THE THREE DAGGER-THRUSTS
There is no doubt that the Sphex displays her most cunning resources at
the moment of immolating a Cricket; it is important, therefore, to
ascertain the manner wherein the victim is sacrificed. Profiting by the
repeated attempts which I had made when I was studying the tactics of
the Cerceres, I at once applied to the Sphex the method which had
succeeded with the other Wasps, a method that consisted in taking the
prey from the huntress and forthwith replacing it by another, living
prey. The substitution is all the easier inasmuch as we have seen the
Sphex herself releasing her victim in order to go down the burrow for a
moment alone. Her daring familiarity, which makes her come and take
from your fingers and even out of your hand the Cricket whom you have
stolen from her and now offer her again, also lends itself admirably to
the successful issue of the experiment, by allowing you to observe
every detail of the drama closely.
Again, to find live Crickets is an easy matter: we have but to lift the
first stone that we see and we find them crouching underneath,
sheltered from the sun. These Crickets are young ones, of the same
year, who as yet boast but rudimentary wings and who, not possessing
the industry of the full-grown insect, have not learnt to dig those
cavernous retreats where they would be safe from the Sphex’
investigations. In a few moments I have as many live Crickets as I
could wish for. This completes my preparations. I climb to the top of
my observatory, establish myself on the level ground, in the centre of
the Sphex village, and wait.
A huntress appears upon the scene, carts her Cricket to the entrance of
the home and goes down her burrow by herself. I quickly remove the
Cricket and substitute one of mine, placing him, however, some distance
away from the hole. The kidnapper returns, looks round, and runs and
seizes the victim, which is too far off for her. I am all eyes, all
attention. Nothing would induce me to give up my part in the tragic
spectacle which I am about to witness. The terrified Cricket takes to
flight, hopping as fast as he can; the Sphex pursues him hot-foot,
reaches him, rushes upon him. There follows, amid the dust, a confused
encounter, wherein each champion, now victor, now vanquished, by turns
is at the top or at the bottom. Success, for a moment undecided, at
last crowns the aggressor’s efforts. Despite his vigorous kicks,
despite the snaps of his pincer-like mandibles, the Cricket is laid low
and stretched upon his back.
The murderess soon makes her arrangements. She places herself belly to
belly with her adversary, but in the opposite direction, grasps one of
the threads at the tip of the Cricket’s abdomen with her mandibles and
masters with her fore-legs the convulsive efforts of his thick hinder
thighs. At the same time, her middle-legs hug the heaving sides of the
beaten insect; and her hind-legs, pressing like two levers on the front
of the head, force the joint of the neck to open wide. The Sphex then
curves her abdomen vertically, so as to offer only an unattackable
convex surface to the Cricket’s mandibles; and we see, not without
emotion, its poisoned lancet drive once into the victim’s neck, next
into the joint of the front two segments of the thorax, and lastly
towards the abdomen. In less time than it takes to relate, the murder
is consummated; and the Sphex, after adjusting the disorder of her
toilet, makes ready to haul home the victim, whose limbs are still
quivering in the throes of death.
Let us consider for a moment the excellence of the tactics of which I
have given a feeble glimpse. The Cerceris attacks a passive adversary,
incapable of flight, almost devoid of offensive weapons, whose sole
chances of safety lie in a stout cuirass, the weak point of which,
however, is known to the murderess. But what a difference here! The
quarry is armed with dreadful mandibles, capable of disembowelling the
assailant if they succeed in seizing her; it sports a pair of powerful
legs, regular clubs bristling with a double row of sharp spikes, which
can be used either to enable the Cricket to hop out of his enemy’s
reach, or to send her sprawling with brutal kicks. Observe, therefore,
the precautions which the Sphex takes before setting her sting in
motion. The victim, turned upon his back, cannot, for lack of any
purchase, use his hind-levers to escape with, which he certainly would
do if he were attacked in the normal position, as are the big Weevils
of the Great Cerceris. His spurred legs, mastered by the Sphex’
fore-feet, cannot act as offensive weapons either; and his mandibles,
kept at a distance by the Wasp’s hind-legs, open in wide menace without
being able to seize a thing. But it is not enough for the Sphex to
render her Cricket incapable of hurting her; she must also hold him so
firmly pinioned that he cannot make the slightest movement capable of
diverting the sting from the points at which the poison is to be
injected; and it is probably with the object of stilling the movements
of the abdomen that one of its terminal threads is grasped. No, if a
fertile imagination had allowed itself free scope to invent a plan of
attack at will, it could not have contrived anything better; and it is
open to doubt whether the athletes of the classic palestræ, when
grappling with an adversary, boasted more scientific attitudes.
I have said that the sting is driven several times into the patient’s
body: first under the neck, then behind the prothorax, next and lastly
towards the top of the abdomen. It is in these three dagger-thrusts
that the infallibility and the intuitive science of instinct appear in
all their splendour. Let us first recall the principal conclusions to
which our earlier study of the Cerceris has led us. The victims of the
Wasps whose larvæ live on prey are not proper corpses, in spite of
their immobility, which is sometimes complete. They suffer simply from
a total or partial locomotory paralysis, from a more or less thorough
annihilation of animal life; but vegetable life, the life of the organs
of nutrition, is maintained for a long while yet and preserves from
decomposition the prey which the larva is not to devour for some time
to come. To produce this paralysis the Hunting Wasps employ precisely
the process which the advanced science of our own day might suggest to
the experimental physiologists, that is to say, they injure, by means
of their poisoned sting, the nerve-centres that control the locomotory
organs. We know besides that the several centres or ganglia of the
nervous system of articulate animals are, within certain limits,
independent of one another in their action, so that an injury to any
one of them does not, or at any rate not immediately, entail more than
the paralysis of the corresponding segment; and this applies all the
more when the different ganglia are farther apart. When, on the other
hand, they are welded together, the lesion of this common centre
induces paralysis of all the segments over which its ramifications are
distributed. This is the case with the Buprestes and the Weevils, whom
the Cerceres paralyse with a single thrust of the sting, aimed at the
common mass of the nerve-centres of the thorax. But open a Cricket.
