When the cavity and entrance to it are completed, the next part of the process is to lay the foundations of the city to be included in it, which, contrary to the usual custom of builders, wasps begin at the top, continuing downwards. I have already told you that the coatings which compose the dome are a sort of rough but thin paper, and that the rest of the nest is composed of the same substance variously applied. "Whence," you will inquire, "do the wasps derive it?" They are manufacturers of the article, and prepare it from a material even more singular than any of those which haveof late been proposed for this purpose; namely, the fibres of wood[840]. These they detach by means of their jaws from window-frames, posts and rails, &c., and, when they have amassed a heap of the filament, moisten the whole with a few drops of a viscid glue from their mouth, and, kneading it with their jaws into a sort of paste orpapier mâché, fly off with it to their nest. This ductile mass they attach to that part of the building upon which they are at work, walking backwards and spreading it into laminæ of the requisite thinness by means of their jaws, tongue, and legs. This operation is repeated several times, until at length, by aid of fresh supplies of the material and the combined exertions of so many workmen, the proper number of layers of paper that are to compose the roof is finished. This paper is as thin as that of the letter which you are reading; and you may form an idea of the labour which even the exterior of a wasp's nest requires, on being told that not fewer than fifteen or sixteen sheets of it are usually placed above each other with slight intervening spaces, making the whole upwards of an inch and a half in thickness. When the dome is completed, the uppermost comb is next begun, in which, as well as all the other parts of the building, precisely the same material and the same process, with little variation, are employed. In the structure of the connecting pillars there seems a greater quantity of glue made use of than in the rest of the work, doubtless with the view of giving them a superior solidity.—Whenthe first comb is finished, the continuation of the roof or walls of the building is brought down lower; a new comb is erected; and thus the work successively proceeds until the whole is finished. As a comparatively small proportion of the society is engaged in constructing the nest, its entire completion is the work of several months: yet, though the fruit of such severe labour, it has scarcely been finished a few weeks before winter comes on, when it merely serves for the abode of a few benumbed females, and is entirely abandoned at the approach of spring; wasps never using the same nest for more than one season[841].
The nests of the hornet in their general construction resemble those of the common wasp, but the paper of which they are composed is of a much more rough texture; the columns which support the comb are higher and more massive; and that in the centre larger than the rest.
These last, as well as wasps, conceal their nest, suspending it in the corners of outhouses, &c.; but there are other species which construct their habitations in open day-light, affixing them to the branches of shrubs or trees.
One of these, described by Latreille, the work ofVespa holsatica, a species not uncommon with us, resembles in shape a cone of the cedar of Lebanon, and is composed of an envelope and the comb, the former consisting of three partial envelopes, each of the interior of which is longer than the preceding. The comb comprises about thirty hexagonal cells circularly arranged, those of the circumference being lower and smaller[842].
A vespiary somewhat similar to the above, but of a depressed globular figure, and composed of more numerous envelopes, so as to assume a considerable resemblance to a half-expanded Provence rose, is figured by Reaumur[843]: and for a very beautiful specimen apparently of the same kind (except that it contains but one stage of cells), which was found in the garden at East-Dale, I am indebted to the kindness of Henry Thompson, esq. of Hull.
Another species (Odynerus Parietum[844]?) attaches its small group of about twenty inverted crucible-like cells to a piece of wood without any covering[845].
But all these yield in point of singularity of structure to the habitation ofPolistes nidulans, a native of Cayenne, which constructs its nest of a beautifully polished white and solid pasteboard, impenetrable by the weather. These are in shape somewhat like a bell, often a foot and a half long, and fixed by their upper end to the branch of a tree from which they are securely suspended. Their interior is composed of numerous concave horizontal combs, with the openings of the cells turned downwards, fastened to the sides without any pillars, and having a hole through each to admit of access to the uppermost[846].
I close my account of the habitations of insects with the description of those constructed by the white ants orTermites, a tribe alluded to in former letters.
