Part 10

Her first care, after being roused to activity by the returning warmth of the season, is to discover a place suitable for her intended colony; and, accordingly, in the spring, wasps may be seen prying into every hole of a hedge-bank, particularly where field-mice have burrowed. Some authors report that she is partial to the forsaken galleries of the mole; but this does not accord with our observations, as we have never met with a single vespiary in any situation likely to have been frequented by moles. But though we cannot assert the fact, we think it highly probable that the deserted nest of the field-mouse, which is not uncommon in hedge-banks, may be sometimes appropriated by a mother wasp as an excavation convenient for her purpose. Yet, if she does make choice of the burrow of a field-mouse, it requires to be afterwards considerably enlarged in the interior chamber, and the entrance gallery very much narrowed.

The desire of the wasp to save herself the labour of excavation, by forming her nest where other animals have burrowed, is not without a parallel in the actions of quadrupeds, and even of birds. In the splendid continuation of Wilson's American Ornithology, by Charles L. Bonaparte (whose scientific pursuits have thrown around that name a beneficent lustre, pleasingly contrasted with his uncle's glory), there is an interesting example of this instinctive adoption of the labours of others. "In the trans-Mississippian territories of the United States, the burrowing-owl resides exclusively in the villages of the marmot, or prairie-dog, whose excavations are so commodious as to render it unnecessary that the owl should dig for himself, as he is said to do where no burrowing animals exist. The villages of the prairie-dog are very numerous and variable in their extent,--sometimes covering only a few acres, and at others spreading over the surface of the country for miles together. They are composed of slightly-elevated mounds, having the form of a truncated cone, about two feet in width at the base, and seldom rising as high as eighteen inches from the surface of the soil. The entrance is placed either at the top or on the side, and the whole mound is beaten down externally, especially at the summit, resembling a much-used footpath. From the entrance, the passage into the mound descends vertically for one or two feet, and is thence continued obliquely downwards until it terminates in an apartment, within which the industrious prairie-dog constructs, on the approach of cold weather, a comfortable cell for his winter's sleep. The cell, which is composed of fine dry grass, is globular in form, with an opening at top, capable of admitting the finger; and the whole is so firmly compacted, that it might without injury be rolled over the floor."

In case of need the wasp is abundantly furnished by nature with instruments for excavating a burrow out of the solid ground, as she no doubt most commonly does--digging the earth with her strong mandibles, and carrying it off or pushing it out as she proceeds. The entrance gallery is about an inch or less in diameter, and usually runs in a winding or zig-zag direction, from one to two feet in depth. In the chamber to which this gallery leads, and which, when completed, is from one to two feet in diameter, the mother wasp lays the foundations of her city, beginning with the walls.

The building materials employed by wasps were long a matter of conjecture to scientific inquirers; for the bluish-grey papery substance of the whole structure has no resemblance to any sort of wax employed by bees for a similar purpose. Now that the discovery has been made, we can with difficulty bring ourselves to believe that a naturalist so acute and indefatigable as M. Réaumur, should have, for twenty years, as he tells us, endeavoured, without success, to find out the secret. At length, however, his perseverance was rewarded. He remarked a female wasp alight on the sash of his window, and begin to gnaw the wood with her mandibles; and it struck him at once that she was procuring materials for building. He saw her detach from the wood a bundle of fibres about a tenth of an inch in length, and finer than a hair; and as she did not swallow these, but gathered them into a mass with her feet, he could not doubt that his first idea was correct. In a short time she shifted to another part of the window-frame, carrying with her the fibres she had collected, and to which she continued to add, when he caught her, in order to examine the nature of her bundle; and he found that it was not yet moistened nor rolled into a ball, as is always done before employing it in building. In every other respect it had precisely the same colour and fibrous texture as the walls of a vespiary. It struck him as remarkable that it bore no resemblance to wood gnawed by other insects, such as the goat-moth caterpillar, which is granular like sawdust. This would not have suited the design of the wasp, who was well aware that fibres of some length form a stronger texture. He even discovered, that before detaching the fibres, she bruised them (les charpissoit) into a sort of lint (charpie) with her mandibles. All this the careful naturalist imitated by bruising and paring the same wood of the window-sash with his penknife, till he succeeded in making a little bundle of fibres scarcely to be distinguished from that collected by the wasp.

We have ourselves frequently seen wasps employed in procuring their materials in this manner, and have always observed that they shift from one part to another more than once in preparing a single load--a circumstance which we ascribe entirely to the restless temper peculiar to the whole order of hymenopterous insects. Réaumur found that the wood which they preferred was such as had been long exposed to the weather, and is old and dry. White of Selborne, and Kirby and Spence, on the contrary, maintain that wasps obtain their paper from sound timber, hornets only from that which is decayed. Our own observations, however, confirm the statement of Réaumur with respect to wasps, as, in every instance which has fallen under our notice, the wood selected was very much weathered; and in one case, an old oak post in a garden at Lee, in Kent, half destroyed by dry-rot, was seemingly the resort of all the wasps in the vicinity. In another case, the deal bond in a brick wall, which had been built thirty years, is at this moment (June, 1829) literally striped with the gnawings of wasps, which we have watched at the work for hours together. (J. R.)

