Pubic or “crab” lice are parasitic insects that survive by feeding on human blood. Pubic lice are different parasites than head or body lice and are usually found in the pubic hair, but can also be found in other coarse body hair like eyebrows, beard, chest or armpit hair. Pubic lice have forms: the egg (also called a nit), the nymph, and the adult.
Nit: Nits are lice eggs. They can be hard to see and are found firmly attached to the hair shaft. They are oval and usually yellow to white. Pubic lice nits take about 6-10 days to hatch.
Nymph: The nymph is an immature louse that hatches from the nit (egg). A nymph looks like an adult pubic louse but it is smaller. Pubic lice nymphs take about 2-3 weeks after hatching to mature into adults capable of reproducing. To live, a nymph must feed on blood.
Adult: The adult pubic louse resembles a miniature crab when viewed through a strong magnifying glass. Pubic lice have six legs; their two front legs are very large and look like the pincher claws of a crab. This is how they got the nickname “crabs.” Pubic lice are tan to greyish-white in colour. Females lay nits and are usually larger than males. To live, lice must feed on blood. If the louse falls off a person, it dies within 1-2 days.
Adult pubic lice are 1.1-1.8 mm in length. Pubic lice typically are found attached to hair in the pubic area but sometimes are found on coarse hair elsewhere on the body (for example, eyebrows, eyelashes, beard, moustache, chest, armpits, etc.).
Pubic lice infestations (pthiriasis) are usually spread through sexual contact. Dogs, cats, and other pets do not play a role in the transmission of human lice.
Where Are Pubic Lice Found?
Pubic lice usually are found in the genital area on pubic hair; but they may occasionally be found on other coarse body hair, such as hair on the legs, armpits, moustache, beard, eyebrows, or eyelashes.
Pubic lice on the eyebrows or eyelashes of children may be a sign of sexual exposure or abuse. Lice found on the head is generally head lice, not pubic lice.
Note: Animals do not get or spread pubic lice.
Pubic lice can cause itching, blue spots and sores in the infected area. It may also be possible to see grey-white lice or hair nits (the egg form of pubic lice).