Part 9

What will the Sphex do to obtain this result? Man, and even a learned man, would hesitate, bewilder himself with vain attempts, and perhaps despair of success. Let him come and take a lesson from the Sphex, who, without having learned, without ever seeing any one else at work, is thoroughly up in her profession of operator. She knows that under her victim’s skull lies a circlet of nerve-knots, somewhat analogous to the brain of higher animals. She knows too that this chief nerve centre directs the action of the mouth-parts, and, moreover, is the seat of will, without whose command no muscle acts; finally, she is aware that if this kind of brain be injured, all resistance will cease, the insect no longer possessing will-power. As for the method of operation, it is the easiest thing possible for her, and when we have studied at her school we may try in our turn. The sting is no longer employed; in her wisdom the Sphex decides compression to be preferable to the poisoned sting. Let us bow to her decision, for we shall presently see how prudent it is to be convinced of our ignorance compared with the animal’s knowledge. Lest by re-writing my account I fail to do justice to the sublime talent of this masterly operation, I transcribe my notes written on the spot directly after witnessing the exciting spectacle.

The Sphex, finding that her prey resists too much, hooking itself here and there to blades of grass, pauses to perform the singular operation about to be described—a kind of coup de grâce. The Hymenopteron, still astride her victim, makes the articulation in the upper part of the neck, at the nape, to open wide. Then she seizes the neck with her mandibles, groping as far forward as possible under the skull, but making no outward wound, grasps and chews repeatedly the nerve-centres of the head. This renders her victim quite motionless, and incapable of the least resistance, whereas previously the feet, though unable to move in the manner necessary for walking, vigorously resisted being dragged along. This is the fact in all its eloquence. While leaving intact the thin, supple membrane of the neck, the insect finds a way into the skull with the point of its mandibles, and bruises the brain. There is neither effusion of blood nor wound, but merely external compression. Of course I kept the paralysed ephippiger under inspection in order to watch the consequences of the operation at my leisure, and equally of course I hastened to repeat on living specimens what the Sphex had taught me. I will now compare my results with hers.

Two ephippigers, whose cervical ganglia I compressed with pincers, fell quickly into a state like that of her victims, only they sounded their harsh cymbals if irritated by the point of a needle, and their feet made some irregular languid movements. The difference in the results obtained doubtless arises from the fact that my victim had not been previously stung in the thoracic ganglia, as those had been which the Sphex had struck in the breast. Allowing for this important point, it will be seen that I made no bad pupil, and imitated my teacher in physiology, the Sphex, not ill. I own that it was not without a certain satisfaction that I found I had done almost as well as the insect does.

As well! What have I just said? Wait a little, and it will be seen that I had to attend the Sphex’s school for many another day. For my two ephippigers speedily died—died outright, and after three or four days I had only decaying bodies under my eyes. But the ephippiger of the Sphex? Need I say that ten days after the operation this was perfectly fresh, as it has to be for the larva whose destined prey it is. Yet more, a few hours after the operation under the skull, there reappeared as if nothing had happened movements of an irregular kind in feet, antennæ, palpi, ovipositor, and mandibles—in short, the creature was again in the same state as before the Sphex bit its brain. And the movements went on, only feebler each day. The Sphex had only benumbed her victim for a period amply sufficient to enable her to get it home without resistance, while I, who thought myself her rival, was but a clumsy, barbarous butcher, and killed mine. She, with her inimitable dexterity, compressed the brain scientifically to cause a lethargy of a few hours; I, brutal through ignorance, perhaps crushed this delicate organ, primal source of life, with my pincers. If anything could prevent my blushing at my defeat, it would be that few if any could rival the Sphex in skill.

Ah! now I comprehend why she did not use her sting to injure the ganglia of the neck. A drop of poison instilled here, at the centre of vital force, would annihilate all nerve power, and death would soon follow. But the Sphex does not at all desire death. Dead food by no means suits the larvæ, and still less a body smelling of decay. All that is needed is lethargy, a passing torpor, hindering resistance while the victim is carted along—resistance difficult to overcome and dangerous to the Sphex. This torpor is obtained by the proceeding known in laboratories of experimental science as compression of the brain. The Sphex acts like a Flourens who, baring an animal’s brain and pressing on the cerebrum, abolishes at once sensibility, will, intelligence, and motion. The pressure ceases and all reappears. So reappear the remains of life in the ephippiger as the lethargic effects of a skilful pressure go off. The ganglia of the skull, squeezed by the mandibles, but without mortal contusions, gradually recover activity, and put an end to the general torpor. It is alarmingly scientific!

