Pubic Louse (also known as Crab Louse or Crabs)
Pthirus pubis
- Order & Family
- Order Psocodea (formerly Phthiraptera), Family Pthiridae
- Size
- 1.1 mm to 1.8 mm (about the size of a pinhead)
Natural Habitat
Human pubic hair, but can also be found in coarse hair elsewhere on the body such as eyelashes, eyebrows, beard, chest, and armpits.
Diet & Feeding
Obligate hematophage (feeds exclusively on human blood) several times a day.
Behavior Patterns
They are sedentary parasites that cling to hair shafts with powerful crab-like claws. They move slowly and do not jump or fly. Their life cycle consists of three stages: egg (nit), nymph, and adult, taking about 2-3 weeks to complete.
Risks & Benefits
Risks include intense itching (pruritus) due to allergic reactions to saliva, blue spots (maculae caeruleae) on the skin, and secondary bacterial infections from scratching. They are primarily transmitted through close physical/sexual contact or occasionally through infested bedding/towels. They have no known ecosystem benefits.