THE ODYNERI

The Mason-Wasps by Jean-Henri Fabre, is part of the HackerNoon Books Series. You can jump to any chapter in this book here. THE ODYNERI

CHAPTER II. THE ODYNERI

The Eumenes’ suspension-cord and ascending-sheath are rendered necessary by the large number and the incomplete paralysis of the caterpillars provided for the larva; the object of the ingenious system is to avert danger. This, at least, is how I regard the concatenation of causes and effects. But I yield to no one in my distrust of whys and wherefores; I know how slippery our footing becomes when we venture on interpretations; and, before declaring the reasons of any fact observed, I seek for a batch of proofs. If the singular installation of the Eumenes’ egg is really due to the reasons suggested, then, wherever we find similar conditions of danger, namely, a multiplicity of dishes combined with incomplete torpor, we must also find a similar method of protection, or some other method having an equivalent effect. The repetition of the act will bear witness to the correctness of the interpretation; and, if it is not reproduced elsewhere, with such variations as may be required, the case of the Eumenes will remain a very curious instance, without acquiring the far-reaching significance which I suspect it of bearing. Let us generalize, the better to establish the facts.

Now not far removed from the Eumenes are the Odyneri, the Solitary Wasps observed by Réaumur.1 They have the same costumes, the same wings folded lengthwise, the same predatory instincts and, above all, as the supreme condition, the same accumulations of prey retaining sufficient power of movement to be dangerous. If my arguments are well-founded, if I am right in my conjectures, the egg of the Odynerus should be slung from the ceiling of the cell like the egg of the Eumenes. My conviction, based upon logic, is so positive that I already seem to see this egg, recently laid, quivering at the end of the life-line.

Ah, I confess that it needed a robust faith to cherish the audacious hope of discovering anything further when the masters had seen nothing! I read and reread Réaumur’s essay on the Solitary Wasp. [30]The Insect’s Herodotus gives us a host of particulars, but says nothing, absolutely nothing, about the hanging egg. I consult Léon Dufour,2 who treats subjects of this kind with his usual raciness: he has seen the egg; he describes it; but of the suspension-thread not a word. I consult Lepeletier,3 Audouin,4 Blanchard:5 they are absolutely silent on the means of protection which I expect to find. Is it possible that a detail of such great importance can have escaped all these observers? Am I the dupe of my imagination? Is the protective system, though proved to my mind by close logical reasoning, merely one of my [31]dreams? Either the Eumenes have lied to me or my hopes are justified. As a disciple rebelling against his masters, a disciple strong in arguments which I believed invincible, I set to work investigating, convinced that I should succeed. And I did succeed; I found what I was looking for; I found something better still. Let me set things down in detail.

There are various Odyneri established in my neighbourhood. I know one who takes possession of the abandoned nests of Eumenes Amadei. This nest, a structure of unusual solidity, is not a ruin when its owner moves away; it loses only its neck. The cupola, preserved untouched, is a fortified retreat of too convenient a nature to remain vacant. Some Spider adopts the cavern, after lining it with silk; Osmiæ6 take refuge in it in rainy weather, or else make it their dormitory, wherein to spend the night; an Odynerus divides it, by means of clay partitions, into three or four chambers, which become the cradles of as many larvæ. A second species uses the deserted nests of the Pelopæus;7 a third, removing the pith from [32]a dry bramble-stem, obtains, for the use of her family, a long sheath, which she subdivides into stories; a fourth bores a gallery in the dead wood of some fig-tree; a fifth digs herself a shaft in the soil of a footpath and surmounts it with a cylindrical, vertical kerb. All these industries are worth studying, but I should have preferred to discover that which Réaumur and Dufour have rendered famous.

On a steep bank of red clay, I at length recognize, in no great profusion, the signs of a village of Odyneri. Here are the characteristic chimneys mentioned by the two historians, that is to say, the curved tubes, with their guilloche-work, that hang at the entrance to the dwelling. The bank is exposed to the heat of the noonday sun. A little tumbledown wall surmounts it; behind is a dense screen of pines. The whole forms a warm refuge, such as the Wasp requires for setting up house. Moreover, we are now in the second fortnight of the month of May, which is just the working-season, according to the masters. The outside architecture, the site and the period all agree with what Réaumur and Léon Dufour have told us. Have I really chanced upon one or other of their Odyneri? This remains [33]to be seen and without delay. Not one of the ingenious constructors of guilloche porticoes shows herself, not one arrives; I must wait. I take up my position close by, to watch the homing insects.