Fortune has her entomological caprices; you run after her and do not come up with her; you forget her, and lo, here she is tapping at your door! How many useless excursions, how many fruitless plans, you made to try to see Sphex occitanica sacrifice her victim! Twenty years go by; these pages are already in the printer’s hands, when, in the first days of this month (August 8, 1878), my son Emile darts into my study. “Quick! quick!” he cries, “a Sphex is dragging along her prey under the plane trees, before the door of the court!” Emile, initiated into the affair by what I had told him, and, better still, by like facts seen in our out-of-door life, was quite right. I hurried away, and saw a splendid S. occitanica dragging a paralysed ephippiger by the antennæ. She moved toward the poultry yard, seemingly desirous of scaling the wall, to make her burrow under some roof tile. Some years before I had seen a similar Sphex accomplish the ascent with her game, and choose her domicile under the arch of an ill-joined tile. Perhaps this new one was descended from her whose difficult ascent I have chronicled. A like feat is probably about to be repeated, and this time before numerous witnesses, for all the household working under the shade of the plane trees formed a circle round the Sphex. They wonder at the audacious tameness of the insect, noways disturbed by the gallery of interested spectators. All are struck by her proud and robust bearing, as, with raised head and the victim’s antennæ well grasped by her mandibles, she drags after her the enormous burden. I alone among the spectators feel some regret. “Ah, had I but some live ephippigers!” I could not help saying, without the least hope of seeing my wish realised. “Live ephippigers!” replied Emile; “why, I have some quite fresh, caught this morning.” Four steps at a time he flew upstairs to his little study, where barricades of dictionaries enclosed a park wherein was brought up a fine caterpillar of Sphinx euphorbiæ. He brought back three ephippigers as good as heart could wish—two females and one male. How came these insects at hand just at the right moment for an experiment vainly tried twenty years before? This is another story. A southern shrike had nested on one of the tall plane trees in the avenue. Some days before the Mistral, the rude wind of our parts, had blown so violently that branches bent as well as reeds, and the nest overturned by the undulations of its branch let fall the four nestlings it contained. The next day I found the brood on the ground—three killed by the fall, the fourth still alive. The survivor was entrusted to Emile, who thrice a day went cricket-hunting on the turf in the neighbourhood to feed his charge. But crickets are not very large, while the nestling’s appetite was. Something else was preferred—ephippigers, collected from time to time on the dry stalks and prickly leaves of the Eryngium. The three insects brought me by Emile came from the shrike’s larder. My pity for the fallen nestlings had brought me this unhoped-for good luck.

Having made the circle of spectators draw back and leave free passage for the Sphex, I took away her prey with my pincers, giving her immediately in exchange one of my ephippigers with an ovipositor like that of the one abstracted. Stamping was the only sign of impatience shown by the bereaved Hymenopteron. She ran at the new prey, too corpulent to try to avoid pursuit, seized it with her mandibles by the saddle-shaped corslet, got astride, and curving her abdomen, passed its end under the ephippiger’s thorax. There doubtless the stings are given, but the difficulty of observation prevents me from telling how many. The ephippiger—gentle victim—lets itself be operated on unresistingly, like the dull sheep of our slaughter-houses. The Sphex takes her time and manœuvres her lancet with a deliberation favourable to the observer; but the prey touches the ground with the whole lower part of its body, and what happens there cannot be seen. As for interfering and lifting the ephippiger a little so as to see better, it is not to be thought of; the murderess would sheath her weapon and retire. The next act is easy to observe. After having stabbed the thorax, the end of the abdomen appears under the neck, which she forces widely open by pressing the nape. Here the sting enters with marked persistence, as if more effective than elsewhere. One might suppose that the nerve centre struck was the lower part of the œsophagean collar, but the persistence of movement in the mouthpieces, mandibles, jaws, and palpi, animated by this source of nerve power, shows that this is not so. Through the neck the Sphex simply reaches the thoracic ganglia, or at least the first, more easily attainable through the thin skin of the neck than through the integuments of the chest.