The bundles of ligneous fibres thus detached are moistened before being used, with a glutinous liquid, which causes them to adhere together, and are then kneaded into a sort of paste, or papier maché.

The method employed by the wasp in making its nest has been so admirably described by Mr. S. Stone, that we cannot do better than copy his description, which appeared in "Beeton's Annual" of 1865.

"Having found a place suitable--the deserted burrows of the field-mice being perhaps more generally selected than any other by the underground species, the chamber formed by that animal for its nest being exactly the kind of place required by the insect--it proceeds to attach its web to the centre of the roof of the chamber. This consists, in the first instance, of a pedicle, or footstalk, about half an inch in length, at the extremity of which a single cell is formed, which is presently surrounded by others.

"Simultaneously with the formation of these cells, an umbrella-shaped covering is prepared above them. More cells are added, an egg being deposited in each of them as soon as formed, while constant additions are made to the covering until it has assumed a globular form, with only an aperture sufficiently large for the insect to pass in and out. Before the completion of the first covering, a second, just large enough to enclose it, is begun, and while this is in progress a third is commenced, and then a fourth, and so on. When young wasps have been produced in sufficient numbers to carry on the work without the assistance of the parent, an event which usually takes place in about six weeks from the commencement of the nest, she does not again leave home, but occupies herself solely in the task of depositing eggs as fast as cells can be formed by the workers for their reception.

"There are two methods by which the nests are enlarged by the workers after the queen has given up the task of building; some species choosing one, some adopting the other. One consists in forming a series of regular sheets or layers, which are made to overlap each other like the slates or tiles on the roof of a building, in the same way as is pursued by the queen of every species so long as she continues to be the architect. When a few of these sheets have been completed, that is, when they have been made to assume a spherical form, with only a small aperture for ingress and egress, each internal sheet is cut away, nearly but not quite, as fast as additional ones are formed externally, the shell or covering therefore slightly increasing in thickness as the nest increases in size. Thus architects among the human race are careful to proportion the thickness, and consequently the strength of the walls to the magnitude of the building designed to be erected.

"The other method consists in forming hollow pieces, or raising, as it were, blisters all over the plain surface which the queen has left; and upon these other blisters, and so on continually; cutting away, as in the former case, the under skin on the formation of the outer one. The latter method is adopted by the workers of V. crabro, V. vulgaris, and V. germanica; the former by V. Norvegica, V. sylvestris, V. rufa, and probably by V. arborea. Cutting away the inner portions of the coverings is a necessary process in order to make room for the increased size of the comb or combs. The material cut away is not thrown by as useless, but is worked up afresh; indeed this is effected in, and by, the very act of removing it; it is then either used in enlarging the combs or it is brought out and employed in making additions to the outside.

"As the nest increases in size, it is obvious that the cavity in which it is placed must be proportionably enlarged; accordingly, each wasp, as it emerges from the aperture, may be observed to bring out with it a small lump of earth which it has scraped from the walls of the chamber, care being taken to keep a clear space of about a quarter of an inch between the covering of the nest, and the walls of the chamber. About the same space also occurs between the combs, which are placed horizontally, with the mouth of the cells downwards; supporting columns or pillars being constructed at regular intervals so as to keep them at a proper distance apart, thus allowing the insects room to pass between them for the purpose of feeding the grubs. Supporting columns or pillars are also placed between the roof of the chamber and the crown of the nest, connecting the one with the other; and these supports are constantly strengthened as the increasing weight of the nest renders such a precaution necessary.

"The material of which the wasps' nests are composed is a sort of paper manufactured chiefly from wood by the insects themselves; one species using sound wood for the purpose, another that which has become decayed. This they scrape by means of their jaws from posts, rails, gates, hurdles, &c., in which act it becomes mixed with some peculiar fluid with which they are provided; it then possesses nearly the same properties as the pulp from which paper is made, but is of firmer consistence. This is gathered in a small lump under the chest, to which it adheres, and in that way is carried to the nest.

"The operators having, after the exhibition of a considerable amount of fickleness in the choice, fixed upon a suitable place for commencing, or recommencing operations--for these remarks have reference to a nest already somewhat advanced in the building--place themselves along the edge of a yet unfinished piece, then walking slowly backward, spread the material as they go, along this edge, where it forms a thick streak; they then go forward to the point at which they began to spread the composition, again marching slowly backward, press this streak between their jaws, which acts as a pair of pincers, thus thinning it out throughout its whole length. They then go forward a second time, pressing it still thinner, and then a third, and so on, until they have rendered it sufficiently thin. Before this is accomplished, the operators have generally to go five or six times over their work. They do not return to the same spot with their next burden, but seek a fresh one, and thus allow the work they recently executed to become dry and firm, previous to making further additions to it. Possibly the material first 'used up' was from wood of a dark colour; the next may be from light-coloured wood, and the next from that of an intermediate colour; and this it is which gives so much beauty to the coverings of the nests of these insects.

