Chapter X. The Bee Eating Philanthus
Jean-Henri Fabre More Hunting Wasp
Bee-Wolf (Philanthus triangulum)
To meet among the Wasps, those eager lovers of flowers, a species that goes hunting more or less on its own account is certainly a notable event. That the larder of the grub should be provided with prey is natural enough; but that the provider, whose diet is honey, should herself make use of the captives is anything but easy to understand. We are quite astonished to see a nectar-drinker become a blood-drinker. But our astonishment ceases if we consider things more closely. The double method of feeding is more apparent than real: the crop which fills itself with sugary liquid does not gorge itself with game. The Odynerus, when digging into the body of her prey, does not touch the flesh, a fare absolutely scorned as contrary to her tastes; she satisfies herself with lapping up the defensive drop which the grub (1) distils at the end of its intestine. This fluid no doubt represents to her some highly-flavoured beverage with which she seasons from time to time the staple diet fetched from the drinking-bar of the flowers, some appetizing condiment or perhaps — who knows? — some substitute for honey. Though the qualities of the delicacy escape me, I at least perceive that the Odynerus does not covet anything else. Once its jar is emptied, the larva is flung aside as worthless offal, a certain sign of a non-carnivorous appetite. Under these conditions, the persecutor of the Chrysomela ceases to surprise us by indulging in the crying abuse of a double diet.
We even begin to wonder whether other species may not be inclined to derive a direct advantage from the hunting imposed upon them for the maintenance of the family. The Odynerus' method of work, the splitting open of the anal still-room, is too far removed from the obvious procedure to have many imitators; it is a secondary detail and impracticable with a different kind of game. But there is sure to be a certain variety in the direct means of utilizing the capture. Why, for instance, when the victim paralysed by the sting contains a delicious broth in some part of its stomach, should the huntress scruple to violate her dying prey and force it to disgorge without injuring the quality of the provisions? There must be those who rob the dead, attracted not by the flesh but by the exquisite contents of the crop.
In point of fact, there are; and they are even numerous. We may mention in the first rank the Wasp that hunts Hive-bees, the Bee-eating Philanthus (P. apivorus, LATR.). I long suspected her of perpetrating these acts of brigandage on her own behalf, having often surprised her gluttonously licking the Bee's honey-smeared mouth; I had an inkling that she did not always hunt solely for the benefit of her larvae. The suspicion deserved to be confirmed by experiment. Also, I was engaged in another investigation, which might easily be conducted simultaneously with the one suggested: I wanted to study, with all the leisure of work done at home, the operating-methods employed by the different Hunting Wasps. I therefore made use, for the Philanthus, of the process of experimenting under glass which I roughly outlined when speaking of the Odynerus. It was even the Bee-huntress who gave me my first data in this direction. She responded to my wishes with such zeal that I believed myself to possess an unequalled means of observing again and again, even to excess, what is so difficult to achieve on the actual spot. Alas, the first-fruits of my acquaintance with the Philanthus promised me more than the future held in store for me! But we will not anticipate; and we will place the huntress and her game together under the bell-glass. I recommend this experiment to whoever would wish to see with what perfection in the art of attack and defence a Hunting Wasp wields the stiletto. There is no uncertainty here as to the result, there is no long wait: the moment when she catches sight of the prey in an attitude favourable to her designs, the bandit rushes forward and kills. I will describe how things happen.
I place under the bell-glass a Philanthus and two or three Hive-bees. The prisoners climb the glass wall, towards the light; they go up, come down again and try to get out; the vertical polished surface is to them a practicable floor. They soon quiet down; and the spoiler begins to notice her surroundings. The antennae are pointed forwards, enquiringly; the hind-legs are drawn up with a little quiver of greed in the tarsi; the head turns to right and left and follows the evolutions of the Bees against the glass. The miscreant's posture now becomes a striking piece of acting: you can read in it the fierce longings of the creature lying in ambush, the crafty waiting for the moment to commit the crime. The choice is made: the Philanthus pounces on her prey.
Turn by turn tumbling over and tumbled, the two insects roll upon the ground. The tumult soon abates; and the murderess prepares to strangle her capture. I see her adopt two methods. In the first, which is more usual than the other, the Bee is lying on her back; and the Philanthus, belly to belly with her, grips her with her six legs while snapping at her neck with her mandibles. The abdomen is now curved forward from behind, along the prostrate victim, feels with its tip, gropes about a little and ends by reaching the under part of the neck. The sting enters, lingers for a moment in the wound; and all is over. Without releasing her prey, which is still tightly clasped, the murderess restores her abdomen to its normal position and keeps it pressed against the Bee's.
In the second method, the Philanthus operates standing. Resting on her hind-legs and on the tips of her unfurled wings, she proudly occupies an erect attitude, with the Bee held facing her between her four front legs. To give the poor thing a position suited to receive the dagger-stroke, she turns her round and back again with the rough clumsiness of a child handling its doll. Her pose is magnificent to look at. Solidly planted on her sustaining tripod, the two hinder tarsi and the tips of the wings, she at last crooks her abdomen upwards and again stings the Bee under the chin. The originality of the Philanthus' posture at the moment of the murder surpasses the anything that I have hitherto seen.