All is over. Without one convulsion or sign of pain the ephippiger is rendered henceforward an inert mass. For the second time I deprived the Sphex of the subject operated on, replacing it by the second female at my disposal. The same manœuvres were followed by the same result. Three times, almost without a pause, the Sphex repeated her skilled surgery, first on her own capture, then on those exchanged by me. Will she do so a fourth time on the male which I still have? It is doubtful, not that she is weary, but because the game does not suit her. I have never seen a Sphex with any but female prey, which, filled as they are with eggs, are the favourite food of the larvæ. My suspicion was well founded. Deprived of her third capture, she obstinately refused the male which I offered her. She ran hither and thither with hurried steps, seeking her lost prey. Three or four times she approached the ephippiger, walked round it, cast a disdainful glance at it, and finally flew away. This was not what her larvæ wanted. Experiment reiterated it after twenty years’ interval.

The three females, two stabbed under my eyes, remained mine. All the feet were quite paralysed, Whether in its natural position or on its back or side, the creature retains whichever is given it. Constant oscillations of the antennæ, and, at intervals, some pulsations of the stomach and movements of the mouthpieces, are the only sign of life. Motion is destroyed but not feeling, for at the least prick where the skin is thin, the whole body shudders faintly. Perhaps one day physiology will discover in these victims a subject for fine studies on the functions of the nervous system. The Hymenopteron’s sting, incomparably skilful in reaching a given point and inflicting a wound to affect it alone, will replace, with immense advantage, the brutal scalpel of the experimenter, which disembowels where it should lightly touch. Meanwhile, here are the results obtained from the three victims, but from another point of view.

Only movement of the feet being destroyed, there being no injury save that to the nerve centres, the source of motion, the creature perishes, not from its wound, but from inanition. The experiment was tried thus:

Two uninjured ephippigers found in the fields were imprisoned without food, one in the dark, the other in the light. In four days the latter died of hunger, in five the former. This difference of a day is easily explained. In the light the creature is more eager to recover liberty, and as every movement of the animal machine causes a corresponding expenditure of energy, greater activity used up sooner the reserves of the organisation. With light, more agitation and shorter life; in darkness, less movement and longer life; both insects fasted equally. One of the three stabbed was kept in the dark and foodless. In this case there was not only darkness and want of food, but the serious wounds inflicted by the Sphex, and yet for seventeen days it perpetually moved its antennæ. As long as this kind of pendulum oscillates, the clock of life has not stopped. On the eighteenth day the creature ceased to wave its antennæ and died. Thus the seriously wounded insect lived in the same conditions as the uninjured one four times as long. What seems as if it should be a cause of death is really the cause of life.

However paradoxical it may at first appear, this result is perfectly simple. Intact, the creature agitates and spends itself; paralysed, it makes only those feeble, internal movements, inseparable from all organised life, and the waste of substance is in proportion to the amount of action employed. In the first case the animal machine works and spends itself; in the second it is at rest and saves itself up. Nourishment no longer repairing loss, the insect in motion spends in four days its food reserves and dies; the motionless one does not spend them, and lives eighteen. Physiology tells us that life is continual destruction, and the Sphex’s victims are a most elegant demonstration of this fact.

One more remark. Fresh food is absolutely necessary to larvæ of the Hymenopteron. If the prey were stored intact, in four or five days it would be a dead body, given up to decay, and the newly hatched grubs would find no food but a corrupted mass. Touched by the sting it can live two or three weeks—a period more than sufficient for the egg to hatch and the grub to develop. The paralysis has thus a double result—immobility, so as not to endanger the life of the delicate larvæ, and long preservation of the flesh to assure wholesome nourishment for them. Even when enlightened by science human logic could find nothing better.

My two other ephippigers, stung by the Sphex, were kept in darkness with food. To feed inert creatures, differing only from dead bodies by the perpetual oscillation of their long antennæ, seems at first an impossibility; however, the play of the mouth organs gave me some hope, and I made the attempt. My success surpassed my expectations. There was no question, of course, of offering them a lettuce leaf or any other green thing on which they might have browsed in their normal condition; they were feeble invalids, to be nourished with a feeding-cup, so to say, and broth. I used sugar and water.

The insect being laid on its back, I put a drop of sugared liquid on its mouth with a straw. Instantly the palpi stirred, mandibles and jaws moved; the drop was consumed with evident satisfaction, especially if the fast had been somewhat prolonged. I renewed the dose till it was refused. The repast took place once or twice a day at irregular intervals, as I could not devote myself very much to a hospital of this kind.

