Among the solitary bees there are so many curious circumstances to be described, that a single volume would not suffice to contain the particulars; we shall here only relate such as concern their habitations. One of these forms its nest under ground, which is composed of several cells artfully let into each other, but not covered with a common inclosure; each cell consists of two or three membranes, inexpressibly fine, and placed over each other. The cavity, in which the nest is placed, is smeared over with a layer of matter, like that of which the cells are formed, and apparently similar to the viscous humour which snails spread in their passage from one place to another, and it is probable that they are formed of the same materials; this substance, though of so delicate a nature, gives them such a degree of consistency, that they may be handled without altering their form. An egg is deposited at the bottom of each cell, where, after it is hatched, the worm finds itself in the midst of a plentiful stock of provision; for in each cell there is placed a quantity of paste, or a kind of wax, which is to serve as food for the worm, and support the wall of the cell. The worm is also instructed so to conduct itself, and eat this food, as to leave sufficient props for supporting the walls of its apartment. Many species of these bees content themselves with penetrating into the earth, scooping out hollow cavities therein, polishing the walls, then depositing an egg and a sufficient quantity of provisions.
There is another species, that forms its nest under ground with remarkable industry; this bee generally makes a perpendicular hole in the earth about three inches deep, and cylindrical, till within about three-fourths of an inch of the bottom, when it begins to enlarge; as soon as the bee has given it the suitable proportions, it proceeds to line not only the whole inside of its dwelling, but round the entrance; the substance with which it is lined is of a crimson colour, and looks like satin. From this circumstance Reaumur[95] terms it the tapestry bee. This tapestry or lining is formed of fragments of the flowers of the wild poppy, which she cuts out curiously, and then seizing them with her legs, conveys them to her nest. If the pieces are wrinkled, she first straightens and then affixes them to her walls with wonderous art; she generally applies two layers of these fragments one over the other. If the piece she has cut and transported be too large for the place she intends it for, she clips off the superfluous parts and conveys the shreds out of the apartment. After the bee has lined her cell, she fills it nearly half an inch deep with a paste proper to nourish the larva when hatched from the egg; when the bee has amassed a sufficient quantity of paste, she then takes her tapestry, and folds it over the paste and egg, which are by these means inclosed as it were in a bag of paste; this done, she fills up with earth the empty space that is above the bag. There is another bee which does the same with rose-leaves, and in the substance of a thick post. A friend of mine had a piece of wood cut from a strong post that supported the roof of a cart-house, full of these cells or round holes, three-eighths of an inch in diameter, and about three-fourths deep, each of which was filled with these rose-leaf cases finely covered in at top and bottom.
[95] Reaumur Memoires pour l’Histoire des Insectes, edit. 8vo. tom. 6, partie 1, p. 170.
The mason bee is so called by Reaumur from the manner of its building its nest. These bees collect with their jaws small parcels of earth and sand, which they glue together with a strong cement furnished from the proboscis; and of this they form a simple but commodious habitation, which is generally placed along walls that are exposed to the south. Each nest resembles a lump of rude earth, of about six or seven inches diameter, thrown against the wall; the labour of constructing so large an edifice must be very great, as the bee can only carry a few grains at a time. The exterior form is rude and irregular, but the construction and art exhibited in the interior parts make up for this seeming defect; it is generally divided into twelve or fifteen cells, separated from each other by a thick wall; in each of these an egg is deposited by the parent bee. The cells are not constructed all at once, for when one is finished, she places an egg therein, with a sufficient quantity of honey to nourish the larva; she then builds another. When the insect is arrived at a proper state, it penetrates through its inclosures by means of its strong jaws. When all the bees have quitted the nest, there are as many holes on the surface thereof as there are cells within. We find no neutral bees among this species, or at least we do not know of any being yet discovered.
Another species of the solitary bee (apis centuncularis, Linn.) constructs her nest in pieces of rotten wood, and has therefore been called the carpenter bee.[96] She divides it into stages, disposing them sometimes in three rows, with partitions curiously left between each; in these she deposits her eggs, with the food necessary for the young ones when hatched. They separate the wood in a very expeditious manner, by dividing its ligneous fibres or threads, till they have made a proper sized hole.
[96] Geoffroy Hist. abregee des Insectes, tom. 2, p. 401.
The art and sagacity displayed by another bee,[97] whose nest is constructed of single pieces of leaves, is truly wonderful. The nest itself is cylindrical, formed of several cells, placed one within the other, as thimbles are in a hard-ware shop. The cells consist of several pieces cut from one leaf, of forms and proportions proper to coincide with the place each is intended to occupy. The outer case or cover is formed with equal care and exactness. In a word, says Bonnet, there is so much exactness, symmetry, uniformity, and skill, in this little master-piece, that we should not believe it to be the work of a fly, if we did not know at what school she learnt the art of constructing it. In each cell the mother deposits an almost liquid substance, and yet so nicely are the cells formed, as not to suffer any of this substance to be lost. But for a minute account of the works of this bee, and the curious mechanism of its cells, we must refer the reader to Reaumur’s admirable history of insects.
[97] Reaumur Memoires pour l’Histoire des Insectes, tom. 6, par. 1, p. 122.
The proceedings of the mason ichneumon wasp,[98] sphex, Linn. are totally different from those of the common wasp, though equally curious. It generally begins its work in May, and continues it for the greatest part of June. The true object of her labour seems to be the digging of a hole a few inches deep in the ground; yet in the constructing of this, she forms a hollow tube above ground, the base of which is the aperture of the hole, and which is raised as high above ground as the hole is deep below; it is formed with a great deal of care, resembling a gross kind of fillagree work, consisting of the sand drawn from the hole. The sand out of which she excavates her cell, is nearly as hard as a common stone; this it readily softens with a penetrating liquor with which she is well provided; a drop or two of it is imbibed immediately by the sand on which it falls, which is instantly rendered so soft, that she can separate and knead it with her teeth and fore feet, forming it into a small ball, which she places on the edge of the hole as the foundation stone of the pillar she is going to erect; the whole of it is formed of such balls, ranged circularly, and then placed one above the other. She leaves her work at intervals, probably in order to renew her stock of that liquor which is so necessary for her operations. These intervals are of short duration; she soon returns, and labours with so much activity and ardour, that in a few hours she will dig a hole two or three inches deep, and raise a hollow pillar two inches high. After the column has been raised a certain height perpendicular from the ground, it begins to curve a little, which curvature increases till it is finished, though the cylindrical form is maintained: she constructs several of these holes all of the same form, and for the same purpose. It is easy to see why the hole was dug in the ground; that it was destined to receive an egg; but it is not so easy to perceive why the tube of sand was formed. By attending to the labours of the wasp, one end, however, may be discovered; it will be found to serve the purpose of a scaffold, and that the balls are as useful to the wasp, as materials, &c. to the mason; and are therefore placed as much within her reach as possible. She uses them to stop and fill up the hole after she has deposited an egg therein, so that the pillar is then destroyed, and not the least remains left in the nest. The parent wasp generally leaves ten or twelve worms as provision necessary and proper for the growth of the young larva: no purveyor could take better precautions than our wasp, for she has received her instructions from HIM who provides for the necessities of all his creatures. In selecting the worms, she chooses those of a proper size, that they may be sufficient in quantity, and of an age that will not be in danger of perishing with hunger, in which case they would have been corrupted; she therefore selects them when they have their full growth. It is also observed, that if she choose a larger sort, she gives a less number of them, and so reciprocally.
[98] Reaumur Mem. pour l’Histoire des Insectes, tom. xi. par. 2, p. 9.