Anoplura (sucking lice)
Rhyncophthirina
Ischnocera (avian lice )
Amblycera (chewing lice)

Lice (singular: louse) (order Phthiraptera) are an order of over 3000 species of wingless parasitic insects. They are all obligate ectoparasites of mammals and birds, excluding the Monotremes (the duck-billed platypus and spiny ant-eater) and bats.

The order has traditionally been divided into two suborders; the sucking lice (Anoplura) and chewing lice (Mallophaga), however, recent classifications suggest that the Mallophaga are paraphyletic and four suborders are now recognised:

• Anoplura: sucking lice, including head and pubic lice (see also Pediculosis or Head lice)
• Rhyncophthirina: parasites of elephants and warthogs
• Ischnocera: avian lice
• Amblycera: chewing lice, a primitive order of lice

Lice are highly host specific and many species even prefer specific sites on their host's body. As lice spend their whole life on the host they have developed adaptations which enable them to maintain a close contact with him. These adaptations are reflected in their size (0.5 mm to 8 mm), stout legs and claws in order to cling tightly to hair, fur and feathers, wingless and dorsoventrally flattened. They feed on skin (epidermal) debris, feather parts, sebaceous secretions and blood. Their colour varies from pale beige to dark grey. If feeding on blood they may be considerably darker.

The picture depicts the chewing louse Damalinia limbata found on Angora goats.