Human head louse

Scientific Name: Pediculus humanus capitis

Order & Family: Order: Psocodea, Family: Pediculidae

Size: Adults are approximately 2–3 mm long (about the size of a sesame seed).

Human head louse

Natural Habitat

Exclusively on the human scalp, typically found near the base of the hair shaft close to the skin.

Diet & Feeding

Obligate ectoparasites that feed exclusively on human blood several times a day.

Behavior Patterns

They are wingless and spread through direct head-to-head contact. Females lay eggs (nits) and cement them to hair shafts. They cannot jump or fly and die within 24–48 hours if separated from a human host.

Risks & Benefits

Risks include intense itching (allergic reaction to saliva), scalp irritation, and potential secondary bacterial infections from scratching. They are not known to transmit systemic diseases. There are no ecological benefits to humans.

Identified on: 3/17/2026