Ah, how long the hours seem, spent motionless, under a burning sun, at the foot of a declivity which sends the heat of an oven beating down upon you! Bull, my inseparable companion, has retired some distance into the shade, under a clump of evergreen oaks. He has found a layer of sand whose depths still retain some traces of the last shower. He digs himself a bed; and in the cool furrow the sybarite stretches himself flat upon his belly. Lolling his tongue and thrashing the boughs with his tail, he keeps his soft, deep gaze fixed upon me:

“What are you doing over there, you booby, baking in the heat? Come here, under the foliage; see how comfortable I am!”

That is what I seem to read in my companion’s eyes.

“Oh, my Dog, my friend,” I should answer, if you could only understand, “man is tormented by a desire for knowledge, whereas your torments are confined to a desire [34]for bones and, from time to time, a desire for your sweetheart! This, notwithstanding our devoted friendship, creates a certain difference between us, even though people nowadays say that we are more or less related, almost cousins. I feel the need to know things and am content to bake in the heat; you feel no such need and retire into the cool shade.”

Yes, the hours drag when you lie waiting for an insect that does not come. In the pinewood hard by, a couple of Hoopoes are chasing each other with the amorous provocations of spring:

“Oopoopoo!” cries the cock, in a muffled tone. “Oopoopoo!”

Latin antiquity called the Hoopoe Upupa; Greek antiquity named it Ἔποψ. But Pliny turned the ἔ into ou and must have pronounced the word Oupoupa, as the cry imitated by the name teaches me to do. Rarely have I received a lesson in Latin pronunciation better authenticated than yours,8 you beautiful bird, who provide a diversion for my long hours of weariness. Faithful to your idiom, you say “Oopoopoo!” as you said in the days of [35]Aristotle and Pliny, as you said when your note sounded for the first time. But our own idioms, our primitive idioms, what has become of them? The scholar cannot even recover their traces. Man alters; animals do not change.

At last, here we are at last! See, the Odynerus arrives, with a flight as silent as the Eumenes’. She disappears into the curved cylinder of the vestibule, bringing home a grub beneath her abdomen. I place a small glass test-tube at the entrance to the nest. When the insect emerges, it will be caught. Done! The Wasp is caught and at once decanted into the asphyxiating-flask, with its strips of paper steeped in bisulphide of carbon. And now, my Dog, still lolling your tongue and frisking your tail, we can be off; the day has not been wasted. We will come back to-morrow.

Upon investigation, my Odynerus does not correspond with what I expected to see. This is not the species of which Réaumur speaks (O. spinipes); nor is it the species studied by Dufour (O. Reaumurii); it is another. (O. reniformis, Latr.), a different one, though addicted to the same arts. Already the naturalist of the Landes had [36]allowed himself to be deceived by that similarity in architecture, provisions and habits; he thought that he was observing Réaumur’s Solitary Wasp, whereas in reality his tube-builder presented specific differences.

We know the worker; it remains for us to become acquainted with her work. The entrance to the nest opens in the perpendicular wall of the bank. It is a round hole, on the edge of which is built a curved tube, with the orifice turned downwards. Made with the materials cleared from the burrow under construction, this tubular vestibule is composed of grains of earth, not arranged in continuous courses, but leaving small vacant intervals. It is a species of open-work, a lacework of clay. Its length is about an inch and its internal diameter a fifth of an inch. This portico is continued by the gallery, of the same diameter, which slants into the soil to a depth of nearly six inches. Here this main gallery branches into short corridors, each giving access to a cell which is independent of its neighbours. Each larva has its chamber, which can be reached by a special passage. I have counted as many as ten of them; and there may be more. These chambers have nothing [37]remarkable about them, either in construction or in capacity; they are just culs-de-sac ending the corridors that give access to them. Some are horizontal, some more or less sloping; there is no fixed rule. When a cell contains what it is meant to contain, the egg and the provisions, the Odynerus closes the entrance with a little earthen lid; she then digs another near it, on one side of the principal gallery. Lastly, the common road to the cells is blocked with earth; the tube at the entrance is demolished, to furnish material for the work done inside the nest; and every vestige of the habitation disappears.

