Social Life in the Insect World

Let us now examine the motives which induce the Philanthus to kill its bee instead of paralysing it. The murder once committed, it does not release its victim for a moment, but holding it tightly clasped with its six legs pressed against its body, it commences to ravage the corpse. I see it with the utmost brutality rooting with its mandibles in the articulation of the neck, and often also in the more ample articulation of the corselet, behind the first pair of legs; perfectly aware of the fine membrane in that part, although it does not take advantage of the fact when employing its sting, although this vulnerable point is the more accessible of the two breaches in the bee's armour. I see it squeezing the bee's stomach, compressing it with its own abdomen, crushing it as in a vice. The brutality of this manipulation is striking; it shows that there is no more need of care and skill. The bee is a corpse, and a little extra pushing and squeezing will not deteriorate its quality as food, provided there is no effusion of blood; and however rough the treatment, I have never been able to discover the slightest wound.

These various manipulations, above all the compression of the throat, lead to the desired result: the honey in the stomach of the bee ascends to the mouth. I see the drops of honey welling out, lapped up by the glutton as soon as they appear. The bandit greedily takes in its mouth the extended and sugared tongue of the dead insect; then once more it presses the neck and the thorax, and once more applies the pressure of its abdomen to the honey-sac of the bee. The honey oozes forth and is instantly licked up. This odious meal at the expense of the corpse is taken in a truly sybaritic attitude: the Philanthus lies upon its side with the bee between its legs. This atrocious meal lasts often half an hour and longer. Finally the exhausted corpse is abandoned; regretfully, it seems, for from time to time I have seen the ogre return to the feast and repeat its manipulation of the body. After taking a turn round the top of the bell-glass the robber of the dead returns to the victim, squeezes it once more, and licks its mouth until the last trace of honey has disappeared.

The frantic passion of the Philanthus for the honey of the bee is betrayed in another fashion. When the first victim has been exhausted I have introduced a second bee, which has been promptly stabbed under the chin and squeezed as before in order to extract its honey. A third has suffered the same fate without appeasing the bandit. I have offered a fourth, a fifth; all are accepted. My notes record that a Philanthus sacrificed six bees in succession before my eyes, and emptied them all of honey in the approved manner. The killing came to an end not because the glutton was satiated, but because my functions as provider were becoming troublesome; the dry month of August leaves but few insects in the flowerless garden. Six bees emptied of their honey—what a gluttonous meal! Yet the famishing creature would doubtless have welcomed a copious addition thereto had I had the means of furnishing it!

We need not regret the failure of bees upon this occasion; for what I have already written is sufficient testimony of the singular habits of this murderer of bees. I am far from denying that the Philanthus has honest methods of earning its living; I see it among the flowers, no less assiduous than the rest of the Hymenoptera, peacefully drinking from their cups of nectar. The male, indeed, being stingless, knows no other means of supporting himself. The mothers, without neglecting the flowers as a general thing, live by brigandage as well. It is said of the Labba, that pirate of the seas, that it pounces upon sea-birds as they rise from the waves with captured fish in their beaks. With a blow of the beak delivered in the hollow of the stomach, the aggressor forces the victim to drop its prey, and promptly catches it as it falls. The victim at least escapes with nothing worse than a blow at the base of the neck. The Philanthus, less scrupulous, falls upon the bee, stabs it to death and makes it disgorge in order to nourish herself upon its honey.

Nourish, I say, and I do not withdraw the expression. To support my statement I have better reasons than those already presented. In the cages in which various predatory Hymenoptera whose warlike habits I am studying are confined, waiting until I have procured the desired prey—not always an easy proceeding—I have planted a few heads of flowers and a couple of thistle-heads sprinkled with drops of honey, renewed at need. On these my captives feed. In the case of the Philanthus the honeyed flowers, although welcomed, are not indispensable. It is enough if from time to time I place in the cage a few living bees. Half a dozen a day is about the proper allowance. With no other diet than the honey extracted from their victims I keep my specimens of Philanthus for a fortnight and three weeks.

So much is plain: in a state of freedom, when occasion offers, the Philanthus must kill on her own account as she does in captivity. The Odynerus asks nothing of the Chrysomela but a simple condiment, the aromatic juice of the anal pouch; the Philanthus demands a full diet, or at least a notable supplement thereto, in the form of the contents of the stomach. What a hecatomb of bees must not a colony of these pirates sacrifice for their personal consumption, to say nothing of their stores of provisions! I recommend the Philanthus to the vengeance of apiarists.

For the moment we will not look further into the original causes of the crime. Let us consider matters as we know them, with all their real or apparent atrocity. In order to nourish herself the Philanthus levies tribute upon the crop of the bee. This being granted, let us consider the method of the aggressor more closely. She does not paralyse its captives according to the customary rites of the predatory insects; she kills them. Why? To the eyes of understanding the necessity of a sudden death is as clear as day. Without eviscerating the bee, which would result in the deterioration of its flesh considered as food for the larvæ; without having recourse to the bloody extirpation of the stomach, the Philanthus intends to obtain its honey. By skilful manipulation, by cunning massage, she must somehow make the bee disgorge. Suppose the bee stung in the rear of the corselet and paralysed. It is deprived of locomotion, but not of vitality. The digestive apparatus, in particular, retains in full, or at least in part, its normal energies, as is proved by the frequent dejections of paralysed victims so long as the intestine is not emptied; a fact notably exemplified by the victims of the Sphex family; helpless creatures which I have before now kept alive for forty days with the aid of a little sugared water. Well! without therapeutic means, without emetics or stomach-pumps, how is a stomach intact and in good order to be persuaded to yield up its contents? That of the bee, jealous of its treasure, will lend itself to such treatment less readily than another. Paralysed, the creature is inert; but there are always internal energies and organic resistances which will not yield to the pressure of the manipulator. In vain would the Philanthus gnaw at the throat and squeeze the flanks; the honey would not return to the mouth as long as a trace of life kept the stomach closed.

