Human Head Louse (Egg/Nit or Nymph)

Scientific Name: Pediculus humanus capitis

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

Size: Nits are approximately 0.8mm; adults are 2.0 to 3.0mm in length.

Human Head Louse (Egg/Nit or Nymph)

Natural Habitat

Exclusively found on the human scalp, particularly behind the ears and near the neckline, where they attach eggs to hair shafts.

Diet & Feeding

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

Behavior Patterns

They are wingless and cannot jump or fly, moving only by crawling. Eggs (nits) are glued to the base of the hair shaft and hatch in 7-10 days into nymphs, which mature into adults after about 9-12 days.

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 infectious diseases.

Identified on: 12/28/2025