The surface of the bank is of clay baked in the sun; it is almost brick. I break into it with difficulty, making use of a small pocket-trowel. Underneath, it is much less hard.

How does the frail miner manage to sink a gallery in this brick? She employs, I cannot doubt, the method described by Réaumur. I will therefore reproduce a passage from the master’s writings, to give my younger readers a glimpse into the habits of the Odyneri, habits which my very small colony did not enable me to observe in all their details:

“It is at the end of May that these Wasps set to work; and one can see them busily labouring during the whole of June. Though their actual object is only to dig in the sand a hole a few inches deep and not much wider than their bodies, one might suppose that they had another end in view; for, to make this hole, they build on the outside a hollow tube, which has as its base the circumference of the entrance to the hole and which, after following a direction perpendicular to the surface containing that aperture, turns downwards. This tube becomes longer in proportion as the hole becomes deeper; it is built of the sand drawn from the hole; it is fashioned in coarse filigree, or a sort of guilloche. It is made of big, granular, winding fillets, which do not touch at all points. The gaps left in between make it look as if it were artistically constructed, whereas it is only a sort of scaffolding by means of which the mother’s tactics are rendered swifter and surer.

“Though I knew these insects’ two teeth to be capital instruments, capable of breaking into very hard substances, the task which they had to perform appeared to me rather severe for them. The sand on which they had to act was scarcely less hard than ordinary [39]stone; at least, one’s finger-nails made but a poor impression upon its outer layer, which the sun’s rays had dried more thoroughly than the rest. But, when I succeeded in observing these workers at the moment when they were beginning to bore a hole, they taught me that they did not need to subject their teeth to so harsh an ordeal.

“I saw that the Wasp begins by softening the sand which she proposes to remove. Her mouth discharges upon it a drop or two of water, which is promptly swallowed by the sand, turning it instantly into a soft paste which her teeth scrape and remove without difficulty. Two of her legs, the foremost pair, immediately proceed to gather it into a little pellet, about the size of a currant-seed. It is with this pellet, the first one removed, that the Wasp lays the foundations of the tube which we have described. She carries her pellet of mortar to the edge of the hole which she has just made by removing it; her teeth and feet turn it about, flatten it and make it stand up higher than it did before. This done, the Wasp again sets about removing sand and loads herself with another pellet of mortar. Soon she contrives to have extracted enough [40]sand to make the entrance of the hole perceptible and to have laid the foundation of the tube.

“But the work can proceed quickly only so long as the Wasp is able to moisten the sand. She is obliged to take trouble to renew her store of water. I do not know whether she simply went to take in water at some stream, or whether she drew, from some plant or fruit, a more sticky fluid; what I do know is that she returned without delay and set to work with renewed zeal. I observed one Wasp who managed, in about an hour, to sink a hole the length of her body and who raised a chimney as tall as the hole was deep. At the end of a few hours the tube stood two inches high and she was still deepening the hole that lay underneath.

“It did not appear to me that she had any rule respecting the depth which she gives it. I have found some whose hole ran more than four inches from the orifice; others whose hole measured only two or three inches. Again, over one hole you will find a tube twice or three times as long as that over another. Not all the mortar removed from the hole is invariably employed to prolong it. In cases where the [41]Wasp has given the tube a length which she considers sufficient, you see her simply arrive at the opening to the tube, put her head beyond its edge and forthwith drop her pellet, which falls to the ground. In this way I have often observed a quantity of rubbish at the foot of certain holes.