Well, with this meagre diet one of the ephippigers lived twenty-one days. This was little longer than the life of the one which I allowed to die of inanition. It is true that twice the insect had had a bad fall, having dropped from the experiment table to the floor through some awkwardness of mine. The bruises consequent may have hastened its end. As for the other, exempt from accidents, it lived six weeks. As the nourishment offered, sugar and water, could not indefinitely replace the natural food, it is very probable that it would have lived longer still had its customary diet been available. Thus the point which I had in view is demonstrated: victims pierced by the sting of the Hymenopteron die from inanition and not of their wound.

XII

THE IGNORANCE OF INSTINCT

The Sphex has just shown us with what infallible, transcendent art she acts, guided by the unconscious inspiration of instinct: she will now show how poor she is in resources, how limited in intelligence, and even illogical in cases somewhat out of her usual line. By a strange contradiction, characteristic of the instinctive faculties, with deep science is associated ignorance not less deep. Nothing is impossible to instinct, however great be the difficulty. In constructing her hexagonal cells with their floor of three lozenge-shaped pieces, the bee resolves, with absolute precision, the arduous problems of maximum and minimum, to solve which man would need a powerful, mathematical mind. Hymenoptera, whose larvæ live on prey, have methods in their murderous art hardly equalled by those of a man versed in the most delicate mysteries of anatomy and physiology. Nothing is difficult to instinct so long as the action moves in the unchanging groove allotted to the animal, but, again, nothing is easy to instinct if the action deviates from it. The very insect which amazes us and alarms us by its high intelligence will, a moment later, astonish us by its stupidity before some fact extremely simple, but strange to its usual habits. The Sphex will offer an example.

Let us follow her dragging home an ephippiger. If fortune favour us, we may be present at a little scene which I will describe. On entering the shelter under a rock where the burrow is made, the Sphex finds, perched on a blade of grass, a carnivorous insect which, under a most sanctimonious aspect, hides the morals of a cannibal. The danger threatened by this bandit in ambush on her path must be known to the Sphex, for she leaves her game and runs bravely at the Mantis to administer some sharp blows and dislodge, or at all events, alarm and inspire it with respect. It does not move, but closes its deadly weapons—the two terrible saws of the arm and forearm. The Sphex returns to her prey, harnesses herself to the antennæ, and passes audaciously under the blade of grass where the Mantis sits. From the direction of her head one can see that she is on her guard, and is holding the enemy motionless under her threatening eyes. Such courage is duly rewarded; the prey is stored without further misadventure.

A word more of the Praying Mantis, the Prégo Diéou as it is called in Provence, i.e. the Pray-to-God. And, indeed, its long, pale green wings, like ample veils, its head upraised to heaven, its arms folded and crossed on its breast, give it a false resemblance to a nun in ecstatic devotion. All the same, it is a ferocious creature, bent on carnage. Although not especially favourite hunting-grounds, the workshops of various burrowing Hymenoptera are often visited by it. Posted on some bush near the burrows, it waits until chance brings some Sphex returning home within reach, thus achieving a double capture, catching together Sphex and prey. Its patience is long tried; the Sphex is suspicious and on her guard, but from time to time a rash one lets herself be caught. By a sudden rustle of half-spread wings, as by a convulsive movement, the Mantis terrifies the approaching Sphex, which hesitates for a moment, and then with the suddenness of a spring the toothed forearm folds back on an arm also toothed, and the insect is seized between the blades of the double saw, as though the jaws of a wolf trap were closing on the beast as it takes the bait. Then, without unclosing the cruel machine, the Mantis gnaws little mouthfuls of its victim. Such are the ecstasies, the prayers, and the mystic meditations of the Prégo Diéou.

Among the scenes of carnage which the Mantis has left in my memory, let me describe the following. It passes before a working-place of Philanthus apivorus. These miners nourish their larvæ with hive-bees, which they seize on flowers while collecting pollen and honey. If the Philanthus feels that the bee is full of honey, it does not fail to squeeze it before storing it, either on the way, or at the entrance of the hole, to make it disgorge the delicious liquid; this it drinks by licking the tongue of the unfortunate bee, which, dying, extends it at full length. This profanation of a dying creature, squeezed by its murderer to empty its body and enjoy the contents, has something so hideous that I should call it a crime if a Philanthus could be held responsible. In the midst of this horrible banquet I have seen both murderer and prey seized by the Mantis; the robber was plundered by a second robber. Horrible to relate, while the Mantis held it transpierced by the points of the double saw, and was already gnawing the under parts, the Philanthus went on licking the honey, unable to abandon the delicious food even in the throes of death. Let us cast a veil over these horrors.

