Head louse (eggs known as nits)

Scientific Name: Pediculus humanus capitis

Order & Family: Order: Psocodea; Family: Pediculidae

Size: Commonly 2-3 mm for adults; nits (eggs) are approximately 0.8 mm.

Head louse (eggs known as nits)

Natural Habitat

Exclusively the human scalp and hair, remaining close to the scalp for warmth.

Diet & Feeding

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

Behavior Patterns

They cannot fly or jump; they move by crawling. Eggs (nits) are cemented to the hair shaft. Life cycle includes egg, three nymphal stages, and adult.

Risks & Benefits

Cause intense itching and scalp irritation due to an allergic reaction to saliva. While they do not spread disease, secondary infections can occur from scratching. No ecological benefits to humans.

Identified on: 4/19/2026