The desire for knowledge in natural history has its cruel side. To learn precisely the point attacked by the sting and to make myself thoroughly acquainted with the horrible talent of the murderess, I have investigated more assassinations under glass than I would dare to confess. Without a single exception, I have always seen the Bee stung in the throat. In the preparations for the final blow, the tip of the abdomen may well come to rest on this or that point of the thorax or abdomen; but it does not stop at any of these, nor is the sting unsheathed, as can readily be ascertained. Indeed, once the contest is opened, the Philanthus becomes so entirely absorbed in her operation that I can remove the cover and follow every vicissitude of the tragedy with my pocket-lens.
After recognizing the invariable position of the wound, I bend back and open the articulation of the head. I see under the Bee's chin a white spot, measuring hardly a twenty-fifth of an inch square, where the horny integuments are lacking and the delicate skin is shown uncovered. It is here, always here, in this tiny defect in the armour, that the sting enters. Why is this spot stabbed rather than another? Can it be the only vulnerable point, which would necessarily determine the thrust of the lancet? Should any one entertain so petty a thought, I advise him to open the articulation of the corselet, behind the first pair of legs. He will there see what I see: the bare skin, quite as fine as under the neck, but covering a much larger surface. The horny breast-plate offers no wider breach. If the Philanthus were guided in her operation solely by the question of vulnerability, it is here certainly that she ought to strike, instead of persistently seeking the narrow slit in the neck. The weapon would not need to hesitate and grope; it would obtain admission into the tissues off-hand. No, the stroke of the lancet is not forced upon it mechanically: the assassin scorns the large defect in the corselet and prefers the place under the chin, for eminently logical reasons which we will now attempt to unravel.
Immediately after the operation I take the Bee from the Philanthus. What strikes me is the sudden inertia of the antennae and the mouth-parts, organs which in the victims of most of the Hunting Wasps continue to move for so long a time. There are here not any of the signs of life to which I have been accustomed in my old studies of insect paralysis: the antennary threads waving slowly to and fro, the palpi quivering, the mandibles opening and closing for days, weeks and months on end. At most, the tarsi tremble for a minute or two; that constitutes the whole death-struggle. Complete immobility ensues. The inference drawn from this sudden inertia is inevitable: the Wasp has stabbed the cervical ganglia. Hence the immediate cessation of movement in all the organs of the head; hence the real instead of the apparent death of the Bee. The Philanthus is a butcher and not a paralyser.
This is one step gained. The murderess chooses the under part of the chin as the point attacked in order to strike the principal nerve-centres, the cephalic ganglia, and thus to do away with life at one blow. When this vital seat is poisoned by the toxin, death is instantaneous. Had the Philanthus' object been simply to effect paralysis, the suppression of locomotor movements, she would have driven her weapon into the flaw in the corselet, as the Cerceres do with the Weevils, who are much more powerfully armoured than the Bee. But her intention is to kill outright, as we shall see presently; she wants a corpse, not a paralytic patient. This being so, we must agree that her operating-method is supremely well-inspired: our human murderers could achieve nothing more thorough or immediate.
We must also agree that her attitude when attacking, an attitude very different from that of the paralysers, is infallible in its death-dealing efficacy. Whether she deliver her thrust lying on the ground or standing erect, she holds the Bee in front of her, breast to breast, head to head. In this posture all that she need do is to curve her abdomen in order to reach the gap in the neck and plunge the sting with an upward slant into her captive's head. Suppose the two insects to be gripping each other in the reverse attitude, imagine the dirk to slant slightly in the opposite direction; the results would be absolutely different and the sting, driven downwards, would pierce the first thoracic ganglion and produce merely partial paralysis. What skill, to sacrifice a wretched Bee! In what fencing-school was the slayer taught her terrible upward blow under the chin?
If she learnt it, how is it that her victim, such a past mistress in architecture, such an adept in socialistic polity, has so far learnt no corresponding trick to serve in her own defence? She is as powerful as her executioner; like the other, she carries a rapier, an even more formidable one and more painful, at least to my fingers. For centuries and centuries the Philanthus has been storing her away in her cellars; and the poor innocent meekly submits, without being taught by the annual extermination of her race how to deliver herself from the aggressor by a well-aimed thrust. I despair of ever understanding how the assailant has acquired her talent for inflicting sudden death, when the assailed, who is better-armed and quite as strong, wields her dagger anyhow and therefore ineffectively. If the one has learnt by prolonged practice in attack, the other should also have learnt by prolonged practice in defence, for attack and defence possess a like merit in the fight for life. Among the theorists of the day, is there one clear-sighted enough to solve the riddle for us?
