Since no fossils of lice have been found, we can only speculate when they originated. We do know the ancient Egyptians and Greeks wrote of them. Lice have been found on prehistoric Native American mummies. These lice have abdomens longer than they are broad and their 6 legs are equal in size. In contrast, the abdomen of the crab louse is about as wide or even slightly wider than its length, and the second and third pairs of legs are thicker than the first pair.
Crab lice are much smaller than head and body lice.
Depending on temperature, lice eggs, which are called nits, usually hatch into nymphs within 10 days. There are three nymphal stages, the third followed by the adult stage. All stages must have blood meals if they are to survive and continue their development. Adult lice live about 30 days. Public Health Implications Louse-transmitted diseases are not a serious threat in the United States.