Matters are different with a corpse. The springs relax; the muscles yield; the resistance of the stomach ceases, and the vessels containing the honey are emptied by the pressure of the thief. We see, therefore, that the Philanthus is obliged to inflict a sudden death which instantly destroys the contractile power of the organs. Where shall the deadly blow be delivered? The slayer knows better than we, when she pierces the victim beneath the chin. Through the narrow breach in the throat the cerebral ganglions are reached and immediate death ensues.

The examination of these acts of brigandage is not sufficient in view of my incorrigible habit of following every reply by another query, until the granite wall of the unknowable rises before me. Although the Philanthus is skilled in forcing the bee to disgorge, in emptying the crop distended with honey, this diabolical skill cannot be merely an alimentary resource, above all when in common with other insects she has access to the refectory of the flowers. I cannot regard her talents as inspired solely by the desire of a meal obtained by the labour of emptying the stomach of another insect. Something must surely escape us here: the real reason for emptying the stomach. Perhaps a respectable reason is concealed by the horrors I have recorded. What is it?

Every one will understand the vagueness which fills the observer's mind in respect of such a question as this. The reader has the right to be doubtful. I will spare him my suspicions, my gropings for the truth, and the checks encountered in the search, and give him the results of my long inquiry. Everything has its appropriate and harmonious reason. I am too fully persuaded of this to believe that the Philanthus commits her profanation of corpses merely to satisfy her appetite. What does the empty stomach mean? May it not—Yes!—But, after all, who knows? Well, let us follow up the scent.

The first care of the mothers is the welfare of the family. So far all we know of the Philanthus concerns her talent for murder. Let us consider her as a mother. We have seen her hunt on her own account; let us now watch her hunt for her offspring, for the race. Nothing is simpler than to distinguish between the two kinds of hunting. When the insect wants a few good mouthfuls of honey and nothing else, she abandons the bee contemptuously when she has emptied its stomach. It is so much valueless waste, which will shrivel where it lies and be dissected by ants. If, on the other hand, she intends to place it in the larder as a provision for her larvæ, she clasps it with her two intermediate legs, and, walking on the other four, drags it to and fro along the edge of the bell-glass in search of an exit so that she may fly off with her prey. Having recognised the circular wall as impassable, she climbs its sides, now holding the bee in her mandibles by the antennæ, clinging as she climbs to the vertical polished surface with all six feet. She gains the summit of the glass, stays for a little while in the flask-like cavity of the terminal button or handle, returns to the ground, and resumes her circuit of the glass and her climbing, relinquishing the bee only after an obstinate attempt to escape with it. The persistence with which the Philanthus retains her clasp upon the encumbering burden shows plainly that the game would go straight to the larder were the insect at liberty.

Those bees intended for the larvæ are stung under the chin like the others; they are true corpses; they are manipulated, squeezed, exhausted of their honey, just as the others. There is no difference in the method of capture nor in their after-treatment.

As captivity might possibly result in a few anomalies of action, I decided to inquire how matters went forward in the open. In the neighbourhood of some colonies of Philanthidæ I lay in wait, watching for perhaps a longer time than the question justified, as it was already settled by what occurred in captivity. My scrupulous watching at various times was rewarded. The majority of the hunters immediately entered their nests, carrying the bees pressed against their bodies; some halted on the neighbouring undergrowth; and these I saw treating the bee in the usual manner, and lapping the honey from its mouth. After these preparations the corpse was placed in the larder. All doubt was thus destroyed: the bees provided for the larvæ are previously carefully emptied of their honey.

Since we are dealing with the subject, let us take the opportunity of inquiring into the customs of the Philanthus in a state of freedom. Making use of her victims when absolutely lifeless, so that they would putrefy in the course of a few days, this hunter of bees cannot adopt the customs of certain insects which paralyse their prey, and fill their cellars before laying an egg. She must surely be obliged to follow the method of the Bembex, whose larva receives, at intervals, the necessary nourishment; the amount increasing as the larva grows. The facts confirm this deduction. I spoke just now of the tediousness of my watching when watching the colonies of the Philanthus. It was perhaps even more tedious than when I was keeping an eye upon the Bembex. Before the burrows of Cerceris tuberculus and other devourers of the weevil, and before that of the yellow-winged Sphex, the slayer of crickets, there is plenty of distraction, owing to the busy movements of the community. The mothers have scarcely entered the nest before they are off again, returning quickly with fresh prey, only to set out once more. The going and coming is almost continuous until the storehouse is full.

The burrows of the Philanthus know nothing of such animation, even in a populous colony. In vain my vigils prolonged themselves into whole mornings or afternoons, and only very rarely does the mother who has entered with a bee set forth upon a second expedition. Two captures by the same huntress is the most that I have seen in my long watches. Once the family is provided with sufficient food for the moment the mother postpones further hunting trips until hunting becomes necessary, and busies herself with digging and burrowing in her underground dwelling. Little cells are excavated, and I see the rubbish from them gradually pushed up to the surface. With that exception there is no sign of activity; it is as though the burrow were deserted.

To lay the nest bare is not easy. The burrow penetrates to a depth of about three feet in a compact soil; sometimes in a vertical, sometimes in a horizontal direction. The spade and pick, wielded by hands more vigorous but less expert than my own, are indispensable; but the conduct of the excavation is anything but satisfactory. At the extremity of the long gallery—it seems as though the straw I use for sounding would never reach the end—we finally discover the cells, egg-shaped cavities with the longer axis horizontal. Their number and their mutual disposition escape me.