If so, I will take the opportunity of putting to him a second problem that puzzles me: the carelessness, nay, more, the stupidity of the Bee in the presence of the Philanthus. You would be inclined to think that the victim of persecution, learning gradually from the misfortunes suffered by her family, would show distress at the ravisher's approach and at least attempt to escape. In my cages I see nothing of the sort. Once the first excitement due to incarceration under the bell-glass or the wire-gauze cover has passed, the Bee seems hardly to trouble about her formidable neighbour. I see one side by side with the Philanthus on the same honeyed thistle-head: assassin and future victim are drinking from the same flask. I see some one who comes heedlessly to enquire who that stranger can be, crouching in wait on the table. When the spoiler makes her rush, it is usually at a Bee who meets her half-way, and, so to speak, flings herself into her clutches, either thoughtlessly or out of curiosity. There is no wild terror, no sign of anxiety, no tendency to make off. How comes it that the experience of the ages, that experience which, we are told, teaches the animal so many things, has not taught the Bee the first element of apiarian wisdom: a deep-seated horror of the Philanthus? Can the poor wretch take comfort by relying on her trusty dagger? But she yields to none in her ignorance of fencing; she stabs without method, at random. However, let us watch her at the supreme moment of the killing.
When the ravisher makes play with her sting, the Bee does the same with hers and furiously. I see the needle now moving this way or that way in space, now slipping, violently curved, along the murderess' convex surface. These sword-thrusts have no serious results. The manner in which the two combatants are at grips has this effect, that the Philanthus' abdomen is inside and the Bee's outside. The latter's sting therefore finds under its point only the dorsal surface of the foe, a convex, slippery surface and so well armoured as to be almost invulnerable. There is here no breach into which the weapon can slip by accident; and so the operation is conducted with absolute surgical safety, notwithstanding the indignant protests of the patient.
After the fatal stroke has been administered, the murderess remains for a long time belly to belly with the dead, for reasons which we shall shortly perceive. There may now be some danger for the Philanthus. The attitude of attack and defence is abandoned; and the ventral surface, more vulnerable than the other, is within reach of the sting. Now the deceased still retains the reflex use of her weapon for a few minutes, as I learnt to my cost. Having taken the Bee too early from the bandit and handling her without suspecting any risk, I received a most downright sting. Then how does the Philanthus, in her long contact with the butchered Bee, manage to protect herself against that lancet, which is bent upon avenging the murder? Is there any chance of a commutation of the death-penalty? Can an accident ever happen in the Bee's favour? Perhaps.
One incident strengthens my faith in this perhaps. I had placed four Bees and as many Eristales under the bell-glass at the same time, with the object of estimating the Philanthus' entomological knowledge in the matter of the distinction of species. Reciprocal quarrels break out in the mixed colony. Suddenly, in the midst of the fray, the killer is killed. She tumbles over on her back, she waves her legs; she is dead. Who struck the blow? It was certainly not the excitable but pacific Drone-fly; it was one of the Bees, who struck home by accident during the thick of the fight. Where and how? I cannot tell. The incident occurs only once in my notes, but it throws a light upon the question. The Bee is capable of withstanding her adversary; she can then and there slay her would-be slayer with a thrust of the sting. That she does not defend herself to better purpose, when she falls into her enemy's clutches, is due to her ignorance of fencing and not to the weakness of her weapon. And here again arises, more insistently than before, the question which I asked above: how is it that the Philanthus has learnt for offensive what the Bee has not learnt for defensive purposes? I see but one answer to the difficulty: the one knows without having learnt; the other does not know because she is incapable of learning.
Let us now consider the motives that induce the Philanthus to kill her Bee instead of paralysing her. When the crime has been perpetrated, she manipulates her dead victim without letting go of it for a moment, holding its belly pressed against her own six legs. I see her recklessly, very recklessly, rooting with her mandibles in the articulation of the neck, sometimes also in the larger articulation of the corselet, behind the first pair of legs, an articulation of whose delicate membrane she is perfectly well aware, even though, when using her sting, she did not take advantage of this point, which is the most readily accessible of all. I see her rough-handling the Bee's belly, squeezing it against her own abdomen, crushing it in the press. The recklessness of the treatment is striking; it shows that there is no need for keeping up precautions. The Bee is a corpse; and a little hustling here and there will not deteriorate its quality, provided there be no effusion of blood. In point of fact, however rough the handling, I fail to discover the slightest wound.
These various manipulations, especially the squeezing of the neck, at once bring about the desired results: the honey in the crop mounts to the Bee's throat. I see the tiny drops spurt out, lapped up by the glutton as soon as they appear. The bandit greedily, over and over again, takes the dead insect's lolling, sugared tongue into her mouth; then she once more digs into the neck and thorax, subjecting the honey-bag to the renewed pressure of her abdomen. The syrup comes and is instantly lapped up and lapped up again. In this way the contents of the crop are exhausted in small mouthfuls, yielded one at a time. This odious meal at the expense of a corpse's stomach is taken in a sybaritic attitude; the Philanthus lies on her side with the Bee between her legs. The atrocious banquet sometimes lasts for half an hour or longer. At last the drained Bee is discarded, not without regret, it seems, for from time to time I see the manipulation renewed. After taking a turn round the top of the bell-jar, the robber of the dead returns to her prey and squeezes it, licking its mouth until the last trace of honey has disappeared.
