insect world, at all events in
our parts, contains no more fantastic creature. The children here, who
are remarkable for finding names which really depict the animal, call
the larva "the Devilkin." It is indeed a spectre, a diabolical phantom
worthy of the pencil of a Callot. (Jacques Callot (1592-1635), the
French engraver and painter, famous for the grotesque nature of his
subjects.--Translator's Note.) There is nothing to beat it in the
extravagant medley of figures in his "Temptation of Saint Anthony." Its
flat abdomen, scalloped at the edges, rises into a twisted crook; its
peaked head carries on the top two large, divergent, tusk-shaped horns;
its sharp, pointed face, which can turn and look to either side,
would fit the wily purpose of some Mephistopheles; its long legs have
cleaver-like appendages at the joints, similar to the arm-pieces which
the knights of old used to bear upon their elbows. Perched high upon the
shanks of its four hind-legs, with its abdomen curled, its thorax raised
erect, its front-legs, the traps and implements of warfare, folded
against its chest, it sways limply from side to side, on the tip of the
bough.
Any one seeing it for the first time in its grotesque pose will give
a start of surprise. The Tachytes knows no such alarm. If she catches
sight of it, she seizes it by the neck and stabs it. It will be a treat
for her children. How does she manage to recognize in this spectre the
near relation of the Praying Mantis? When frequent hunting-expeditions
have familiarized her with the last-named and suddenly, in the midst of
the chase, she encounters the Devilkin, how does she become aware that
this strange find makes yet another excellent addition to her larder?
This question, I fear, will never receive an adequate reply. Other
huntresses have already set us the problem; others will set it to us
again. I shall return to it, not to solve it, but to show even more
plainly how obscure and profound it is. But we will first complete the
story of the Mantis-killing Tachytes.
The colony which forms the subject of my investigations is established
in a mound of fine sand which I myself cut into, a couple of years ago,
in order to unearth a few Bembex larvae. The entrances to the Tachytes'
dwelling open upon the little upright bank of the section. At the
beginning of July the work is in full swing. It must have been going on
already for a week or two, for I find very forward larvae, as well as
recent cocoons. There are here, digging into the sand or returning from
expeditions with their booty, some hundred females, whose burrows, all
very close to one another, cover an area of barely a square yard. This
hamlet, small in extent, but nevertheless densely populated, shows us
the Mantis-slayer under a moral aspect which is not shared by the Locust
slayer, Panzer's Tachytes, who resembles her so closely in costume.
Though engaged in individual tasks, the first seeks the society of her
kind, as do certain of the Sphex-wasps, while the second establishes
herself in solitude, after the fashion of the Ammophila. Neither the
personal form nor the nature of the occupation determines sociability.
Crouching voluptuously in the sun, on the sand at the foot of the bank,
the males lie waiting for the females, to plague them as they pass. They
are ardent lovers, but cut a poor figure. Their linear dimensions
are barely half those of the other sex, which implies a volume only
one-eighth as great. At a short distance they appear to wear on their
heads a sort of gaudy turban. At close quarters this headgear is seen to
consist of the eyes, which are very large and a bright lemon-yellow and
which almost entirely surround the head.
At ten o'clock in the morning, when the heat begins to grow intolerable
to the observer, there is a continual coming and going between the
burrows and the tufts of grass, everlasting, thyme and wormwood, which
constitute the Tachytes' hunting-grounds within a moderate radius. The
journey is so short that the Wasp brings her game home on the wing,
usually in a single flight. She holds it by the fore-part, a very
judicious precaution, which is favourable to rapid stowage in the
warehouse, for then the Mantis' legs stretch backwards, along the axis
of the body, instead of folding and projecting sideways, when their
resistance would be difficult to overcome in a narrow gallery. The lanky
prey dangles beneath the huntress, all limp, lifeless and paralysed.
The Tachytes, still flying, alights on the threshold of the home and
immediately, contrary to the custom of Panzer's Tachytes, enters with
her prey trailing behind her. It is not unusual for a male to come upon
the scene at the moment of the mother's arrival. He is promptly snubbed.
