More Hunting Wasps Part 8

The Mantis-hunting Tachytes consumes its heap of Mantes, the h.o.r.n.y envelope included, without leaving any remains but scanty crumbs, quite insufficient to establish the number of items provided. After the meal is completed, any inventory of the rations becomes impossible. I therefore have recourse to the cells which still contain the egg or the very young larva and, above all, to those whose provisions have been invaded by a tiny parasitic Gnat, a Tachina (Cf. "The Hunting Wasps": chapters 4 and 16.--Translator's Note.), which drains the game without cutting it up and leaves the whole skin intact. Twenty-five larders, put to the count, give me the following result:

8 cells each containing 3 items 5 cells each containing 4 items 4 cells each containing 6 items 3 cells each containing 7 items 2 cells each containing 8 items 1 cell containing 9 items 1 cell containing 12 items 1 cell containing 16 items --- 25

The predominant game is the Praying Mantis, green; next comes the Grey Mantis, ash-coloured. A few Empusae make up the total. The specimens vary in dimensions within fairly elastic limits: I measure some which are a third to a half inch long, averaging two-thirds to one inch long, and some which are two-fifths, averaging three quarters. I see pretty plainly that their number increases in proportion as their size diminishes, as though the Tachytes were seeking to make up for the smallness of the game by increasing the amount; none the less I find it quite impossible to detect the least equivalence by combining the two factors of number and size. If the huntress really estimates the provisions, she does so very roughly; her household accounts are not at all well kept; each head of game, large or small, must always count as one in her eyes.

Put on my guard, I look to see whether the honey-gathering Bees have a double service, like the game-hunting Wasps'. I estimate the amount of honeyed paste; I gauge the cups intended to contain it. In many cases the result resembles the first obtained: the abundance of provisions varies from one cell to another. Certain Osmiae (O. cornuta and O.

tricornis (Cf. "Bramble-bees and Others": pa.s.sim; and, in particular, chapters 3 to 5.--Translator's Note.)) feed their larvae on a heap of pollen-dust moistened in the middle with a very little disgorged honey.

One of these heaps may be three or four times the size of some other in the same group of cells. If I detach from its pebble the nest of the Mason-bee, the Chalicodoma of the Walls, I see cells of large capacity, sumptuously provisioned; close beside these I see others, of less capacity, with victuals parsimoniously allotted. The fact is general; and it is right that we should ask ourselves the reason for these marked differences in the relative quant.i.ty of foodstuffs and for these unequal rations.

I at last began to suspect that this is first and foremost a question of s.e.x. In many Bees and Wasps, indeed, the male and the female differ not only in certain details of internal or external structure--a point of view which does not affect the present problem--but also in length and bulk, which depend in a high degree on the quant.i.ty of food.

Let us consider in particular the Bee-eating Philanthus. Compared with the female, the male is a mere abortion. I find that he is only a third to half the size of the other s.e.x, as far as I can judge by sight alone.

To obtain exactly the respective quant.i.ties of substance, I should need delicate balances, capable of weighing down to a milligramme. My clumsy villager's scales, on which potatoes may be weighed to within a kilogramme or so, do not permit of this precision. I must therefore rely on the evidence of my sight alone, evidence, for that matter, which is amply sufficient in the present instance. Compared with his mate, the Mantis-hunting Tachytes is likewise a pigmy. We are quite astonished to see him pestering his giantess on the threshold of the burrows.

We observe differences no less p.r.o.nounced of size--and consequently of volume, ma.s.s and weight--in the two s.e.xes of many Osmiae. The differences are less emphatic, but are still on the same side, in the Cerceres, the Stizi, the Spheges, the Chalicodomae and many more. It is therefore the rule that the male is smaller than the female. There are of course some exceptions, though not many; and I am far from denying them. I will mention certain Anthidia where the male is the larger of the two. Nevertheless, in the great majority of cases the female has the advantage.

