MODEL RELEASED. Head lice. General practice doctor examines the hair of a 6-year-old boy for nits. Nits are the tiny eggs laid by head lice and glued to hairs close to the scalp. Infestations of head lice can be diagnosed from the presence of nits. Head lice are small wingless insects that live on and suck blood from the scalp. They cause intense itching leading to scratching and skin inflammation. Hair washing with lotions or shampoos containing malathion or carbaryl kills the lice rapidly. Dead lice and nits are then removed using a fine-toothed comb. Head lice are spread by direct contact. They occur most commonly in children.