This is the time for work, not for amusement. The rebuffed male
resumes his post as a watcher in the sun; and the housewife stows her
provisions.
But she does not always do so without hindrance. Let me recount one of
the misadventures of this work of storage. There is in the neighbourhood
of the burrows a plant which catches insects with glue. It is the Oporto
silene (S. portensis), a curious growth, a lover of the sea-side dunes,
which, though of Portuguese origin, as its name would seem to indicate,
ventures inland, even as far as my part of the country, where it
represents perhaps a survivor of the coastal flora of what was once a
Pliocene sea. The sea has disappeared; a few plants of its shores have
remained behind. This Silene carries in most of its internodes, in those
both of the branches and of the main stalk, a viscous ring, two- to
four-fifths of an inch wide, sharply delimited above and below. The
coating of glue is of a pale brown. Its stickiness is so great that the
least touch is enough to hold the object. I find Midges, Plant-lice and
Ants caught in it, as well as tufted seeds which have blown from the
capitula of the Cichoriaceae. A Gad-fly, as big as a Blue bottle, falls
into the trap before my eyes. She has barely alighted on the perilous
perch when lo, she is held by the hinder tarsi! The Fly makes violent
efforts to take wing; she shakes the slender plant from top to bottom.
If she frees her hinder tarsi she remains snared by the front tarsi
and has to begin all over again. I was doubting the possibility of her
escape when, after a good quarter of an hour's struggle, she succeeded
in extricating herself.
But, where the Gad-fly has got off, the Midge remains. The winged Aphis
also remains, the Ant, the Mosquito and many another of the smaller
insects. What does the plant do with its captures? Of what use are
these trophies of corpses hanging by a leg or a wing? Does the
vegetable bird-limer, with its sticky rings, derive advantage from these
death-struggles? A Darwinian, remembering the carnivorous plants, would
say yes. As for me, I don't believe a word of it. The Oporto silene is
ringed with bands of gum. Why? I don't know. Insects are caught in these
snares. Of what use are they to the plant? Why, none at all; and that's
all about it. I leave to others, bolder than myself, the fantastic idea
of taking these annular exudations for a digestive fluid which will
reduce the captured Midges to soup and make them serve to feed the
Silene. Only I warn them that the insects sticking to the plant do not
dissolve into broth, but shrivel, quite uselessly, in the sun.
Let us return to the Tachytes, who is also a victim of the vegetable
snare. With a sudden flight, a huntress arrives, carrying her drooping
prey. She grazes the Silene's lime-twigs too closely. Behold the Mantis
caught by the abdomen. For twenty minutes at least the Wasp, still on
the wing, tugs at her, tugging again and again, to overcome the cause of
the hitch and release the spoil. The hauling-method, a continuation of
the flight, comes to nothing; and no other is attempted. At last the
insect wearies and leaves the Mantis hanging to the Silene.
Now or never was the moment for the intervention of that tiny glimmer
of reason which Darwin so generously grants to animals. Do not, if you
please, confound reason with intelligence, as people are too prone to
do. I deny the one; and the other is incontestable, within very modest
limits. It was, I said, the moment to reason a little, to discover the
cause of the hitch and to attack the difficulty at its source. For the
Tachytes the matter was of the simplest. She had but to grab the body
by the skin of the abdomen immediately above the spot caught by the glue
and to pull it towards her, instead of persevering in her flight without
releasing the neck. Simple though this mechanical problem was, the
insect was unable to solve it, because she was not able to trace the
effect back to the cause, because she did not even suspect that the
stoppage had a cause.
Ants doting on sugar and accustomed to cross a foot-bridge in order
to reach the warehouse are absolutely prevented from doing so when the
bridge is interrupted by a slight gap. They would only need a few grains
of sand to fill the void and restore the causeway. They do not for a
moment dream of it, plucky navvies though they be, capable of raising
miniature mountains of excavated soil. We can get them to give us an
enormous cone of earth, an instinctive piece of work, but we shall never
obtain the juxtaposition of three grains of sand, a reasoned piece of
work. The Ant does not reason, any more than the Tachytes.