And this is as it should be. It is the mother, the mother alone, who laboriously digs underground galleries and chambers, kneads the plaster for coating the cells, builds the dwelling-house of cement and bits of grit, bores the wood and divides the burrow into storeys, cuts the disks of leaf which will be joined together to form honey-pots, works up the resin gathered in drops from the wounds in the pine-trees to build ceilings in the empty spiral of a Snail-sh.e.l.l, hunts the prey, paralyses it and drags it indoors, gathers the pollen-dust, prepares the honey in her crop, stores and mixes the paste. This severe labour, so imperious and so active, in which the insect's whole life is spent, manifestly demands a bodily strength which would be quite useless to the male, the amorous trifler. Thus, as a general rule, in the insects which carry on an industry the female is the stronger s.e.x.

Does this pre-eminence imply more abundant provisions during the larval stage, when the insect is acquiring the physical growth which it will not exceed in its future development? Simple reflection supplies the answer: yes, the aggregate growth has its equivalent in the aggregate provisions. Though so slight a creature as the male Philanthus finds a ration of two Bees sufficient for his needs, the female, twice or thrice as bulky, will consume three to six at least. If the male Tachytes requires three Mantes, his consort's meal will demand a batch of something like ten. With her comparative corpulence, the female Osmia will need a heap of paste twice or thrice as great as that of her brother, the male. All this is obvious; the animal cannot make much out of little.

Despite this evidence, I was anxious to enquire whether the reality corresponded with the previsions of the most elementary logic. Instances are not unknown in which the most sagacious deductions have been found to disagree with the facts. During the last few years, therefore, I have profited by my winter leisure to collect, from spots noted as favourable during the working-season, a few handfuls of coc.o.o.ns of various Digger-wasps, notably of the Bee-eating Philanthus, who has just furnished us with an inventory of provisions. Surrounding these coc.o.o.ns and thrust against the wall of the cell were the remnants of the victuals--wings, corselets, heads, wing-cases--a count of which enabled me to determine how many head of game had been provided for the larva, now enclosed in its silken abode. I thus obtained the correct list of provisions for each of the huntress' coc.o.o.ns. On the other hand, I estimated the quant.i.ties of honey, or rather I gauged the receptacles, the cells, whose capacity is proportionate to the ma.s.s of the provisions stored. After making these preparations, registering the cells, coc.o.o.ns and rations and putting all my figures in order, I had only to wait for the hatching-season to determine the s.e.x.

Well, I found that logic and experiment were in perfect agreement. The Philanthus-coc.o.o.ns with two Bees gave me males, always males; those with a larger ration gave me females. From the Tachytes-coc.o.o.ns with double or treble that ration I obtained females. When fed upon four or five Nut-weevils, the Sand Cerceris was a male; when fed upon eight or ten, a female. In short, abundant provisions and s.p.a.cious cells yield females; scanty provisions and narrow cells yield males. This is a law upon which I may henceforth rely.

At the stage which we have now reached a question arises, a question of major importance, touching the most nebulous aspect of embryogeny.

How is it that the larva of the Philanthus, to take a particular case, receives three to five Bees from its mother when it is to become a female and not more than two when it is to become a male? Here the various head of game are identical in size, in flavour, in nutritive properties. The food-value is precisely in proportion to the number of items supplied, a helpful detail which eliminates the uncertainties wherein we might be left by the provision of game of different species and varying sizes. How is it, then, that a host of Bees and Wasps, of honey-gatherers as well as huntresses, store a larger or smaller quant.i.ty of victuals in their cells according as the nurselings are to become females or males?

The provisions are stored before the eggs are laid; and these provisions are measured by the needs of the s.e.x of an egg still inside the mother's body. If the egg-laying were to precede the rationing, which occasionally takes place, as with the Odyneri (Cf. "The Hunting Wasps": chapters 2 and 8.--Translator's Note.), for example, we might imagine that the gravid mother enquires into the s.e.x of the egg, recognizes it and stacks victuals accordingly. But, whether destined to become a male or a female, the egg is always the same; the differences--and I have no doubt that there are differences--are in the domain of the infinitely subtle, the mysterious, imperceptible even to the most practised embryogenist. What can a poor insect see--in the absolute darkness of its burrow, moreover--where science armed with optical instruments has not yet succeeded in seeing anything? And besides, even were it more discerning than we are in these genetic obscurities, its visual discernment would have nothing whereupon to practice. As I have said, the egg is laid only when the corresponding provisions are stored. The meal is prepared before the larva which is to eat it has come into the world. The supply is generously calculated by the needs of the coming creature; the dining-room is built large or small to contain a giant or a dwarf still germinating in the ovarian ducts. The mother, therefore, knows the s.e.x of her egg beforehand.

