In these ants the difference between the large, heavy, winged males and females, and the small, long-legged, active workers, is so great, that various forms of the same species have been often referred to distinct genera; in Eciton, for example, the female has a single petiolate abdominal segment, the worker two.
I, Atta cephalus; 2, Eciton drepanophora; 3, Eciton erratica.
An interesting species of the last is the leaf-cutting ant (Eciton) which lives in large underground colonies and feeds upon a fungus produced by leaf-cuttings stored in subterranean passages to promote fermentation.
One of the most interesting features of ant-societies is the dimorphism or polymorphism that may often be seen among the workers, the same species being represented by two or more forms. Thus the British " wood ant " (Formica rufa) has a smaller and a larger race of workers (" minor " and " major " forms), while in Ponera we find a blind race of workers and another race provided with eyes, and in Atta, Eciton and other genera, four or five forms of workers are produced, the largest of which, with huge heads and elongate trenchant mandibles, are known as the " soldier " caste.
Very many ants live by preying upon various insects, such as the British " red ants " with well-developed stings (Myrmica rubra), and the notorious " driver ants " of Africa and America, the old-world species of which belong to Dorylus and allied genera, and the new-world species to Eciton (fig.
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