THE AGENIÆ; THE PELOPÆUS’ VICTUALS

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 AGENIÆ; THE PELOPÆUS’ VICTUALS

CHAPTER IV. THE AGENIÆ; THE PELOPÆUS’ VICTUALS

Judging only by instincts and habits, a characteristic superior to all others, we must rank not far below the builder whose nest we have been considering certain other Wasps of our country-side, Spider-hunters like the first and, like her, worthy, or perhaps even more worthy, of the title of Πηλοποιός, a worker in clay or mud, a potter. My district possesses two of these ceramic artists: Agenia punctum, Panz., and A. hyalipennis, Zetterstedt.

With all their talent they are very frail creatures, clad in black and hardly larger than the ordinary Gnat. Their pottery amazes us when we remember the feebleness of the artisan. It surprises us even more by its regularity, which may be compared with the product of the turning-lathe. Adhering broadly to a flat base and leaning one against the other, the Pelopæus’ cells, in the full elegance of the first phase, are merely semicylinders whose circular contour is accentuated only at the mouth; while those of the Ageniæ, which are almost isolated from one another and take hold of their support only at a restricted spot, retain from end to end a regular convexity, suggesting the tiny pots of a miniature set of crockery. If any one deserves the epithet of spirifex, or turner, it is the Agenia rather than the Pelopæus. No other manipulator of potter’s clay possesses her dexterity.

The pots of A. punctum are shaped like oval jars, each smaller than a cherry-stone. Those of A. hyalipennis affect a conoid form, narrow at the base and wider at the mouth, like the primitive drinking-cup, the cyathus of the ancients. Both have a polished interior and a very much granulated exterior, the maker allowing the little mouthful of mortar which she has brought to project outside, without seeking to level it, as she does so carefully upon the inner wall. These granulations are the equivalent of the slanting fillets left by the Pelopæus. No rough-cast, no plaster is applied to conceal the pretty bit of earthenware; no reinforcement of casing is added. Such as it was when the potter moulded the neck, such [86]it remains after it has received its lid and its little Spider with an egg laid upon her side. The Agenia’s urns then, notwithstanding their brittleness, are left entirely unprotected, whether they be placed end to end in a winding row or grouped in a confused cluster.

Nevertheless, the mother displays a precaution unknown to the Pelopæus. A drop of water placed inside the latter’s cell quickly spreads and disappears, soaking the walls. In an Agenia’s cell it remains at the point touched, without penetrating the thickness. The urn therefore is glazed on the inner surface, like our ordinary pots, which are made watertight by the silicate of lead furnished by the potter’s galena. The waterproofing employed cannot be other than the Agenia’s saliva, an agent which is anything but plentiful, because of the insect’s exiguous dimensions, and so it is applied only on the side. Indeed, if I stand a cell on a drop of water, I see the moisture at once spread from bottom to top and turn the vessel into pulp, until nothing is left but a thin inner layer, which is less yielding.

I do not know where the Ageniæ get their materials. Do they follow the Pelopæus’ [87]custom and collect loam ready prepared, wet earth, mud or naturally plastic clay; or, copying the method of the Mason-bees, do they use cement scraped together atom by atom and converted into paste with the saliva? Direct observation has failed to tell me anything in this respect. From the colour of the cells, which are now red, like the soil of our stony expanses, now whitish, like the dust of the highways, now greyish, like certain chalk-beds in the neighbourhood, I see plainly that the material for the pots is collected everywhere indifferently, but I am unable to determine whether, at the actual moment of collection, it is paste or powder.

I incline, however, to the latter alternative, because of the impermeable inner surface of the cells. Earth already soaked with natural moisture would not readily absorb the Agenia’s saliva and could not acquire the watertight qualities which I find that it possesses. This peculiarity makes it highly probable that the cement is collected dry and that the insect mixes it in order to turn it into plastic clay. Then how are we to explain the outside of the pot, which melts upon contact with a drop of water, and the inside, which remains intact? [88]Very simply: for the outside materials the potter uses only the water with which she slakes her thirst from time to time; for the inside materials she uses pure saliva, a precious agent which has to be thriftily employed, so that she may equip her family with a sufficiency of earthenware. To construct her pots, the Agenia must possess two separate fluid-reservoirs: the crop, a bottle which is filled with spring-water; and the gland, a phial in which the watertight chemical product is sparingly elaborated.