A strange conclusion, which plays havoc with our current notions! The logic of the facts leads us to it directly. And yet it seems so absurd that, before accepting it, we seek to escape the predicament by another absurdity. We wonder whether the quant.i.ty of food may not decide the fate of the egg, originally s.e.xless. Given more food and more room, the egg would become a female; given less food and less room, it would become a male. The mother, obeying her instincts, would store more food in this case and less in that; she would build now a large and now a small cell; and the future of the egg would be determined by the conditions of food and shelter.

Let us make every test, every experiment, down to the absurd: the crude absurdity of the moment has sometimes proved to be the truth of the morrow. Besides, the well-known story of the Hive-bee should make us wary of rejecting paradoxical suppositions. Is it not by increasing the size of the cell, by modifying the quality and quant.i.ty of the food, that the population of a hive transforms a worker larva into a female or royal larva? It is true that the s.e.x remains the same, since the workers are only incompletely developed females. The change is none the less miraculous, so much so that it is almost lawful to enquire whether the transformation may not go further, turning a male, that poor abortion, into a st.u.r.dy female by means of a plentiful diet. Let us therefore resort to experiment.

I have at hand some long bits of reed in the hollow of which an Osmia, the Three-horned Osmia, has stacked her cells, bounded by earthen part.i.tions. I have related elsewhere (Cf. "Bramble-bees and Others": chapters 2 to 5.--Translator's Note.) how I obtain as many of these nests as I could wish for. When the reed is split lengthwise, the cells come into view, together with their provisions, the egg lying on the paste, or even the budding larva. Observations multiplied ad nauseam have taught me where to find the males and where the females in this apiary. The males occupy the fore-part of the reed, the end next to the opening; the females are at the bottom, next to the knot which serves as a natural stopper to the channel. For the rest, the quant.i.ty of the provisions in itself points to the s.e.x: for the females it is twice or thrice as great as for the males.

In the scantily-provided cells, I double or treble the ration with food taken from other cells; in the cells which are plentifully supplied, I reduce the portion to a half or a third. Controls are left: that is to say, some cells remain untouched, with their provisions as I found them, both in the part which is abundantly provided and in that which is more meagrely rationed. The two halves of the reed are then restored to their original position and firmly bound with a few turns of wire. We shall see, when the time comes, whether these changes increasing or decreasing the victuals have determined the s.e.x.

Here is the result: the cells which at first were sparingly provided, but whose supplies were doubled or trebled by my artifice, contain males, as foretold by the original amount of victuals. The surplus which I added has not completely disappeared, far from it: the larva has had more than it needed for its evolution as a male; and, being unable to consume the whole of its copious provisions, it has spun its coc.o.o.n in the midst of the remaining pollen-dust. These males, so richly supplied, are of handsome but not exaggerated proportions; you can see that the additional food has profited them to some small extent.

The cells with abundant provisions, reduced to a half or a third by my intervention, contain coc.o.o.ns as small as the male coc.o.o.ns, pale, translucent and limp, whereas the normal coc.o.o.ns are dark-brown, opaque and firm to the touch. These, we perceive at once, are the work of starved, anaemic weavers, who, failing to satisfy their appet.i.te and having eaten the last grain of pollen, have, before dying, done their best with their poor little drop of silk. Those coc.o.o.ns which correspond with the smallest allowance of food contain only a dead and shrivelled larva; others, in whose case the provisions were less markedly decreased, contain females in the adult form, but of very diminutive size, comparable with that of the males, or even smaller. As for the controls which I was careful to leave, they confirm the fact that I had males in the part near the orifice of the reed and females in the part near the knot closing the channel.