If you bring up a tame Fox and set his platter of food before him, this
creature of a thousand tricks confines himself to tugging with all his
might at the leash which keeps him a step or two from his dinner. He
pulls as the Tachytes pulls, exhausts himself in futile efforts and then
lies down, with his little eyes leering fixedly at the dish. Why does he
not turn round? This would increase his radius; and he could reach then
the food with his hind-foot and pull it towards him. The idea never
occurs to him. Yet another animal deprived of reason.
Friend Bull, my Dog, is no better-endowed, despite his quality as a
candidate for humanity. In our excursions through the woods, he happens
to get caught by the paw in a wire snare set for rabbits. Like the
Tachytes, he tugs at it obstinately and only pulls the noose tighter.
I have to release him when he does not himself succeed in snapping the
wire by his hard pulling. When he tries to leave the room, if the two
leaves of the door are just ajar, he contents himself with pushing his
muzzle, like a wedge, into the too narrow aperture. He moves forward,
pushing in the direction which he wishes to take. His simple, dog-like
method has one unfailing result: the two leaves of the door, when
pushed, merely shut still closer. It would be easy for him to pull one
of them towards him with his paw, which would make the passage wider;
but this would be a movement backward, contrary to his natural impulse;
and so he does not think of it. Yet another creature that does not
reason.
The Tachytes, who stubbornly persists in tugging at her limed Mantis
and refuses to acknowledge any other method of wresting her from the
Silene's snare, shows us the Wasp in an unflattering light. What a very
poor intellect! The insect becomes only the more wonderful, therefore,
when we consider its supreme talent as an anatomist. Many a time I have
insisted upon the incomprehensible wisdom of instinct; I do so again at
the risk of repeating myself. An idea is like a nail: it is not to be
driven in save by repeated blows. By hitting it again and again, I hope
to make it enter the most rebellious brains. This time I shall attack
the problem from the other end, that is, I shall first allow human
knowledge to have its say and shall then interrogate the insect's
knowledge.
The outward structure of the Praying Mantis would of itself be enough to
teach us the arrangement of the nerve-centres which the Tachytes has to
injure in order to paralyse its victim, which is destined to be devoured
alive but harmless. A narrow and very long prothorax divides the front
pair of legs from the two hinder pairs. There must therefore be an
isolated ganglion in front and two ganglia, close to each other,
about two-fifths of an inch back. Dissection confirms this forecast
completely. It shows us three fairly bulky thoracic ganglia, arranged in
the same manner as the legs. The first which actuates the fore-legs, is
placed opposite their roots. It is the largest of the three. It is also
the most important, for it presides over the insect's weapons, over the
two powerful arms, toothed like saws and ending in harpoons. The other
two, divided from the first by the whole length of the prothorax, each
face the origin of the corresponding legs; consequently they are very
near each other. Beyond them are the abdominal ganglia, which I pass
over in silence, as the operating insect does not have to trouble about
them. The movements of the belly are mere pulsations and are in no way
dangerous.
Now let us do a little reasoning on behalf of our non-reasoning insect.
The sacrificer is weak; the victim is comparatively powerful. Three
strokes of the lancet must abolish all offensive movement. Where will
the first stroke be delivered? In front is a real engine of warfare, a
pair of powerful shears with toothed jaws. Let the fore-arm close
upon the upper arm; and the imprudent insect, crushed between the two
saw-blades, will be torn to pieces; wounded by the terminal hook, it
will be eviscerated. This ferocious mechanism is the great danger; it is
this that must be mastered at the outset, at the risk of life; the rest
is less urgent. The first blow of the stylet, cautiously directed, is
therefore aimed at the lethal fore-legs, which imperil the vivisector's
own existence. Above all, there must be no hesitation. The blow must be
accurate then and there, or the sacrificer will be caught in the
vice and perish. The two other pairs of legs present no danger to the
operator, who might neglect them if she had only her own security to
think of; but the surgeon is operating with a view to the egg, which
demands complete immobility in the provisions. Their centres of
innervation will therefore be stabbed as well, with the leisure which
the Mantis, now put out of action, permits. These legs, as well as their
nervous centres, are situated very far behind the first point attacked.
