Bramble-Bees and Others

by Jean-Henri Fabre

No, the chaffinch is not perplexed by so small a matter; he is an expert in materials, he understands botanical equivalents. In the absence of the branches of the evernias, he picks the long beards of the usneas, the wartlike rosettes of the parmelias, the membranes of the stictises torn away in shreds; if he can find nothing better, he makes shift with the bushy tufts of the cladonias. As a practical lichenologist, when one species is rare or lacking in the neighbourhood, he is able to fall back on others, varying greatly in shape, colour and texture. And, if the impossible happened and lichen failed entirely, I credit the Chaffinch with sufficient talent to be able to dispense with it and to build the foundations of his nest with some coarse moss or other.

What the worker in lichens tells us the other weavers of textile materials confirm. Each has his favourite flora, which hardly ever varies when the plant is easily accessible and which can be supplemented by plenty of others when it is not. The bird's botany would be worth examining; it would be interesting to draw up the industrial herbal of each species. In this connection, I will quote just one instance, so as not to stray too far from the subject in hand.

The Red-backed Shrike (Lanius collurio), the commonest variety in my district, is noteworthy because of his savage mania for forked gibbets, the thorns in the hedgerows whereon he impales the voluminous contents of his game-bag—little half-fledged birds, small Lizards, Grasshoppers, caterpillars, Beetles—and leaves them to get high. To this passion for the gallows, which has passed unnoticed by the country-folk, at least in my part, he adds another, an innocent botanical passion, which is so much in evidence that everybody, down to the youngest bird's-nester, knows all about it. His nest, a massive structure, is made of hardly any other materials than a greyish and very fluffy plant, which is found everywhere among the corn. This is the Filago spathulata of the botanists; and the bird also makes use, though less frequently, of the Filago germanica, or common cotton-rose. Both are known in Provencal by the name herbo dou tarnagas, or Shrike-herb. This popular designation tells us plainly how faithful the bird is to its plant. To have struck the agricultural labourer, a very indifferent observer, the Shrike's choice of materials must be remarkably persistent.

Have we here a taste that is exclusive? Not in the least. Though cotton-roses of all species are plentiful on level ground, they become scarce and impossible to find on the parched hills. The bird, on its side, is not given to journeys of exploration and takes what it finds to suit it in the neighbourhood of its tree or hedge. But on arid ground, the Micropus erectus, or upright micropus, abounds and is a satisfactory substitute for the Filago so far as its tiny, cottony leaves and its little fluffy balls of flowers are concerned. True, it is short and does not lend itself well to weaver's work. A few long sprigs of another cottony plant, the Helichrysum staechas, or wild everlasting, inserted here and there, will give body to the structure. Thus does the Shrike manage when hard up for his favourite materials: keeping to the same botanical family, he is able to find and employ substitutes among the fine cotton-clad stalks.

He is even able to leave the family of the Compositae and to go gleaning more or less everywhere. Here is the result of my botanizings at the expense of his nests. We must distinguish between two genera in the Shrike's rough classification: the cottony plants and the smooth plants. Among the first, my notes mention the following: Convolvulus cantabrica, or flax-leaved bindweed; Lotus symmetricus, or bird's-foot trefoil; Teucrium polium, or poly; and the flowery heads of the Phragmites communis, or common reed. Among the second are these: Medicago lupulina, or nonesuch; Trifolium repens, or white clover; Lathyrus pratensis, or meadow lathyrus; Capsella bursa pastoris, or shepherd's purse; Vicia peregrina, or broad-podded vetch; Convolvulus arvensis, or small bindweed; Pterotheca nemausensis, a sort of hawkweed; and Poa pratensis, or smooth-stalked meadow-grass. When it is downy, the plant forms almost the whole nest, as is the case with the flax-leaved bindweed; when smooth, it forms only the framework, destined to support a crumbling mass of micropus, as is the case with the small bindweed. When making this collection, which I am far from giving as the birds' complete herbarium, I was struck by a wholly unexpected detail: of the various plants, I found only the heads still in bud; moreover, all the sprigs, though dry, possessed the green colouring of the growing plant, a sign of swift desiccation in the sun. Save in a few cases, therefore, the Shrike does not collect the dead and withered remains: it is from the growing plants that he reaps his harvest, mowing them down with his beak and leaving the sheaves to dry in the sun before using them. I caught him one day hopping about and pecking at the twigs of a Biscayan bindweed. He was getting in his hay, strewing the ground with it.

The evidence of the Shrike, confirmed by that of all the other workers—weavers, basket-makers or woodcutters—whom we may care to call as witnesses, shows us what a large part must be assigned to discernment in the bird's choice of materials for its nest. Is the insect as highly gifted? When it works with vegetable matter, is it exclusive in its tastes? Does it know only one definite plant, its special province? Or has it, for employment in its manufactures, a varied flora, in which its discernment exercises a free choice? For answers to these questions we may look, above all, to the Leaf-cutting Bees, the Megachiles. Reaumur has told the story of their industry in detail; and I refer the reader who wishes for further particulars to the master's Memoirs.

The man who knows how to use his eyes in his garden will observe, some day or other, a number of curious holes in the leaves of his lilac- and rose-trees, some of them round, some oval, as if idle but skilful hands had been at work with the pinking-iron. In some places, there is scarcely anything but the veins of the leaves left. The author of the mischief is a grey-clad Bee, a Megachile. For scissors, she has her mandibles; for compasses, producing now an oval and anon a circle, she has her eye and the pivot of her body. The pieces cut out are made into thimble-shaped wallets, destined to contain the honey and the egg: the larger, oval pieces supply the floor and sides; the smaller, round pieces are reserved for the lid. A row of these thimbles, placed one on top of the other, up to a dozen or more, though often there are less: that is, roughly, the structure of the Leaf-cutter's nest.

When taken out of the recess in which the mother has manufactured it, the cylinder of cells seems to be an indivisible whole, a sort of tunnel obtained by lining with leaves some gallery dug underground. The real thing does not correspond with its appearance: under the least pressure of the fingers, the cylinder breaks up into equal sections, which are so many compartments independent of their neighbours as regards both floor and lid. This spontaneous break up shows us how the work is done. The method agrees with those adopted by the other Bees. Instead of a general scabbard of leaves, afterwards subdivided into compartments by transverse partitions, the Megachile constructs a string of separate wallets, each of which is finished before the next is begun.

A structure of this sort needs a sheath to keep the pieces in place while giving them the proper shape. The bag of leaves, in fact, as turned out by the worker, lacks stability; its numerous pieces, not glued together, but simply placed one after the other, come apart and give way as soon as they lose the support of the tunnel that keeps them united. Later, when it spins its cocoon, the larva infuses a little of its fluid silk into the gaps and solders the pieces to one another, especially the inner ones, so much so that the insecure bag in due course becomes a solid casket whose component parts it is no longer possible to separate entirely.

The protective sheath, which is also a framework, is not the work of the mother. Like the great majority of the Osmiae, the Megachiles do not understand the art of making themselves a home straight away: they want a borrowed lodging, which may vary considerably in character. The deserted galleries of the Anthophorae, the burrows of the fat Earth-worms, the tunnels bored in the trunks of trees by the larva of the Cerambyx-beetle (The Capricorn, the essay on which has not yet been published in English.—Translator's Note.), the ruined dwellings of the Mason-bee of the Pebbles, the Snail-shell nests of the Three-horned Osmia, reed-stumps, when these are handy, and crevices in the walls are all so many homes for the Leaf-cutters, who choose this or that establishment according to the tastes of their particular genus.