Is this enough to dispose of the very improbable supposition that the determination of the s.e.x depends on the quant.i.ty of food? Strictly speaking, there is still one door open to doubt. It may be said that experiment, with its artifices, does not succeed in realizing the delicate natural conditions. To make short work of all objections, I cannot do better than have recourse to facts in which the experimenter's hand has not intervened. The parasites will supply us with these facts; they will show us how alien the quant.i.ty and even the quality of the food are from either specific or s.e.xual characters. The subject of enquiry thus becomes double, instead of single as it was when I plundered one cell in my split reeds to enrich another. Let us follow this double current for a little while.

An Ammophila, the Silky Ammophila (Cf. "The Hunting Wasps": chapter 13.--Translator's Note.), which feeds on Looper caterpillars (Known also as Measuring-worms, Inchworms, Spanworms and Surveyors: the caterpillars of the Geometrid Moths.--Translator's Note.), has just been reared in my refectory on Spiders. Replete to the regulation point, it spins its coc.o.o.n. What will emerge from this? If the reader expects to see any modifications, caused by a diet which the species, left to itself, had never effected, let him be undeceived and that quickly. The Ammophila fed on Spiders is precisely the same as the Ammophila fed on caterpillars, just as man fed on rice is the same as man fed on wheat.

In vain I pa.s.s my lens over the product of my art: I cannot distinguish it from the natural product; and I defy the most meticulous entomologist to perceive any difference between the two. It is the same with my other boarders who have had their diet altered.

I see the objection coming. The differences may be inappreciable, for my experiments touch only a first rung of the ladder. What would happen if the ladder were prolonged, if the offspring of the Ammophila fed on Spiders were given the same food generation after generation? These differences, at first imperceptible, might become accentuated until they grew into distinct specific characters; the habits and instincts might also change; and in the end the caterpillar-huntress might become a Spider-huntress, with a shape of her own. A species would be created, for, among the factors at work in the transformation of animals, the most important of all is incontestably the type of food, the nature of the thing wherewith the animal builds itself. All this is much more important than the trivialities which Darwin relies upon.

To create a species is magnificent in theory, so that we find ourselves regretting that the experimenter is not able to continue the attempt.

But, once the Ammophila has flown out of the laboratory to slake her thirst at the flowers in the neighbourhood, just to try to find her again and induce her to entrust you with her eggs, which you would rear in the refectory, to increase the taste for Spiders from generation to generation! Merely to dream of it were madness. Shall we, in our helplessness, admit ourselves beaten by the evolutionary effects of diet? Not a bit of it! One experiment--and you could not wish for a more decisive--is continually in progress, apart from all artifices, on an enormous scale. It is brought to our notice by the parasites.

They must, we are told, have acquired the habit of living on others in order to save themselves work and to lead an easier life. The poor wretches have made a sorry blunder. Their life is of the hardest. If a few establish themselves comfortably, dearth and dire famine await most of the rest. There are some--look at certain of the Oil-beetles--exposed to so many chances of destruction that, to save one, they are obliged to procreate a thousand. They seldom enjoy a free meal. Some stray into the houses of hosts whose victuals do not suit them; others find only a ration quite insufficient for their needs; others--and these are very numerous--find nothing at all. What misadventures, what disappointments do these needy creatures suffer, unaccustomed as they are to work! Let me relate some of their misfortunes, gleaned at random.

The Girdled Dioxys (D. cincta) loves the ample honey-stores of the Chalicodoma of the Pebbles. There she finds abundant food, so abundant that she cannot eat it all. I have already pa.s.sed censure on this waste.

