What is this humour? Some special product, some mixture of nitrobenzene? I cannot say for certain. I know only that the insect employs it in self-defence. When [[216]]frightened, it exudes it to ward off the assailant. The anal reservoir begins to work when the first little drop appears from the scent-bottles. What shall we say of this protective device which becomes the cause of excruciating torture? Unsophisticated creatures, acquire the power of stinking, after this; distil benzene; become bitter if you were not bitter before: you will always find a devourer to scrunch you, an epicure to nibble your rump! South-American butterflies, pray take note!
I will not close the lamentable history of the Chrysomela-grub without telling what becomes of the creature after this horrible mutilation. The complete inertia produced by the thoracic injuries has nothing to teach us that we do not already know from the facts perceived in the larvæ destined for the cells. We will therefore consider the case in which the grub is stung three or four times at the tip of the abdomen only. I secure the creature when the Odynerus abandons it, after greedily munching the last three segments and scraping out the end of the intestine, whose defensive and locomotory pimple has disappeared. These three segments are bruised and of a sickly colour; but I cannot discover the least rent in the skin. The abdomen [[217]]is paralysed. The insect no longer uses its anal lever when walking. The legs are perfectly mobile and the grub employs them: it crawls, it drags itself along, progressing with a vigour which would be normal but for the obstruction of the hind-quarters. The head also moves; the mouth-parts snap as usual. Apart from the paralysis of the abdomen and the mutilation of the rectum, the victim is in every respect the same as the lusty larva, browsing peacefully on the poplar-leaf. We have here a magnificent demonstration of the principle before which certain peevish objections are bound to fall to the ground: the effect of the sting is not felt, at least not at first, except at the points attacked. The sting strikes the nerve-centres of the abdomen and the abdomen is paralysed; it spares the thorax and the legs and head both remain active.
Ten hours after the operation, I examine the grubs again. The hind-legs are tremulous and are no longer of use for locomotion. Paralysis is overtaking them. Next day, they are inert; so are the middle legs. The head and the fore-legs are still working. On the day after, the whole grub is motionless, except the head. Lastly, on the fourth day, the creature is dead, really [[218]]dead, for it shrivels, dries up and goes black, while the larvæ subjected to the thoracic operation with a view to being used for provisions remain full and fresh-coloured for weeks and months. Did the grub die of its stings in the abdomen? No, for the others, stung in the thorax, do not die. It is the Odynerus’ cruel tooth and not the sting that killed it. With the tip of the abdomen crushed under the mandibles and the intestinal capsule pulled out by the roots, life has ceased to be possible. [[219]]
[1] Cf. the essay on the Resin-bees in Bramble-bees and Others: chap. x.—Translator’s Note. [↑]
[2] The Common Snail.—Translator’s Note. [↑]
[3] Cf. The Life and Love of the Insect: chap. xi.—Translator’s Note. [↑]
[4] Not yet published in English.—Translator’s Note. [↑]
[5] The Hunting Wasps: chaps. viii. to x. and xviii.—Translator’s Note. [↑]