Crab lice (singular, louse), scientific name Pthius pubis and commonly called "crabs", are one of three kinds of human lice in the large group of lice families. (The others are head lice and body lice , which live in clothing.) They are wingless, about 1 to 3 mm long. They attach themselves to hair strands, and hatch out of pods with lids, or "nits", that are too tightly attached to be brushed off but must be removed by pulling with the nails or a fine-toothed comb.

The crab louse can live in almost any form of humanoid hair, but is found most commonly in pubic hair, leading to its other common name of pubic louse. Its legs are adapted to climbing along relatively widely spaced hairs, and so can be found in eyelashes, genital hair , beards, moustaches , and even armpit hairs. The individual louse can survive up to a week apart from its necessary human host, so that crab lice can be passed on in sleeping bags and bedding. The female may lay up to 40 eggs a time, resulting in a fluctuating but growing population. The louse feeds on blood and can leave irritating spots on the skin, sometimes mistaken for pimples, a condition called Pediculosis pubis.

Shampooing with an insecticidal shampoo (often containing lindane) is the usual treatment.

External links

• University of chicago: Crab lice
• EmbarrassingProblems.com: Crabs