This is a photomicrograph of a female pubic louse. The condition known as "crabs" is so named because of the resemblance of a pubic louse to a crab. The bodies of pubic lice are shorter and rounder than those of head lice. (Image courtesy of the Centers for Disease Control and Prevention.)

This is a photomicrograph of a male pubic louse. The condition known as "crabs" is so named because of the resemblance of a pubic louse to a crab. The bodies of pubic lice are shorter and rounder than those of head lice.

This photograph shows pubic lice clinging to individual hairs (the small, whitish specks). The reddish, crusted areas with scabs (excoriated areas) are caused by scratching. (Image courtesy of the Centers for Disease Control and Prevention.)

This picture compares the relative size and shape of the head louse and the pubic louse.