"Vespa crabro and V. vulgaris are the only species which use decayed wood or touchwood in the fabrication of their nests; the other species employ sound wood, varied occasionally by sound vegetable fibre obtained from plants of different kinds.

"From the upper combs in a nest, workers are produced; from the lower ones, queens or females; and from the intermediate ones, males. Workers become developed early in the season, males not till an advanced period; and young females or queens not until towards the close of the season.

"The nests of V. crabro, V. vulgaris, and V. germanica, when of full size, measure not unfrequently twelve inches in diameter, the communities working on, in a favourable season, until the month of November; while the labours of the other species close, and the communities break up towards the end of August; their nests scarcely attaining to half the size of those above mentioned."

The accompanying illustration exhibits the nest of the common wasp in an early stage. The first cover has been completed, and a second is in course of progress. We have now before us a beautiful series of wasps' nests, in their various stages, prepared by Mr. Stone, in order to show the progressive enlargement of the edifice.

First, there is the single cell attached to a small part that had penetrated the roof of the burrow. Next comes a more advanced stage, in which three cells are made, and the roof is just begun, being not quite half an inch in diameter. Then come five cells, and a tolerably large roof; and then twelve cells, with a complete roof.

The next stage is that which is represented in the illustration, where the group of cells is seen suspended from its slender footstalk, and a second covering is in progress. By degrees the nest enlarges until the second layer or tier of cells is begun, while the first tier is occupied in the centre by the pupæ, sheltered by their little silk doors, and on the circumference by the larvæ, whose cells are still open in order to allow themselves to be fed by the nurse-wasps.

In these nests, the difference between the homes of Vespa vulgaris and those of V. germanica is very strongly marked, the former being yellowish brown, and the latter grey. One nest of V. germanica, is remarkable for being thickly studded with the long, white eggs of some insect, probably a parasite, which has gained admittance to the burrow, in spite of the care of its guardians. It may be here mentioned, that V. germanica is by far the most common species of wasp in England.

The illustration at p. 90 represents a completed nest of V. germanica. The rough, thick covering is seen outside, and within are the tiers of cells, each layer being supported by pillars from the layer immediately above. These pillars are always formed at the angle where these cells touch each other, so as to obtain as strong a foundation as possible. Only a very small space is left between the combs, just enough room, in fact, for the nurse-wasps to pass as they feed the young. The reader will remember that the young wasps all hang with their heads downwards, being held in their places by a sort of clasper at the end of the tail.]

When the foundress-wasp has completed a certain number of cells, and deposited eggs in them, she soon intermits her building operations, in order to procure food for the young grubs, which now require all her care. In a few weeks these become perfect wasps, and lend their assistance in the extension of the edifice; enlarging the original coping of the foundress by side walls, and forming another platform of cells, suspended to the first by columns, as that had been suspended to the ceiling.

a a, the external wall; b, c c, five small terraces of cells for the neuter wasps, d d, e e, three rows of larger cells for the males and females.]

In this manner several platforms of combs are constructed, the outer walls being extended at the same time; and, by the end of the summer, there is generally from twelve to fifteen platforms of cells. Each contains about 1060 cells--forty-nine being contained in an inch and a half square, and, of course, making the enormous number of about 16,000 cells in one colony. Réaumur, upon these data, calculates that one vespiary may produce every year more than 30,000 wasps, reckoning only 10,000 cells, and each serving successively for the cradle of three generations. But, although the whole structure is built at the expense of so much labour and ingenuity, it has scarcely been finished before the winter sets in, when it becomes nearly useless, and serves only for the abode of a few benumbed females, who abandon it on the approach of spring, and never return; for wasps do not, like mason-bees, ever make use of the same nest for more than one season.

Both Réaumur and the younger Huber studied the proceedings of the common wasp in the manner which has been so successful in observing bees--by means of glazed hives, and other contrivances. In this, these naturalists were greatly aided by the extreme affection of wasps for their young; for though their nest is carried off, or even cut in various directions, and exposed to the light, they never desert it, nor relax their attention to their progeny. When a wasp's nest is removed from its natural situation, and covered with a glass hive, the first operation of the inhabitants is to repair the injuries it has suffered. They carry off with surprising activity all the earth or other matters which have fallen by accident into the nest; and when they have got it thoroughly cleared of everything extraneous, they begin to secure it from further derangement, by fixing it to the glass with papyraceous columns, similar to those which we have already described. The breaches which the nest may have suffered are then repaired, and the thickness of the walls is augmented, with the design, perhaps, of more effectually excluding the light.

* * * * *

The nest of the hornet is nearly the same in structure with that of the wasp; but the materials are considerably coarser, and the columns to which the platforms of cells are suspended are larger and stronger, the middle one being twice as thick as any of the others. The hornet, also, does not build underground, but in the cavities of trees, or in the thatch or under the eaves of barns. Réaumur once found upon a wall a hornet's nest which had not been long begun, and had it transferred to the outside of his study-window; but in consequence, as he imagined, of the absence of the foundress-hornet at the time it was removed, he could not get the other five hornets, of which the colony consisted, either to add to the building or repair the damages which it had sustained.