Pubic Louse (Crab Louse)

Scientific Name: Pthirus pubis

Order & Family: Order: Psocodea, Family: Pthiridae

Size: 1.1 to 1.8 mm (about the size of a pinhead).

Pubic Louse (Crab Louse)

Natural Habitat

Human pubic hair, occasionally other coarse body hair (eyelashes, eyebrows, facial hair, chest hair).

Diet & Feeding

Obligate blood feeders, obtaining blood meals directly from human hosts.

Behavior Patterns

They are stationary and attach themselves to the base of hair shafts. Eggs (nits) are glued to the hair. The life cycle from egg to adult takes about 3 to 4 weeks.

Risks & Benefits

Causes intense pruritus (itching) and pediculosis pubis. Can lead to secondary bacterial infections from scratching. Transmitted mainly through sexual contact.

Identified on: 3/9/2026