Head Louse (Nits)

Scientific Name: Pediculus humanus capitis

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

Size: Nits (eggs) are approx. 0.8 mm. Adults are 2–3 mm (about the size of a sesame seed).

Head Louse (Nits)

Natural Habitat

The scalp and hair of humans. They are found worldwide and are highly host-specific.

Diet & Feeding

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

Behavior Patterns

Nits are glued firmly to hair shafts. Adults cannot fly or jump; they spread through direct head-to-head contact. They cannot survive more than 24-48 hours off a host's head.

Risks & Benefits

Risks include intense itching, scalp irritation, and potential secondary bacterial infections from scratching. They are not known to transmit systemic diseases. There are no known ecological benefits to humans.

Identified on: 1/11/2026