Pubic Louse (Crab Louse)
Scientific Name: Pthirus pubis
Order & Family: Order: Psocodea (formerly Phthiraptera), Family: Pthiridae
Size: Very small, approximately 1.5 to 2.0 mm in length (roughly the size of a pinhead), often appearing shorter and broader than head lice.
Natural Habitat
Exclusively inhabits coarse human body hair, most typically the pubic region, but occasionally found near eyelashes, eyebrows, beards, armpits, or chest hair. They do not live on the scalp.
Diet & Feeding
Hematophagous (blood-feeders). They feed exclusively on human blood several times a day.
Behavior Patterns
They are relatively immobile ectoparasites that grasp coarse hair shafts with large, crab-like claws. They lay eggs (nits) on the hair shaft near the skin. They are obligate parasites and cannot survive away from a human host for more than 24-48 hours.
Risks & Benefits
Risks: They cause intense itching (pruritus) due to allergic reaction to their saliva, skin irritation, and potential secondary bacterial skin infections from scratching. They are spread primarily through sexual contact or shared bedding/clothing. Benefits: None known.
Identified on: 3/11/2026