Fabre's Book of Insects

by Jean-Henri Fabre

Having made the nest safe she leaves the spot, refreshes herself after her exertions with a few mouthfuls of green stuff, and prepares to begin again.

The Grey Locust mother is armed at the tip of her body—and so are other female Locusts in varying degrees—with four short tools, arranged in pairs and shaped like a hooked fingernail. On the upper pair, which are larger than the others, these hooks are turned upwards; on the lower and smaller pair they are turned downwards. They form a sort of claw, and are scooped out slightly, like a spoon. These are the pick-axes, the boring-tools with which the Grey Locust works. With these she bites into the soil, lifting the dry earth a little, as quietly as if she were digging in soft mould. She might be working in butter; and yet what the bore digs into is hard, unyielding earth.

The best site for laying the eggs is not always found at the first attempt. I have seen the mother make five [[239]]wells one after the other before finding a suitable place. When at last the business is over, and the insect begins to rise from the hole in which she is partly buried, one can see that she is covering her eggs with milk-white foam, similar to that of the Mantis.

This foamy matter often forms a button at the entrance to the well, a knot which stands up and attracts the eye by its whiteness against the grey background of the soil. It is soft and sticky, but hardens pretty soon. When this closing button is finished the mother moves away and troubles no more about her eggs, of which she lays a fresh batch elsewhere after a few days.

Sometimes the foamy paste does not reach the surface; it stops some way down, and before long is covered with the sand that slips from the edge. But in the case of my Locusts in captivity I always know, even when it is concealed, exactly where the barrel of eggs lies. Its structure is always the same, though there are variations in detail. It is always a sheath of solidified foam. Inside, there is nothing but foam and eggs. The eggs all lie in the lower portion, packed one on top of another; and the upper part consists only of soft, yielding foam. This portion plays an important part when the young larvæ are hatched. I will call it the ascending-shaft.

The wonderful egg-casket of the Mantis is not the result of any special talent which the mother can exercise [[240]]at will. It is due to mechanism. It happens of itself. In the same way the Locusts have no industry of their own, especially devised for laying eggs in a keg of froth. The foam is produced with the eggs, and the arrangement of eggs at the bottom and centre, and froth on the outside and the top, is purely mechanical.

There are many Locusts whose egg-cases have to last through the winter, since they do not open until the fine weather returns. Though the soil is loose and dusty at first, it becomes caked together by the winter rains. Supposing that the hatching takes place a couple of inches below the surface, how is this crust, this hard ceiling, to be broken? How is the larva to come up from below? The mother’s unconscious art has arranged for that.

The young Locust finds above him, when he comes out of the egg, not rough sand and hardened earth, but a straight tunnel, with solid walls that keep all difficulties away. This ascending-shaft is full of foam, which the larva can easily penetrate, and which will bring him quite close to the surface. Here only a finger’s-breadth of serious work remains to be done.

The greater part of the journey, therefore, is accomplished without effort. Though the Locust’s building is done quite mechanically, without the least intelligence, it is certainly singularly well devised. [[241]]

The little creature has now to complete his deliverance. On leaving his shell he is of a whitish colour, clouded with light red. His progress is made by worm-like movements; and, so that it may be as easy as possible, he is hatched, like the young Grasshopper, in a temporary jacket which keeps his antennæ and legs closely fixed to his body. Like the White-faced Decticus he keeps his boring-tool at his neck. Here there is a kind of tumour that swells and subsides alternately, and strikes the obstacle before it as regularly as a piston. When I see this soft bladder trying to overcome the hardness of the earth I come to the unhappy creature’s aid, and damp the layer of soil.