THE WISDOM OF INSTINCT
To paralyse her prey, the Languedocian Sphex, I have no doubt, pursues
the method of the Cricket-huntress and drives her lancet repeatedly
into the Ephippiger’s breast in order to strike the ganglia of the
thorax. The process of wounding the nerve-centres must be familiar to
her; and I am convinced beforehand of her consummate skill in that
scientific operation. This is an art thoroughly known to all the
Hunting Wasps, who carry a poisoned dart that has not been given them
in vain. At the same time, I must confess that I have never yet
succeeded in witnessing the deadly performance. This omission is due to
the solitary life led by the Languedocian Sphex.
When a number of burrows are dug on a common site and then provisioned,
one has but to wait on the spot to see now one huntress and now another
arrive with the game which they have caught. It is easy in these
circumstances to try upon the new arrivals the substitution of a live
prey for the doomed victim and to repeat the experiment as often as we
wish. Besides, the certainty that we shall not lack subjects of
observation, as and when wanted, enables us to arrange everything in
advance. With the Languedocian Sphex these conditions of success do not
exist. To set out expressly to look for her, with one’s material
prepared, is almost useless, as the solitary insect is scattered one by
one over vast expanses of ground. Moreover, if you do come upon her, it
will most often be in an idle hour and you will get nothing out of her.
As I said before, it is nearly always unexpectedly, when your thoughts
are elsewhere engaged, that the Sphex appears, dragging her Ephippiger
after her.
This is the moment, the only propitious moment, to attempt a
substitution of prey and invite the huntress to let you witness her
lancet-thrusts. Quick, let us procure an alternative morsel, a live
Ephippiger! Hurry, time presses: in a few minutes the burrow will have
received the victuals and the glorious occasion will be lost! Must I
speak of my mortification at these moments of good fortune, the mocking
bait held out by chance? Here, before my eyes, is matter for
interesting observations; and I cannot profit by it! I cannot surprise
the Sphex’ secret for the lack of something to offer her in the place
of her prize! Try it for yourself, try setting out in quest of an
alternative piece with only a few minutes at your disposal, when it
took me three days of wild running about before I found Weevils for my
Cerceres! And yet I made the desperate experiment twice over. Ah, if
the keeper had caught me this time, tearing like mad through the
vineyards, what a good opportunity it would have been for crediting me
with robbery and having me up before the magistrate! Vine-branches and
clusters of grapes: not a thing did I respect in my mad rush, hampered
by the trailing shoots. I must have an Ephippiger at all costs, I must
have him that moment. And once I did get my Ephippiger during one of
these frenzied expeditions. I was radiant with joy, never suspecting
the bitter disappointment in store for me.
If only I arrive in time, if only the Sphex be still engaged in
transport work! Thank heaven, everything is in my favour! The Wasp is
still some distance away from her burrow and still dragging her prize
along. With my forceps I pull gently at it from behind. The huntress
resists, stubbornly clutches the antennæ of her victim and refuses to
let go. I pull harder, even drawing the carter back as well; it makes
no difference: the Sphex does not loose her hold. I have with me a pair
of sharp scissors, belonging to my little entomological case. I use
them and promptly cut the harness-ropes, the Ephippiger’s long antennæ.
The Sphex continues to move ahead, but soon stops, astonished at the
sudden decrease in the weight of the burden which she is trailing, for
this burden is now reduced merely to the two antennæ, snipped off by my
mischievous wiles. The real load, the heavy, pot-bellied insect,
remains behind and is instantly replaced by my live specimen. The Wasp
turns round, lets go the ropes that now draw nothing after them, and
retraces her steps. She comes face to face with the prey substituted
for her own. She examines it, walks round it gingerly, then stops,
moistens her foot with saliva, and begins to wash her eyes. In this
attitude of meditation, can some such thought as the following pass
through her mind:
‘Come now! Am I awake or am I asleep? Do I know what I am about or do I
not? That thing’s not mine. Who or what is trying to humbug me?’
At any rate, the Sphex shows no great hurry to attack my prey with her
mandibles. She keeps away from it and shows not the smallest wish to
seize it. To excite her, I offer the insect to her in my fingers, I
almost thrust the antennæ under her teeth. I know that she does not
suffer from shyness; I know that she will come and take from your
fingers, without hesitation, the prey which you have snatched from her
and afterwards present to her. But what is this? Scorning my offers,
the Sphex retreats instead of snapping up what I place within her
reach. I put down the Ephippiger, who, obeying a thoughtless impulse,
unconscious of danger, goes straight to his assassin. Now we shall see!