What do we find to set the three pairs of legs in motion? We find what
the Sphex knew long before the anatomists: three nerve-centres at a
great distance one from the other. Hence the magnificent logic of her
needle-thrusts thrice repeated. Proud science, bend the knee!
Despite the appearances that might make us think otherwise, the
Crickets immolated by the Yellow-winged Sphex are no more dead than the
Weevils pierced by the Cerceris’ dart. The flexibility of the victims’
integuments, faithfully revealing the slightest internal movement,
enables us in this case to dispense with the artificial methods which I
employed to demonstrate the presence of a remnant of life in the Cleoni
of the Great Cerceris. In fact, if we assiduously observe a Cricket
stretched on his back, a week, a fortnight even or more after the
murder, we see the abdomen heaving deeply at long intervals. Pretty
often we can still perceive a few quiverings in the palpi and
exceedingly-pronounced movements on the part of both the antennæ and
the abdominal threads, which diverge and separate and then suddenly
come together. I have succeeded, by placing the sacrificed Crickets in
glass tubes, in keeping them perfectly fresh for a month and a half.
Consequently, the Sphex-grubs, which live for less than a fortnight
before shrouding themselves in their cocoons, are certain of fresh meat
until their banquet is finished.
The chase is over; the three or four Crickets that are the allotted
portion of each cell are stacked methodically, lying on their backs,
with their heads at the far end of the cell and their feet at the
entrance. An egg is laid on one of them. The burrow must now be closed.
The sand resulting from the excavation, which is lying in a heap
outside the front-door, is quickly swept backwards down the passage.
From time to time some fair-sized bits of gravel are picked out singly,
by scratching the heap of rubbish with the fore-feet, and carried with
the mandibles to strengthen the crumbly mass. Should the Wasp find none
within reach to suit her, she goes and searches for them in the
neighbourhood, and seems to choose them as conscientiously as a mason
would choose the chief stones for his building. Vegetable remains, tiny
fragments of dead leaves, are also employed. In a few moments every
outward trace of the underground dwelling has disappeared; and, if we
have not been careful to mark the site of the abode, it becomes
impossible for the most watchful eye to find it again. When this is
finished, a new burrow is dug, provisioned and walled up as often as
the teeming ovaries demand. Having completed the laying of her eggs,
the Sphex resumes her careless, vagrant life, until the first cold snap
puts an end to her well-filled existence.
The Sphex’ task is accomplished; and I will finish mine with an
examination of her weapon. The organ destined for the elaboration of
her poison consists of two prettily-ramified tubes, ending separately
in a common reservoir or phial, shaped like a pea. From this phial
starts a slender channel which runs down the axis of the sting and
conducts the little drop of poison to its tip. The dimensions of the
lancet are very small and not such as one would expect from the size of
the Sphex, and especially from the effects which its prick produces on
the Crickets. The point is quite smooth and entirely deprived of those
backward indentations which we find in the Hive-bee’s sting. The reason
for this is obvious. The Bee uses her sting only to avenge an injury,
even at the cost of her life; and the teeth of the dart resist its
withdrawal from the wound and thus cause mortal ruptures in the viscera
at the extremity of the abdomen. What would the Sphex have done with a
weapon that would have been fatal to her on her first expedition?
Supposing that the dart could be withdrawn in spite of its teeth, I
doubt whether any Hymenopteron using her weapon chiefly to wound the
game destined for her larvæ would be supplied with a toothed sting.
With her, the dirk is not a show weapon, unsheathed to satisfy revenge:
revenge, the so-called pleasure of the gods, but a very costly
pleasure, for the vindictive Bee sometimes pays for it with her life;
it is an implement for use, a tool, on which the future of the grubs
depends. It must therefore be one easy to wield in the struggle with
the captured prey; it must be capable of being inserted in the flesh
and withdrawn without the least hesitation, a condition much better
fulfilled by a smooth than by a barbed blade.
I wished to find out at my own expense if the Sphex’ sting is very
painful, this sting which lays low sturdy victims with terrible
rapidity. Well, I confess with profound admiration that it is
insignificant and bears no comparison, for intensity of pain, with the
stings of the irascible Bees and Social Wasps. It hurts so little that,
instead of using the forceps, I would not scruple to take in my fingers
any live Sphex-wasps that I needed in my experiments. I can say the
same of the different Cerceres, of the Philanthi, [14] of the Palari,
of even the huge Scoliæ, [15] whose very view inspires dismay, and,
generally speaking, of all the Hunting Wasps that I have been able to
observe. I make an exception of the Spider-huntresses, the Pompili;
[16] and even then their sting is much less painful than the Bees’.
One last word: we know how furiously the Hymenoptera armed with a
purely defensive dart—the Social Wasps, for instance—rush upon him who
is bold enough to disturb their dwelling-house and punish him for his
temerity. On the other hand, those whose sting is intended for killing
game are very pacific, as though they were aware of the importance
which the little drop of poison in their phial possesses for their
family. This tiny drop is the safeguard of their race, I might say, its
livelihood; and so they are very economical in its use, reserving it
for the serious business of the chase, without any parade of vindictive
courage. I was not once punished with a sting when I established myself
amid the villages of our various Hunting Wasps, though I overturned
their nests and stole the larvæ and the provisions. You must lay hold
of the insect to make it use its weapon; and even then it does not
always pierce the skin, unless you place within its reach a part more
delicate than the fingers, such as, for instance, the wrist.