We return to the Sphex, with whose burrow we must make acquaintance before going further. It is made of fine sand, or rather in the fine dust at the bottom of a natural shelter. Its passage is very short—an inch or two without a turn, leading into a single spacious oval chamber, and all is a rude, hastily made den, rather than a dwelling hollowed with art and leisure. I have already said that the captured prey, left for a brief moment or two where it was hunted, is the cause of the simplicity of this abode and of there being but one chamber or cell to each hollow. For who can say whither the chances of the day’s hunt may lead? The dwelling must be near the heavy prey, and to-day’s abode, too far off to admit of carrying the second ephippiger there, cannot be used to-morrow. Thus each time prey is caught there must be new digging out—a new burrow with its one cell, now here, now there. Now let us try some experiments to see how the insect behaves amid circumstances new to it.

First experiment.—A Sphex, dragging her prey, is at a few inches from her burrow. Without disturbing her I cut the antennæ of the ephippiger, which we already know serve as harness. Having recovered from her astonishment at the sudden lightening of her load, the Sphex returns and unhesitatingly seizes the base of the antennæ, the short stumps not cut off. Very short they are—hardly a millimetre long; no matter, they suffice for the Sphex, who grips what remains of her ropes and drags anew. With many precautions not to hurt her, I cut off the two stumps, now level with the skull. Finding nothing to seize at the parts familiar to her, she takes hold on one side of one of the long palpi of her victim, and drags it, not at all put out by this modification in her style of harnessing herself. I leave her alone. The prey is got home and placed with its head to the mouth of the burrow. The Sphex enters to make a short inspection of the interior before proceeding to store provisions. Her tactics recall those of S. flavipennis in like circumstances. I profit by this brief moment to take the abandoned prey, deprive it of all its palpi, and place it a little farther off—a pace from the burrow. The Sphex reappears and goes straight to her game, which she saw from her threshold. She seeks above the head, she seeks below, on one side, and finds nothing to seize. A desperate attempt is made; opening wide her mandibles she tries to grasp the ephippiger by the head, but her pincers cannot surround anything so large, and slip off the round, polished skull. She tries several times in vain; at length, convinced of the futility of her efforts, draws back, and seems to renounce further attempts. She appears discouraged—at least she smooths her wings with her hind feet, while with her front tarsi, first passing them through her mouth, she washes her eyes, a sign among Hymenoptera, as I believe, that they give a thing up.

Yet there were points by which the ephippiger might be seized and dragged as easily as by the antennæ and palpi. There are the six feet, there is the ovipositor—all organs slender enough to be thoroughly grasped and used as traction ropes. I own that the easiest way of getting the prey into the storehouse is to introduce it head first by the antennæ; yet, drawn by one foot, especially a front one, it would enter almost as easily, for the orifice is wide and the passage short, even if there be one. How came it then that the Sphex never once tried to seize one of the six tarsi or the point of the ovipositor, while she did make the impossible, absurd attempt to grip with mandibles far too short the huge head of her prey? Perhaps the idea did not occur to her. Let us try to suggest it. I place under her mandibles first a foot, then the end of the abdominal sabre. She refuses obstinately to bite; my repeated solicitations come to nothing. A very odd kind of hunter this to be so embarrassed by her game and unable to think of seizing it by a foot if it cannot be taken by the horns! Perhaps my presence and all these unusual events may have troubled her faculties; let us leave her to herself, with her burrow and ephippiger, and give her time to consider and to imagine in the calm of solitude some means of managing the business. I walked away and returned in a couple of hours to find the Sphex gone, the burrow open, and the ephippiger where I had laid it. The conclusion is that the Sphex tried nothing, but departed, abandoning home, game—everything, when to utilise them all that was needed would have been to take the prey by one foot. Thus this rival of Flourens, who just now startled us by her science when pressing the brain to induce lethargy, is invariably dull when the least unusual event occurs. The Sphex, which knows so well how to reach the thoracic ganglia of a victim with her sting, and those of the brain with her mandibles, and which makes such a judicious difference between a poisoned sting that would destroy the vital influence of the nerves, and compression causing only momentary torpor, cannot seize her prey in a new way. To understand that a foot may be taken instead of the antennæ is impossible; nothing will do but the antennæ or another filament of the head or one of the palpi. For want of these ropes her whole race would perish, unable to surmount this trifling difficulty.