“The object for which the hole is pierced in a solid mass of mortar or sand cannot appear in doubt: it is plainly intended to receive an egg, together with a store of foodstuffs. But we do not so easily see to what end the mother has built the mortar shaft. By continuing to follow her labours, we shall discover that it means to her what a stack of well-laid stones means to the masons building a wall. Not the whole of the tunnel which she has excavated is intended as a lodging for the larva which will be born inside; a portion will be quite enough. Yet it was necessary that the hole should be dug to a certain depth, in order that the larva may not find itself exposed to too great a heat when the sun’s rays fall on the outer layer of sand. It will occupy only the end of the tunnel. The mother knows what space she must leave vacant and this space she retains; but she fills up all the remainder and replaces in the upper [42]portion of the hole as much of the sand removed from it as is necessary to stop it up. It is to have this mortar within reach that she has built that shaft. Once the egg is laid and the store of victuals placed within its reach, we see the mother come and gnaw the end of the shaft, after first moistening it, carry the pellet inside and next return for more, in the same manner, until the hole is blocked right up to the opening.”

Réaumur goes on to speak of the victuals heaped up in the cells, the “green grubs9,” as he calls them, heedless of the ugly alliteration. Not having seen the same things, because my Odynerus is of a different species, I will continue my story. I counted the head of game in three cells only: the colony was a small one; I had to deal tenderly with it if I would follow its history to the end. In one of the cells, before the provisions were broached, I counted twenty-four pieces; in each of the two others, which were likewise intact, I counted twenty-two. Réaumur found only eight to twelve pieces in the larder of his Odynerus; and Dufour, [43]in the store-room of his, discovered a batch of ten to twelve. Mine requires twice as many, a couple of dozen, which may be due to the smaller size of the game. No predatory Wasp of my acquaintance, apart from the Bembeces,10 who obtain their supplies from day to day, approaches this prodigality in numbers. Two dozen grub-worms to make a meal for only one! How far removed are we from the single caterpillar of the Hairy Ammophila! And what delicate precautions must be taken for the safety of the egg in the midst of such a crowd! A scrupulous vigilance is necessary here, if we would obtain a true conception of the dangers to which the Odynerus’ egg is exposed and of the means that save it from danger.

And, in the first place, what variety of game is this? It consists of worms as thick as a knitting-needle and varying slightly in length. The biggest measure a centimetre.11 The head is small, of an intense, glossy black. The segments, unlike those of the caterpillars, have no legs, either true or false, but all, without exception, are furnished with ambulatory organs in the [44]shape of a pair of small fleshy nipples. These worms, though of the same species, to judge by their general characteristics, differ in colouring. They are a pale, yellowish green, with two wide longitudinal stripes of pale pink in some and of a more or less deep green in others. Between these two stripes, on the back, runs a streak of pale yellow. The whole body is sprinkled with little black tubercles, each bearing a hair on its crest. The absence of legs proves that they are not caterpillars, not the larvæ of Butterflies or Moths. According to Audouin’s experiments, Réaumur’s “green grubs” are the larvæ of a Weevil, Phytonomus variabilis, an inhabitant of the lucerne-fields. Can my worms, pink or green, also belong to some little Weevil? It is quite possible.

Réaumur described the grubs composing the victuals of his Odynerus as alive; he tried to rear some, hoping to see a Fly or a Beetle appear from them. Léon Dufour, on his side, called them live caterpillars. The mobility of the game provided escaped neither of the two observers; they had before their eyes grubs that moved about and gave full signs of life.

What they saw I also see. My little [45]larvæ frisk and fidget; curled at first in the shape of a ring, they uncurl themselves and curl again, if I do no more than slowly turn the small glass tube in which I have imprisoned them. When touched with the point of a needle, they struggle abruptly. Some succeed in shifting their position. While engaged in rearing the Odynerus’ egg, I opened the cell lengthwise, so as to reduce it to a semicylinder; in the little trench thus made, which was kept horizontal, I placed a few head of game. Next day usually I found that one of them had fallen out, a proof of movement, of a change of position, even when nothing was disturbing its repose.

These larvæ, I am firmly convinced, have been wounded by the Odynerus’ sting, for she would not carry a rapier merely for show. Possessing a weapon, she employs it. However, the wound is so slight that Réaumur and Léon Dufour did not suspect its existence. To their mind the prey was alive; to mine it is very nearly alive. In these conditions we can see to what perils the Odynerus’ egg would be exposed but for exquisitely prudent precautions. There they are, those restless grubs, to the number of two dozen in one cell, side by side with [46]the egg, which a mere nothing is enough to endanger. By what means will this very delicate germ escape the perils of the crowd?

