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 Spheges[11] 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.