By Lice Clinics of America

If you are a human with hair longer than an eighth of an inch (~0.3 cm), you can get head lice.

Lice transmission occurs primarily when a louse moves from the hair of one head to the hair of another via head-to-head contact.

Although there are many kinds of lice in the world that afflict birds and other animals, head lice are parasites that live off human blood, which they get by feeding on the scalp.

Head lice prefer clean hair that is long enough for them to crawl along and attach eggs to.

Learn more about head lice and lice treatment.