There is a long neutral interval, that of the prothorax, into which it
is quite useless to drive the sting. This interval has to be crossed; by
a backward movement conforming with the secrets of the victim's internal
anatomy, the second ganglion must be reached and then its neighbour, the
third. In short, the surgical operation may be formulated thus: a
first stab of the lancet in front; a considerable movement to the rear,
measuring about two-fifths of an inch; lastly, two lancet-thrusts at
two points very close together. Thus speaks the science of man; thus
counsels reason, guided by anatomical structure. Having said this much
let us observe the insect's practice.
There is no difficulty about seeing the Tachytes operate in our
presence; we have only to resort to the method of substitution, which
has already done me so much service, that is, to deprive the huntress of
her prey and at once to give her, in exchange, a living Mantis of about
the same size. This substitution is impracticable with the majority
of the Tachytes, who reach the threshold of their dwelling in a single
flight and at once vanish underground with their game. A few of them,
from time to time, harassed perhaps by their burden, chance to alight at
a short distance from their burrow, or even drop their prey. I profit by
these rare occasions to witness the tragedy.
The dispossessed Wasp recognizes instantly, from the proud bearing of
the substituted Mantis, that she is no longer embracing and carrying off
an inoffensive carcase. Her hovering, hitherto silent, develops a buzz,
perhaps to overawe the victim; her flight becomes an extremely rapid
oscillation, always behind the quarry. It is as who should say the quick
movement of a pendulum swinging without a wire to hang from. The Mantis,
however, lifts herself boldly upon her four hind-legs; she raises the
fore-part of her body, opens, closes and again opens her shears and
presents them threateningly at the enemy; using a privilege which no
other insect shares, she turns her head this way and that, as we do when
we look over our shoulders; she faces her assailant, ready to strike a
return blow wheresoever the attack may come. It is the first time that
I have witnessed such defensive daring. What will be the outcome of it
all?
The Wasp continues to oscillate behind the Mantis, in order to avoid the
formidable grappling-engine; then, suddenly, when she judges that the
other is baffled by the rapidity of her manoeuvres, she hurls herself
upon the insect's back, seizes its neck with her mandibles, winds her
legs round its thorax and hastily delivers a first thrust of the sting,
to the front, at the root of the lethal legs. Complete success! The
deadly shears fall powerless. The operator then lets herself slip as she
might slide down a pole, retreats along the Mantis' back and, going a
trifle lower, less than a finger's breadth, she stops and paralyses,
this time without hurrying herself, the two pairs of hind-legs. It is
done: the patient lies motionless; only the tarsi quiver, twitching in
their last convulsions. The sacrificer brushes her wings for a moment
and polishes her antennae by passing them through her mouth, an habitual
sign of tranquillity returning after the emotions of the conflict; she
seizes the game by the neck, takes it in her legs and flies away with
it.
What do you say to it all? Do not the scientist's theory and the
insect's practice agree most admirably? Has not the animal accomplished
to perfection what anatomy and physiology enabled us to foretell?
Instinct, a gratuitous attribute, an unconscious inspiration, rivals
knowledge, that most costly acquisition. What strikes me most is the
sudden recoil after the first thrust of the sting. The Hairy Ammophila,
operating on her caterpillar, likewise recoils, but progressively,
from one segment to the next. Her deliberate surgery might receive a
quasi-explanation if we ascribe it to a certain uniformity. With the
Tachytes and the Mantis this paltry argument escapes us. Here are
no lancet-pricks regularly distributed; on the contrary, the
operating-method betrays a lack of symmetry which would be
inconceivable, if the organization of the patient did not serve as a
guide. The Tachytes therefore knows where her prey's nerve-centres lie;
or, to speak more correctly, she behaves as though she knew.