Alas, no: the Sphex continues to recoil, like a regular coward, and
ends by flying away. I never saw her again. Thus ended, to my
confusion, an experiment that had filled me with such enthusiasm.
Later and by degrees, as I inspected an increasing number of burrows, I
came to understand my failure and the obstinate refusal of the Sphex. I
always found the provisions to consist, without a single exception, of
a female Ephippiger, harbouring in her belly a copious and succulent
cluster of eggs. This appears to be the favourite food of the grubs.
Well, in my hurried rush through the vines, I had laid my hands on an
Ephippiger of the other sex. I was offering the Sphex a male. More
far-seeing than I in this important question of provender, the Wasp
would have nothing to say to my game:
‘A male, indeed! Is that a dinner for my larvæ? What do you take them
for?’
What nice discrimination they have, these dainty epicures, who are able
to differentiate between the tender flesh of the female and the
comparatively dry flesh of the males! What an unerring glance, which
can distinguish at once between the two sexes, so much alike in shape
and colour! The female carries a sword at the tip of her abdomen, the
ovipositor wherewith the eggs are buried in the ground; and that is
about the only external difference between her and the male. This
distinguishing feature never escapes the perspicacious Sphex; and that
is why, in my experiment, the Wasp rubbed her eyes, hugely puzzled at
beholding swordless a prey which she well knew carried a sword when she
caught it. What must not have passed through her little Sphex brain at
the sight of this transformation?
Let us now watch the Wasp when, having prepared the burrow, she goes
back for her victim, which, after its capture and the operation that
paralysed it, she has left at no great distance. The Ephippiger is in a
condition similar to that of the Cricket sacrificed by the
Yellow-winged Sphex, a condition proving for certain that stings have
been driven into her thoracic ganglia. Nevertheless, a good many
movements still continue; but they are disconnected, though endowed
with a certain vigour. Incapable of standing on its legs, the insect
lies on its side or on its back. It flutters its long antennæ and also
its palpi; it opens and closes its mandibles and bites as hard as in
the normal state. The abdomen heaves rapidly and deeply. The ovipositor
is brought back sharply under the belly, against which it almost lies
flat. The legs stir, but languidly and irregularly; the middle legs
seem more torpid than the others. If pricked with a needle, the whole
body shudders convulsively; efforts are made to get up and walk, but
without success. In short, the insect would be full of life, but for
its inability to move about or even to stand upon its legs. We have
here therefore a wholly local paralysis, a paralysis of the legs, or
rather a partial abolition and ataxy of their movements. Can this very
incomplete inertia be caused by some special arrangement of the
victim’s nervous system, or does it come from this, that the Wasp
perhaps administers only a single prick, instead of stinging each
ganglion of the thorax, as the Cricket-huntress does? I cannot tell.
Still, for all its shivering, its convulsions, its disconnected
movements, the victim is none the less incapable of hurting the larva
that is meant to devour it. I have taken from the burrow of the Sphex
Ephippigers struggling just as lustily as when they were first
half-paralysed; and nevertheless the feeble grub, hatched but a few
hours since, was digging its teeth into the gigantic victim in all
security; the dwarf was biting into the colossus without danger to
itself. This striking result is due to the spot selected by the mother
for laying her egg. I have already said how the Yellow-winged Sphex
glues her egg to the Cricket’s breast, a little to one side, between
the first and second pair of legs. Exactly the same place is chosen by
the White-edged Sphex; and a similar place, a little farther back,
towards the root of one of the large hind-thighs, is adopted by the
Languedocian Sphex, all three thus giving proof, by this uniformity, of
wonderful discernment in picking out the spot where the egg is bound to
be safe.
Consider the Ephippiger pent in the burrow. She lies stretched upon her
back, absolutely incapable of turning. In vain she struggles, in vain
she writhes: the disordered movements of her legs are lost in space,
the room being too wide to afford them the support of its walls. The
grub cares nothing for the victim’s convulsions: it is at a spot where
naught can reach it, not tarsi, nor mandibles, nor ovipositor, nor
antennæ; a spot absolutely stationary, devoid of so much as a surface
tremor. It is in perfect safety, on the sole condition that the
Ephippiger cannot shift her position, turn over, get upon her feet; and
this one condition is admirably fulfilled.
