Pubic louse

Scientific Name: Pthirus pubis

Order & Family: Order: Psocodea; Family: Pthiridae

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

Pubic louse

Natural Habitat

Found exclusively on humans, primarily in the pubic hair region, but can also inhabit other coarse hair such as eyelashes, eyebrows, beard, and armpits.

Diet & Feeding

Obligate hematophage; they feed exclusively on human blood throughout all life stages.

Behavior Patterns

They are relatively immobile and remain attached to hair shafts; they move slowly by grasping thick hairs with their specialized large claws. The life cycle involves three stages: egg (nit), nymph, and adult. They are typically transmitted through close physical or sexual contact.

Risks & Benefits

Risks include intense itching (pruritus) caused by an allergic reaction to their saliva, and small bluish spots on the skin where they have fed. They do not typically transmit diseases but can lead to secondary skin infections from scratching. There are no ecological benefits to humans.

Identified on: 3/25/2026