Some already contain the cocoon—slender and translucid, like that of the Cerceris, and, like it, recalling the shape of certain homœopathic phials, with oval bodies surmounted by a tapering neck. By the extremity of the neck, which is blackened and hardened by the dejecta of the larvæ, the cocoon is fixed to the end of the cell without any other support. It reminds one of a short club, planted by the end of the handle, in a line with the horizontal axis of the cell. Other cells contain the larva in a stage more or less advanced. The grub is eating the last victim proffered; around it lie the remains of food already consumed. Others, again, show me a bee, a single bee, still intact, and having an egg deposited on the under-side of the thorax. This bee represents the first instalment of rations; others will follow as the grub matures. My expectations are thus confirmed; as with Bembex, slayer of Diptera, so Philanthus, killer of bees, lays her egg upon the first body stored, and completes, at intervals, the provisioning of the cells.

The problem of the dead bee is elucidated; there remains the other problem, of incomparable interest—Why, before they are given over to the larvæ, are the bees robbed of their honey? I have said, and I repeat, that the killing and emptying of the bee cannot be explained solely by the gluttony of the Philanthus. To rob the worker of its booty is nothing; such things are seen every day; but to slaughter it in order to empty its stomach—no, gluttony cannot be the only motive. And as the bees placed in the cells are squeezed dry no less than the others, the idea occurs to me that as a beefsteak garnished with confitures is not to every one's taste, so the bee sweetened with honey may well be distasteful or even harmful to the larvæ of the Philanthus. What would the grub do if, replete with blood and flesh, it were to find under its mandibles the honey-bag of the bee?—if, gnawing at random, it were to open the bees stomach and so drench its game with syrup? Would it approve of the mixture? Would the little ogre pass without repugnance from the gamey flavour of a corpse to the scent of flowers? To affirm or deny is useless. We must see. Let us see.

I take the young larvæ of the Philanthus, already well matured, but instead of serving them with the provisions buried in their cells I offer them game of my own catching—bees that have filled themselves with nectar among the rosemary bushes. My bees, killed by crushing the head, are thankfully accepted, and at first I see nothing to justify my suspicions. Then my nurslings languish, show themselves disdainful of their food, give a negligent bite here and there, and finally, one and all, die beside their uncompleted meal. All my attempts miscarry; not once do I succeed in rearing my larvæ as far as the stage of spinning the cocoon. Yet I am no novice in my duties as dry-nurse. How many pupils have passed through my hands and have reached the final stage in my old sardine-boxes as well as in their native burrows! I shall draw no conclusions from this check, which my scruples may attribute to some unknown cause. Perhaps the atmosphere of my cabinet and the dryness of the sand serving them for a bed have been too much for my nurslings, whose tender skins are used to the warm moisture of the subsoil. Let us try another method.

To decide positively whether honey is or is not repugnant to the grubs of the Philanthus was hardly practicable by the method just explained. The first meals consisted of flesh, and after that nothing in particular occurred. The honey is encountered later, when the bee is largely consumed. If hesitation and repugnance were manifested at this point they came too late to be conclusive; the sickness of the larvæ might be due to other causes, known or unknown. We must offer honey at the very beginning, before artificial rearing has spoilt the grub's appetite. To offer pure honey would, of course, be useless; no carnivorous creature would touch it, even were it starving. I must spread the honey on meat; that is, I must smear the dead bee with honey, lightly varnishing it with a camel's-hair brush.

Under these conditions the problem is solved with the first few mouthfuls. The grub, having bitten on the honeyed bee, draws back as though disgusted; hesitates for a long time; then, urged by hunger, begins again; tries first on one side, then on another; in the end it refuses to touch the bee again. For a few days it pines upon its rations, which are almost intact, then dies. As many as are subjected to the same treatment perish in the same way.

Do they simply die of hunger in the presence of food which their appetites reject, or are they poisoned by the small amount of honey absorbed at the first bites? I cannot say; but, whether poisonous or merely repugnant, the bee smeared with honey is always fatal to them; a fact which explains more clearly than the unfavourable circumstances of the former experiment my lack of success with the freshly killed bees.

This refusal to touch honey, whether poisonous or repugnant, is connected with principles of alimentation too general to be a gastronomic peculiarity of the Philanthus grub. Other carnivorous larvæ—at least in the series of the Hymenoptera—must share it. Let us experiment. The method need not be changed. I exhume the larvæ when in a state of medium growth, to avoid the vicissitudes of extreme youth; I collect the bodies of the grubs and insects which form their natural diet and smear each body with honey, in which condition I return them to the larvæ. A distinction is apparent: all the larvæ are not equally suited to my experiment. Those larvæ must be rejected which are nourished upon one single corpulent insect, as is that of the Scolia. The grub attacks its prey at a determined point, plunges its head and neck into the body of the insect, skilfully divides the entrails in order to keep the remains fresh until its meal is ended, and does not emerge from the opening until all is consumed but the empty skin.

To interrupt the larva with the object of smearing the interior of its prey with honey is doubly objectionable; I might extinguish the lingering vitality which keeps putrefaction at bay in the victim, and I might confuse the delicate art of the larva, which might not be able to recover the lode at which it was working or to distinguish between those parts which are lawfully and properly eaten and those which must not be consumed until a later period. As I have shown in a previous volume, the grub of the Scolia has taught me much in this respect. The only larvæ acceptable for this experiment are those which are fed on a number of small insects, which are attacked without any special art, dismembered at random, and quickly consumed. Among such larvæ I have experimented with those provided by chance—those of various Bembeces, fed on Diptera; those of the Palaris, whose diet consists of a large variety of Hymenoptera; those of the Tachytus, provided with young crickets; those of the Odynerus, fed upon larvæ of the Chrysomela; those of the sand-dwelling Cerceris, endowed with a hecatomb of weevils. As will be seen, both consumers and consumed offer plenty of variety. Well, in every case their proper diet, seasoned with honey, is fatal. Whether poisoned or disgusted, they all die in a few days.