This science which is unconscious of itself has not been acquired, by
her and by her race, through experiments perfected from age to age and
habits transmitted from one generation to the next. It is impossible,
I am prepared to declare a hundred times, a thousand times over, it is
absolutely impossible to experiment and to learn an art when you are
lost if you do not succeed at the first attempt. Don't talk to me of
atavism, of small successes increasing by inheritance, when the novice,
if he misdirected his weapon, would be crushed in the trap of the two
saws and fall a prey to the savage Mantis! The peaceable Locust, if
missed, protests against the attack with a few kicks; the carnivorous
Mantis, who is in the habit of feasting on Wasps far more powerful than
the Tachytes, would protest by eating the bungler; the game would devour
the hunter, an excellent catch. Mantis-paralysing is a most perilous
trade and admits of no half-successes; you have to excel in it from the
first, under pain of death. No, the surgical art of the Tachytes is not
an acquired art. Whence then does it come, if not from the universal
knowledge in which all things move and have their being!
What would happen if, in exchange for her Praying Mantis, I were to give
the Tachytes a young Grasshopper? In rearing insects at home, I have
already noted that the larvae put up very well with this diet; and I
am surprised that the mother does not follow the example of the Tarsal
Tachytes and provide her family with a skewerful of Locusts instead
of the risky prey which she selects. The diet would be practically the
same; and the terrible shears would no longer be a danger. With such a
patient would her operating-method remain the same; should we again
see a sudden recoil after the first stab under the neck; or would the
vivisector modify her art in conformity with the unfamiliar nervous
organization?
This second alternative is highly improbable. It would be nonsense to
expect to see the paralyser vary the number and the distribution of the
wounds according to the genus of the victim. Supremely skilled in the
task that has fallen to its lot, the insect knows nothing further.
The first alternative seems to offer a certain chance and deserves a
test. I offer the Tachytes, deprived of her Mantis, a small Grasshopper,
whose hind-legs I amputate to prevent his leaping. The disabled Acridian
jogs along the sand. The Wasp flies round him for a moment, casts a
contemptuous glance upon the cripple and withdraws without attempting
action. Let the prey offered be large or small, green or grey, short
or long, rather like the Mantis or quite different, all my efforts
miscarry. The Tachytes recognizes in an instant that this is no
business of hers; this is not her family game; she goes off without even
honouring my Grasshoppers with a peck of her mandibles.
This stubborn refusal is not due to gastronomical causes. I have stated
that the larvae reared by my own hands feed on young Grasshoppers as
readily as on young Mantes; they do not seem to perceive any difference
between the two dishes; they thrive equally on the game chosen by me
and that selected by the mother. If the mother sets no value on the
Grasshopper, what then can be the reason of her refusal? I can see only
one: this quarry, which is not hers, perhaps inspires her with fear, as
any unknown thing might do; the ferocious Mantis does not alarm her,
but the peaceable Grasshopper terrifies her. And then, if she were to
overcome her apprehensions, she does not know how to master the Acridian
and, above all, how to operate upon him. To every man his trade, to
every Wasp her own way of wielding her sting. Modify the conditions ever
so slightly; and these skilful paralysers are at an utter loss.
To every insect also its own art of fashioning the cocoon, an art which
varies greatly, an art in which the larva displays all the resources
of its instincts. The Tachytes, the Bembeces, the Stizi, the Palari and
other burrowers build composite cocoons, hard as fruit-stones, formed of
an encrustation of sand in a network of silk. We are already acquainted
with the work of the Bembex. I will recall the fact that their larva
first weaves a conical, horizontal bag of pure white silk, with wide
meshes, held in place by interlaced threads which fix it to the walls
of the cell. I have compared this bag, because of its shape, with a
fishtrap. Without leaving this hammock, stretching its neck through the
orifice, the worker gathers from without a little heap of sand, which
it stores inside its workshop. Then, selecting the grains one by one,
it encrusts them all around itself in the fabric of the bag and cements
them with the fluid from its spinnerets, which hardens at once. When
this task is finished, the house has still to be closed, for it has been
wide open all this time to permit of the renewal of the store of sand
as the heap inside becomes exhausted. For this purpose a cap of silk is
woven across the opening and finally encrusted with the materials which
the larva has retained at its disposal.
