The habitations of ants are very curiously constructed, displaying great ingenuity, although with great diversity in the different species. The greater number of species form their habitations in the ground. These rise above the surface in the form of a dome ; hence the name ant-hills commonly given them. The largest ant-hills formed by any British species are those of the large red or horse ants (formica rufa), which are sometimes as big as a small haycock; but travelers in South America describe ant-hills of 15 or 20 ft. in height. The nest of F. rufa is outwardly of rude appearance—a con fused heap of such portable materials as, were within reach; but within, it contains numerous small apartments, of different sizes, arranged in separate stories, some deep in the earth, some above its surface, and communicating with each other by means of galleries. Tjse is made of the earth excavated from below to mix with other materials in the construction of the upper parts of the fabric. Many species of ants, sometimes called mason ants, construct habitations by a still more elaborate masonry. making use, for this purpose, of soft clay, which they spread and mold by means of their mandi bles and feet, appearing all the while to examine their work by their antenzue. The par tition-walls of the galleries and apartments of the formica brunnea are about half a line thick, and about in. high; the roofs are somewhat arched, and pillars are fre quent in this marvelous architecture. M. Huber saw a working-ant of another spe cies (F. fusca), without assistance, make and cover in a gallery which was 2 or 3 in. long, and of which the interior was rendered perfectly concave. There are other species, sometimes called carpenter ants, which make their habitations in the trunks of old trees, gnawing the wood into apartments and galleries, with floors and partitions as thin as card. Formica flares forms its partition-walls of a sort of papier• of sawdust, earth, and spider's web. F. 8maragdina, an East Indian species, forms its nest of a thin silk-like tissue. F. bispinosa, in Cayenne, makes a felt of the down which envelops the seeds of the bombar crtba. An East Indian species, myrmica kirbii, forms a globular nest of a congeries of tile-like lamina of cow-dung, the inte rior exhibition. an assemblage of apartments and galleries. Some Australian ants form their nests of the leaves of trees glued together, after being first brought into the proper position by the united strength of multitudes.
Of the ants which form their nests in the ground, some, instead of constructing ant-hills, seek the protection of stones, roots of trees, etc. This is the case with some of the British species, and also with the sugar-ant of the West Indies, already men tioned.
Many interesting anecdotes are on record illustrative of the instincts of ants, and of the sagacity which they seem to possess. They appear also to have some power of communicating with each other, in which it has been supposed that the antenna arc chiefly employed. Some such power might be supposed to be necessary, if we could
venture to reason from analogy upon such a subject, not only to their architectural and other ordinary operations, in which many must take part, systematically and conjointly, but also in their predatory and warlike excursions; for these also some of the species have. If, during the predatory excursions of the (Ma cephalotes (a South American species), an intervening space occurs which they cannot cross, some of the creatures link themselves together—as monkeys, in like circumstances, have been known to do— forming a bridge over which the main body passes. Ants are, in general, both courage ous and pugnacious. Many battles take place among them, both between individuals and large parties; and after a battle, combatants may be found locked in each other's arms, as having died together in the struggle. More extraordinary than anything of this kind, however, is the fact, sufficiently ascertained, that some species of ants go on regular forays to carry off the larvae and pupal of certain other species, which they to their own habitations to rear and employ them as slaves in the work which might be regarded as properly belonging to workers of their own race—a fact to which no other at all analo,gotis has yet presented itself in natural history. The species known thus to make and keep slaves are polyergus rufescens and format sa nguinca, both sometimes called amazon ants. It has been noted as a curious circumstance, that the kidnappers are red or pale-colored ants, and the slaves jet black. The kidnapping excursions take place only at a particular period of the year, when the nests of the black ants contain the neuter brood. The army of red ants (P. rufeseeng) marches forth, the vanguard, which consists of 8 or 10 only, continually changing; and on their arriving at the nest of the negro ants, a desperate conflict ensues, which ends in the defeat of the negroes; and thereupon the red ants, with their powerful mandibles, tear open the now unde fended ant-hill, enter it, and emerge, carrying the pup? in their mouths, with which they return in perfect order to their own nest. The pupa; are there treated with great care, and spend their lives among the red ants, excavating passages, collecting food, carrying larvae, etc., as if this had been their original destination. The amazon ants are not natives of Britain, although plentiful in some parts of Europe.
Formic acid has been employed as a stimulant in gout and paralysis, and is sometimes exhibited in continental practice by means of which are prepared by boiling crushed ants, or whole ant-hills, and immersing the diseased limb in the steam.
T?otrrEs (q.v.), or WHITE ANTS, are very different from the true ants, and belong to the order neuroptera.