In countless multitudes the Driver or Foraging ants break forth from the primeval forest, marching through the country in compact order, like a well-drilled army. Every creature they meet in their way falls a victim to their dreadful onslaught--rats, mice, lizards, and even the huge python, when in a state of surfeit from recent feeding. If a house obstructs their route, they do not turn out of the way, but go quite through it. Though they sting cruelly when molested, the West Indian planter is not sorry to see them in his house, for it is but a passing visit, and their appearance is the death-warrant for every spider, scorpion, cockroach, or reptile that pollutes his dwelling. Unfortunately, this thorough cleansing is but of short duration, as in less than a week tropical life calls forth a new generation of vermin.
The wonderful societies of the ants, their strength and perseverance, their unwearied industry, their astonishing intelligence, are so well known, and have been so often and so admirably described[22], that it would be trespassing on the patience of my readers were I to enter into any lengthened details on the subject. And yet, the observations of naturalists have chiefly been confined to the European species, while the economy of the infinitely more numerous tropical ants, confined to countries or places hardly ever visited, or even unknown to civilised man, remains an inexhaustible field for future inquiry.
The study of their various buildings alone, from the little we know of them, would occupy a zealous entomologist for years. Here we have an American species that forms its globular nest of the size of a large Dutch cheese, of small twigs artistically interlaced; there another, which (_Formica bispinosa_) uses cotton for its building material, and through the chemical agency of its pungent secretion converts it into a spongy substance.
On the west coast of Borneo, Mr. Adams noticed two kinds of ants’ nests--one species of the size of a man’s hand, adhering to the trunk of trees resembling, when cut through, a section of the lungs; the other was composed of small withered bits of sticks and leaves, heaped up in the axils of branches, somewhat in the form of flattened cylinders and compressed cones. A third species, still more ingenious, constructs its domicile out of a large leaf, bending the two halves by the weight of united millions till the opposite margins meet at the under surface of the mid-rib, where they are secured by a gummy matter. The stores and larvæ are conveyed into the nest so made by regular beaten tracks along the trunk and branches of the tree.