But, with several heads of game, all in the same stage of paralysis,
the larva’s danger would be great. Though it would have nothing to fear
from the insect first attacked, because of its position out of the
reach of its victim, it would have every occasion to dread the
proximity of the others, which, stretching their legs at random, might
strike it and rip it open with their spurs. This is perhaps the reason
why the Yellow-winged Sphex, who heaps up three or four Crickets in the
same cell, practically annihilates all movement in its victims, whereas
the Languedocian Sphex, victualling each burrow with a single piece of
game, leaves her Ephippigers the best part of their power of motion and
contents herself with making it impossible for them to change their
position or stand upon their legs. She may thus, though I cannot say so
positively, economize her dagger-thrusts.
While the only half-paralysed Ephippiger cannot imperil the larva,
fixed on a part of the body where resistance is impossible, the case is
different with the Sphex, who has to cart her prize home. First, having
still, to a great extent, preserved the use of its tarsi, the victim
clutches with these at any blade of grass encountered on the road along
which it is being dragged; and this produces an obstacle to the hauling
process which is difficult to overcome. The Sphex, already heavily
burdened by the weight of her load, is liable to exhaust herself with
her efforts to make the other insect relax its desperate grip in grassy
places. But this is the least serious drawback. The Ephippiger
preserves the complete use of her mandibles, which snap and bite with
their customary vigour. Now what these terrible nippers have in front
of them is just the slender body of the enemy, at a time when she is in
her hauling attitude. The antennæ, in fact, are grasped not far from
their roots, so that the mouth of the victim dragged along on its back
faces either the thorax or the abdomen of the Sphex, who, standing high
on her long legs, takes good care, I am convinced, not to be caught in
the mandibles yawning underneath her. At all events, a moment of
forgetfulness, a slip, the merest trifle can bring her within the reach
of two powerful nippers, which would not neglect the opportunity of
taking a pitiless vengeance. In the more difficult cases at any rate,
if not always, the action of those formidable pincers must be done away
with; and the fish-hooks of the legs must be rendered incapable of
increasing their resistance to the process of transport.
How will the Sphex go to work to obtain this result? Here man, even the
man of science, would hesitate, would waste his time in barren efforts
and would perhaps abandon all hope of success. He can come and take one
lesson from the Sphex. She, without ever being taught it, without ever
seeing it practised by others, understands her surgery through and
through. She knows the most delicate mysteries of the physiology of the
nerves, or rather she behaves as if she did. She knows that under her
victim’s skull there is a circlet of nervous nuclei, something similar
to the brain of the higher animals. She knows that this main centre of
innervation controls the action of the mouth-parts and moreover is the
seat of the will, without whose orders not a single muscle acts;
lastly, she knows that, by injuring this sort of brain, she will cause
all resistance to cease, the insect no longer possessing any will to
resist. As for the mode of operating, this is the easiest matter in the
world to her; and, when we have been taught in her school, we are free
to try her process in our turn. The instrument employed is no longer
the sting: the insect, in its wisdom, has deemed compression preferable
to a poisoned thrust. Let us accept its decision, for we shall see
presently how prudent it is to be convinced of our own ignorance in the
presence of the animal’s knowledge. Lest by editing my account I should
fail to give a true impression of the sublime talent of this masterly
operator, I here copy out my note as I pencilled it on the spot,
immediately after the stirring spectacle.
The Sphex finds that her victim is offering too much resistance,
hooking itself here and there to blades of grass. She then stops to
perform upon it the following curious operation, a sort of coup de
grâce. The Wasp, still astride her prey, forces open the articulation
of the neck, high up, at the nape. Then she seizes the neck with her
mandibles and, without making any external wound, probes as far forward
as possible under the skull, so as to seize and chew up the ganglia of
the head. When this operation is done, the victim is utterly
motionless, incapable of the least resistance, whereas previously the
legs, though deprived of the power of connected movement needed for
walking, vigorously opposed the process of traction.
There is the fact in all its eloquence. With the points of its
mandibles, the insect, while leaving uninjured the thin and supple
membrane of the neck, goes rummaging into the skull and munching the
brain. There is no effusion of blood, no wound, but simply an external
pressure. Of course, I kept for my own purposes the Ephippiger
paralysed before my eyes, in order to ascertain the effects of the
operation at my leisure; also, of course, I hastened to repeat in my
turn, upon live Ephippigers, what the Sphex had just taught me. I will
here compare my results with the Wasp’s.
