Document Type

Household Insects and Pests

Publication Date



In the United States, approximately 10 – 12 million people, mostly children, are infested annually with head lice, Pediculus humanus capitis DeGeer. The first indication of an infestation is the itching and scratching caused by these bloodsucking insects. Examination of the hair and scalp will usually reveal the white or grayish crawling forms (about the size of a sesame seed) and yellowish- white eggs (nits) attached to the hair shafts close to the scalp.

Lice are usually transferred by the sharing of combs, brushes, hats or bedding, or resting one’s head on upholstered furniture or pillows recently used by an infested person. Head lice are not found on other animals; therefore, pets, livestock or other animals are not responsible for any transfer of head lice to people. Although head lice may cause irritation and itching, they are not considered serious vectors (carriers) of disease organisms in the United States.

Three lice that can infest humans are head lice, P. humanus capitis; body lice, P. humanus humanus L.; and pubic or crab lice, Phthiris pubis (L.). Body lice, which are similar in size to head lice, live on clothing in close contact with the skin. Pubic lice, which are crab-shaped and 1/16 inch long with large claws on the middle legs, are found primarily in the pubic region, but may occur in armpits, beards and eyebrows. Because head lice are far more prevalent than the other two types of lice, this publication discusses head lice only.

Publication Number

SP341-S 10/06(Rev) 07-0068

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Entomology Commons