Human Head Louse

Scientific Name: Pediculus humanus capitis

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

Size: 2 to 3 mm in length (roughly the size of a sesame seed).

Human Head Louse

Natural Habitat

Exclusively on the human scalp and hair, often concentrated behind the ears and at the nape of the neck.

Diet & Feeding

Obligate hematophages; they feed exclusively on human blood several times a day.

Behavior Patterns

They are wingless and cannot jump or fly; they move by crawling from hair to hair. They attach their eggs (nits) to hair shafts near the scalp with a glue-like substance. They can only survive for 24-48 hours off a human host.

Risks & Benefits

Risks include intense itching (pruritus due to allergic reactions to saliva), sleep loss, and secondary bacterial infections from scratching. They are not known to transmit systemic diseases. There are no ecological benefits to humans; they are considered parasitic pests.

Identified on: 3/13/2026