Head louse

Scientific Name: Pediculus humanus capitis

Order & Family: Order Psocodea, Family Pediculidae

Size: 2-3 mm long (roughly the size of a sesame seed).

Head louse

Natural Habitat

The scalp and hair of humans; they are obligate ectoparasites that cannot survive long off a host.

Diet & Feeding

Exclusively human blood, which they obtain by biting the scalp multiple times a day.

Behavior Patterns

Lice cannot jump or fly; they crawl from person to person through direct head-to-head contact. Females lay eggs (nits) and cement them to hair shafts close to the scalp for warmth.

Risks & Benefits

Risks include intense itching (pruritus) due to an allergic reaction to louse saliva, and potential secondary skin infections from scratching. They do not transmit diseases.

Identified on: 3/2/2026