Pubic Louse (Crab Louse)

Natural Habitat

Exclusively on humans, primarily in pubic and perianal hair, but can occasionally be found in coarse hair elsewhere on the body such as eyelashes, armpits, or chests.

Diet & Feeding

Obligate hematophagous insects, meaning they feed exclusively on human blood. They feed several times a day.

Behavior Patterns

They are sedentary pests that grasp hair shafts with specialized claw-like legs. Unlike head lice, they move very slowly. The life cycle consists of the egg (nit), three nymphal stages, and the adult, taking about 2-3 weeks to complete.

Risks & Benefits

Risks include intense itching (pruritus) due to an allergic reaction to their saliva, and skin discoloration known as maculae caeruleae. They do not transmit diseases but their presence often indicates the need for an STI screening. Benefit: None to humans or the ecosystem.

Identified on: 2/3/2026