Head lice are tiny six-legged insects that cling to the hair near to the scalp and neck and feed on human blood. Each louse is about the size of a sesame seed - 3mm long fully grown - and can be hard to spot. Empty lice eggs, called nits, are glued onto hairs and can be easier to see. When a large number of lice live in a person's hair, it is called an infestation.
Head lice are parasites that are found on human heads and are spread by personal contact or the sharing of combs, brushes, caps, and other clothing. They are a common problem with preschool and schoolchildren. Head lice cause a tickling feeling of something moving in the hair, itching, and sores on the head. The affected individual and/or family members should all be treated.