The Pelopæus knows nothing of these scientific methods. To the mud collected ready-made she adds nothing that develops resisting-powers later; when attacked by water, her cells quickly become soaked and allow the moisture to ooze through to the inside. Hence probably, in her case, the necessity for a thick casing of plaster to protect the too permeable dwelling. Each potter has her portion: the giantess, the rough covering of loam; the dwarf, the thin coating of varnish.

Despite their inner glaze, the Agenia’s cells are too readily affected by water and moreover too fragile to remain exposed to the open air with impunity. They need a shelter quite as badly as those of the [89]Pelopæus. This shelter is found in all manner of places, excepting our houses, where the frail potter very rarely takes refuge. A tiny cavity under the stump of a tree; a hole in some wall or other, exposed to the sun; an old Snail-shell under a heap of stones; a Capricorn’s disused burrow bored in the oak; an Anthophora’s1 deserted dwelling; a fat Earth-worm’s mine-shaft opening on a dry bank; the hole whence the Cicada2 has emerged: anything, in short, suits her, provided that the accommodation be sheltered from the rain. Once only did Agenia punctum, who is more frequent than the other, pay me a visit. She had established her collection of pots in some little paper bags lying on the shelves of a green-house and intended to hold seeds. This nest-building on a sheet of paper reminded me of the Pelopæus confiding her cells to the books in a distillery or the curtains of a window. Indifferent to the nature of the support for their nests, both potters sometimes choose very curious sites.[90]

Now that we know the provision-jar, let us ascertain what it contains. The Pelopæus’ larvæ are fed on Spiders, a diet likewise dear to the Ageniæ and to the Pompili.3 The game does not lack variety, even in the same nest and the same cell. Any Spider may form part of the ration, provided that her dimensions do not exceed the capacity of the jar. My abstracts of victuals mention the following genera: Epeira,4 Segestria, Clubionus,5 Attus, Theridion and Lycosa;6 and the list could no doubt be extended, were it worth while to continue the bill of fare. The Epeiræ are most numerous. Those recurring most frequently belong to the following species: E. diadema, scalaris, adianta, pallida and angulata. The Diadem Epeira, or Cross Spider,7 with three crosses of white dots on her back, is the dish that occurs oftenest.

I should hesitate to regard this frequency [91]as indicating a special predilection of the Pelopæus for this kind of game. In her hunting-trips the Wasp does not go far from her home; she visits the old walls near by, the hedges, the little gardens all around and captures whatever offers. Now in these conditions the Cross Spider happens, at the nesting-period, to be the commonest. Every reed-fenced garden-patch in front of the rough cottage beloved by the potter, every hawthorn-hedge surrounding a cabbage-plot shows me the Spider with the pontifical cross weaving her net or waiting for her prey in the centre of her web. If I need a Spider for my studies, I am certain of finding the Diadem Epeira within a few steps of my house. That much keener investigator, the Pelopæus, must easily effect this kind of capture; and this, it seems to me, is the reason why that particular morsel predominates in the provision-store.

If the Epeira, the habitual foundation of the meal, happen to be lacking, any other Spider is regarded as adequate, even when she belongs to a very different group. We have here the wise eclecticism of the Crabro-wasps8 and Bembeces, who welcome any [92]member of the Fly clan, provided that the prey be not disproportionate to the huntress’ strength. We should be wrong, however, to erect this indifference into too absolute a principle: there is reason to believe that the Pelopæus recognizes different qualities of nourishment and flavour between one Spider and another. A more fastidious expert than Lalande,9 with his legendary passion for plump, nutty Spiders, she must rate this species more highly than that; and there are some which she must absolutely despise. These include the House Spider (Tegenaria domestica), who weaves her cobwebs in the corners of our houses.

