Bramble-Bees and Others

by Jean-Henri Fabre

The large tubes she will use only in grave emergencies and I am unable to state exactly what these exceptional circumstances are. Perhaps she decides to make use of those roomy dwellings when the eggs have to be laid at once and there is no other shelter in the neighbourhood. While my cylinder-hives gave me plenty of well-filled reeds of the first and second class, they provided me with but half-a-dozen at most of the third, notwithstanding my precaution to furnish the apparatus with a varied assortment.

The Osmia's repugnance to big cylinders is quite justified. The work in fact is longer and more costly when the tubes are wide. An inspection of a nest constructed under these conditions is enough to convince us. It now consists not of a string of chambers obtained by simple transverse partitions, but of a confused heap of clumsy, many-sided compartments, standing back to back, with a tendency to group themselves in storeys without succeeding in doing so, because any regular arrangement would mean that the ceilings possessed a span which it is not in the builder's power to achieve. The edifice is not a geometrical masterpiece and it is even less satisfactory from the point of view of economy. In the previous constructions, the sides of the reed supplied the greater part of the walls and the work was limited to one partition for each cell. Here, except at the actual periphery, where the tube itself supplies a foundation, everything has to be obtained by sheer building: the floor, the ceiling, the walls of the many-sided compartment are one and all made of mortar. The structure is almost as costly in materials as that of the Chalicodoma or the Pelopaeus.

It must be pretty difficult, too, when one thinks of its irregularity. Fitting as best she can the projecting angles of the new cell into the recessed corners of the cell already built, the Osmia runs up walls more or less curved, upright or slanting, which intersect one another at various points, so that each compartment requires a new and complicated plan of construction, which is very different from the circular-partition style of architecture, with its row of parallel dividing-disks. Moreover, in this composite arrangement, the size of the recesses left available by the earlier work to some extent decides the assessment of the sexes, for, according to the dimensions of those recesses, the walls erected take in now a larger space, the home of a female, and now a smaller space, the home of a male. Roomy quarters therefore have a double drawback for the Osmia: they greatly increase the outlay in materials; and also they establish in the lower layers, among the females, males who, because of their earlier hatching, would be much better placed near the mouth of the nest. I am convinced of it: if the Osmia refuses big reeds and accepts them only in the last resort, when there are no others, it is because she objects to additional labour and to the mixture of the sexes.

The Snail-shell, then, is but an indifferent home for her, which she is quite ready to abandon should a better offer. Its expanding cavity represents an average between the favourite small cylinder and the unpopular large cylinder, which is accepted only when there is no other obtainable. The first whorls of the spiral are too narrow to be of use to the Osmia, but the middle ones have the right diameter for cocoons arranged in single file. Here things happen as in a first-class reed, for the helical curve in no way affects the method of structure employed for a rectilinear series of cells. Circular partitions are erected at the required distances, with or without a serving-hatch, according to the diameter. These mark out the first cells, one after the other, which are reserved solely for the females. Then comes the last whorl, which is much too wide for a single row of cells; and here we once more find, exactly as in a wide reed, a costly profusion of masonry, an irregular arrangement of the cells and a mixture of the sexes.

Having said so much, let us go back to the Osmia of the quarries. Why, when I offer them simultaneously Snail-shells and reeds of a suitable size, do the old frequenters of the shells prefer the reeds, which in all probability have never before been utilized by their race? Most of them scorn the ancestral dwelling and enthusiastically accept my reeds. Some, it is true, take up their quarters in the Snail-shell; but even among these a goodly number refuse my new shells and return to their birth-place, the old Snail-shell, in order to utilize the family property, without much labour, at the cost of a few repairs. Whence, I ask, comes this general preference for the cylinder, never used hitherto? The answer can be only this: of two lodgings at her disposal the Osmia selects the one that provides a comfortable home at a minimum outlay. She economizes her strength when restoring an old nest; she economizes it when replacing the Snail-shell by the reed.

