Fabre's Book of Insects

by Jean-Henri Fabre

And this half-alive object, this nothing-at-all, is capable of marvellous foresight. It knows hardly anything of the present, but it sees very clearly into the future.

For three years on end the larva wanders about in the heart of the trunk. It goes up, goes down, turns to this side and that; it leaves one vein for another of better flavour, but without ever going too far from the inner depths, where the temperature is milder than near the surface, and greater safety reigns. But a day is at hand when the hermit must leave its safe retreat and face the perils of the outer world. Eating is not everything, after all; we have to get out of this.

But how? For the grub, before leaving the trunk, must turn into a long-horned Beetle. And though the grub, being well equipped with tools and muscular strength, finds no difficulty in boring through the wood and going where it pleases, it by no means follows that the coming Capricorn has the same powers. The Beetle’s short spell of life must be spent in the open air. Will it be able to clear itself a way of escape?

It is quite plain, at all events, that the Capricorn will be absolutely unable to make use of the tunnel bored by the grub. This tunnel is a very long and very irregular [[218]]maze, blocked with great heaps of wormed wood. It grows constantly smaller and smaller as it approaches the starting-point, because the larva entered the trunk as slim as a tiny bit of straw, whereas to-day it is as thick as one’s finger. In its three years’ wanderings it always dug its gallery to fit the size of its body. Evidently the road of the larva cannot be the Capricorn’s way out. His overgrown antennæ, his long legs, his inflexible armour-plates would find the narrow, winding corridor impassable. The passage would have to be cleared of its wormed wood, and, moreover, greatly enlarged. It would be easier to attack the untouched timber and dig straight ahead. Is the insect capable of doing so? I determined to find out.

I made some cavities of suitable size in some oak logs that had been chopped in two, and in each of these cells I placed a Capricorn that had just been transformed from the grub. I then joined the two sides of the logs, fastening them together with wire. When June came I heard a sound of scraping inside the logs, and waited anxiously to see if the Capricorns would appear. They had hardly three-quarters of an inch to pierce. Yet not one came out. On opening the logs I found all my captives dead. A pinch of sawdust represented all they had done.

I had expected more from their sturdy mandibles. In spite of their boring-tools the hermits died for lack of [[219]]skill. I tried enclosing some in reed-stumps, but even this comparatively easy work was too much for them. Some freed themselves, but others failed.

Notwithstanding his stalwart appearance the Capricorn cannot leave the tree-trunk by his own unaided efforts. The truth is that his way is prepared for him by the grub—that bit of intestine.

Some presentiment—to us an unfathomable mystery—causes the Capricorn-grub to leave its peaceful stronghold in the very heart of the oak and wriggle towards the outside, where its foe the Woodpecker is quite likely to gobble it up. At the risk of its life it stubbornly digs and gnaws to the very bark. It leaves only the thinnest film, the slenderest screen, between itself and the world at large. Sometimes, even, the rash one opens the doorway wide.

This is the Capricorn’s way out. The insect has but to file the screen a little with his mandibles, to bump against it with his forehead, in order to bring it down. He will even have nothing at all to do when the doorway is open, as often happens. The unskilled carpenter, burdened with his extravagant head-dress, will come out from the darkness through this opening when the summer heat arrives.

As soon as the grub has attended to the important business of making a doorway into the world, it begins to busy itself with its transformation into a Beetle. [[220]]First, it requires space for the purpose. So it retreats some distance down its gallery, and in the side of the passage digs itself a transformation-chamber more sumptuously furnished and barricaded than any I have ever seen. It is a roomy hollow with curved walls, three to four inches in length and wider than it is high. The width of the cell gives the insect a certain degree of freedom of movement when the time comes for forcing the barricade, which is more than a close-fitting case would do.