Lice are dorsoventrally flattened, wingless insects tht live in close contact with the skin, hair, and feathers of their vetertebrate hosts. They develop with simple metamorphosis, I.e., each stage is very similar to the next. There are two major groups of lice. One group, the Mallophaga, is also called the chewing lice. The mallophagan lice have broad heads and strongly chitinized jaws that are used for feeding on feathers, hairs, and epidermal scales. The mallophagan lice are found on birds and mammals. The second group, the Anoplura, is composed of the sucking lice. These lice have narrow heads and mouth parts that are adapted for sucking the host’s blood and cutaneous fluids. The anopluran lice are exclusively parasites of mammals.

Cats are host to only a single louse, a Mallophagan, Felicolasubrostratus. Cats are ocasionally blamed for infesting the human members of their households with the human lice, Pediculushumanuscapitis (the head louse, Fig. 5-38) and Pthiruspubis (the pubic louse, Fig 5-39), but humans, almost without exception, acquire these infestations from other humans. If one of these human lice is found on the cat, then the family must be led to understand that the cat is a victim of and not the source of their infestation.