(Cf. "The Mason-bees": chapter 10.--Translator's Note.) Now a little Osmia (O. cyanoxantha, Perez) makes her nest in the Mason's deserted cells; and this Bee, a victim of her ill-omened dwelling, also harbours the Dioxys. This is a manifest error on the parasite's part. The nest of the Chalicodoma, the hemisphere of mortar on its pebble, is what she is looking for, to confide her eggs to it. But the nest is now occupied by a stranger, by the Osmia, a circ.u.mstance unknown to the Dioxys, who comes stealing up to lay her egg in the mother's absence. The dome is familiar to her. She could not know it better if she had built it herself. Here she was born; here is what her family wants. Moreover, there is nothing to arouse her suspicions: the outside of the home has not changed its appearance in any respect; the stopper of gravel and green putty, which later will form a violent contrast with its white front, is not yet constructed. She goes in and sees a heap of honey.

To her thinking this can be nothing but the Chalicodoma's portion. We ourselves would be beguiled, in the Osmia's absence. She lays her eggs in this deceptive cell.

Her mistake, which is easy to understand, does not in any way detract from her great talents as a parasite, but it is a serious matter for the future larva. The Osmia, in fact, in view of her small dimensions, collects but a very scanty store of food: a little loaf of pollen and honey, hardly the size of an average pea. Such a ration is insufficient for the Dioxys. I have described her as a waster of food when her larva is established, according to custom, in the cell of the Mason-bee. This description no longer applies; not in the very least. Inadvertently straying to the Osmia's table, the larva has no excuse for turning up its nose; it does not leave part of the food to go bad; it eats up the lot without having had enough.

This famine-stricken refectory can give us nothing but an abortion. As a matter of fact, the Dioxys subjected to this n.i.g.g.ardly test does not die, for the parasite must have a tough const.i.tution to enable it to face the disastrous hazards which lie in wait for it; but it attains barely half its ordinary dimensions, which means one-eighth of its normal bulk. To see it thus diminished, we are surprised at its tenacious vitality, which enables it to reach the adult form in spite of the extreme deficiency of food. Meanwhile, this adult is still the Dioxys; there is no change of any kind in her shape or colouring.

Moreover, the two s.e.xes are represented; this family of pigmies has its males and females. Dearth and the farinaceous mess in the Osmia's cell has had no more influence over species or s.e.x than abundance and flowing honey in the Chalicodoma's home.

The same may be said of the Spotted Sapyga (S. punctata (A parasitic Wasp. Cf. "The Mason-bees": chapters 9 and 10.--Translator's Note.)), which, a parasite of the Three-p.r.o.nged Osmia, a denizen of the bramble, and of the Golden Osmia, an occupant of empty Snail-sh.e.l.ls, strays into the house of the Tiny Osmia (O. parvula (This bee makes her home in the brambles. Cf. "Bramble-dwellers and Others": chapters 2 and 3.--Translator's Note.)), where, for lack of sufficient food, it does not attain half its normal size.

A Leucopsis (Cf. "The Mason-bees": chapter 11.--Translator's Note.) inserts her eggs through the cement wall of our three Chalicodomae. I know her under two names. When she comes from the Chalicodoma of the Pebbles or Walls, whose opulent larva saturates her with food, she deserves by her large size the name of Leucopsis gigas, which Fabricius bestows upon her; when she comes from the Chalicodoma of the Sheds, she deserves no more than the name of L. grandis, which is all that Klug grants her. With a smaller ration "the giant" is to some degree diminished and becomes no more than "the large." When she comes from the Chalicodoma of the Shrubs, she is smaller still; and, if some nomenclator were to seek to describe her, she would no longer deserve to be called more than middling. From dimension 2 she has descended to dimension 1 without ceasing to be the same insect, despite the change of diet; and at the same time both s.e.xes are present in the three nurselings, despite the variation in the quant.i.ty of victuals.

I obtain Anthrax sinuata ("The Mason-bees": chapters 8, 10 and 11.--Translator's Note.) from various bees' nests. When she issues from the coc.o.o.ns of the Three-horned Osmia, especially the female coc.o.o.ns, she attains the greatest development that I know of. When she issues from the coc.o.o.ns of the Blue Osmia (O. cyanea, KIRB.), she is sometimes hardly one-third the length which the other Osmia gives her. And we still have the two s.e.xes--that goes without saying--and still identically the same species.