Second experiment.—The Sphex is busy closing her burrow where the prey is stored and the egg laid. With her fore tarsi she sweeps backward before her door, and launches from the entrance a spurt of dust, which passes beneath her, and springs up behind in a parabolic curve as continuous as if it were a slender stream of some liquid, so rapidly does she sweep. From time to time she chooses some sand grains with her mandibles, strengthening materials inserted singly in the dusty mass. To consolidate this she beats it with her head, and heaps it with her mandibles. Walled up by this masonry, the entrance rapidly disappears. In the midst of the work I intervene. Having put the Sphex aside I clear out the short gallery carefully with the blade of a knife, take away the materials which block it, and entirely restore the communication of the cell with the outer air. Then, without injuring the edifice, I draw the ephippiger out of the cell where it is lying with its head to the far end, and its ovipositor to the entrance. The egg is as usual on its breast, near the base of one of the hind legs—a proof that the Sphex had given her last touch to the burrow, and would never return. These dispositions made, and the ephippiger placed safely in a box, I gave up my place to the Sphex, who had been watching while her domicile was rifled. Finding the entrance open, she entered and remained some moments, then came forth and took up her work where I interrupted it, beginning to stop the entrance conscientiously, sweeping the dust backward, and transporting sand grains to build them with minute care, as if doing a useful work. The orifice being again thoroughly blocked, she brushed herself, seemed to give a glance of satisfaction at her work, and finally flew off.

Yet she must have known that the burrow was empty, since she had gone inside, and made prolonged stay, but yet after this visit to the plundered dwelling, she set to work to close it with as much care as if nothing had happened. Did she propose to turn it later to account, returning with a fresh prey, and laying a new egg? In that case the burrow was closed to defend it from indiscreet visitors while the Sphex was away. Or it was a measure of prudence against other miners who might covet a ready-made chamber, or a wise precaution against internal wear and tear, and, in fact, some predatory Hymenoptera are careful when obliged to suspend work to defend the mouth of their burrow by closing it up temporarily. I have seen certain Ammophilæ, whose burrow is a vertical well, close the entrance with a little flat stone when the insect goes a-hunting, or stops mining when the hour to leave off work comes at sunset. But in that case the stoppage is slight—a mere slab set on the top of the well. It takes but a moment when the insect comes to displace the little flat stone, and the door is open. But what we have just seen the Sphex construct is a solid barrier—strong masonry, where layers of alternate dust and gravel occupy the whole passage. It is definitive, and no temporary work, as is sufficiently shown by the careful way in which it is constructed. Besides, as I think I have already proved, it is very doubtful, considering the manner in which she acted, whether the Sphex would return to use the dwelling which she had prepared. A new ephippiger will be caught elsewhere, and elsewhere too will the storehouse destined for it be hollowed. As, however, these are but conclusions drawn by reasoning, let us consult experiment, more conclusive here than logic. I let nearly a week pass in order to allow the Sphex to return to the burrow so methodically closed, and use it if she liked for her nest-laying. Events answered to the logical deduction; the burrow was just as I had left it, well closed, but without food, egg, or larva. The demonstration was decisive; the Sphex had not returned.

Thus we see the plundered Sphex go into her house, pay a leisurely visit to the empty chamber, and the next moment behave as if she had not perceived the absence of the big prey which a little while before had encumbered the cell. Did she not realise the absence of food and egg? Was she really so dull—she, so clear-sighted when playing the murderer—that the cell was empty? I dare not accuse her of such stupidity. She did perceive it. But why then that other piece of stupidity which made her close, and very conscientiously too, an empty chamber which she did not mean to store? It was useless—downright absurd—to do this, and yet she worked with as much zeal as if the future of the larva depended on it. The various instinctive actions of insects are then necessarily connected; since one thing has been done, such another must inevitably follow to complete the first, or prepare the way for the next, and the two acts are so necessarily linked that the first must cause the second, even when by some chance this last has become not only superfluous, but sometimes contrary to the creature’s interest. What object could there be in stopping a burrow now useless, since it no longer contained prey and egg, and which will remain useless, since the Sphex will not return to it? One can only explain this irrational proceeding by regarding it as the necessary consequence of preceding actions. In the normal state of things the Sphex hunts her prey, lays an egg, and closes the hole. The prey has been caught, the egg laid, and now comes the closing of the burrow, and the insect closes it without reflecting at all, or guessing the fruitlessness of her labour.