What are Lice?

Head lice are tiny, wingless insects that live on the human scalp. They are about as big as sesame seeds. Head lice sustain themselves by sucking blood—just as mosquitoes do. However, unlike mosquitoes, lice cannot fly or jump from one person to another; they can only crawl. Children often get head lice from head-to-head contact with other children, but may also get them by sharing personal items such as hats, combs, or headbands.

magnified ilustration of an egg
magnified ilustration of a louse

What are lice, eggs (nits)?

Lice eggs are laid by the female louse. They are about the size of a poppy seed and are difficult to see because their color blends in easily with hair. Lice eggs are laid near the root of the hair and are attached to the hair shaft with a glue-like substance that can't be washed or blown away.

Nits are the empty eggshells left behind when lice hatch from eggs. Dandruff, sand and flakes of hairspray are commonly mistaken for lice eggs or nits. Eggs and nits are not easily removed and must be carefully combed out with a fine-tooth comb.

Eggs and nits vary in color, from yellowish-brown to white. Since the hair grows, nits are usually found further away from the root of the hair. Many schools have a "No Nit Policy," which means children who have had head lice are not readmitted to school until all the nits are gone. If you have seen live lice on your child's head, it is very important to comb out eggs and nits as part of the lice treatment process. Lice treatment products should not be used if lice or nits have not been seen.

How long do head lice live?

Head lice live for approximately 40–50 days and go through 3 stages in their life cycle:

lice-life-cycle

Egg Stage: The female louse lays the egg with a special glue that cements it to the hair shaft near the root. The lice egg develops and hatches approximately 10 days later.

Nymph Stage: Once the louse hatches, it is called a nymph and is barely visible to the naked eye. The nymph cannot reproduce because it is not fully developed. After about 12 days, it becomes an adult.

Adult Stage: The female adult louse can lay up to 10 eggs per a day—starting another generation of lice. The adult stage lasts about 30 days. Lice do not live longer than 2 days if they are separated from the head.

What are Pubic/Body Lice?

Two other types of lice are Pubic and Body Lice. For more complete information about symptoms and treatment see Pubic and Body Lice