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, clinging to hairs near the skin to maintain body temperature and accessibility to food.

Diet & Feeding

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

Behavior Patterns

They are wingless and cannot jump or fly; they move by crawling. Eggs (nits) are cemented to hair shafts. They suffer from dehydration and starve quickly (within 24–48 hours) if separated from a human host.

Risks & Benefits

Risks include intense itching (pruritus) due to an allergic reaction to saliva, loss of sleep, and potential secondary bacterial skin infections from scratching. They are not known to transmit systemic diseases. There are no ecological benefits to humans.

Identified on: 4/25/2026