Informational Site NetworkInformational Site Network
Privacy
 
   Home - Articles - Books

THE TACHYTES




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.





Next: CHANGE OF DIET

Previous: THE PROBLEM OF THE SCOLIAE



Add to del.icio.us Add to Reddit Add to Digg Add to Del.icio.us Add to Google Add to Twitter Add to Stumble Upon
Add to Informational Site Network
Report
Privacy
SHAREADD TO EBOOK