For the infection, see Pediculosis. For the district of Diyarbakır Province in Turkey, see Lice, Turkey. For other uses, see Louse (disambiguation). Louse (plural: lice) is the common name for members of the order Phthiraptera, which contains nearly 5,000 species of wingless insect. Lice are obligate parasites, living externally on warm-blooded hosts which include every species of bird and mammal, except for monotremes, pangolins, bats and cetaceans.