On the kitchen-ceiling and on the rafters of the granary this Spider is her near neighbour: the silken lair stretches in close proximity to the earthen nest. Instead of expeditions in the neighbourhood, a little patrolling of the actual premises where she has settled down would provide the Pelopæus with abundant sport, for there is game swarming at her very door. Why [93]does she not profit by this plenty? The dish is not to her liking; and it would be very difficult to tell the reason why. The fact remains that, in all my stock-taking of victuals, I have never found the House Spider among the provisions, although the species, if captured young, would seem to fulfil the required conditions. This disdain is a pity both for our sake and for the Pelopæus’; for ours, in the first place, because we should otherwise possess, inside our dwellings, an inspector of ceilings whose duty it would be to exterminate the spinners of cobwebs that cause the housewives such trouble; next, for the sake of the Pelopæus, who, once inscribed on the hallowed roll of useful insects, would enjoy an established reputation and receive a friendly welcome in the farm-house, instead of being driven out when too lavish with her mud.

The Spider, armed with poison-fangs, is a dangerous quarry to tackle; when of fair size, she demands of her adversary an audacity and above all a tactical skill which the Pelopæus, it seems to me, does not fully possess. Moreover, the small diameter of the cells would not admit a bulky prey, such as the Tarantula hunted by the Ringed [94]Calicurgus.10 The Calicurgus deposits her corpulent victim in a cavern obtained without labour in the old plaster at the foot of a wall; the Pelopæus places hers in a jar, a laborious construction whose capacity has to be reduced to suit the larva. The Pelopæus, therefore, hunts game of moderate size, smaller than one would at first expect from the insect’s vigorous appearance. If she encounters a species that is apt to become plump, she always selects a young one. This happens in the case of the Cross Spider, who, when full-grown, with her belly swollen with eggs, almost rivals the Calicurgus’ Tarantula and who is admitted to the provision-jar only when of niggardly dimensions, very different from those which maturity will bring. For the rest, the size varies, between one specimen and another, by a hundred per cent and more. The essential point is that the quarry can be stored in the narrow jar. This variation in the size of the items provided leads to corresponding variations in their number. One cell is stuffed with a dozen Spiders; another contains only five or six. The average number is eight. The nurseling’s sex must of a surety play its part, [95]as with the other Wasps, in regulating the luxuries of the table.

The culminating feature in the biography of any hunting insect is the method of attack; and so I did my utmost to observe the Pelopæus at grips with her quarry. My patient waits in front of her favourite hunting-grounds, old walls and bramble-thickets, were not crowned with any great success. I have seen the Pelopæus fall suddenly upon the Spider madly fleeing and clasp and carry off her victim almost without delaying her flight. The other game-hunters alight on the ground, solemnly make their fastidious preparations and distribute their lancet-strokes with the calm deliberation which a delicate operation demands. The Pelopæus darts forward, seizes her prey and makes off, very much as the Bembeces do. There is reason to believe, so sudden is the rape, that she makes use of her sting and her mandibles only during the flight, on her journey home. This fierce procedure, which is incompatible with scientific surgery, explains even better than the narrowness of the cells her preference for Spiders of small dimensions. A sturdy prey, armed with its two poison-fangs, would constitute a deadly peril to the ravisher disdainful of precautions. [96]The lack of artifice calls for a feeble victim. It also makes us suspect that the Spider so hastily set upon is killed.

Indeed, I have over and over again armed my eyes with a magnifying-glass and scrutinized the contents of cells whose eggs had not yet hatched, a proof that the provisions were of recent date: there is never a quiver of either palpi or tarsi in the victims stored away. It is only with difficulty that I manage to preserve them: in ten days’ time, more or less, I see them grow mouldy and putrefy. The Spiders, therefore, are dead, or very nearly so, when they are potted by the Pelopæus. Is the skilful paralysis which the Calicurgus practises upon the Tarantula, who keeps fresh for seven weeks, unknown to the Pelopæus, or is it impracticable in the fierceness of the attack? Are we, in her case, dealing not with a delicate practitioner, who is able to abolish movement without destroying life, but rather with a brutal sacrificer, who, to deprive her victims of their power of movement, kills them? Everything in their withered aspect and their rapid decay assures us that this is so.

