Pubic Louse (Crab Louse)

Scientific Name: Pthirus pubis

Order & Family: Order: Psocodea (formerly Anoplura), Family: Pthiridae

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

Pubic Louse (Crab Louse)

Natural Habitat

Exclusively found on humans, typically in pubic hair but can also occupy coarse body hair like armpits, eyelashes, or beards.

Diet & Feeding

Obligate blood-feeders; they consume human blood several times a day to survive.

Behavior Patterns

Slow-moving insects that grasp hair shafts with specialized claw-like legs. They lay eggs (nits) at the base of hairs and cannot survive longer than 24-48 hours off a human host.

Risks & Benefits

Risks include intense itching (pruritus) due to allergic reactions to saliva and potential secondary skin infections from scratching. They are not known to transmit systemic diseases but are markers for close physical contact or shared personal items.

Identified on: 6/11/2026