The genital areas of mature men and women are often covered by thatches of coarse pubic hair. These hairs can become infested with a small insect, called pubic lice (or crabs), through sexual contact, or sharing clothing or bedding with an infested individual.

Pubic lice are generally tan in color and are about the size of the head of a pin. They are relatively flat and when seen on the skin they often look like small scabs.

The lice have claws that help them attach to the pubic hairs where they lay their eggs. The eggs, called nits, look like small brown dots and are attached firmly to the base of the hairs near the skin. Adult lice feed on human blood by inserting their mouthpieces into small blood vessels in the skin. While the lice feed on human blood, proteins in their saliva are transferred into the skin.

After a person has been infested for several days, or if the person has had a previous infestation, the proteins are recognized by antibodies in the skin and release chemicals that cause itching and inflammation in the pubic area – the first sign of infestation. Fortunately, infestation with pubic lice, a condition called pediculosis, can be treated with over-the-counter medications.