What Are Head Lice?

Lice are tiny insects that can be found on various parts of the body, including the head, eyebrows, and eyelashes. These insects live on humans and feed on their blood. Lice that live close to the scalp are known as head lice.

Head lice are found most often on the back of the neck and behind the ears. Although lice can’t jump or fly, they can spread very easily from person to person through head-to-head contact or through shared clothing or personal items (such as a hat, towel, or hairbrush). Contrary to popular myth, personal hygiene has nothing to do with getting head lice.

Identifying Lice

To understand how to identify lice, it helps to know the three different forms of head lice:

  • Eggs (nits)

    Nits are oval-shaped lice eggs that attach themselves to the hair shaft. They are hard to see with the naked eye, as they’re only about as large as a knot in a piece of thread. Usually white or yellow in color, they are often confused with dandruff or scabs. Nits usually take about 8-9 days to hatch. Eggs that are likely to hatch are usually located very close to the base of the hair shaft.

  • Nymph

    A nymph is an immature louse (singular of lice) that hatches from the nit. It takes about 9-12 days for a nymph to mature into an adult.

  • Adult louse

    An adult louse is about the size of a sesame seed, has six legs, and is tan to grayish-white in color. An adult louse, which must feed on blood in order to live, can survive up to 30 days on a person’s head but will die within one or two days if it falls off a person.

Head lice can usually be detected by looking closely for live lice or eggs in the hair. Use of a magnifying glass can assist in the search.

Learn more about how to check for lice.

If you’re not sure whether your child has head lice, ask a school nurse or other health care provider to conduct a thorough search.