This frenzied passion of the Philanthus for the Bee's syrup is declared in yet another fashion. When the first victim has been sucked dry, I slip under the glass a second victim, which is promptly stabbed under the chin and then subjected to pressure to extract the honey. A third follows and undergoes the same fate without satisfying the bandit. I offer a fourth and a fifth. They are all accepted. My notes mention one Philanthus who in front of my eyes sacrificed six Bees in succession and squeezed out their crops in the regulation manner. The slaughter came to an end not because the glutton was sated but because my functions as a purveyor were becoming rather difficult: the dry month of August causes the insects to avoid my harmas, which at this season is denuded of flowers. Six crops emptied of their honey: what an orgy! And even then the ravenous creature would very likely not have scorned a copious additional course, had I possessed the means of supplying it!
There is no reason to regret this break in the service; the little that I have said is more than enough to prove the singular characteristics of the Bee-slayer. I am far from denying that the Philanthus has an honest means of earning her livelihood; I find her working on the flowers as assiduously as the other Wasps, peacefully drawing her honeyed beakers. The males even, possessing no lancet, know no other manner of refreshment. The mothers, without neglecting the table d'hote of the flowers, support themselves by brigandage as well. We are told of the Skua, that pirate of the seas, that he swoops down upon the fishing birds, at the moment when they rise from the water with a capture. With a blow of the beak delivered in the pit of the stomach he makes them give up their prey, which is caught by the robber in mid-air. The despoiled bird at least gets off with nothing worse than a contusion at the base of the throat. The Philanthus, a less scrupulous pirate, pounces on the Bee, stabs her to death and makes her disgorge in order to feed upon her honey.
I say feed and I do not withdraw the word. To support my statement I have better reasons than those set forth above. In the cages in which various Hunting Wasps, whose stratagems of war I am engaged in studying, are waiting till I have procured the desired prey — not always an easy thing — I have planted a few flower-spikes, a thistle-head or two, on which are placed drops of honey renewed at need. Here my captives come to take their meals. With the Philanthus, the provision of honeyed flowers, though favourably received, is not indispensable. I have only to let a few live Bees into her cage from time to time. Half a dozen a day is about the proper allowance. With no other food than the syrup extracted from the slain, I keep my insects going for a fortnight or three weeks.
It is as plain as a pikestaff: outside my cages, when the opportunity offers, the Philanthus must also kill the Bee on her own account. The Odynerus asks nothing from the Chrysomela but a mere condiment, the aromatic juice of the rump; the other extracts from her victim an ample supplement to her victuals, the crop full of honey. What a hecatomb of Bees must not a colony of these freebooters make for their personal consumption, not to mention the stored provisions! I recommend the Philanthus to the signal vengeance of our Bee-masters.
Let us go no deeper into the first causes of the crime. Let us accept things as we know them for the moment, with their apparent or real atrocity. To feed herself, the Philanthus levies tribute on the Bee's crop. Having made sure of this, let us consider the bandit's method more closely. She does not paralyse her capture according to the rites customary among the Hunting Wasps; she kills it. Why kill it? If the eyes of our understanding be not closed, the need for sudden death is clear as daylight. The Philanthus proposes to obtain the honeyed broth without ripping up the Bee, a proceeding which would damage the game when it is hunted on behalf of the larvae, without resorting to the murderous extirpation of the crop. She must, by able handling, by skilful pressure, make the Bee disgorge, she must milk her, in a manner of speaking. Suppose the Bee stung behind the corselet and paralysed. That deprives her of her power of locomotion, but not of her vitality. The digestive organs in particular retain or very nearly retain their normal energy, as is proved by the frequent excretions that take place in the paralysed prey, so long as the intestine is not empty, as is proved above all by the victims of the Languedocian Sphex (2), those helpless creatures which I used to keep alive for forty days on end with a soup consisting of sugar and water. It is absurd to hope, without therapeutic means, without a special emetic, to coax a sound stomach into emptying its contents. The stomach of the Bee, who is jealous of her treasure, would lend itself to the process even less readily than another. When paralysed, the insect is inert; but there are always internal energies and organic forces which will not yield to the manipulator's pressure. The Philanthus will nibble at the throat and squeeze the sides in vain: the honey will not rise to the mouth so long as a vestige of life keeps the crop closed.
Things are different with a corpse. The tension is relaxed, the muscles become slack, the resistance of the stomach ceases and the bag of honey is emptied by the robber's vigorous pressure. You see, therefore, that the Philanthus is expressly obliged to inflict a sudden death, which will do away at once with the elasticity of the organs. Where is the lightning stroke to be delivered? The slayer knows better than we do, when she sticks the Bee under the chin. The cerebral ganglia are reached through the little hole in the neck and death ensues immediately.