A strange result! Honey, the nectar of the flowers, the sole diet of the apiary under its two forms and the sole nourishment of the predatory insect in its adult phase, is for the larva of the same insect an object of insurmountable disgust, and probably a poison. The transfiguration of the chrysalis surprises me less than this inversion of the appetite. What change occurs in the stomach of the insect that the adult should passionately seek that which the larva refuses under peril of death? It is no question of organic debility unable to support a diet too substantial, too hard, or too highly spiced. The grubs which consume the larva of the Cetoniæ, for example (the Rose-chafers), those which feed upon the leathery cricket, and those whose diet is rich in nitrobenzine, must assuredly have complacent gullets and adaptable stomachs. Yet these robust eaters die of hunger or poison for no greater cause than a drop of syrup, the lightest diet imaginable, adapted to the weakness of extreme youth, and a delicacy to the adult! What a gulf of obscurity in the stomach of a miserable worm!

These gastronomic experiments called for a counter-proof. The carnivorous grub is killed by honey. Is the honey-fed grub, inversely, killed by carnivorous diet? Here, again, we must make certain exceptions, observe a certain choice, as in the previous experiments. It would obviously be courting a flat refusal to offer a heap of young crickets to the larvæ of the Anthophorus and the Osmia, for example; the honey-fed grub would not bite such food. It would be absolutely useless to make such an experiment. We must find the equivalent of the bee smeared with honey; that is, we must offer the larva its ordinary food with a mixture of animal matter added. I shall experiment with albumen, as provided by the egg of the hen; albumen being an isomer of fibrine, which is the principal element of all flesh diet.

Osmia tricornis will lend itself to my experiment better than any other insect on account of its dry honey, or bee-bread, which is largely formed of flowery pollen. I knead it with the albumen, graduating the dose of the latter so that its weight largely exceeds that of the bee-bread. Thus I obtain pastes of various degrees of consistency, but all firm enough to support the larva without danger of immersion. With too fluid a mixture there would be a danger of death by drowning. Finally, on each cake of albuminous paste I install a larva of medium growth.

This diet is not distasteful; far from it. The grubs attack it without hesitation and devour it with every appearance of a normal appetite. Matters could not go better if the food had not been modified according to my recipes. All is eaten; even the portions which I feared contained an excessive proportion of albumen. Moreover—a matter of still greater importance—the larvæ of the Osmia fed in this manner attain their normal growth and spin their cocoons, from which adults issue in the following year. Despite the albuminous diet the cycle of evolution completes itself without mishap.

What are we to conclude from all this? I confess I am embarrassed. Omne vivum ex ovo, says the physiologist. All animals are carnivorous in their first beginnings; they are formed and nourished at the expense of the egg, in which albumen predominates. The highest, the mammals, adhere to this diet for a considerable time; they live by the maternal milk, rich in casein, another isomer of albumen. The gramnivorous nestling is fed first upon worms and grubs, which are best adapted to the delicacy of its stomach; many newly born creatures among the lower orders, being immediately left to their own devices, live on animal diet. In this way the original method of alimentation is continued—the method which builds flesh out of flesh and makes blood out of blood with no chemical processes but those of simple reconstruction. In maturity, when the stomach is more robust, a vegetable diet may be adopted, involving a more complex chemistry, although the food itself is more easily obtained. To milk succeeds fodder; to the worm, seeds and grain; to the dead or paralysed insects of the natal burrow, the nectar of flowers.

Here is a partial explanation of the double system of the Hymenoptera with their carnivorous larvæ—the system of dead or paralysed insects followed by honey. But here the point of interrogation, already encountered elsewhere, erects itself once again. Why is the larva of the Osmia, which thrives upon albumen, actually fed upon honey during its early life? Why is a vegetable diet the rule in the hives of bees from the very commencement, when the other members of the same series live upon animal food?

If I were a "transformist" how I should delight in this question! Yes, I should say: yes, by the fact of its germ every animal is originally carnivorous. The insect in particular makes a beginning with albuminoid materials. Many larvæ adhere to the alimentation present in the egg, as do many adult insects also. But the struggle to fill the belly, which is actually the struggle for life, demands something better than the precarious chances of the chase. Man, at first an eager hunter of game, collected flocks and became a shepherd in order to profit by his possessions in time of dearth. Further progress inspired him to till the earth and sow; a method which assured him of a certain living. Evolution from the defective to the mediocre, and from the mediocre to the abundant, has led to the resources of agriculture.

The lower animals have preceded us on the way of progress. The ancestors of the Philanthus, in the remote ages of the lacustrian tertiary formations, lived by capturing prey in both phases—both as larvæ and as adults; they hunted for their own benefit as well as for the family. They did not confine themselves to emptying the stomach of the bee, as do their descendants to-day; they devoured the victim entire. From beginning to end they remained carnivorous. Later there were fortunate innovators, whose race supplanted the more conservative element, who discovered an inexhaustible source of nourishment, to be obtained without painful search or dangerous conflict: the saccharine exudation of the flowers. The wasteful system of living upon prey, by no means favourable to large populations, has been preserved for the feeble larvæ; but the vigorous adult has abandoned it for an easier and more prosperous existence. Thus the Philanthus of our own days was gradually developed; thus was formed the double system of nourishment practised by the various predatory insects which we know.

The bee has done still better; from the moment of leaving the egg it dispenses completely with chance-won aliments. It has invented honey, the food of its larvæ. Renouncing the chase for ever, and becoming exclusively agricultural, this insect has acquired a degree of moral and physical prosperity that the predatory species are far from sharing. Hence the flourishing colonies of the Anthophoræ, the Osmiæ, the Euceræ, the Halicti, and other makers of honey, while the hunters of prey work in isolation; hence the societies in which the bee displays its admirable talents, the supreme expression of instinct.

