Chewing louse (suborder Amblycera and Ischnocera), also called biting louse, any of about 2,900 species of small, wingless insects (order Phthiraptera), worldwide in distribution, that have chewing mouthparts, a flattened body, and shortened front legs used to transport food to the mouth. Chewing lice may be from 1 to 5 mm (0.039 to 0.19 inch) in length, and their colour ranges from white to black. The life cycle is spent on the feathers or hair of the host, though one genus lives in the throat pouches of pelicans and cormorants.
Chewing lice attack mainly birds (see bird louse) and some mammals (as Bovicola on cattle), but they are not human parasites. Many species are host specific. One dog louse is the intermediate host of the dog tapeworm, and one rat louse transmits murine typhus among rats. Chewing lice that are parasitic on mammals feed on skin secretions, dried blood, fur, and skin debris. Although they are not blood suckers, chewing lice can cause serious discomfort. Symptoms of infestation include itching, loss of appetite, and lowered egg production in fowl. Infested animals are usually treated with a dust or dip.
Some authorities consider the two suborders as a single group called Mallophaga.