Two Ephippigers whose cervical ganglia I squeeze and compress with a
forceps fall rapidly into a state resembling that of the victims of the
Sphex. Only, they grate their cymbals if I tease them with a needle;
and the legs still retain a few disordered and languid movements. The
difference no doubt is due to the fact that my patients were not
previously injured in their thoracic ganglia, as were those of the
Sphex, who were first stung on the breast. Allowing for this important
condition, we see that I was none too bad a pupil and that I imitated
pretty closely my teacher of physiology, the Sphex. I confess it was
not without a certain satisfaction that I succeeded in doing almost as
well as the insect.
As well? What am I talking about? Wait a bit and you shall see that I
still have much to learn from the Sphex. For what happens is that my
two patients very soon die: I mean, they really die; and, in four or
five days, I have nothing but putrid corpses before my eyes. And the
Wasp’s Ephippiger? I need hardly say that the Wasp’s Ephippiger, even
ten days after the operation, is perfectly fresh, just as she will be
required by the larva for which she has been destined. Nay, more: only
a few hours after the operation under the skull, there reappeared, as
though nothing had occurred, the disorderly movements of the legs,
antennæ, palpi, ovipositor and mandibles; in a word, the insect
returned to the condition wherein it was before the Sphex bit its
brain. And these movements were kept up after, though they became
feebler every day. The Sphex had merely reduced her victim to a passing
state of torpor, lasting amply long enough to enable her to bring it
home without resistance; and I, who thought myself her rival, was but a
clumsy and barbarous butcher: I killed my prize. She, with her
inimitable dexterity, shrewdly compressed the brain to produce a
lethargy of a few hours; I, brutal through ignorance, perhaps crushed
under my forceps that delicate organ, the main seat of life. If
anything could prevent me from blushing at my defeat, it would be the
conviction that very few, if any, could vie with these clever ones in
cleverness.
Ah, I now understand why the Sphex does not use her sting to injure the
cervical ganglia! A drop of poison injected here, at the centre of
vital force, would destroy the whole nervous system; and death would
follow soon after. But it is not death that the huntress wishes to
obtain; the larvæ have not the least use for dead game, for a corpse,
in short, smelling of corruption; and all that she wants to bring about
is a lethargy, a passing torpor, which will put a stop to the victim’s
resistance during the carting process, this resistance being difficult
to overcome and moreover dangerous for the Sphex. The torpor is
obtained by a method known in laboratories of experimental physiology:
compression of the brain. The Sphex acts like a Flourens, [30] who,
laying bare an animal’s brain and bearing upon the cerebral mass,
forthwith suppresses intelligence, will, sensibility and movement. The
pressure is removed; and everything reappears. Even so do the remains
of the Ephippiger’s life reappear, as the lethargic effects of a
skilfully-directed pressure pass off. The ganglia of the skull,
squeezed between the mandibles but without fatal contusions, gradually
recover their activity and put an end to the general torpor. Admit that
it is all alarmingly scientific.
Fortune has her entomological whims: you run after her and catch no
glimpse of her; you forget about her and behold, she comes tapping at
your door! How vainly I watched and waited, how many useless journeys I
made to see the Languedocian Sphex sacrifice her Ephippigers! Twenty
years pass; these pages are in the printer’s hands; and, one day early
this month, on the 8th of August 1878, my son Emile comes rushing into
my study:
‘Quick!’ he shouts. ‘Come quick: there’s a Sphex dragging her prey
under the plane-trees, outside the door of the yard!’
Emile knew all about the business, from what I had told him, to amuse
him when we used to sit up late, and better still from similar
incidents which he had witnessed in our life out of doors. He is right.
I run out and see a magnificent Languedocian Sphex dragging a paralysed
Ephippiger by the antennæ. She is making for the hen-house close by and
seems anxious to scale the wall, with the object of fixing her burrow
under some tile on the roof; for, a few years ago, in the same place, I
saw a Sphex of the same species accomplish the ascent with her game and
make her home under the arch of a badly-joined tile. Perhaps the
present Wasp is descended from the one who performed that arduous
climb.
A like feat seems about to be repeated; and this time before numerous
witnesses, for all the family, working under the shade of the
plane-trees, come and form a circle around the Sphex. They wonder at
the unceremonious boldness of the insect, which is not diverted from
its work by a gallery of onlookers; all are struck by its proud and
lusty bearing, as, with raised head and the victim’s antennæ firmly
gripped in its mandibles, it drags the enormous burden after it. I,
alone among the spectators, feel a twinge of regret at the sight:
‘Ah, if only I had some live Ephippigers!’ I cannot help saying, with
not the least hope of seeing my wish realized.
‘Live Ephippigers?’ replies Émile. ‘Why, I have some perfectly fresh
ones, caught this morning!’
He dashes upstairs, four steps at a time, and runs to his little den,
where a fence of dictionaries encloses a park for the rearing of some
fine caterpillars of the Spurge Hawk-moth. He brings me three
Ephippigers, the best that I could wish for, two females and a male.
How did these insects come to be at hand, at the moment when they were
wanted, for an experiment tried in vain twenty years ago? That is
another story. A Lesser Grey Shrike had nested in one of the tall
plane-trees of the avenue. Now a few days earlier, the mistral, the
brutal north-west wind of our parts, blew with such violence as to bend
the branches as well as the reeds; and the nest, turned upside down by
the swaying of its support, had dropped its contents, four small birds.
Next morning I found the brood upon the ground; three were killed by
the fall, the fourth was still alive. The survivor was entrusted to the
cares of Émile, who went Cricket-hunting twice a day on the
neighbouring grass-plots for the benefit of his young charge. But
Crickets are small and the nurseling’s appetite called for many of
them. Another dish was preferred, the Ephippiger, of whom a stock was
collected from time to time among the stalks and prickly leaves of the
eryngo. The three insects which Émile brought me came from the Shrike’s
larder. My pity for the fallen nestling had procured me this
unhoped-for success.
After making the circle of spectators stand back so as to leave the
field clear for the Sphex, I take away her prey with a pair of pincers
and at once give her in exchange one of my Ephippigers, carrying a
sword at the end of her belly, like the game which I have abstracted.
The dispossessed Wasp stamps her feet two or three times; and that is
the only sign of impatience which she gives. She goes for her new prey,
which is too stout, too obese even to try to avoid pursuit, grips it
with her mandibles by the saddle-shaped corselet, gets astride and,
curving her abdomen, slips the end of it under the Ephippiger’s thorax.
Here, no doubt, some stings are administered, though I am unable to
state the number exactly, because of the difficulty of observation. The
Ephippiger, a peaceable victim, suffers herself to be operated on
without resistance; she is like the silly Sheep of our
slaughter-houses. The Sphex takes her time and wields her lancet with a
deliberation which favours accuracy of aim. So far, the observer has
nothing to complain of; but the prey touches the ground with its breast
and belly, and exactly what happens underneath escapes his eye. As for
interfering and lifting the Ephippiger a little, so as to see better,
that must not be thought of: the murderess would resheathe her weapon
and retire. The act that follows is easy to observe. After stabbing the
thorax, the tip of the abdomen appears under the victim’s neck, which
the operator forces open by pressing the nape. At this point the sting
probes with marked persistency, as if the prick administered here were
more effective than elsewhere. One would be inclined to think that the
nerve-centre attacked is the lower part of the œsophageal chain; but
the continuance of movement in the mouth-parts—the mandibles, jaws and
palpi—controlled by this seat of innervation shows that such is not the
case. Through the neck the Sphex reaches simply the ganglia of the
thorax, or at any rate the first of them, which is more easily
accessible through the thin skin of the neck than through the
integuments of the chest.
And in a moment it is all over. Without the least shiver denoting pain,
the Ephippiger becomes henceforth an inert mass. I remove the Sphex’
patient for the second time and replace it by the other female at my
disposal. The same proceedings are repeated, followed by the same
result. The Sphex has performed her skilful surgery thrice over, almost
in immediate succession, first with her own prey and then with my
substitutes. Will she do so a fourth time with the male Ephippiger whom
I still have left? I have my doubts, not because the Wasp is tired, but
because the game does not suit her. I have never seen her with any prey
but females, who, crammed with eggs, are the food which the larvæ
appreciate above all others. My suspicion is well founded; deprived of
her capture, the Sphex stubbornly refuses the male whom I offer to her.
She runs hither and thither, with hurried steps, in search of the
vanished game; three or four times she goes up to the Ephippiger, walks
round him, casts a scornful glance at him; and at last she flies away.
He is not what her larvæ want; experiment demonstrates this once again
after an interval of twenty years.
The three females stabbed, two of them before my eyes, remain in my
possession. In each case all the legs are completely paralysed. Whether
lying naturally, on its belly or on its back or side, the insect
retains indefinitely whatever position we give it. A continued
fluttering of the antennæ, a few intermittent pulsations of the belly,
and the play of the mouth-parts are the only signs of life. Movement is
destroyed but not susceptibility; for, at the least prick administered
to a thin-skinned spot, the whole body gives a slight shudder. Perhaps,
some day, physiology will find in such victims the material for
valuable work on the functions of the nervous system. The Wasp’s sting,
so incomparably skilful at striking a particular point and
administering a wound which affects that point alone, will supplement,
with immense advantage, the experimenter’s brutal scalpel, which rips
open where it ought to give merely a light touch. Meanwhile, here are
the results which I have obtained from the three victims, but in
another direction.
