A bird louse is any chewing louse (small, biting insects) of order Phthiraptera which parasitizes warm-blooded animals, especially birds. Bird lice may feed on feathers, skin, or blood. They have no wings, and their biting mouth parts distinguish them from true lice, which suck blood.
Almost all domestic birds are hosts for at least one species of bird louse. Chickens and other poultry are attacked by many kinds of bird lice.
Earlier all chewing lice were considered to form the paraphyletic order Mallophaga while the sucking lice were thought to form the order Anoplura. However, reclassification (Clay, 1970) has combined these orders into the order Phthiraptera. The bird lice belong to two suborders, Amblycera and Ischnocera, although some members of these suborders do not parasitize birds and are therefore not bird lice.
The families which parasitize birds are: