Lice - Lice On Humans, Lice On Other Animals

Lice are small, wingless, biting or sucking insects, many of which are ecto-parasites. There are about 3,000 species of lice in the orders Mallophaga and Anopleura. The Anopleura are sucking lice, which are parasites of mammals, and which feed only on blood. The Mallophaga are chewing or biting lice, and are primarily pests of birds, feeding on skin and feathers.

Most species of lice are specific to one or a few related species of host animals, and lice cannot survive away from their appropriate hosts. Lice are generally spread from host to host by direct body contact, or through shared clothing or bedding (in the case of human lice).

Both orders of lice have direct development, in which the eggs hatch into nymphs that look like miniature versions of the adult. Lice have a flattened body and poorly developed eyes, or no eyes at all.

Most lice commonly occur in the fur or feathers of their warm-blooded hosts. These lice have specialized, hook-like appendages on their relatively short legs for securing these parasitic insects onto the body of their hosts.