Go back

What Are Crabs?

Crabs, also known as pubic lice (Pthirus pubis), are tiny crab-like parasites that can infest your pubic hair. They attach themselves to these coarse hairs so they can feed on your blood. You might also find them in your armpit or facial hair but, unlike head lice, they typically don’t infest the hair on your head. You can get crabs from having sexual contact with someone who currently has crabs or through contact with affected clothing, towels, or bed linens.

The Three Stages of Crabs

Crabs go through three phases, all of which you might find on your pubic hair:

  1. Nit. The nit is the pubic louse’s egg, which it lays and attaches to the base of the hair. The whitish, oval-shaped nits are difficult to see and will hatch within a week to 10 days if left untreated.
  2. Nymph. When the nit hatches, it takes this immature form. Nymphs need blood to survive, so they’ll bite the skin around your genitals. This causes the characteristic itching reaction that affected people experience starting about five days into the infestation. Nymphs mature to their adult form within two to three weeks.
  3. Louse. Adult crabs are fully mature and visible if you look closely. If you view them under a magnifying glass, you’ll see they have six legs, with the front two resembling the large pincers of a crab — hence, their common name. At this stage, the lice can reproduce. They must still feed on human blood to survive and will die within a day or two if they fall off your hair.


There are approximately 3 million crabs cases in the United States each year. Crabs can infest anyone worldwide and, contrary to some people’s belief, aren’t associated with poor hygiene. Fortunately, they’re easily treated using medicated lotions and shampoos.

Back to top