The relation of these acts of brigandage cannot satisfy my distressing habit of following each reply obtained with a fresh question, until the granite wall of the unknowable rises before me. If the Philanthus is an expert in killing Bees and emptying crops swollen with honey, this cannot be merely an alimentary resource, especially when, in common with the others, she has the banqueting-hall of the flowers. I cannot accept her atrocious talent as inspired merely by the craving for a feast obtained at the expense of an empty stomach. Something certainly escapes us: the why and wherefore of that crop drained dry. A creditable motive may lie hidden behind the horrors which I have related. What is it?
Any one can understand the vagueness of the observer's mind when he first asks himself this question. The reader is entitled to be treated with consideration. I will spare him the recital of my suspicions, my gropings and my failures and will come straight to the results of my long investigation. Everything has its harmonious reason for existence. I am too fully persuaded of this to believe that the Philanthus pursues her habit of profaning corpses solely to satisfy her greed. What does the emptied crop portend? May it not be that..? Why, yes…After all, who knows?…Let us try along these lines.
The mother's first care is the welfare of the family. So far, we have seen the Philanthus hunting only for her stomach's sake; let us watch her hunting as a mother. Nothing is easier than to distinguish the two performances. When the Wasp wants a few good mouthfuls and nothing more, she scornfully abandons the Bee after picking her crop. The Bee is to her a worthless remnant, which will shrivel where it lies and be dissected by the Ants. If, on the other hand, she wants to stow away the Bee as a provision for her larvae, she clasps her in her two intermediate legs and, walking on the other four, goes round and round the edge of the bell-glass, seeking for an outlet through which to fly off with her prey. When she recognizes the circular track as impossible, she climbs up the sides, this time holding the Bee by the antennae with her mandibles and clinging to the polished and perpendicular surface with her six feet. She reaches the top of the glass, stays for a little while in the hollow of the knob at the top, returns to the ground, resumes her circling and her climbing and does not decide to relinquish her Bee until she has stubbornly attempted every means of escape. This persistence on her part to retain her hold on the cumbrous burden tells us pretty plainly that the game would go straight to the cells if the Philanthus had her liberty.
Well, these Bees intended for the larvae are stung under the chin like the others; they are real corpses; they are manipulated, squeezed, drained of their honey exactly as the others are. In all these respects, there is no difference between the hunt conducted to provide food for the larvae and the hunt conducted merely to gratify the mother's appetite.
As the worries of captivity might well be the cause of a few anomalies in the insect's actions, I felt that I ought to enquire how things happen in the open. I lay in wait near some colonies of Philanthi, for longer perhaps than the question deserved, as it had already been settled by what had happened under glass. My tedious watches were rewarded from time to time. Most of the huntresses returned home immediately, with the Bee under their abdomen; some halted on the brambles hard by; and here I saw them squeezing the dead Bee and making her disgorge the honey, which was greedily lapped up. After these preliminaries the corpse was stored. Every doubt is therefore removed: the provisions of the larva are first carefully drained of their honey.
Since we are on the spot, let us prolong our stay and enquire into the customs of the Philanthus in a state of liberty. Serving dead prey, which goes bad in a few days, the Bee-huntress cannot adopt the method of certain insects which paralyse a number of separate heads of game and fill the cell with provisions, completing the ration before laying the egg. She needs the method of the Bembex, whose larva receives the necessary nourishment at intervals, as it grows larger. The facts confirm this deduction. Just now I described as tedious my watches near the colonies of the Philanthi. They were tedious in fact, even more so perhaps than those which the Bembeces used to inflict upon me in the old days. Outside the burrows of the Great Cerceris and other Weevil-lovers, outside those of the Yellow-winged Sphex, the Cricket-slayer, there is plenty of distraction, thanks to the bustling movement of the hamlet. The mother has hardly come back home before she goes out again, soon returning laden with a new prey and once more setting out upon the chase. The going and coming is repeated at close intervals until the warehouse is full.
The burrow of the Philanthus is far from showing any such animation, even in a populous colony. In vain were my watches prolonged for whole mornings or afternoons; it was but very rarely that the mother whom I had seen go in with a Bee came out again for a second expedition. Two captures at most by the same huntress was all that I was able to see during my long vigils. Feeding from day to day involves this deliberation. Once the family is supplied with a sufficient ration for the moment, the mother suspends her hunting-trips until further need arises and occupies herself with mining-work in her underground house. Cells are dug; I see the rubbish gradually pushed up to the surface. Beyond this there is not a sign of activity; it is as though the burrow were deserted.
The inspection of the site is no easy matter. The shaft descends to a depth of nearly three feet in a compact soil, either vertically or horizontally. The spade and pick, wielded by stronger but less expert hands than mine, are indispensable, for which reason the process of excavation is far from satisfying me fully. At the end of this long tunnel, which the straw which I use for sounding despairs of ever reaching, the cells are at last encountered, oval cavities with a horizontal major axis. Their number and general arrangement escape me.