The different species, which are numerous, build nests of very various forms. Some (T. atroxandmordax)construct upon the ground a cylindrical turret of clay about three quarters of a yard high, surrounded by a projecting conical roof, so as in shape considerably to resemble a mushroom, and composed interiorly of innumerable cells of various figures and dimensions. Others (asT. Destructor,T. Arborum, Sm.) prefer a more elevated site, and build their nests, which are of different sizes, from that of a hat to that of a sugar-cask, and composed of pieces of wood glued together, amongst the branches of trees often seventy or eighty feet high. But by far the most curious habitations, and to which, therefore, I shall confine a minute description, are those formed by theTermes fatalis, a species very common in Guinea and other parts of the coast of Africa, of whose proceedings we have a very particular and interesting account in the 71st volume of thePhilosophical Transactions, from the pen of Mr. Smeathman.
These nests are formed entirely of clay, and are generally twelve feet high and broad in proportion, so that when a cluster of them, as is often the case, are placed together, they may be taken for an Indian village, and are in fact sometimes larger than the huts which the natives inhabit. The first process in the erection of these singular structures, is the elevation of two or three turrets of clay about a foot high, and in shape like a sugar-loaf. These, which seem to be the scaffolds of the future building, rapidly increase in number and height, until at length being widened at the base, joined at the top into one dome, and consolidated all round into a thick wall of clay, they form a building of the size above mentioned, and of the shape of a hay-cock, which when clothed, as it generally soon becomes, with a coating ofgrass, it at a distance very much resembles. When the building has assumed this its final form, the inner turrets, all but the tops, which project like pinnacles from different parts of it, are removed, and the clay employed over again in other services.
It is the lower part alone of the building that is occupied by the inhabitants. The upper portion or dome, which is very strong and solid, is left empty, serving principally as a defence from the vicissitudes of the weather and the attacks of natural or accidental enemies, and to keep up in the lower part a genial warmth and moisture necessary to the hatching of the eggs and cherishing of the young ones. The inhabited portion is occupied by theroyal chamber, or habitation of the king and queen; thenurseriesfor the young; thestore-housesfor food; and innumerable galleries, passages, and empty rooms: arranged according to the following plan.
In the centre of the building, just under the apex, and nearly on a level with the surface of the ground, is placed the royal chamber, an arched vault of a semi-oval shape, or not unlike a long oven; at first not above an inch long, but enlarged as the queen increases in bulk to the length of eight inches or more. In this apartment the king and queen constantly reside; and from the smallness of the entrances, which are barely large enough to admit their more diminutive subjects, can never possibly come out; thus, like many human potentates, purchasing their sovereignty at the dear rate of the sacrifice of liberty. Immediately adjoining the royal chamber, and surrounding it on all sides to the extent of a foot or more, are placed what Mr.Smeathman calls theroyal apartments, an inextricable labyrinth of innumerable arched rooms of different shapes and sizes, either opening into each other or communicating by common passages, and intended for the accommodation of the soldiers and attendants, of whom many thousands are always in waiting on their royal master and mistress. Next to the royal apartments come thenurseriesand themagazines. The former are invariably occupied by the eggs and young ones, and in the infant state of the nest are placed close to the royal chamber; but when the queen's augmented size requires a larger apartment, as well as additional rooms for the increased number of attendants wanted to remove her eggs, the small nurseries are taken to pieces, rebuilt at a greater distance a size bigger, and their number increased at the same time. In substance they differ from all the other apartments, being formed of particles of wood apparently joined together with gums. A collection of these compact, irregular, and small wooden chambers, not one of which is half an inch in width, is inclosed in a common chamber of clay sometimes as big as a child's head.—Intermixed with the nurseries lie the magazines, which are chambers of clay always well stored with provisions, consisting of particles of wood, gums, and the inspissated juices of plants.
These magazines and nurseries, separated by small empty chambers and galleries, which run round them or communicate from one to the other, are continued on all sides to the outer wall of the building, and reach up within it two-thirds or three-fourths of its height. They do not, however, fill up the whole of the lower part of the hill, but are confined to the sides, leaving an openarea in the middle, under the dome, very much resembling the nave of an old cathedral, having its roof supported by three or four very large Gothic arches, of which those in the middle of the area are sometimes two and three feet high, but as they recede on each side rapidly diminish like the arches of aisles in perspective. A flattish roof, imperforated in order to keep out the wet, if the dome should chance to be injured, covers the top of the assemblage of chambers, nurseries, &c.; and the area, which is a short height above the royal chamber, has a flattish floor also water-proof, and so contrived as to let any rain that may chance to get in run off into the subterraneous passages.