This is what I should say if I were a "transformist." All this is a chain of highly logical deductions, and it hangs together with a certain air of reality, such as we like to look for in a host of "transformist" arguments which are put forward as irrefutable. Well, I make a present of my deductive theory to whosoever desires it, and without the least regret; I do not believe a single word of it, and I confess my profound ignorance of the origin of the twofold system of diet.

One thing I do see more clearly after all my experiments and research: the tactics of the Philanthus. As a witness of its ferocious feasting, the true motive of which was unknown to me, I treated it to all the unfavourable epithets I could think of; called it assassin, bandit, pirate, robber of the dead. Ignorance is always abusive; the man who does not know is full of violent affirmations and malign interpretations. Undeceived by the facts, I hasten to apologise and express my esteem for the Philanthus. In emptying the stomach of the bee the mother is performing the most praiseworthy of all duties; she is guarding her family against poison. If she sometimes kills on her own account and abandons the body after exhausting it of honey, I dare not call her action a crime. When the habit has once been formed of emptying the bee's crop for the best of motives, the temptation is great to do so with no other excuse than hunger. Moreover—who can say?—perhaps there is always some afterthought that the larvæ might profit by the sacrifice. Although not carried into effect the intention excuses the act.

I therefore withdraw my abusive epithets in order to express my admiration of the creature's maternal logic. Honey would be harmful to the grubs. How does the mother know that honey, in which she herself delights, is noxious to her young? To this question our knowledge has no reply. But honey, as we have seen, would endanger the lives of the grubs. The bees must therefore be emptied of honey before they are fed to them. The process must be effected without wounding the victim, for the larva must receive the latter fresh and moist; and this would be impracticable if the insect were paralysed on account of the natural resistance of the organs. The bee must therefore be killed outright instead of being paralysed, otherwise the honey could not be removed. Instantaneous death can be assured only by a lesion of the primordial centre of life. The sting must therefore pierce the cervical ganglions; the centre of innervation upon which the rest of the organism is dependent. This can only be reached in one way: through the neck. Here it is that the sting will be inserted; and here it is inserted in a breach in the armour no larger than a pin's head. Suppress a single link of this closely knit chain, and the Philanthus reared upon the flesh of bees becomes an impossibility.

That honey is fatal to larvæ is a fact pregnant with consequences. Various predatory insects feed their young with honey-makers. Such, to my knowledge, are the Philanthus coronatus, Fabr., which stores its burrows with the large Halictus; the Philanthus raptor, Lep., which chases all the smaller Halictus indifferently, being itself a small insect; the Cerceris ornata, Fabr., which also kills Halictus; and the Polaris flavipes, Fabr., which by a strange eclecticism fills its cells with specimens of most of the Hymenoptera which are not beyond its powers. What do these four huntresses, and others of similar habits, do with their victims when the crops of the latter are full of honey? They must follow the example of the Philanthus or their offspring would perish; they must squeeze and manipulate the dead bee until it yields up its honey. Everything goes to prove as much; but for the actual observation of what would be a notable proof of my theory I must trust to the future.

CHAPTER XIV

It was a memorable night! I will name it the Night of the Great Peacock. Who does not know this superb moth, the largest of all our European butterflies[3] with its livery of chestnut velvet and its collar of white fur? The greys and browns of the wings are crossed by a paler zig-zag, and bordered with smoky white; and in the centre of each wing is a round spot, a great eye with a black pupil and variegated iris, resolving into concentric arcs of black, white, chestnut, and purplish red.

Not less remarkable is the caterpillar. Its colour is a vague yellow. On the summit of thinly sown tubercles crowned with a palisade of black hairs are set pearls of a turquoise-blue. The burly brown cocoon, which is notable for its curious tunnel of exit, like an eel-pot, is always found at the base of an old almond-tree, adhering to the bark. The foliage of the same tree nourishes the caterpillar.

On the morning of the 6th of May a female emerged from her cocoon in my presence on my laboratory table. I cloistered her immediately, all damp with the moisture of metamorphosis, in a cover of wire gauze. I had no particular intentions regarding her; I imprisoned her from mere habit; the habit of an observer always on the alert for what may happen.

I was richly rewarded. About nine o'clock that evening, when the household was going to bed, there was a sudden hubbub in the room next to mine. Little Paul, half undressed, was rushing to and fro, running, jumping, stamping, and overturning the chairs as if possessed. I heard him call me. "Come quick!" he shrieked; "come and see these butterflies! Big as birds! The room's full of them!"

I ran. There was that which justified the child's enthusiasm and his hardly hyperbolical exclamation. It was an invasion of giant butterflies; an invasion hitherto unexampled in our house. Four were already caught and placed in a bird-cage. Others—numbers of them—were flying across the ceiling.

This astonishing sight recalled the prisoner of the morning to my mind. "Put on your togs, kiddy!" I told my son; "put down your cage, and come with me. We shall see something worth seeing."

We had to go downstairs to reach my study, which occupies the right wing of the house. In the kitchen we met the servant; she too was bewildered by the state of affairs. She was pursuing the huge butterflies with her apron, having taken them at first for bats.

It seemed as though the Great Peacock had taken possession of my whole house, more or less. What would it be upstairs, where the prisoner was, the cause of this invasion? Happily one of the two study windows had been left ajar; the road was open.

Let us consider only such areas as were in darkness. There the pilgrims were numerous. I found them almost everywhere in the neighbourhood of their goal. When the captive was in my study the butterflies did not all enter by the open window, the direct and easy way, the captive being only a few yards from the window. Several penetrated the house downstairs, wandered through the hall, and reached the staircase, which was barred at the top by a closed door.

