the crab louse or pubic louse is an insect, which is a parasite on humans. it is found most often in pubic hair, but also lives in other areas on the body with dense hair. it can be spread from one human to another by sexual intercourse, but also through garments, towels and besheets, for example in a hotel. crab lice are still visible with the human eye, they are about 1.5-2mm in size.