As I foresaw by my process of reasoning, the egg is slung from the ceiling of the cell. A very short thread fastens it to the top wall and lets it hang free in space. The first time that I saw this egg, quivering at the end of its thread at the least jerk and confirming by its oscillations the correctness of my theoretical views, I experienced one of those moments of inward joy which atone for much vexation and weariness. I was to have many more such moments, as will be seen. If we pursue our investigations in the insect world with loving patience and a practised eye, we always find some marvel in store for us. The egg, I was saying, swings from the ceiling, held by a very short and extremely fine thread. The cell is sometimes horizontal, sometimes slanting. In the first case, the egg hangs perpendicularly to the axis of the cell and its lower end approaches to within a twelfth of an inch of the opposite wall; in the second case, the vertical direction of the egg forms a more or less acute angle with that axis.

I wished to follow the progress of this [47]hanging egg at my leisure, with the greater convenience of observation which is possible at home. With the egg of Eumenes Amadei this was all but impracticable, because of the cell, which could not be moved together with the block that most often serves as its foundation. A house of this kind demands observation on the spot. The Odynerus’ dwelling does not present the same drawback. When a cell is laid bare and found to be in the condition which I desire, I dig round it with the point of a knife until I detach a cylinder of earth containing the cell, which is reduced to an open trough, so as to conceal nothing of what is to happen inside. The victuals are extracted piecemeal, with every care, and decanted separately into a glass tube. I shall thus avoid the accidents that might be occasioned by the swarming heap of grubs during the inevitable shaking of the journey. The egg alone remains, swinging in the empty enclosure. A large tube receives the cylinder of earth, which is wedged in position with pads of cotton-wool. I place my booty in a tin box and carry it in my hand in such a position that the egg hangs vertically without striking against the walls of the cell.[48]

Never have I effected a removal which called for such nice precautions. An accidental movement might easily break the suspension-thread, which is so delicate that it needs the magnifying-glass to distinguish it; excessive oscillation might bruise the egg against the walls of the cell: I had to beware of turning it into a sort of bell-clapper dashing against its bronze prison. I walked, therefore, with the stiffness of an automaton, all of one piece, with steps methodically calculated. What a misfortune should some acquaintance appear and make me stop a moment, for a chat or a shake of the hand: the least distraction on my part would perhaps ruin my schemes! Still more embarrassing would it be should Bull, who cannot endure a black look, find himself muzzle to muzzle with a rival and try to get quits with him by flying at his throat. I should have to put an end to the fray, to avoid the scandal of a well-brought-up Dog showing intolerance of the village cur. The squabble would end in the breakdown of all my experimental scaffolding. And to think that the eager preoccupations of a person not entirely devoid of sense may sometimes be dependent on a Dog-fight![49]

Lord be praised, the road is deserted! The journey is accomplished without hindrance; the thread, my great anxiety, does not break; the egg is not bruised; everything is in order. The little clod of earth is put in a place of safety, with the cell in a horizontal position. I distribute near the egg two or three of the grubs which I have collected; the complete allowance of provisions would cause trouble, now that the cell possesses only half its enclosing wall and is reduced to a semicylinder. Two days later, I find the egg hatched. The young larva, yellow in colour, is hanging by its hinder end, head downwards. It is busy with its first grub, whose skin is already growing limp. The suspension-cord consists of the short thread that supported the egg, with the addition of the slough, now reduced to a sort of crumpled ribbon. In order to remain sheathed in the end of this hollow ribbon, the hinder end of the new-born larva is at first slightly constricted and then swells into a button. If I disturb it while at rest, or if the victuals move, the larva withdraws, shrinking back upon itself, but without retreating into the ascending-sheath, as does the Eumenes’ larva. The tethering-cord does not serve as a scabbard, [50]as a refuge into which the larva can retire; it is rather an anchor-chain, which gives it a purchase on the ceiling and enables it to protect itself by shrinking to a safe distance from the heap of victuals. When things are quiet, the larva lengthens out and returns to its grub. Thus do matters happen at the start, according to my observations, of which some were made at home, in my rearing-jars, and others on the spot, when I unearthed cells containing a larva young enough for my purpose.