These data show us that the visitors to the wedding-feast did not go straight to their goal as they would have done were they attracted by any kind of luminous radiations, whether known or unknown to our physical science. Something other than radiant energy warned them at a distance, led them to the neighbourhood of the precise spot, and left the final discovery to be made after a vague and hesitating search. The senses of hearing and smell warn us very much in this way; they are not precise guides when we try to determine exactly the point of origin of a sound or smell.

What sense is it that informs this great butterfly of the whereabouts of his mate, and leads him wandering through the night? What organ does this sense affect? One suspects the antennæ; in the male butterfly they actually seem to be sounding, interrogating empty space with their long feathery plumes. Are these splendid plumes merely items of finery, or do they really play a part in the perception of the effluvia which guide the lover? It seemed easy, on the occasion I spoke of, to devise a conclusive experiment.

On the morrow of the invasion I found in my study eight of my nocturnal visitors. They were perched, motionless, upon the cross-mouldings of the second window, which had remained closed. The others, having concluded their ballet by about ten o'clock at night, had left as they had entered, by the other window, which was left open night and day. These eight persevering lovers were just what I required for my experiment.

With a sharp pair of scissors, and without otherwise touching the butterflies, I cut off their antennæ near the base. The victims barely noticed the operation. None moved; there was scarcely a flutter of the wings. Their condition was excellent; the wound did not seem to be in the least serious. They were not perturbed by physical suffering, and would therefore be all the better adapted to my designs. They passed the rest of the day in placid immobility on the cross-bars of the window.

A few other arrangements were still to be made. In particular it was necessary to change the scene; not to leave the female under the eyes of the mutilated butterflies at the moment of resuming their nocturnal flight; the difficulty of the search must not be lessened. I therefore removed the cage and its captive, and placed it under a porch on the other side of the house, at a distance of some fifty paces from my study.

At nightfall I went for a last time to inspect my eight victims. Six had left by the open window; two still remained, but they had fallen on the floor, and no longer had the strength to recover themselves if turned over on their backs. They were exhausted, dying. Do not accuse my surgery, however. Such early decease was observed repeatedly, with no intervention on my part.

Six, in better condition, had departed. Would they return to the call that attracted them the night before? Deprived of their antennæ, would they be able to find the captive, now placed at a considerable distance from her original position?

The cage was in darkness, almost in the open air. From time to time I visited it with a net and lantern. The visitors were captured, inspected, and immediately released in a neighbouring room, of which I closed the door. This gradual elimination allowed me to count the visitors exactly without danger of counting the same butterfly more than once. Moreover, the provisional prison, large and bare, in no wise harmed or endangered the prisoners; they found a quiet retreat there and ample space. Similar precautions were taken during the rest of my experiments.

After half-past ten no more arrived. The reception was over. Total, twenty-five males captured, of which one only was deprived of its antennæ. So of the six operated on earlier in the day, which were strong enough to leave my study and fly back to the fields, only one had returned to the cage. A poor result, in which I could place no confidence as proving whether the antennæ did or did not play a directing part. It was necessary to begin again upon a larger scale.

Next morning I visited the prisoners of the day before. What I saw was not encouraging. A large number were scattered on the ground, almost inert. Taken between the fingers, several of them gave scarcely a sign of life. Little was to be hoped from these, it would seem. Still, I determined to try; perhaps they would regain their vigour at the lover's hour.

The twenty-four prisoners were all subjected to the amputation of their antennæ. The one operated on the day before was put aside as dying or nearly so. Finally the door of the prison was left open for the rest of the day. Those might leave who could; those could join in the carnival who were able. In order to put those that might leave the room to the test of a search, the cage, which they must otherwise have encountered at the threshold, was again removed, and placed in a room of the opposite wing, on the ground floor. There was of course free access to this room.

Of the twenty-four lacking their antennæ sixteen only left the room. Eight were powerless to do so; they were dying. Of the sixteen, how many returned to the cage that night? Not one. My captives that night were only seven, all new-comers, all wearing antennæ. This result seemed to prove that the amputation of the antennæ was a matter of serious significance. But it would not do to conclude as yet: one doubt remained.

"A fine state I am in! How shall I dare to appear before the other dogs?" said Mouflard, the puppy whose ears had been pitilessly docked. Had my butterflies apprehensions similar to Master Mouflard's? Deprived of their beautiful plumes, were they ashamed to appear in the midst of their rivals, and to prefer their suits? Was it confusion on their part, or want of guidance? Was it not rather exhaustion after an attempt exceeding the duration of an ephemeral passion? Experience would show me.

On the fourth night I took fourteen new-comers and set them apart as they came in a room in which they spent the night. On the morrow, profiting by their diurnal immobility, I removed a little of the hair from the centre of the corselet or neck. This slight tonsure did not inconvenience the insects, so easily was the silky fur removed, nor did it deprive them of any organ which might later on be necessary in the search for the female. To them it was nothing; for me it was the unmistakable sign of a repeated visit.

This time there were none incapable of flight. At night the fourteen shavelings escaped into the open air. The cage, of course, was again in a new place. In two hours I captured twenty butterflies, of whom two were tonsured; no more. As for those whose antennæ I had amputated the night before, not one reappeared. Their nuptial period was over.

Of fourteen marked by the tonsure two only returned. Why did the other twelve fail to appear, although furnished with their supposed guides, their antennæ? To this I can see only one reply: that the Great Peacock is promptly exhausted by the ardours of the mating season.

With a view to mating, the sole end of its life, the great moth is endowed with a marvellous prerogative. It has the power to discover the object of its desire in spite of distance, in spite of obstacles. A few hours, for two or three nights, are given to its search, its nuptial flights. If it cannot profit by them, all is ended; the compass fails, the lamp expires. What profit could life hold henceforth? Stoically the creature withdraws into a corner and sleeps the last sleep, the end of illusions and the end of suffering.

