Parasitic lice are flattened-looking insects, wingless, living permanently on the bodies of birds and mammals without killing them. Their mouthparts are used for biting skin, feather, or fur but in the sucking lice they are used exclusively for feeding on blood. The legs are short and are often modified for clinging onto either fur or feathers. Different lice are linked with specific hosts, such as the species with distinct mouthparts that are found only on warthogs and African elephants. Many lice are also restricted to certain areas of the body, so more than one species can inhabit a host at the same time.
 

Human lice are small, pale, and elongate, with short, stongly clawed legs for gripping onto their hosts. The small head bears distinctively dark eyes. The human louse, Pediculus humanus, also occurs on some monkeys.
 

The Body Louse lives and lays eggs in the fibers of clothing, whereas the Head Louse lives entirely in the hair and glues its eggs (nits) to hair.
 

Worldwide. On humans, apes, and monkeys.
 

Outbreaks of head lice are common among young children. Resistance to insecticidal shampoos is developing and regular washing and fine combing is just as effective. Up until WWII, many more soldiers died of louse-borne epidemic typhus and relapsing fever than were killed in battle.