The Tachytes builds in quite another fashion, although its work, once
finished, does not differ from that of the Bembex. The larva surrounds
itself, to begin with, about the middle of its body with a silken girdle
which a number of threads, very irregularly distributed, hold in place
and connect with the walls of the cell. Sand is collected, within reach
of the worker, on this general scaffolding. Then begins the work of
minor masonry, with grains of sand for rubble and the secretion of the
spinnerets for cement. The first course is laid upon the fore-edge of
the suspensory ring. When the circle is completed, a second course of
grains of sand, stuck together by the fluid silk, is raised upon the
hardened edge of what has just been done. Thus the work proceeds,
by ring-shaped courses, laid edge to edge, until the cocoon, having
acquired half of its proper length, is rounded into a cap and finally is
closed. The building-methods of the Tachytes-larva remind me of a mason
constructing a round chimney, a narrow tower of which he occupies the
centre. Turning on his own axis and using the materials placed to his
hand, he encloses himself little by little in his sheath of masonry.
In the same way the worker encloses itself in its mosaic. To build the
second half of the cocoon, the larva turns round and builds in the same
way on the other edge of the original ring. In about thirty-six hours
the solid shell is completed.
I am rather interested to see the Bembex and the Tachytes, two workers
in the same guild, employ such different methods to achieve the same
result. The first begins by weaving an eel-trap of pure silk and next
encrusts the grains of sand inside; the second, a bolder architect, is
economical of the silk envelope, confines itself to a hanging girdle and
builds course by course. The building-materials are the same: sand and
silk; the surroundings amid which the two artisans work are the same: a
cell in a soil of sandy gravel; yet each of the builders possesses its
individual art, its own plan, its one method.
The nature of the food has no more effect upon the larva's talents than
the environment in which it lives or the materials employed. The proof
of this is furnished by Stiza ruficornis, another builder of cocoons in
grains of sand cemented with silk. This sturdy Wasp digs her burrows in
soft sandstone. Like the Mantis-killing Tachytes, she hunts the various
Mantides of the countryside, consisting mainly of the Praying Mantis;
only her large size requires them to be more fully developed, without
however having attained the form and the dimensions of the adult. She
places three to five of them in each cell.
In solidity and volume her cocoon rivals that of the largest Bembex;
but it differs from it, at first sight, by a singular feature of which
I know no other example. From the side of the shell, which is uniformly
smoothed on every side, a rough knob protrudes, a little clod of sand
stuck on to the rest. The work of Stizus ruficornis can at once be
recognized, among all the other cocoons of a similar nature, by this
protuberance.
Its origin will be explained by the method which the larva follows in
constructing its strong-box. At the beginning, a conical bag is woven
of pure white silk; you might take it for the initial eel-trap of the
Bembeces, only this bag has two openings, a very wide one in front and
another, very narrow one at the side. Through the front opening the
Stizus provides itself with sand as and when it spends this material on
encrusting the interior. This strengthens the cocoon; and the cap
which closes it is made next. So far it is exactly like the work of the
Bembex. We now have the worker enclosed, engaged in perfecting the inner
wall. For these final touches a little more sand is needed. It obtains
it from outside by means of the aperture which it has taken the
precaution of contriving in the side of its building, a narrow
dormer-window just large enough to allow its slender neck to pass. When
the store has been taken in, this accessory orifice, which is used only
during the last few moments, is closed with a mouthful of mortar, thrust
outward from within. This forms the irregular nipple which projects from
the side of the shell.
For the present I shall not expatiate further upon Stizus ruficornis,
whose complete biography would be out of place in this chapter. I will
limit myself to mentioning its method of constructing strong-boxes in
order to compare it with that of the Bembex and above all with that
of the Tachytes, a consumer, like itself, of Praying Mantes. From this
parallel it seems to me to follow that the conditions of life in
which men see to-day the origin of instincts--the type of food, the
surroundings amid which the larval life is passed, the materials
available for a defensive wrapper and other factors which the
evolutionists are accustomed to invoke--have no actual influence upon
the larva's industry. My three architects in glued sand, even when all
the conditions, down to the nature of the provisions, are the same,
adopt different means to execute an identical task. They are engineers
who have not graduated from the same school, who have not been educated
on the same principles, though the lesson of things is almost the
same for all of them. The workshop, the work, the provisions have not
determined the instinct. The instinct comes first; it lays down laws
instead of being subject to them.