The lower figure represents the nest of another species of ant belonging to the same genus, and called scientifically, Polyrachis textor. The nest is most ingeniously made of little pieces of wood and tendrils, put together so as to form a kind of open net-work, through which the interior of the nest is plainly visible. This insect inhabits Malacca.]
STRUCTURES OF WHITE ANTS, OR TERMITES.
When we look back upon the details which we have given of the industry and ingenuity of numerous tribes of insects, both solitary and social, we are induced to think it almost impossible that they could be surpassed. The structures of wasps and bees, and still more those of the wood-ant (Formica rufa), when placed in comparison with the size of the insects, equal our largest cities compared with the stature of man. But when we look at the buildings erected by the white ants of tropical climates, all that we have been surveying dwindles into insignificance. Their industry appears greatly to surpass that of our ants and bees, and they are certainly more skilful in architectural contrivances. The elevation, also, of their edifices is more than five hundred times the height of the builders. Were our houses built according to the same proportions, they would be twelve or fifteen times higher than the London Monument, and four or five times higher than the pyramids of Egypt, with corresponding dimensions in the basements of the edifices. These statements are, perhaps, necessary to impress the extraordinary labours of ants upon the mind; for we are all more or less sensible to the force of comparisons. The analogies between the works of insects and of men are not perfect; for insects are all provided with instruments peculiarly adapted to the end which they instinctively seek, while man has to form a plan by progressive thought, and upon the experience of others, and to complete it with tools which he also invents.
The termites do not stand above a quarter of an inch high, while their nests are frequently twelve feet, and Jobson mentions some which he had seen as high as twenty feet; “of compass,” he adds, "to contain a dozen men, with the heat of the sun baked into that hardness, that we used to hide ourselves in the ragged tops of them when we took up stands to shoot at deer or wild beasts."[DI] Bishop Heber saw a number of these high ant-hills in India, near the principal entrance of the Sooty or Moorshedabad river. “Many of them,” he says, “were five or six feet high, and probably seven or eight feet in circumference at the base, partially overgrown with grass and ivy, and looking at a distance like the stumps of decayed trees. I think it is Ctesias, among the Greek writers, who gives an account alluded to by Lucian in his ‘Cock,’ of monstrous ants in India, as large as foxes. The falsehood probably originated in the stupendous fabrics which they rear here, and which certainly might be supposed to be the work of a much larger animal than their real architect.”[DJ] Herodotus has a similar fable of the enormous size and brilliant appearance of the ants of India.
Nor is it only in constructing dwellings for themselves that the termites of Africa and of other hot climates employ their masonic skill. Though, like our ants and wasps, they are almost omnivorous, yet wood, particularly when felled and dry, seems their favourite article of food; but they have an utter aversion to feeding in the light, and always eat their way with all expedition to the interior. It thence would seem necessary for them either to leave the bark of a tree, or the outer portion of the beam or door of a house, undevoured, or to eat in open day. They do neither; but are at the trouble of constructing galleries of clay, in which they can conceal themselves, and feed in security. In all their foraging excursions, indeed, they build covert ways, by which they can go out and return to their encampment.[DK]
Others of the species (for there are several), instead of building galleries, exercise the art of miners, and make their approaches under ground, penetrating beneath the foundation of houses or areas, and rising again either through the floors, or by entering the bottom of the posts that support the building, when they follow the course of the fibres, and make their way to the top, boring holes and cavities in different places as they proceed. Multitudes enter the roof, and intersect it with pipes or galleries, formed of wet clay, which serve for passages in all directions, and enable them more readily to fix their habitations in it. They prefer the softer woods, such as pine and fir, which they hollow out with such nicety, that they leave the surface whole, after having eaten away the inside. A shelf or plank attacked in this manner looks solid to the eye, when, if weighed, it will not out-balance two sheets of pasteboard of the same dimensions. It sometimes happens that they carry this operation so far on stakes in the open air, as to render the bark too flexible for their purpose; when they remedy the defect by plastering the whole stick with a sort of mortar which they make with clay, so that, on being struck, the form vanishes, and the artificial covering falls in fragments on the ground. In the woods, when a large tree falls from age or accident, they enter it on the side next the ground, and devour it at leisure, till little more than the bark is left. But in this case they take no precaution of strengthening the outward defence, but leave it in such a state as to deceive an eye unaccustomed to see trees thus gutted of their insides: and “you may as well,” says Mr. Smeathman, “step upon a cloud.” It is an extraordinary fact, that when these creatures have formed pipes in the roof of a house, instinct directs them to prevent its fall, which would ensue from their having sapped the posts on which it rests; but as they gnaw away the wood, they fill up the interstices with clay, tempered to a surprising degree of hardness, so that, when the house is pulled down, these posts are transformed from wood to stone. They make the walls of their galleries of the same composition as their nests, varying the materials according to their kind; one species using the red clay, another black clay, and the third a woody substance, cemented with gums, as a security from the attacks of their enemies, particularly the common ant, which, being defended by a strong, horny shell, is more than a match for them, and when it can get at them, rapaciously seizes them, and drags them to its nest for food for its young brood. If any accident breaks down part of their walls, they repair the breach with all speed. Instinct guides them to perform their office in the creation, by mostly confining their attacks to trees that are beginning to decay, or such timber as has been severed from its roots for use, and would decay in time. Vigorous, healthy trees do not require to be destroyed, and accordingly, these consumers have no taste for them.[DL]
M. Adanson describes the termites of Senegal as constructing covert ways along the surface of wood which they intend to attack; but though we have no reason to distrust so excellent a naturalist, in describing what he saw, it is certain that they more commonly eat their way into the interior of the wood, and afterwards form the galleries, when they find that they have destroyed the wood till it will no longer afford them protection.