The Great Peacock exists as a butterfly only to perpetuate itself. It knows nothing of food. While so many others, joyful banqueters, fly from flower to flower, unrolling their spiral trunks to plunge them into honeyed blossoms, this incomparable ascetic, completely freed from the servitude of the stomach, has no means of restoring its strength. Its buccal members are mere vestiges, useless simulacra, not real organs able to perform their duties. Not a sip of honey can ever enter its stomach; a magnificent prerogative, if it is not long enjoyed. If the lamp is to burn it must be filled with oil. The Great Peacock renounces the joys of the palate; but with them it surrenders long life. Two or three nights—just long enough to allow the couple to meet and mate—and all is over; the great butterfly is dead.

What, then, is meant by the non-appearance of those whose antennæ I removed? Did they prove that the lack of antennæ rendered them incapable of finding the cage in which the prisoner waited? By no means. Like those marked with the tonsure, which had undergone no damaging operation, they proved only that their time was finished. Mutilated or intact, they could do no more on account of age, and their absence meant nothing. Owing to the delay inseparable from the experiment, the part played by the antennæ escaped me. It was doubtful before; it remained doubtful.

My prisoner under the wire-gauze cover lived for eight days. Every night she attracted a swarm of visitors, now to one part of the house, now to another. I caught them with the net and released them as soon as captured in a closed room, where they passed the night. On the next day they were marked, by means of a slight tonsure on the thorax.

The total number of butterflies attracted on these eight nights amounted to a hundred and fifty; a stupendous number when I consider what searches I had to undertake during the two following years in order to collect the specimens necessary to the continuation of my investigation. Without being absolutely undiscoverable, in my immediate neighbourhood the cocoons of the Great Peacock are at least extremely rare, as the trees on which they are found are not common. For two winters I visited all the decrepit almond-trees at hand, inspected them all at the base of the trunk, under the jungle of stubborn grasses and undergrowth that surrounded them; and how often I returned with empty hands! Thus my hundred and fifty butterflies had come from some little distance; perhaps from a radius of a mile and a quarter or more. How did they learn of what was happening in my study?

Three agents of information affect the senses at a distance: sight, sound, and smell. Can we speak of vision in this connection? Sight could very well guide the arrivals once they had entered the open window; but how could it help them out of doors, among unfamiliar surroundings? Even the fabulous eye of the lynx, which could see through walls, would not be sufficient; we should have to imagine a keenness of vision capable of annihilating leagues of space. It is needless to discuss the matter further; sight cannot be the guiding sense.

Sound is equally out of the question. The big-bodied creature capable of calling her mates from such a distance is absolutely mute, even to the most sensitive ear. Does she perhaps emit vibrations of such delicacy or rapidity that only the most sensitive microphone could appreciate them? The idea is barely possible; but let us remember that the visitors must have been warned at distances of some thousands of yards. Under these conditions it is useless to think of acoustics.

Smell remains. Scent, better than any other impression in the domain of our senses, would explain the invasion of butterflies, and their difficulty at the very last in immediately finding the object of their search. Are there effluvia analogous to what we call odour: effluvia of extreme subtlety, absolutely imperceptible to us, yet capable of stimulating a sense-organ far more sensitive than our own? A simple experiment suggested itself. I would mask these effluvia, stifle them under a powerful, tenacious odour, which would take complete possession of the sense-organ and neutralise the less powerful impression.

I began by sprinkling naphthaline in the room intended for the reception of the males that evening. Beside the female, inside the wire-gauze cover, I placed a large capsule full of the same substance. When the hour of the nocturnal visit arrived I had only to stand at the door of the room to smell a smell as of a gas-works. Well, my artifice failed. The butterflies arrived as usual, entered the room, traversed its gas-laden atmosphere, and made for the wire-gauze cover with the same certainty as in a room full of fresh air.

My confidence in the olfactory theory was shaken. Moreover, I could not continue my experiments. On the ninth day, exhausted by her fruitless period of waiting, the female died, having first deposited her barren eggs upon the woven wire of her cage. Lacking a female, nothing could be done until the following year.

I determined next time to take suitable precautions and to make all preparations for repeating at will the experiments already made and others which I had in mind. I set to work at once, without delay.

In the summer I began to buy caterpillars at a halfpenny apiece.

The market was in the hands of some neighbouring urchins, my habitual providers. On Friday, free of the terrors of grammar, they scoured the fields, finding from time to time the Great Peacock caterpillar, and bringing it to me clinging to the end of a stick. They did not dare to touch it, poor little imps! They were thunderstruck at my audacity when I seized it in my fingers as they would the familiar silkworm.

Reared upon twigs of the almond-tree, my menagerie soon provided me with magnificent cocoons. In winter assiduous search at the base of the native trees completed my collection. Friends interested in my researches came to my aid. Finally, after some trouble, what with an open market, commercial negotiations, and searching, at the cost of many scratches, in the undergrowth, I became the owner of an assortment of cocoons of which twelve, larger and heavier than the rest, announced that they were those of females.

Disappointment awaited me. May arrived; a capricious month which set my preparations at naught, troublesome as these had been. Winter returned. The mistral shrieked, tore the budding leaves of the plane-trees, and scattered them over the ground. It was cold as December. We had to light fires in the evening, and resume the heavy clothes we had begun to leave off.

My butterflies were too sorely tried. They emerged late and were torpid. Around my cages, in which the females waited—to-day one, to-morrow another, according to the order of their birth—few males or none came from without. Yet there were some in the neighbourhood, for those with large antennæ which issued from my collection of cocoons were placed in the garden directly they had emerged, and were recognised. Whether neighbours or strangers, very few came, and those without enthusiasm. For a moment they entered, then disappeared and did not reappear. The lovers were as cold as the season.