As only the movement of the legs has been destroyed, without any wound
save that of the nerve-centres, which are the seat of that movement,
the insect must die of inanition and not of its injuries. The
experiment was conducted as follows: two sound and healthy Ephippigers,
just as I picked them up in the fields, were imprisoned without food,
one in the dark, the other in the light. The second died in four days,
the first in five. This difference of a day is easily explained. In the
light, the insect made greater exertions to recover its liberty; and,
as every movement of the animal machine is accompanied by a
corresponding expenditure of energy, a greater sum total of activity
has involved a more rapid consumption of the reserve force of the
organism. In the light, there is more restlessness and a shorter life;
in the dark, less restlessness and a longer life, while no food at all
was taken in either case.
One of my three stabbed Ephippigers was kept in the dark, fasting. In
her case there were not only the conditions of complete abstinence and
darkness, but also the serious wounds inflicted by the Sphex; and
nevertheless for seventeen days I saw her continually waving her
antennæ. As long as this sort of pendulum keeps on swinging, the clock
of life does not stop. On the eighteenth day the creature ceased its
antennary movements and died. The badly-wounded insect therefore lived,
under the same conditions, four times as long as the insect that was
untouched. What seemed as though it should be a cause of death was
really a cause of life.
However paradoxical it may seem at first sight, this result is
exceedingly simple. When untouched, the insect exerts itself and
consequently uses up its reserves. When paralysed, it has merely the
feeble, internal movements which are inseparable from any organism; and
its substance is economized in proportion to the weakness of the action
displayed. In the first case, the animal machine is at work and wears
itself out; in the second, it is at rest and saves itself. There being
no nourishment now to repair the waste, the moving insect spends its
nutritive reserves in four days and dies; the motionless insect does
not spend them and lives for eighteen days. Life is a continual
dissolution, the physiologists tell us; and the Sphex’ victims give us
the neatest possible demonstration of the fact.
One remark more. Fresh food is absolutely necessary for the Wasp’s
larvæ. If the prey were warehoused in the burrow intact, in four or
five days it would be a corpse abandoned to corruption; and the
scarce-hatched grub would find nothing to live upon but a putrid mass.
Pricked with the sting, however, it can keep alive for two or three
weeks, a period more than long enough to allow the egg to hatch and the
larva to grow. The paralysing of the victim therefore has a twofold
result: first, the living dish remains motionless and the safety of the
delicate grub is not endangered; secondly, the meat keeps good a long
time and thus ensures wholesome food for the larva. Man’s logic,
enlightened by science, could discover nothing better.
My two other Ephippigers stung by the Sphex were kept in the dark with
food. To feed inert insects, hardly differing from corpses except by
the perpetual waving of their long antennæ, seems at first an
impossibility; still, the play of the mouth-parts gave me some hope and
I tried. My success exceeded my anticipations. There was no question
here, of course, of giving them a lettuce-leaf or any other piece of
green stuff on which they might have browsed in their normal state;
they were feeble valetudinarians, who needed spoon-feeding, so to
speak, and supporting with liquid nourishment. I used sugar-and-water.
Laying the insect on its back, I place a drop of the sugary fluid on
its mouth with a straw. The palpi at once begin to stir; the mandibles
and jaws move. The drop is swallowed with evident satisfaction,
especially after a somewhat prolonged fast. I repeat the dose until it
is refused. The meal takes place once a day, sometimes twice, at
irregular intervals, lest I should become too much of a slave to my
patients. Well, one of the Ephippigers lived for twenty-one days on
this meagre fare. It was not much, compared with the eighteen days of
the one whom I had left to die of starvation. True, the insect had
twice had a bad fall, having dropped from the experimenting-table to
the floor owing to some piece of awkwardness on my part. The bruises
which it received must have hastened its end. The other, which suffered
no accidents, lived for forty days. As the nourishment employed,
sugar-and-water, could not indefinitely take the place of the natural
green food, it is very likely that the insect would have lived longer
still if the usual diet had been possible. And so the point which I had
in view is proved: the victims stung by the Digger-wasps die of
starvation and not of their wounds.