Some of them already contain the cocoon, which is slender and semitransparent, like those of the Cerceris, and, like them, suggests the shape of certain homoeopathic phials, with oval bellies surmounted by a tapering neck. The cocoon is fastened to the end of the cell by the tip of this neck, which is darkened and hardened by the larva's excrement; it has no other support. It looks like a short club fixed by the end of the handle along the horizontal axis of the nest. Other cells contain the larva in a more or less advanced stage. The grub is munching the last morsel served to it, with the scraps of the victuals already consumed lying around it. Others lastly show me a Bee, one only, still untouched and bearing an egg laid on her breast. This is the first partial ration; the others will come as and when the grub grows larger. My anticipations are thus confirmed: following the example of the Bembeces, the Fly-killers, the Philanthus, the Bee-killer, lays her egg on the first piece warehoused and at intervals adds to her nurselings' repast.
The problem of the dead game is solved. There remains this other problem, one of incomparable interest: why are the Bees robbed of their honey before being served to the larvae? I have said and I say again that the killing and squeezing cannot be explained and excused simply by reference to the Philanthus' love of gormandizing. Robbing the worker of her booty is nothing out of the way: we see it daily; but cutting her throat in order to empty her stomach is going beyond a joke. And, as the Bees packed away in the cellar are squeezed dry just as much as the others, the thought occurs to my mind that a rumpsteak with jam is not to everybody's liking and that the game stuffed with honey might well be a distasteful or even unwholesome dish for the Philanthus' larvae. What will the grub do when, sated with blood and meat, it finds the Bee's honey-bag under its mandibles and especially when, nibbling at random, it rips open the crop and spoils its venison with syrup? Will it thrive on the mixture? Will the little ogre pass without repugnance from the gamy flavour of a carcase to the scent of flowers? A blunt statement or denial would serve no purpose. We must see. Let us see.
I rear some young Philanthus-grubs, already waxing large; but, instead of supplying them with the prey taken from the burrows, I give them game of my own catching, game replete with nectar from the rosemaries. My Bees, whom I kill by crushing their heads, are readily accepted; and I at first see nothing that corresponds with my suspicions. Then my nurselings languish, disdain their food, give a careless bite here and there and end by perishing, from the first to the last, beside their unfinished victuals. All my attempts miscarry: I do not once succeed in rearing my larvae to the stage of spinning the cocoon. And yet I am no novice in the functions of a foster-father. How many pupils have not passed through my hands and reached maturity in my old sardine-boxes as comfortably as in their natural burrows!
I will not draw rash conclusions from this check; I am conscientious enough to ascribe it to another cause. It may be that the atmosphere of my study and the dryness of the sand serving as a bed have had a bad effect on my charges, whose tender skins are accustomed to the warm moisture of the subsoil. Let us therefore try another expedient.
It is hardly feasible to decide positively by the methods which I have been following whether the honey is or is not repugnant to the grubs of the Philanthus. The first mouthfuls consist of meat; and then nothing particular occurs: it is the natural diet. The honey is met with later, when the morsel has been largely bitten into. If hesitation and lack of appetite are displayed at this stage, they come too late in the day to be conclusive: the larva's discomfort may be due to other, known or unknown, causes. The thing to do would be to offer the grub honey from the first, before artificial rearing has affected its appetite. It is useless, of course, to make the attempt with pure honey: no carnivorous creature would touch it, though it were starving. The jam-sandwich is the only device favourable to my plans, a meagre jam-sandwich, that is to say, the dead Bee lightly smeared or varnished with honey by means of a camel's-hair pencil.
Under these conditions, the problem is solved with the first few mouthfuls. The grub that has bitten into the honeyed prey draws back in disgust, hesitates a long time and then, urged by hunger, begins again, tries this side and that and ends by refusing to touch the dish. For a few days it pines away on top of its almost intact provisions; then it dies. All that are subjected to this regimen succumb. Do they merely perish of inanition in the presence of an unaccustomed food, which revolts their appetite, or are they poisoned by the small quantity of honey absorbed with the early mouthfuls? I cannot tell. The fact remains that, whether poisonous or repugnant, the Bee in the state of bread and jam is death to them; and this result explains, more clearly than the unfavourable circumstance of my former experiment, my failures with the Bee that had not been made to disgorge.
This refusal to touch the unwholesome or distasteful honey is connected with principles of nutrition which are too general to constitute a gastronomic peculiarity of the Philanthus. The other carnivorous larvae, at least in the order of the Hymenoptera, are bound to share it. Let us try. We will go to work as before. I unearth the larvae when they have attained a medium size, to avoid the weakness of infancy; I take away the natural provisions, smear the carcases separately with honey and, when this is done, restore its victuals to each of the grubs. I had to make a choice: not every subject was equally suited to my experiments. I must reject the larvae which are fed on one fat joint, such as those of the Scolia. The grub in fact attacks its prey at a determined point, dips its head and neck into the insect's body, rooting skilfully in the entrails to keep the game fresh until the end of the meal, and does not withdraw from the breach until the whole skin is emptied of its contents.