Can animal industry, like our own, obey the law of economy, the sovran law that governs our industrial machine even as it governs, at least to all appearances, the sublime machine of the universe? Let us go deeper into the question and bring other workers into evidence, those especially who, better equipped perhaps and at any rate better fitted for hard work, attack the difficulties of their trade boldly and look down upon alien establishments with scorn. Of this number are the Chalicodomae, the Mason-bees proper.

The Mason-bee of the Pebbles does not make up her mind to build a brand-new dome unless there be a dearth of old and not quite dilapidated nests. The mothers, sisters apparently and heirs-at-law to the domain, dispute fiercely for the ancestral abode. The first who, by sheer brute force, takes possession of the dome, perches upon it and, for long hours, watches events while polishing her wings. If some claimant puts in an appearance, forthwith the other turns her out with a volley of blows. In this way the old nests are employed so long as they have not become uninhabitable hovels.

Without being equally jealous of the maternal inheritance, the Mason-bee of the Sheds eagerly uses the cells whence her generation issued. The work in the huge city under the eaves begins thus: the old cells, of which, by the way, the good-natured owner yields a portion to Latreille's Osmia and to the Three-horned Osmia alike, are first made clean and wholesome and cleared of broken plaster and then provisioned and shut. When all the accessible chambers are occupied, the actual building begins with a new stratum of cells upon the former edifice, which becomes more and more massive from year to year.

The Mason-bee of the Shrubs, with her spherical nests hardly larger than walnuts, puzzled me at first. Does she use the old buildings or does she abandon them for good? To-day perplexity makes way for certainty: she uses them very readily. I have several times surprised her lodging her family in the empty rooms of a nest where she was doubtless born herself. Like her kinswoman of the Pebbles, she returns to the native dwelling and fights for its possession. Also, like the dome-builder, she is an anchorite and prefers to cultivate the lean inheritance alone. Sometimes, however, the nest is of exceptional size and harbours a crowd of occupants, who live in peace, each attending to her business, as in the colossal hives in the sheds. Should the colony be at all numerous and the estate descend to two or three generations in succession, with a fresh layer of masonry each year, the normal walnut-sized nest becomes a ball as large as a man's two fists. I have gathered on a pine-tree a nest of the Mason-bee of the Shrubs that weighed a kilogram (2.205 pounds avoirdupois.—Translator's Note.) and was the size of a child's head. A twig hardly thicker than a straw served as its support. The casual sight of that lump swinging over the spot on which I had sat down made me think of the mishap that befell Garo. (The hero of La Fontaine's fable, "Le Gland et la Citrouille," who wondered why acorns grew on such tall trees and pumpkins on such low vines, until he fell asleep under one of the latter and a pumpkin dropped upon his nose.—Translator's Note.) If such nests were plentiful in the trees, any one seeking the shade would run a serious risk of having his head smashed.

After the Masons, the Carpenters. Among the guild of wood-workers, the most powerful is the Carpenter-bee (Xylocopa violacea (Cf. "The Life of the Spider": chapter 1.—Translator's Note.)), a very large Bee of formidable appearance, clad in black velvet with violet-coloured wings. The mother gives her larvae as a dwelling a cylindrical gallery which she digs in rotten wood. Useless timber lying exposed to the air, vine-poles, large logs of fire-wood seasoning out of doors, heaped up in front of the farmhouse porch, stumps of trees, vine-stocks and big branches of all kinds are her favourite building-yards. A solitary and industrious worker, she bores, bit by bit, circular passages the width of one's thumb, as clear-cut as though they were made with an auger. A heap of saw-dust accumulates on the ground and bears witness to the severity of the task. Usually, the same aperture is the entrance to two or three parallel corridors. With several galleries there is accommodation for the entire laying, though each gallery is quite short; and the Bee thus avoids those long series which always create difficulties when the moment of hatching arrives. The laggards and the insects eager to emerge are less likely to get in each other's way.