Pubic lice or crab lice are tiny insects that infest a person's pubic hair, although they also can be found on facial hair, armpit hair and eyelashes. The insects look like crabs, and a person with these lice often is said to have "crabs." Their claws let them grasp hairs so they can both move around and remain on their human host. Crab lice, like all lice, feed only on their host's blood. Female lice produce eggs, which are cemented to the hair shaft close to the skin. It takes about 7 to 10 days for an egg to hatch. Most people who are infested with crab lice will have about a dozen or fewer active lice on them at any one time, and the hairs may bear many live and hatched eggs.