The first grub is devoured in twenty-four hours. The larva thereupon, so it seemed, goes through a moult. For at least some time it remains inactive and contracted; then it releases itself from the cord. It is now free, in contact with the heap of grubs and henceforth unable to step out of the way. The life-line has not lasted long; it protected the egg and safeguarded its hatching; but the larva is still very weak and the peril has not diminished. This means that we shall discover other means of protection.

By a very strange exception, whereof so far I know no other instance, the egg is laid before the provisions are stored. I have seen cells which as yet contained absolutely nothing in the way of victuals and which [51]nevertheless had the egg swinging from the ceiling. I have seen others, also furnished with the egg and so far containing only two or three head of game, a first instalment of the abundant dish of twenty-four. This early egg-laying, so utterly unlike what happens in the case of the other predatory Wasps, has its underlying motive, as we shall see; it has its logic at which we cannot fail to marvel.

The egg, laid in the empty cell, is not fixed at random on the first spot that offers upon the enclosing wall, which is vacant at all sides; it is hung near the far end, opposite the entrance. Réaumur had already noted this position of the budding larva, but without insisting on a detail whose importance he did not suspect:

“The grub,” he says, “is born at the bottom of the hole, that is, at the back of the cell.”

He does not speak of the egg, which he does not appear to have seen. This position of the grub was so well known to him that, wishing to attempt the rearing of a grub in a glass cell made with his own hands, he placed the larva at the bottom and the victuals on top of it.[52]

Why do I linger over a petty detail which the famous historian of the Odyneri tells in half-a-dozen words? A petty detail? It is nothing of the kind; on the contrary, it is a circumstance of paramount importance. And this is why: the egg is laid at the back, necessitating an empty cell which will be victualled after the egg is laid. The provisions are now stored, piece by piece, layer upon layer, in front of the egg; the cell is crammed with game right up to the entrance, which in the end is sealed.

Of all these pieces, the obtaining of which may take several days, which are the earliest in point of date? Those nearest the egg. Which are the latest? Those by the entrance. Now it is obvious—besides, it may be proved, if necessary, by direct observation—it is obvious, I say, that the heaped worms lose strength from day to day. The effects of a prolonged fast would be enough to produce this result, to say nothing of the disorders due to a wound which becomes worse as time goes on. The larva born at the back of the cell has therefore beside it, in its first youth, the less dangerous provisions, the oldest in date and consequently the feeblest. As it works its way through the heap, it finds more recent [53]game, which is also more vigorous; but this is attacked without danger, because the larva’s own strength has come.

This progress from the more to the less nearly mortified victims presumes that the grubs do not disturb the order in which they have been stacked. That in fact is what happens. Former historians of the Odyneri have all remarked that the grubs provided for the larva are curled in the shape of a ring:

“The cell,” says Réaumur, “was occupied by green rings, to the number of eight or twelve. Each of these rings consisted of a vermiform larva, alive, curled up and with its back fitting exactly against the wall of the hole. These grubs, laid in this way one on top of the other and even pressed together, had no liberty of movement.”

I, in my turn, remark similar facts in my two dozen grub-worms. They are curled in a ring; they are stacked one upon another, but with a certain confusion in the ranks; their backs touch the wall. I will not attribute this circular curve to the effect of the sting which was very probably administered, for I have never observed it in [54]the caterpillars stabbed by the Ammophilæ; I believe rather that the position is natural to the grub during inaction, even as it is natural for the Iuli12 to coil themselves into a spiral. In this living bracelet there is a tendency to return to the rectilinear conformation; it is a bent bow fighting against the obstacle that surrounds it. By the very fact, therefore, of being curled up, each grub keeps more or less steady by pressing its back a little against the wall; and it retains its place even when the cell approaches the vertical.

Moreover, the shape of the cell has been calculated with a view to this manner of storing. In the part next the entrance, the part which one might call the store-room, the cell is cylindrical and narrow, so as to afford the living rings as little space as possible; they are thus kept in position and are unable to slip. It is here that the grubs are stacked, squeezed one against the other. At the other end, near the back, the cell expands into an ovoid to give the larva elbow-room. The differences between the two diameters is very perceptible. At the entrance I find only four millimetres:13 at [55]the back I find six.14 Thanks to this inequality of width, the cell comprises two apartments: the provision-store in front and the dining-room behind. The Eumenes’ spacious cupola does not permit of this arrangement; there the game is heaped up in disorder, the oldest in date promiscuously with the most recent; and each piece is merely bent, not rolled. The ascending-sheath provides a remedy for the disadvantages of this confusion.