Perhaps, too, the low temperature was unfavourable to the informing effluvia, which might well be increased by heat and lessened by cold as is the case with many odours. My year was lost. Research is disappointing work when the experimenter is the slave of the return and the caprices of a brief season of the year.

For the third time I began again. I reared caterpillars; I scoured the country in search of cocoons. When May returned I was tolerably provided. The season was fine, responding to my hopes. I foresaw the affluence of butterflies which had so impressed me at the outset, when the famous invasion occurred which was the origin of my experiments.

Every night, by squadrons of twelve, twenty, or more, the visitors appeared. The female, a strapping, big-bellied matron, clung to the woven wire of the cover. There was no movement on her part; not even a flutter of the wings. One would have thought her indifferent to all that occurred. No odour was emitted that was perceptible to the most sensitive nostrils of the household; no sound that the keenest ears of the household could perceive. Motionless, recollected, she waited.

The males, by twos, by threes and more, fluttered upon the dome of the cover, scouring over it quickly in all directions, beating it continually with the ends of their wings. There were no conflicts between rivals. Each did his best to penetrate the enclosure, without betraying any sign of jealousy of the others. Tiring of their fruitless attempts, they would fly away and join the dance of the gyrating crowd. Some, in despair, would escape by the open window: new-comers would replace them: and until ten o'clock or thereabouts the wire dome of the cover would be the scene of continual attempts at approach, incessantly commencing, quickly wearying, quickly resumed.

Every night the position of the cage was changed. I placed it north of the house and south; on the ground-floor and the first floor; in the right wing of the house, or fifty yards away in the left wing; in the open air, or hidden in some distant room. All these sudden removals, devised to put the seekers off the scent, troubled them not at all. My time and my pains were wasted, so far as deceiving them was concerned.

The memory of places has no part in the finding of the female. For instance, the day before the cage was installed in a certain room. The males visited the room and fluttered about the cage for a couple of hours, and some even passed the night there. On the following day, at sunset, when I moved the cage, all were out of doors. Although their lives are so ephemeral, the youngest were ready to resume their nocturnal expeditions a second and even a third time. Where did they first go, these veterans of a day?

They knew precisely where the cage had been the night before. One would have expected them to return to it, guided by memory; and that not finding it they would go out to continue their search elsewhere. No; contrary to my expectation, nothing of the kind appeared. None came to the spot which had been so crowded the night before; none paid even a passing visit. The room was recognised as an empty room, with no previous examination, such as would apparently be necessary to contradict the memory of the place. A more positive guide than memory called them elsewhere.

Hitherto the female was always visible, behind the meshes of the wire-gauze cover. The visitors, seeing plainly in the dark night, must have been able to see her by the vague luminosity of what for us is the dark. What would happen if I imprisoned her in an opaque receptacle? Would not such a receptacle arrest or set free the informing effluvia according to its nature?

Practical physics has given us wireless telegraphy by means of the Hertzian vibrations of the ether. Had the Great Peacock butterfly outstripped and anticipated mankind in this direction? In order to disturb the whole surrounding neighbourhood, to warn pretenders at a distance of a mile or more, does the newly emerged female make use of electric or magnetic waves, known or unknown, that a screen of one material would arrest while another would allow them to pass? In a word, does she, after her fashion, employ a system of wireless telegraphy? I see nothing impossible in this; insects are responsible for many inventions equally marvellous.

Accordingly I lodged the female in boxes of various materials; boxes of tin-plate, wood, and cardboard. All were hermetically closed, even sealed with a greasy paste. I also used a glass bell resting upon a base-plate of glass.

Under these conditions not a male arrived; not one, though the warmth and quiet of the evening were propitious. Whatever its nature, whether of glass, metal, card, or wood, the closed receptacle was evidently an insuperable obstacle to the warning effluvia.

A layer of cotton-wool two fingers in thickness had the same result. I placed the female in a large glass jar, and laced a piece of thin cotton batting over the mouth for a cover; this again guarded the secret of my laboratory. Not a male appeared.

But when I placed the females in boxes which were imperfectly closed, or which had chinks in their sides, or even hid them in a drawer or a cupboard, I found the males arrived in numbers as great as when the object of their search lay in the cage of open wire-work freely exposed on a table. I have a vivid memory of one evening when the recluse was hidden in a hat-box at the bottom of a wall-cupboard. The arrivals went straight to the closed doors, and beat them with their wings, toc-toc, trying to enter. Wandering pilgrims, come from I know not where, across fields and meadows, they knew perfectly what was behind the doors of the cupboard.

So we must abandon the idea that the butterfly has any means of communication comparable to our wireless telegraphy, as any kind of screen, whether a good or a bad conductor, completely stops the signals of the female. To give them free passage and allow them to penetrate to a distance one condition is indispensable: the enclosure in which the captive is confined must not be hermetically sealed; there must be a communication between it and the outer air. This again points to the probability of an odour, although this is contradicted by my experiment with the naphthaline.

My cocoons were all hatched, and the problem was still obscure. Should I begin all over again in the fourth year? I did not do so, for the reason that it is difficult to observe a nocturnal butterfly if one wishes to follow it in all its intimate actions. The lover needs no light to attain his ends; but my imperfect human vision cannot penetrate the darkness. I should require a candle at least, and a candle would be constantly extinguished by the revolving swarm. A lantern would obviate these eclipses, but its doubtful light, interspersed with heavy shadows, by no means commends it to the scruples of an observer, who must see, and see well.

Moreover, the light of a lamp diverts the butterflies from their object, distracts them from their affairs, and seriously compromises the success of the observer. The moment they enter, they rush frantically at the flame, singe their down, and thereupon, terrified by the heat, are of no profit to the observer. If, instead of being roasted, they are held at a distance by an envelope of glass, they press as closely as they can to the flame, and remain motionless, hypnotised.