The evidence does not surprise me: we shall see, as we go on, other victimarii inflict [97]death instantly with a stroke of the stiletto, delivered with a science of slaughter no less astonishing than the science of the paralysers. We shall see the reasons that call for these complete murders and we shall recognize, under other aspects, the profound anatomical and physiological knowledge which a rational action would demand in order to rival the unconscious action of instinct. As for the necessity of killing her Spiders under which the Pelopæus labours, I find it impossible even to suspect the cause.

What I do see, without any lengthy investigations, is the logical method whereby the Pelopæus makes the most of the corpses threatened with speedy putrefaction. To begin with, each cell contains a number of victims. The carcase actually attacked by the larva, ground between its mandibles, abandoned and attacked at another point, soon becomes a shapeless and disorganized mass, more liable than ever to putrefy. But it is small and is therefore consumed at a single sitting, before decomposition overtakes it; for once the larva has bitten into a Spider it does not turn elsewhere for food. The others therefore remain intact, which is enough to preserve them in a condition of [98]suitable freshness during the brief period of nourishment. The numerous items composing the ration, consumed in order, one by one, are thus preserved for some days, notwithstanding that they are corpses.

Imagine, on the other hand, a single item, big enough to furnish the whole banquet; the conditions would become detestable. Nibbled here and there, the generous morsel, with its many wounds, would become a fatal mess of putrescence long before it was finished; it would poison the grub with the serum resulting from the wounds. A dish of this kind, single and sumptuous, demands, as a preliminary, the maintenance of organic life, together with the abolition of all movement, in a word, paralysis. It also demands, on the consumer’s part, a special art of eating, an art that respects the more essential and attacks the less essential by degrees, as the Scoliæ and Spheges11 have shown us. For reasons which escape me, the Pelopæus is unacquainted with the paralysers’ art, nor does her larva know how a bulky piece of game may be consumed without danger. She is therefore very happily inspired when she [99]provides her family with a large number of small game. The restricted capacity of the store-houses is not the main motive that dictates her choice: there would be nothing to deter the potter from making bigger pickle-jars, were there any advantage to be gained. The preservation of dead victuals is of the foremost consequence; and, to achieve it within the brief limits of the feeding-period, the huntress fills her bag with none but the smaller Spiders.

Better still: if I open cells that have been recently closed, I always find the egg, not on the surface of the heap, on the last Spider supplied, but right at the bottom, on the piece earliest in date, the first to be stored. Whenever I witness the start of the provisioning, I see the egg lying on the single Spider wherewith the cell is then provided. There is no exception to the rule: the Pelopæus at once fixes her egg on the first morsel served up, before resuming the chase to complete the ration. The Bembeces deal similarly with their dead Flies: the first carcase stowed away receives the egg.

But this conformity of habits goes no farther. The Bembeces continue to bring provisions day by day, as the larva increases [100]in size, a method easily practised in a burrow closed with a mere screen of loose sand, through which the mother passes easily in either direction. The Pelopæus has not the same facilities of ingress and egress: once the earthen jar is closed and sealed, she would have, in order to reenter the cell, to break the lid, which is now dry and would offer a resistance out of all proportion to the means at the disposal of the Wasp accustomed to handling fresh mud. Moreover, each of these laborious burglaries would have to be followed by a rebuilding, which also would be an arduous task.