Two Anthidia, working in resin, A. septemdentatum, LATR., and A.

bellicosum, LEP. (For these Resin-bees, cf. "Bramble-bees and Others": chapter 10.--Translator's Note.), establish their domicile in old Snail-sh.e.l.ls. The second harbours the Burnt Zonitis (Z. proeusta (Cf.

"The Glow-worm and Other Beetles": chapter 6.--Translator's Note.)).

Amply nourished this Meloe then acquires her normal size, the size in which she usually figures in the collections. A like prosperity awaits her when she usurps the provisions of Megachile sericans. (For this Bee, the Silky Leaf-cutter, cf. "Bramble-bees and Others": chapter 8.--Translator's Note.) But the imprudent creature sometimes allows itself to be carried away to the meagre table of the smallest of our Anthidia (A. scapulare, LATR. (A Cotton-bee, cf. idem: chapter 9.--Translator's Note.)), who makes her nests in dry bramble-stems. The scanty fare makes a wretched dwarf of the offspring belonging to either s.e.x, without depriving them of any of their racial features. We still see the Burnt Zonitis, with the distinctive sign of the species: the singed patch at the tip of the wing-cases.

And the other Meloidae--Cantharides, Cerocomae, Mylabres (For these Blister-beetles or Oil-beetles, cf. "The Glow-worm and Other Beetles": chapter 6.--Translator's Note.)--to what inequalities of size are they not subject, irrespective of s.e.x! There are some--and they are numerous--whose dimensions fall to a half, a third, a quarter of the regular dimensions. Among these dwarfs, these misbegotten ones, these victims of atrophy, there are females as well as males; and their smallness by no means cools their amorous ardour. These needy creatures, I repeat, have a hard life of it. Whence do they come, these diminutive Beetles, if not from dining-rooms insufficiently supplied for their needs? Their parasitical habits expose them to harsh vicissitudes. No matter: in dearth as well as in abundance the two s.e.xes appear and the specific features remain unchanged.

It is unnecessary to linger longer over this subject. The demonstration is completed. The parasites tell us that changes in the quant.i.ty and quality of food do not lead to any transformation of species. Fed upon the larva of the Three-horned Osmia or of the Blue Osmia, Anthrax sinuata, whether of handsome proportions or a dwarf, is still Anthrax sinuata; fed upon the allowance of the Anthidium of the empty Snail-sh.e.l.ls, the Anthidium of the brambles, the Megachile or doubtless many others, the Burnt Zonitis is still the Burnt Zonitis. Yet variation of diet ought to be a very potential factor in the problem of progress towards another form. Is not the world of living creatures ruled by the stomach? And the value of this factor is unity, changing nothing in the product.

The same parasites tell us--and this is the chief object of my digression--that excess or deficiency of nutriment does not determine the s.e.x. So we are once more confronted with the strange proposition, which is now more positive than ever, that the insect which ama.s.ses provisions in proportion to the needs of the egg about to be laid knows beforehand what the s.e.x of this egg will be. Perhaps the reality is even more paradoxical still. I shall return to the subject after discussing the Osmiae, who are very weighty witnesses in this grave affair. (Cf.

"Bramble-bees and Others": chapters 3 to 5. The student is recommended to read these three chapters in conjunction with the present chapter, to which they form a sequel, with that on the Osmiae (chapter 2 of the above volume) intervening.--Translator's Note.)

CHAPTER 10. THE BEE-EATING PHILANTHUS.

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 (The Larva of Chrysomela populi, the Poplar Leaf-beetle.--Translator's Note.) 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 subst.i.tute 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 appet.i.te. 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 a.n.a.l 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 gla.s.s 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 antic.i.p.ate; and we will place the huntress and her game together under the bell-gla.s.s.

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 att.i.tude favourable to her designs, the bandit rushes forward and kills. I will describe how things happen.

I place under the bell-gla.s.s a Philanthus and two or three Hive-bees.

The prisoners climb the gla.s.s 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 gla.s.s. 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 att.i.tude, 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'