Fabre's Book of Insects

by Jean-Henri Fabre

Before he begins to feed on his victim he gives it an anæsthetic—he makes it unconscious, as a person is made unconscious with chloroform before a surgical operation. His food, as a rule, is a certain small Snail hardly the size of a cherry, which collects in clusters during the hot weather, on the stiff stubble and other dry stalks by the roadside, and there remains motionless, in profound meditation, throughout the scorching summer days. In some such place as this I have often seen the Glow-worm feasting on his unconscious prey, which he had just paralysed on its shaky support.

But he frequents other places too. At the edge of cool, damp ditches, where the vegetation is varied, many Snails are to be found; and in such spots as these the Glow-worm can kill his victim on the ground. I can reproduce these conditions at home, and can there follow the operator’s performance down to the smallest detail.

I will try to describe the strange sight. I place a little grass in a wide glass jar. In this I install a few Glow-worms and a supply of Snails of a suitable size, neither too large nor too small. One must be patient and wait, and above all keep a careful watch, for the events take place unexpectedly and do not last long. [[57]]

For a moment the Glow-worm examines his prey, which, according to its habit, is completely hidden in the shell, except for the edge of the “mantle,” which projects slightly. Then the hunter draws his weapon. It is a very simple weapon, but it cannot be seen without a magnifying-glass. It consists of two mandibles, bent back into a hook, very sharp and as thin as a hair. Through the microscope one can see a slender groove running down the hook. And that is all.

The insect repeatedly taps the Snail’s mantle with its instrument. It all happens with such gentleness as to suggest kisses rather than bites. As children, teasing one another, we used to talk of “tweaks” to express a slight squeeze of the finger-tips, something more like tickling than a serious pinch. Let us use that word. In conversation with animals, language loses nothing by remaining simple. The Glow-worm gives tweaks to the Snail.

He doles them out methodically, without hurrying, and takes a brief rest after each of them, as though to find out what effect has been produced. The number of tweaks is not great: half a dozen at most, which are enough to make the Snail motionless, and to rob him of all feeling. That other pinches are administered later, at the time of eating, seems very likely, but I cannot say anything for certain on that subject. The first few, [[58]]however—there are never many—are enough to prevent the Snail from feeling anything, thanks to the promptitude of the Glow-worm, who, at lightning speed, darts some kind of poison into his victim by means of his grooved hooks.

There is no doubt at all that the Snail is made insensible to pain. If, when the Glow-worm has dealt some four or five of his twitches, I take away the victim and prick it with a fine needle, there is not a quiver in the wounded flesh, there is not the smallest sign of life. Moreover, I occasionally chance to see Snails attacked by the Lampyris while they are creeping along the ground, the foot slowly crawling, the tentacles swollen to their full extent. A few disordered movements betray a brief excitement on the part of the Snail, and then everything ceases: the foot no longer crawls, the front-part loses its graceful curve, the tentacles become limp and give way under their own weight, dangling feebly like a broken stick. The Snail, to all appearance, is dead.

He is not, however, really dead. I can bring him to life again. When he has been for two or three days in a condition that is neither life nor death I give him a shower-bath. In about a couple of days my prisoner, so lately injured by the Glow-worm’s treachery, is restored to his usual state. He revives, he recovers movement [[59]]and sensibility. He is affected by the touch of a needle; he shifts his place, crawls, puts out his tentacles, as though nothing unusual had occurred. The general torpor, a sort of deep drunkenness, has vanished outright. The dead returns to life.

Human science did not invent the art of making a person insensible to pain, which is one of the triumphs of surgery. Far back in the centuries the Glow-worm, and apparently others too, was practising it. The surgeon makes us breathe the fumes of ether or chloroform: the insect darts forth from his fangs very tiny doses of a special poison.

When we consider the harmless and peaceful nature of the Snail it seems curious that the Glow-worm should require this remarkable talent. But I think I know the reason.