Social Life in the Insect World

by Jean-Henri Fabre

But as the acorn matures this layer becomes more solid in its consistency. The soft tissues harden; the moist tissues dry up. There is a period during which the acorn fulfils to perfection the conditions most conducive to the welfare of the grub. At an earlier period matters would not have reached the desired stage; at a later period the acorn would be too mature.

The exterior of the acorn gives no indication whatever of the progress of this internal cookery. In order not to inflict unsuitable food on the grub, the mother beetle, not sufficiently informed by the look of the acorn, is thus obliged to taste, at the end of her trunk, the tissues at the base of the cup.

The nurse, before giving her charge a spoonful of broth, tests it by tasting it. In the same way the mother beetle plunges her trunk into the base of the cup, to test the contents before bestowing them upon her offspring. If the food is recognised as being satisfactory the egg is laid; if not, the perforation is abandoned without more ado. This explains the perforations which serve no purpose, in spite of so much labour; the tissues at the base of the cup, being carefully tested, are not found to be in the required condition. The elephant-beetles are difficult to please and take infinite pains when the first mouthful of the grub is in question. To place the egg in a position where the new-born grub will find light and juicy and easily digested nutriment is not enough for those far-seeing mothers; their cares look beyond this point. An intermediary period is desirable, which will lead the little larva from the delicacies of its first hours to the diet of hard acorn. This intermediary period is passed in the gallery, the work of the maternal beak. There it finds the crumbs, the shavings bitten off by the chisels of the rostrum. Moreover, the walls of the tunnel, which are softened by mortification, are better suited than the rest of the acorn to the tender mandibles of the larva.

Before setting to work on the cotyledons the grub does, in fact, commence upon the contents and walls of this tiny passage. It first consumes the shavings lying loose in the passage; it devours the brown fragments adhering to the walls; finally, being now sufficiently strengthened, it attacks the body of the acorn, plunges into it, and disappears. The stomach is ready; the rest is a blissful feast.

This intermediary tunnel must be of a certain length, in order to satisfy the needs of infancy, so the mother must labour at the work of drilling. If the perforation were made solely with the purpose of tasting the material at the base of the acorn and recognising its degree of maturity, the operation might be very much shorter, since the hole could be sunk through the cup itself from a point close to the base. This fact is not unrecognised; I have on occasion found the insect perforating the scaly cup.

In such a proceeding I see the attempt of a gravid mother pressed for time to obtain prompt information. If the acorn is suitable the boring will be recommenced at a more distant point, through the surface of the acorn itself. When an egg is to be laid the rule is to bore the hole from a point as distant as is practicable from the base—as far, in short, as the length of the rostrum will permit.

What is the object of this long perforation, which often occupies more than half the day? Why this tenacious perseverance when, not far from the stalk, at the cost of much less time and fatigue, the rostrum could attain the desired point—the living spring from which the new-born grub is to drink? The mother has her own reasons for toiling in this manner; in doing thus she still attains the necessary point, the base of the acorn, and at the same time—a most valuable result—she prepares for the grub a long tube of fine, easily digested meal.

But these are trivialities! Not so, if you please, but high and important matters, speaking to us of the infinite pains which preside over the preservation of the least of things; witnesses of a superior logic which regulates the smallest details.

The Balaninus, so happily inspired as a mother, has her place in the world and is worthy of notice. So, at least, thinks the blackbird, which gladly makes a meal of the insect with the long beak when fruits grow rare at the end of autumn. It makes a small mouthful, but a tasty, and is a pleasant change after such olives as yet withstand the cold.

And what without the blackbird and its rivalry of song were the reawakening of the woods in spring? Were man to disappear, annihilated by his own foolish errors, the festival of the life-bringing season would be no less worthily observed, celebrated by the fluting of the yellow-billed songster.