More Hunting Wasps Part 13

A Grey Worm which had just received its first sting on the third thoracic segment repulses the Ammophila and with a jerk hurls her to a distance. I profit by the occasion and take hold of the grub. The legs of this third segment only are paralysed; the others retain their usual mobility. However helpless in the two injured legs, the animal can walk very well; it buries itself in the earth, returning to the surface at night to gnaw the stump of lettuce with which I have served it. For a fortnight my paralytic retains perfect liberty of action, except in the segment operated on; then it dies, not of its wound but accidentally.

All this time the effect of the poison has not spread beyond the inoculated segment.

At any point where the sting enters, anatomy informs us of the presence of a nervous nucleus. Is this centre directly smitten by the weapon?

Or is it poisoned with virus, from a very small distance, by the progressive impregnation of the neighbouring tissues? This is the doubtful point, though it does not in any way invalidate the precision of the abdominal injections, which are comparatively neglected. As for those in the caterpillar's thorax, their precision is beyond dispute.

After the Ammophilae, the Scoliae and, above all, the Calicurgi, is it really necessary to bring into court yet other witnesses, who would all swear that, with modifications of detail, the movement of their lancet is strictly regulated by the nervous system of the prey? This ought to be enough. The proof is established for those who have ears to hear with.

Others delight in objections whose oddity surprises me. They see in the poison of the Hunting Wasps an antiseptic liquid and in victuals stored in their burrows preserved meats which are kept fresh not by a remnant of life but by the virus and its microbes. Come, my learned masters, let us just talk the matter over, between ourselves. Have you ever seen the larder of a skilled Hunting Wasp, a Sphex for instance, a Scolia, an Ammophila? You haven't, have you? I thought as much. Yet it would be better to begin by doing so, before bringing the preservative microbe on the scene. The slightest examination would have shown you that the victuals cannot be compared exactly with smoked hams. The thing moves, therefore it is not dead. There you have the whole matter, in its artless simplicity. The palpi move, the mandibles open and shut, the tarsi quiver, the antennae and the abdominal filaments wave to and fro, the abdomen throbs, the intestine rejects its contents, the animal reacts to the stimulus of a needle, all of which signs are hardly compatible with the idea of pickled meat.

Have you had the curiosity to look through the pages in which I set forth the detailed results of my observations? You haven't, have you? Again, I thought as much. It is a pity. You would there find, in particular, the history of certain Ephippigers who, after being stung by the Sphex according to rule, were reared by myself by hand. You must agree that these are queer preserves to be produced by the use of an antiseptic fluid. They accept the mouthfuls which I offer them on the tip of a straw; they feed, they sit up and take nourishment. I shall never live to see tinned sardines doing as much.

I will avoid tedious repet.i.tion and content myself with adding to my old sheaf of proofs a few facts which have not yet been related. The Nest-building Odynerus showed us in her cells a few Chrysomela-larvae fixed by the hinder part to the side of the reed. The grub fastens itself in this way to the poplar-leaf to obtain a purchase when the moment has come for leaving the larval slough. Do not these preparations for the nymphosis tell us plainly that the creature is not dead?

The Hairy Ammophila affords us an even better example. A number of caterpillars operated on before my eyes attained, some sooner, some later, the chrysalis stage. My notes are explicit on the subject of some of them, taken on Verbasc.u.m sinuatum. Sacrificed on the 14th of April, they were still irritable when tickled with a straw a fortnight after.

A little later, the pale-green colouring of the early stages is replaced by a reddish brown, except on two or three segments of the median ventral surface. The skin wrinkles and splits, but does not come detached of its own accord. I can easily remove it in shreds. Under this slough appears the firm, chestnut-brown horn integument of the chrysalis. The development of the nymphosis is so correct that for a moment the crazy hope occurs to me that I may see a Turnip-moth come out of this mummy, the victim of a dozen dagger-thrusts. For the rest, there is no attempt at spinning a coc.o.o.n, no jet of silky threads flung out by the caterpillar before turning into a chrysalis. Perhaps under normal conditions metamorphosis takes place without this protection. However, the moth whom I expected to see was beyond the limits of the possible.

In the middle of May, a month after the operation on the caterpillars, my three chrysalids, still incomplete underneath, in the three or four middle segments, withered and at last went mouldy. Is the evidence conclusive this time? Who can conceive such a silly idea as that a prey really dead, a corpse preserved from putrefaction by an antiseptic, could contain what is perhaps the most delicate work of life, the development of the grub into the perfect insect?

The truth must be driven into recalcitrant brains with great blows of the sledge-hammer. Let us once more employ this method. In September I unearth from a heap of mould five Cetonia-grubs, paralysed by the Two-banded Scolia and bearing on the abdomen the as yet unhatched egg of the Wasp. I remove the eggs and install the helpless creatures on a bed of leaf-mould with a gla.s.s cover. I propose to see how long I can keep them fresh, able to move their mandibles and palpi. Already the victims of various Hunting Wasps had instructed me on a similar matter; I knew that traces of life linger for two, three, four weeks and longer. For instance, I had seen the Ephippigers of the Languedocian Sphex continue the waving of their antennae and their paralytic shudders for forty days of artificial feeding by hand; and I used to wonder whether the more or less early death of the other victims was not due to lack of nourishment quite as much as to the operation which they had undergone. However, the insect in its adult form usually has a very brief existence. It soon dies, killed by the mere fact of living, without any other accident.

A larva is preferable for these investigations. Its const.i.tution is livelier, better able to support protracted abstinence, above all during the winter torpor. The Cetonia-grub, a regular lump of bacon, nourished by its own fat during the winter season, fulfils the needful conditions to perfection. What will become of it, lying belly upwards on its bed of leaf-mould? Will it survive the winter?

At the end of a month, three of my grubs turn brown and lapse into rottenness. The other two keep perfectly fresh and move their antennae and palpi at the touch of a straw. The cold weather comes and tickling no longer elicits these signs of life. The inertia is complete; nevertheless their appearance remains excellent, without a trace of the brownish tinge, the sign of deterioration. At the return of the warm weather, in the middle of May, there is a sort of resurrection. I find my two larvae turned over, belly downwards; much more: they are half-buried in the mould. When teased, they coil up lazily; they move their legs as well as their mouth-parts, but slowly and without vigour.

Then their strength seems to revive. The convalescent, resuscitated grubs dig with clumsy efforts into their bed of mould; they dive into it and disappear to a depth of about two inches. Recovery seems to be imminent.

I am mistaken. In June I unearth the invalids. This time, the larvae are dead; their brown colour tells me as much. I expected better things.

Never mind: this is no trifling success. For nine months, nine long months, the grubs stabbed by the Scolia kept fresh and alive. Towards the end, torpor was dispelled, strength and movement returned, sufficiently to enable them to leave the surface where I had placed them and to regain the depths by boring a pa.s.sage through the soil. I really think that after this resurrection there will be no more talk of antiseptics, unless and until tinned Herrings begin to frolic in their brine. (The subject of this and the preceding chapters is continued in an essay ent.i.tled "The Poison of the Bee" for which cf. "Bramble-bees and Others": chapter 11.--Translator's Note.)