Bramble-Bees and Others

by Jean-Henri Fabre

If we had not already seen the same thing with the Leaf-cutters, this would be the place to enlarge upon the useless tasks undertaken by the insect when, with its ovaries apparently depleted, it goes on spending its strength with no maternal object in view and for the sole pleasure of work. I have come across several reeds stopped up with flock though containing nothing at all, or else furnished with one, two or three cells devoid of provisions or eggs. The ever-imperious instinct for gathering cotton and felting it into purses and heaping it into barricades persists, fruitlessly, until life fails. The Lizard's tail wriggles, curls and uncurls after it is detached from the animal's body. In these reflex movements, I seem to see not an explanation, certainly, but a rough image of the industrious persistency of the insect, still toiling away at its business, even when there is nothing useful left to do. This worker knows no rest but death.

I have said enough about the dwelling of the Diadem Anthidium; let us look at the inhabitant and her provisions. The honey is pale-yellow, homogeneous and of a semifluid consistency, which prevents it from trickling through the porous cotton bag. The egg floats on the surface of the heap, with the end containing the head dipped into the paste. To follow the larva through its progressive stages is not without interest, especially on account of the cocoon, which is one of the most singular that I know. With this object in view, I prepare a few cells that lend themselves to observation. I take a pair of scissors, slice a piece off the side of the cotton-wool purse, so as to lay bare both the victuals and the consumer, and place the ripped cell in a short glass tube. During the first few days, nothing striking happens. The little grub, with its head still plunged in the honey, slakes its thirst with long draughts and waxes fat. A moment comes...But let us go back a little farther, before broaching this question of sanitation.

Every grub, of whatever kind, fed on provisions collected by the mother and placed in a narrow cell is subject to conditions of health unknown to the roving grub that goes where it likes and feeds itself on what it can pick up. The first, the recluse, is no more able than the second, the gadabout, to solve the problem of a food which can be entirely assimilated, without leaving an unclean residue. The second gives no thought to these sordid matters: any place suits it for getting rid of that difficulty. But what will the other do with its waste matter, cooped up as it is in a tiny cell stuffed full of provisions? A most unpleasant mixture seems inevitable. Picture the honey-eating grub floating on liquid provisions and fouling them at intervals with its excretions! The least movement of the hinder-part would cause the whole to amalgamate; and what a broth that would make for the delicate nursling! No, it cannot be; those dainty epicures must have some method of escaping these horrors.

They all have, in fact, and most original methods at that. Some take the bull by the horns, so to speak, and, in order not to soil things, refrain from uncleanliness until the end of the meal: they keep the dropping-trap closed as long as the victuals are unfinished. This is a radical scheme, but not in every one's power, it appears. It is the course adopted, for instance, by the Sphex-wasps and the Anthophora-bees, who, when the whole of the food is consumed, expel at one shot the residues amassed in the intestines since the commencement of the repast.

Others, the Osmiae in particular, accept a compromise and begin to relieve the digestive tract when a suitable space has been made in the cell through the gradual disappearance of the victuals. Others again—more hurried these—find means of obeying the common law pretty early by engaging in stercoral manufactures. By a stroke of genius, they make the unpleasant obstruction into building-bricks. We already know the art of the Lily-beetle (Crioceris merdigera. Fabre's essay on this insect has not yet been translated into English; but readers interested in the matter will find a full description in "An Introduction to Entomology," by William Kirby, Rector of Barham, and William Spence: letter 21.—Translator's Note.), who, with her soft excrement, makes herself a coat wherein to keep cool in spite of the sun. It is a very crude and revolting art, disgusting to the eye. The Diadem Anthidium belongs to another school. With her droppings she fashions masterpieces of marquetry and mosaic, which wholly conceal their base origin from the onlooker. Let us watch her labours through the windows of my tubes.

When the portion of food is nearly half consumed, there begins and goes on to the end a frequent defecation of yellowish droppings, each hardly the size of a pin's head. As these are ejected, the grub pushes them back to the circumference of the cell with a movement of its hinder-part and keeps them there by means of a few threads of silk. The work of the spinnerets, therefore, which is deferred in the others until the provisions are finished, starts earlier here and alternates with the feeding. In this way, the excretions are kept at a distance, away from the honey and without any danger of getting mixed with it. They end by becoming so numerous as to form an almost continuous screen around the larva. This excremental awning, made half of silk and half of droppings, is the rough draft of the cocoon, or rather a sort of scaffolding on which the stones are deposited until they are definitely placed in position. Pending the piecing together of the mosaic, the scaffolding keeps the victuals free from all contamination.

To get rid of what cannot be flung outside, by hanging it on the ceiling, is not bad to begin with; but to use it for making a work of art is better still. The honey has disappeared. Now commences the final weaving of the cocoon. The grub surrounds itself with a wall of silk, first pure white, then tinted reddish-brown by means of an adhesive varnish. Through its loose-meshed stuff, it seizes one by one the droppings hanging from the scaffold and inlays them firmly in the tissue. The same mode of work is employed by the Bembex-, Stizus-and Tachytes-wasps and other inlayers, who strengthen the inadequate woof of their cocoons with grains of sand; only, in their cotton-wool purses, the Anthidium's grubs substitute for the mineral particles the only solid materials at their disposal. For them, excrement takes the place of pebbles.

And the work goes none the worse for it. On the contrary: when the cocoon is finished, any one who had not witnessed the process of manufacture would be greatly puzzled to state the nature of the workmanship. The colouring and the elegant regularity of the outer wrapper of the cocoon suggest some kind of basket-work made with tiny bits of bamboo, or a marquetry of exotic granules. I too let myself be caught by it in my early days and wondered in vain what the hermit of the cotton wallet had used to inlay her nymphal dwelling so prettily withal. To-day, when the secret is known to me, I admire the ingenuity of the insect capable of obtaining the useful and the beautiful out of the basest materials.

The cocoon has another surprise in store for us. The end containing the head finishes with a short conical nipple, an apex, pierced by a narrow shaft that establishes a communication between the inside and the out. This architectural feature is common to all the Anthidia, to the resin-workers who will occupy our attention presently, as well as to the cotton-workers. It is found nowhere outside the Anthidium group.

What is the use of this point which the larva leaves bare instead of inlaying it like the rest of the shell? What is the use of that hole, left quite open or, at most, closed at the bottom with a feeble grating of silk? The insect appears to attach great importance to it, from what I see. In point of fact, I watch the careful work of the apex. The grub, whose movements the hole enables me to follow, patiently perfects the lower end of the conical channel, polishes it and gives it an exactly circular shape; from time to time, it inserts into the passage its two closed mandibles, whose points project a little way outside; then, opening them to a definite radius, like a pair of compasses, it widens the aperture and makes it regular.