These passages or galleries, which are of an astonishing size, some being above a foot in diameter and perfectly cylindrical, lined with the same kind of clay of which the hill is composed, served originally, like the catacombs of Paris, as the quarries whence the materials of the building were derived, and afterwards as the grand outlets by which the Termites carry on their depredations at a distance from their habitations. They run in a sloping direction under the bottom of the hill to the depth of three or four feet, and then branching out horizontally on every side, are carried under ground, near to the surface, to a vast distance. At their entrance into the interior they communicate with other smaller galleries, which ascend the inside of the outer shell in a spiral manner, and, winding round the whole building to the top, intersect each other at different heights, opening either immediately into the dome in various places, and into the lower half of the building, or communicating with every part of it by other smaller circularor oval galleries of different diameters. The necessity for the vast size of the main underground galleries evidently arises from the circumstance of their being the great thoroughfares for the inhabitants, by which they fetch their clay, wood, water, or provision; and their spiral and gradual ascent is requisite for the easy access of the Termites, which cannot but with great difficulty ascend a perpendicular. To avoid this inconvenience, in the interior vertical parts of the building, a flat path-way, half an inch wide, is often made to wind gradually, like a road cut out of the side of a mountain, by which they travel with great facility up ascents otherwise impracticable. The same ingenious propensity to shorten their labour seems to have given birth to a contrivance still more extraordinary. This is a kind of bridge of one vast arch, sprung from the floor of the area to the upper apartments at the side of the building, which answers the purpose of a flight of stairs, and must shorten the distance exceedingly in transporting eggs from the royal chambers to the upper nurseries, which in some hills would be four or five feet in the straightest line, and much more if carried through all the winding passages which lead through the inner chambers and apartments. Mr. Smeathman measured one of these bridges, which was half an inch broad, a quarter of an inch thick, and ten inches long, making the side of an elliptic arch of proportionable size, so that it is wonderful it did not fall over or break by its own weight before they got it joined to the side of the column above. It was strengthened by a small arch at the bottom, and had a hollow or groove all the length of the upper surface, either made purposely for the greater safety of the passengers, or elseworn by frequent treading. It is not the least surprising circumstance attending this bridge, the Gothic arches before spoken of, and in general all the arches of the various galleries and apartments, that, as Mr. Smeathman saw every reason for believing, the Termitesprojecttheir arches, and do not, as one would have supposed, excavate them.
Consider what incredible labour and diligence, accompanied by the most unremitting activity and the most unwearied celerity of movement, must be necessary to enable these creatures to accomplish, their size considered, these truly gigantic works. That such diminutive insects, for they are scarcely the fourth of an inch in length, however numerous, should, in the space of three or four years, be able to erect a building twelve feet high and of a proportionable bulk, covered by a vast dome, adorned without by numerous pinnacles and turrets, and sheltering under its ample arch myriads of vaulted apartments of various dimensions, and constructed of different materials—that they should moreover excavate, in different directions and at different depths, innumerable subterranean roads or tunnels, some twelve or thirteen inches in diameter, or throw an arch of stone over other roads leading from the metropolis into the adjoining country to the distance of several hundred feet—that they should project and finish the, for them, vast interior stair-cases or bridges lately described—and, finally, that the millions necessary to execute such Herculean labours, perpetually passing to and fro, should never interrupt or interfere with each other, is a miracle of nature, or rather of the Author of nature, far exceeding the most boasted works and structuresof man: for, did these creatures equal him in size, retaining their usual instincts and activity, their buildings would soar to the astonishing height of more than half a mile, and their tunnels would expand to a magnificent cylinder of more than three hundred feet in diameter; before which the pyramids of Egypt and the aqueducts of Rome would lose all their celebrity, and dwindle into nothings[847]. So that when in the commencement of my last letter I promised to introduce you to insects whose labours produced edifices more astonishing than those of the mightiest Egyptian monarchs, the pyramids, my promise, whatever you then thought of it, was the reverse of hyperbolical.
I am, &c.
END OF THE FIRST VOLUME.
Printer's Mark
Plate IIPlate II
Plate II
Plate IIIPlate III
Plate III