Pubic louse

Scientific Name: Pthirus pubis

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

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

Pubic louse

Natural Habitat

Found exclusively on humans, specifically in coarse hair such as pubic hair, beard hair, eyelashes, or armpits.

Diet & Feeding

Obligate ectoparasite; feeds exclusively on human blood through specialized mouthparts.

Behavior Patterns

They are slow-moving and use powerful, crab-like claws to cling to hair shafts. They undergo simple metamorphosis (egg/nit, nymph, and adult) and cannot survive long away from a human host.

Risks & Benefits

Risks include intense itching (pruritus) due to hypersensitivity to saliva and secondary bacterial skin infections from scratching. They are not known to transmit systemic diseases but are often an indicator of close physical contact.

Identified on: 5/21/2026