Human Head Louse

Scientific Name: Pediculus humanus capitis

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

Size: 2.1 mm to 3.3 mm (roughly the size of a sesame seed).

Human Head Louse

Natural Habitat

Found exclusively on the human scalp, where they attach to hair follicles near the skin for warmth and access to blood.

Diet & Feeding

Strictly hematophagous; they feed on human blood multiple times a day.

Behavior Patterns

They are wingless and cannot jump; they spread through direct head-to-head contact. Females lay eggs (nits) and glue them to hair shafts. They undergo simple metamorphosis (egg, nymph, adult).

Risks & Benefits

They cause intense itching (pruritus) due to an allergic reaction to their saliva. While they are a nuisance and can lead to secondary skin infections from scratching, they are not known vectors of disease. There are no ecological benefits.

Identified on: 5/16/2026