To make it let go with the object of coating the inside of the venison with honey had two drawbacks: I should be compromising the lingering vitality which saves the insect that is being devoured from going bad and, at the same time, I should be disturbing the delicate art of the devouring insect, which, if removed from the lode which it was working, would no longer be able to recover it or to distinguish between the lawful and the unlawful morsels. The larva of the Scolia, consuming its Cetonia-grub, has taught us all that we want to know on this subject in my earlier volume (3). The only acceptable larvae are those supplied with a heap of small insects, which are attacked without any special art, dismembered at random and eaten up quickly. Among these I have tested such as chance threw in my way: those of various Bembeces, all fed on Flies, those of the Palarus, whose bill of fare consists of a very large assortment of Hymenoptera; those of the Tarsal Tachytes, supplied with young Locusts; those of the Nest-building Odynerus, furnished with Chrysomela-grubs; those of the Sand Cerceris, endowed with a pinch of Weevils. A goodly variety, as you see, of consumers and consumed. Well, to all of these the seasoning with honey proved fatal. Whether poisoned or disgusted, they all died in a few days.
A strange result indeed! Honey, the nectar of the flowers, the sole diet of the Bee-tribe in both its forms and the sole resource of the Wasp in her a adult form, is to the larvae of the latter an object of insurmountable repugnance and probably a toxic dish. Even the transformation of the nymphosis surprises me less than this inversion of the appetite. What happens in the insect's stomach to make the adult seek passionately what the youngster refused lest it should die? This is not a question of organic debility unable to endure a too substantial, too hard, too highly spiced dish. The grub that gnaws the Cetonia-larva, that generous piece of butcher's meat; the glutton that crunches its batch of tough Locusts; the one that battens on nitrobenzine-flavoured game: they certainly own unfastidious gullets and accommodating stomachs. And these robust eaters allow themselves to die of hunger or digestive troubles because of a drop of syrup, the lightest food imaginable, suited to the weakness of extreme youth and a feast for the adult besides! What a gulf of obscurity in the stomach of a wretched grub!
These gastronomical researches called for a counterexperiment. The carnivorous larva is killed by honey. Conversely, is the mellivorous larva killed by animal food? Reservations are needful here, as in the previous tests. We should be courting a flat refusal if we offered a pinch of Locusts to the larvae of the Anthophora or the Osmia, for instance For both these Wild Bees cf. „Bramble-bees and Others“: passim. (4). The honey-fed insect would not bite into it. There would be no use whatever in trying. We must find the equivalent of the jam-sandwich aforesaid; in other words, we must give the larva its natural fare with a mixture of animal food. The addition made by my artifices shall be albumen, as found in the egg of the Hen, albumen the isomer of fibrin, which is the essential factor in any form of prey.
On the other hand, the Three-horned Osmia lends herself most admirably to my plans, because of her dry honey, consisting for the greater part of floury pollen. I therefore knead this honey with albumen, graduating the dose until its weight largely exceeds that of the flour. In this way I obtain pastes of different degrees of consistency, but all firm enough to bear the larva without danger of immersion. With too fluid a mixture there would be a risk of death by drowning. Lastly I install a moderately-developed larva on each of my albuminous cakes.
The dish of my inventing does not incite dislike: far from it. The grubs attack it without hesitation and consume it with every appearance of the usual appetite. Things could not go better if the food had not been altered by my culinary recipes. Everything goes down, including the morsels in which I feared that I had overdone the addition of albumen. And — an even more important point — the Osmia-larvae fed in this manner attain their normal dimensions and spin their cocoons, from which adult insects issue in the following year. Notwithstanding the albuminous regimen, the cycle of the evolution is achieved without impediment.
What are we to conclude from all this? I feel greatly embarrassed. Omne vivum ex ovo, the physiologists tell us. Every animal is carnivorous, in its first beginnings: it is formed and nourished at the cost of its egg, in which albumen predominates. The highest, the mammal, adheres to this diet for a long time: it has its mother's milk, rich in casein, another isomer of albumen. The gramnivorous nestling is first fed on grubs, which are better adapted to the niceties of its stomach; many of the minutest new-born creatures, being at once left to their own devices, take to animal food. In this way the original method of nourishment is continued for all alike: the method which allows flesh to be made from flesh and blood from blood, with no chemical process beyond the simplest modification. At maturity, when the stomach has acquired its full strength, vegetable food is adopted, involving a more complicated chemistry but easier to obtain. Milk is followed by fodder, worms by seeds, the prey in the burrow by the nectar of the flowers.
This supplies a partial explanation of the twofold diet of the Hymenoptera with carnivorous larvae: meat first, honey next. But then the note of interrogation is shifted. It stood elsewhere; it now stands here. Why is the Osmia, who as a larva fares so well on albumen, fed on honey at the start? Why do the Bee-tribe receive a vegetable diet when the other members of the order receive an animal diet?
If I were a believer in evolution, I should say yes, by the fact of its germ, every animal is originally carnivorous. The insect in particular starts with albuminoid materials. Many larvae adhere to the egg-food, many adult insects do likewise. But the struggle to fill the belly, which after all is the struggle for life, demands something better than the precarious hazards of the chase. Man, at first a ravenous hunter after game, brought the flock into existence and turned shepherd to avoid a time of dearth. An even greater progress inspired him to scrape the earth and to sow seed, which assures him of a living. The evolution from scarcity to moderation and from moderation to plenty has led to the resources of husbandry.
