Louse

Scientific Name: Pediculus humanus capitis or Phthirus pubis

Order & Family: Order: Psocodea (formerly Anoplura); Family: Pediculidae or Pthiridae

Size: 2mm to 4mm (roughly the size of a sesame seed).

Louse

Natural Habitat

Exclusively on the human body, specifically hair and scalp (head lice) or pubic hair/coarse body hair (pubic lice).

Diet & Feeding

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

Behavior Patterns

They reside near the surface of the skin to stay warm and feed. Females lay eggs (nits) and cement them to the base of hair shafts. They cannot jump or fly and are transmitted through direct physical contact or shared personal items.

Risks & Benefits

Risks include intense itching (pruritus), skin irritation, and potential secondary bacterial infections from scratching. Unlike body lice, head and pubic lice are not known to transmit systemic diseases but are considered a public health nuisance. There are no known benefits to humans or ecosystems.

Identified on: 2/16/2026