It is not therefore the Pelopæus’ practice to feed her offspring day by day; and the hoard of victuals is completed as swiftly as possible. If game be not abundant, if the atmospheric conditions be difficult, several days are required to fill the cell thoroughly. In favourable weather, an afternoon is sufficient. No matter what time the hunting may take, long or short according to circumstances, the laying of the egg at the bottom of the cell, on the first piece served, is a happy device on whose excellence I have already laid stress in my history of the Odynerus. The victuals provided for a cell [101]fill it to the brim and are stacked in the order of acquisition, with the Spiders earliest in date at the bottom and the more recent on the surface. No subsidence, which would lead to a mixture of fresh game and high, is possible, because of the game’s long legs, which in most cases scrape against the walls of the cell with their stiff hairs. The larva, at the bottom of the heap and, moreover, intent upon the morsel attacked, thus proceeds from the oldest to the less old and always finds in front of its teeth, until the end of the meal, victuals that have not had time to spoil by decomposition.

The egg is laid indifferently upon a large joint or a small, according to the chances of the first capture. It is white, cylindrical, slightly curved and measures three millimetres in length, with a diameter of rather less than one millimetre.12 The spot that receives it on the Spider’s body varies hardly at all; it is at the beginning of the abdomen, towards the side. The new-born larva, as is usual with the Hunting Wasps, takes its first bite at the point where the pole of the egg containing the head was fixed. Thus, for its first mouthfuls, it has the juiciest and tenderest part, the Spider’s [102]plump belly. Next comes the thorax, abounding in muscular tissues, and lastly the legs, dry morsels, but not despised. Everything goes down, from the best to the coarsest; and, when the meal is finished, there is practically nothing left of the whole heap of Spiders. This life of gluttony lasts for eight to ten days.

The larva then works at its cocoon, which consists at first of a sack of pure, perfectly white silk, an extremely delicate sack, affording little protection to the recluse. This is only a woof, destined to become a better stuff, not by additional weaving, but by the application of a special lacquer. The spinner is a worker in oiled silk.

In the spinning-mills of the carnivorous Wasps, two methods of manufacture are employed to give the silken fabric greater toughness. On the one hand, the fabric is encrusted with numerous grains of sand, which produces an almost mineral shell wherein the silk has no other function than to serve as a cement for the stony materials. That is how the Bembeces, the Stizi, the Tachytes and the Palari work. On the other hand, the larva elaborates in its [103]stomach, in its chylific ventricle, a liquid varnish which it disgorges into the meshes of a rudimentary tissue of silk. Directly it trickles into the web, the varnish hardens and becomes a lacquer of exquisite daintiness. The larva next ejects at the base of the cocoon, in the form of a hard stercoral plug, the residue of the chemical process accomplished in its stomach for the elaboration of the varnish. This method is that of the Spheges, the Ammophilæ and the Scoliæ, who varnish the inner wrapper of their multiple cocoons; and of the Crabro-wasps, the Cerceres and the Philanthi,13 whose delicate cocoon consists of only a single thickness.

The Pelopæus adopts this last procedure. When finished, her work is an amber-yellow fabric suggesting the outer skin of an onion in fineness, colour, transparency and the rustling sound which it emits when fingered. Relatively long in comparison with its width, as is demanded by the capacity [104]of the cell and the slender form of the future insect, the cocoon is rounded at the top and suddenly truncated at the base, which is rendered hard and opaque by the stercoral plug, the by-product of the lacquer-factory.

The hatching-period varies, of course, according to the temperature and also according to certain conditions which I am not yet in a position to specify. One cocoon, woven in July, gives birth to the perfect insect in the course of August, two or three weeks after the larva’s period of activity; another, dating from August, opens a month later, in September; a third, no matter what its date of origin during the summer quarter, goes through the winter and does not burst until the end of June. By combining the birth-certificates recorded, I seem to distinguish three generations in the year, generations which are often but not invariably realized. The first appears at the end of June: this is the one whose cocoons have gone through the winter; the second is seen in August and the third in September. So long as the very hot weather lasts, evolution is rapid: three or four weeks suffice to complete the Pelopæus’ cycle. When September arrives, the fall in [105]temperature puts an end to these precocious broods; and the last larvæ have to wait for the return of the hot weather before they can undergo their transformation.

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