Human Head Louse

Scientific Name: Pediculus humanus capitis

Order & Family: Order: Psocodea; Family: Pediculidae

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

Human Head Louse

Natural Habitat

The scalp of a human host, specifically near the hair follicles for warmth and food.

Diet & Feeding

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

Behavior Patterns

They are wingless and cannot jump; they move by crawling from hair to hair. They attach eggs (nits) to hair shafts near the scalp with a waterproof glue.

Risks & Benefits

They cause scalp irritation and itching (pediculosis) due to an allergic reaction to their saliva. While highly contagious through direct head-to-head contact, they are not known to spread disease-causing pathogens.

Identified on: 4/30/2026