Note also that the packing of the victuals is not the same from one end of the Odynerus’ skewerful to the other. In the cells whose provisions have not yet or have only recently been broached, I observe this detail: near the egg or the newly-hatched larva, in the part which I have just described as the dining-room, the space is not fully occupied; there are just a few grubs here, three or four, somewhat isolated from the bulk and leaving enough room to ensure the safety of either the egg or the young larva. This is the food supplied for the early meals. If there be danger in the first mouthfuls, which are the most risky of all, the life-line provides a means of withdrawal. More towards the front, the game [56]is piled in close-packed layers, the stack of worms is continuous.

Will the larva, now that it possesses a modicum of strength, force itself imprudently into this heap? Far from it. The victuals are consumed in due order, from the bottommost to the topmost. The larva drags towards it, to a little distance, into the dining-room, the first ring that offers, devours it without danger of being inconvenienced by the others and thus, layer by layer, consumes the batch of two dozen, always in complete security.

Let us retrace our steps and end with a brief summary. The large number of grubs provided for a single cell and their very incomplete paralysis jeopardize the security of the Wasp’s egg and of her new-born larva. How is the danger to be averted? This is the problem; and it has several solutions. The Eumenes, with her sheath, which enables the larva to climb back to the ceiling, gives us one; the Odynerus, in her turn, gives us hers, a solution no less ingenious and much more complicated.

The egg and also the newly-hatched larva have to be saved from the danger of contact with the game. A suspension-thread solves [57]the difficulty. Up to this point, that is the method adopted by the Eumenes; but soon the young larva, having eaten its first grub, drops off the thread that gave it a support whereby to shrink out of harm’s way. A sequence of conditions now begins, all directed towards its welfare.

Prudence demands that the very young larva shall first attack the most inoffensive of the grubs, that is those most nearly deadened by abstinence, in short, the grubs first placed in the cell; it demands, moreover, that the consumption of these grubs shall proceed from the oldest specimens to the most recent, so that the larva may have fresh game to the end. With this object, a curious exception is made to the general rule: the egg is laid before the victualling is commenced. It is laid at the back of the cell; in this way, the stacked provisions will present themselves to the larva in due order of date.

That is not enough: it is important that the grubs shall be unable, in moving, to alter their respective positions. This circumstance is provided for: the store-room is a narrow cylinder in which change of place is difficult.

Even that is not sufficient: the larva must [58]have room enough to move about at ease. The condition is fulfilled: at the back, the cell forms a comparatively spacious dining-room:

Is that all? Not yet. The dining-room must not be encumbered like the rest of the cell. The matter has been seen to: the first course consists of a small number of specimens.

Have we done? By no means. It is not of any use to have a narrow cylinder for the larder: if the grubs straighten out, they will slip lengthwise and disturb the nurseling in the back-room. This has been remedied: the game selected is a larva which deliberately rolls itself into a bracelet and maintains its position by its own tendency to unbend.

It is by the ingenious removal of this series of difficulties that the Odynerus succeeds in leaving a family. We have seen enough of her exquisite foresight to amaze us. What would it be were nothing to remain concealed from our dull eyes!

Can the insect have acquired its skill gradually, from generation to generation, by a long series of casual experiments, of blind gropings? Can such order be born of chaos; such foresight of hazard; such [59]wisdom of stupidity? Is the world subject to the fatalities of evolution, from the first albuminous atom which coagulated into a cell, or is it ruled by an Intelligence? The more I see and the more I observe, the more does this Intelligence shine behind the mystery of things. I know that I shall not fail to be treated as an abominable “final causer.” Little do I care! A sure sign of being right in the future is to be out of fashion in the present.

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This book is part of the public domain. Jean-Henri Fabre (2021). The Mason-WaspsT. Urbana, Illinois: Project Gutenberg. Retrieved October https://www.gutenberg.org/cache/epub/66854/pg66854-images.html

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