The
crab louse (
Pthirus pubis, also
pubic louse) is an
insect that is an
obligate ectoparasite of
humans, feeding exclusively on
blood. The crab louse usually is found in the person's
pubic hair. Although the louse cannot jump, it can also live in other areas of the body that are covered with coarse hair, such as the
eyelashes. Humans are the only known hosts of the crab louse, although a closely related species,
Pthirus gorillae, infects
gorilla populations. The human parasite diverged from
Pthirus gorillae approximately 3.3 million years ago.