This family of about 2,700 species is distributed throughout the world, but with more species in the Old World tropics than elsewhere. Eleven have been recorded in the British Isles, of which two are extinct residents and one has established itself only briefly. These are furry, medium sixed or fairly large moths. They are collectively called tussocks on account of the characteristic tufts of hair on the backs of the larvae, which are incorporated into their silken cocoon, formed above ground. The males have strongly feathered antennae, whereas those of the females are either simple or slightly feathered. The females of some species cover the eggs with hair from substantial furry tufts on the hind end of their abdomen. Those of two species have highly reduced wings and are flightless. The majority are strictly nocturnal. They come regularly to light, but do not feed. All but two produce only one generation a year.
The larvae are hairy, and readily lose their hairs, especially when fully grown. The hairs cause skin irritation in some people, so the larvae should be handled with great care, or not at all. The severity varies between species, with Brown-tail larvae by far the worst in this resect, this species being accorded pest status as a result. The larvae of all but one species feed on woody plants. (Taken from Waring and Townsend’s Field Guide to the Moths of Great Britain and Ireland)