The Life of the Scorpion

by Jean-Henri Fabre

On the terebinth, the simplest of these [[256]]dwellings consists of a lateral fold of the leaf, the edge of which is turned back over the upper surface and fastened to it without losing its green colour. This hem gives a very low-roofed dwelling: the floor and the ceiling meet. Therefore, being unduly confined, the family is not numerous. The timid maker of these green hems bears the name of Pemphigus pallidus, DERB. She is called pale because she has not the knack of painting her house purple.

Elsewhere the lateral fold, still turned over the upper surface of the leaf, grows much thicker, swells with fleshy tissue, develops wrinkles, assumes a crimson hue and becomes a short, hollow, spindle-shaped growth. This home, a fairly successful imitation of the seed-pods of the peony and the larkspur, belongs to the Pemphigus follicularius, PASS.

Elsewhere again the fold, which at first is made in the plane of the leaf, is now bent down at right angles under the leaf, becoming an ear-shaped appendage, a knotted, fleshy crescent, with a straw-yellow as its prevailing colour. This is the work of the Pemphigus semilunaris, PASS. [[257]]

The spherical galls take higher rank in the Plant-louse’s art. They are smooth, pale-yellow globes, varying in size from that of a cherry to that of an average apricot. They hang from the base of the leaves, which, despite these monstrous bladders, retain their normal colour, and, in all other respects, their normal shape. The insect which inflates these pretty capsules is Pemphigus utricularius, PASS.

But the most remarkable structures are the horn-shaped galls, truly Cyclopean monuments compared with their minute builders. Some attain a length of nine inches and are as thick as the neck of a claret-bottle. Grouped in threes or fours at the tips of the upper branches, they form barbaric trophies, twisted and fantastic danger-signals which might have graced the brows of some Alpine Ibex.

The other galls all fall off with the leaves; not a trace of them remains on the tree in winter, and even these firmly cemented to their bough, last for a long time. Only the protracted assaults of wind and weather will destroy them completely. The base itself does not easily disappear. Next year [[258]]it is still in its place, but dilapidated and reduced to the broken stump of a horn of plenty packed with the waxy felt that clothed the population in the days of its prosperity. In these palaces lived Pemphigus cornicularius, PASS.

The purple pitchers of the first phase are provisional stations in which the Lice prepare for wholesale colonization. Each of these humble cottages has its Plant-louse from the foot of the tree. The solitary, who was herself hatched from a germ, makes haste to give birth to live youngsters, who gradually spread over the new leaves, and die. Then the true galls come, the great cities which will provide room for several generations. Here again, all the five classes of specialists between whom we have discriminated set to work, all labouring independently at the first filling out of the cabins. Mutual assistance will come later.

May arrives; and already the simpler galls begin to grow: the lateral folds which, bent back upon the edge, become so many green hems. Beneath the awl of the black Louse, patiently pricking away at the leaf, a narrow border curves inwards from the [[259]]edge. The line of attack measures a couple of centimetres.[2] When it has worked long enough at this or that point, the tiny insect changes its place and goes elsewhere to begin all over again, standing motionless while its implement performs its functions.

Now what is the atom doing thus to warp what would be flat under natural conditions? Merely implanting its sucker. The prick of a needle, however skilfully guided, would bruise the tissues without affecting their form. The little insect must therefore instil a certain virus, which provokes an exaggerated flow of sap; it injects an irritant poison and the plant reacts by the swelling of the wounded parts.

And now the hem is growing wider, with a slowness that defies our scouting: as well try to follow with the eyes the growth of a blade of grass. It is now a slanting roof, a gaping fold. The Louse is in the angle, at her post, doing her duty as a turncock. With her fine probe she stimulates and controls the flow of sap. In twenty-four hours the roof completes its descent, pressing tightly against the leaf. It is a [[260]]lowered trap-door; but the mechanism of the structure works with such caution that the tiny insect, far from being crushed between the two thicknesses of leaf, retains its liberty of movement and moves about inside the fold as it would do in the open air.