Head lice are common, especially among school-aged children. Dr. Green, can you tell us about lice?
Absolutely, Dr. Connolly. Head lice are tiny bugs about the size of a sesame seed. One bug is called a louse. Lice are usually pale and gray, but their bodies can vary in color.
Lice can attach to the hair of anyone's head, whether the hair is dirty or clean. They feed on small amounts of blood from the scalp, but they don't cause serious illness or carry any diseases.
Head lice lay eggs, called nits, and attach them to hair close to the scalp. Nits are oval in shape, and about the size of a knot in thread. Some nits are hard to see because they blend in with certain hair colors, or they can be mistaken for dandruff. After the eggs hatch, the empty nits stay on the hair shaft.
The life cycle of a head louse is about 28 days, and it consists of three phases: nit, nymph, and adult louse. Nits hatch in six to nine days and are usually found very close to the scalp. They can't survive if they are farther away. A nymph looks similar to an adult louse, but much smaller. Nymphs become adults about seven days after hatching. An adult louse can multiply very quickly and lay up to 10 nits a day.