Pubic louse (or 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 (or Crab louse)

Natural Habitat

Exclusively found on humans, typically in coarse hair such as pubic hair, but occasionally in eyelashes, eyebrows, or chest hair.

Diet & Feeding

Obligate hematophages; they feed exclusively on human blood several times a day.

Behavior Patterns

They are sedentary parasites that grasp hair shafts with specialized, crab-like claws. They cannot jump or fly and are usually transmitted through close physical contact or shared linens.

Risks & Benefits

Risks include intense itching (pruritus) due to hypersensitivity to their saliva and potential secondary bacterial skin infections from scratching. They are not known to transmit systemic diseases but are considered a nuisance parasite.

Identified on: 1/11/2026