Crab louse (or Pubic louse)

Found exclusively on humans, typically in coarse hair such as pubic hair, but can also inhabit eyelashes, eyebrows, armpits, and chest hair.

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

They are slow-moving and use specialized claws to grasp hair shafts. They cannot jump or fly. They lay eggs (nits) at the base of hairs and have three nymphal stages before reaching adulthood.

Risks include intense itching (pruritus due to an allergic reaction to saliva) and secondary skin infections from scratching. In the eyelashes (phthiriasis palpebrarum), they can cause blepharitis (eyelid inflammation). They do not transmit diseases. There are no known benefits.