Pubic lice, also known as crabs – are tiny insects that live on coarse human body hair, such as pubic hair (the hair around your genitals). They are very small, roughly 2mm long, but are visible, as are their eggs (called nits). Louse can sometimes be found in other body hair such as underarm hair and beards. They are a different type of louse from head lice and body lice. Pubic lice are sometimes called crabs because their bodies look like tiny crabs.
Pubic lice need human blood to survive, so will only leave the body to move from one person to another. They crawl from hair to hair, they can't fly or jump.