The animals forestalled us this path of progress. The ancestors of the Philanthus, in the remote ages of the lacustrian tertiary formations, lived by prey in both the larval and the adult forms: they hunted for themselves as well as for the family. They did not confine themselves to emptying the Bee's crop, as their descendants do to this day: they devoured the deceased. From the beginning to the end they remained flesh-eaters. Later, fortunate innovators, whose race supplanted the laggards, discovered an inexhaustible nourishment, obtained without dangerous conflicts or laborious search: the sugary secretions of the flowers. The costly habit of living on prey, which does not favour large populations, was maintained for the feeble larvae; but the vigorous adult broke herself of it to lead an easier and more prosperous life. Thus, gradually, was formed the Philanthus of our day; thus was acquired the twofold diet of the various predatory insects our contemporaries.
The Bee has done better still: from the moment of leaving the egg she delivered herself completely from food-stuffs the acquisition of which depended on chance. She discovered honey, the grubs' food. Renouncing the chase for ever and becoming an agriculturalist pure and simple, the insect attains a degree of physical and moral prosperity which the predatory species are far from sharing. Hence the flourishing colonies of the Anthophorae, the Osmiae, the Eucerae (5), the Halicti and other honey-manufacturers, whereas the predatory insects work in isolation; hence the societies in which the Bee displays her wonderful tendencies, the supreme expression of instinct.
This is what I should say if I belonged to that school. It all forms a chain of very logical deductions and proffers itself with a certain air of likelihood which we should be glad to find in a host of evolutionist arguments put forward as irrefutable. Well, I will make a present of my deductive views, without regret, to whoever cares to have them: I don't believe one word of them; and I confess my profound ignorance of the origin of the twofold diet.
What I do understand more clearly, after all these investigations, is the tactics of the Philanthus. When witnessing her ferocious feasting, the real reason of which was unknown to me, I heaped the most ill-sounding epithets upon her, calling her a murderess, a bandit, a pirate, a robber of the dead. Ignorance is always evil-tongued; the man who does not know indulges in rude assertions and mischievous interpretations. Now that my eyes have been opened to the facts, I hasten to apologize and to restore the Philanthus to her place in my esteem. In draining the crops of her Bees the mother is performing the most praiseworthy of all actions: she is protecting her family against poison. If she happens to kill on her own account and to abandon the corpse after making it disgorge, I dare not reckon this against her as a crime. When the habit has been formed of emptying the Bee's crop with a good motive, there is a great temptation to do it again with no other excuse than hunger. Besides, who knows? Perhaps there is always at the back of her hunting some thought of game which might be useful for the larvae. Although not carried into effect, the intention excuses the deed.
I therefore withdraw my epithets in order to admire the insect's maternal logic and to hold it up to the admiration of others. The honey would be pernicious to the health of the larvae. How does the mother know that the syrup, a treat for her, is unwholesome for her young? To this question our science offers no reply. The honey, I say, would imperil the grubs' lives, The Bee must therefore first be made to disgorge. The disgorging must be effected without lacerating the victim, which the nurseling must receive in the fresh state; and the operation is impracticable on a paralysed insect because of the resistance of the stomach. The Bee must therefore be killed outright instead of being paralysed, or the honey will not be voided. Instantaneous death can be inflicted only by wounding the primordial centre of life. The sting must therefore aim at the cervical ganglia, the seat of innervation on which the rest of the organism depends. To reach them there is only one way, through the little gap in the throat. It is here therefore that the sting must be inserted; and it is here in fact that it is inserted, in a spot hardly as large as the twenty-fifth of an inch square. Suppress a single link of this compact chain, and the Bee-fed Philanthus becomes impossible.
That honey is fatal to carnivorous larvae is a fact which teems with consequences. Several Hunting Wasps feed their families upon Bees. These include, to my knowledge, the Crowned Philanthus (P. coronatus, FAB.), who lines her burrows with big Halicti; the Robber Philanthus (P. raptor, LEP.), who chases all the smaller-sized Halicti, suited to her own dimensions, indifferently; the Ornate Cerceris (C. ornata, FAB.), another passionate lover of Halicti; and the Palarus (P. flavipes, FAB.), who, with a curious eclecticism, stacks in her cells the greater part of the Hymenopteron clan that does not exceed her powers. What do these four huntresses and the others of similar habits do with their victims whose crops are more or less swollen with honey? They must follow the example of the Bee-eating Philanthus and make them disgorge, lest their family perish of a honeyed diet; they must manipulate the dead Bee, squeeze her and drain her dry. Everything goes to show it. I leave it to the future to display these dazzling proofs of my doctrine in their proper light.
1. The Larva of Chrysomela populi, the Poplar Leaf-beetle.
2. Cf. „The Hunting Wasp“: chapters 8 to 10.
3. Chapters 2 to 5 of the present volume contain the whole of the matter referred to above.
4. For both these Wild Bees cf. „Bramble-bees and Others“: passim.
5. A genus of long-horned Burrowing Bees.