Crab louse
| Crab louse | |
|---|---|
_Female,_from_a_human_host.jpg) |
|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Phthiraptera |
| Suborder: | Anoplura |
| Family: | Pthiridae |
| Genus: | Pthirus |
| Species: | P. pubis |
| Binomial name | |
|
Pthirus pubis (Linnaeus, 1758) |
|
| Synonyms | |
|
Pediculus pubis Linnaeus, 1758 |
|
Pediculus pubis Linnaeus, 1758
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, and is more distantly related to the genus Pediculus, which contains the human head and body lice.
An adult crab louse is about 1.3–2 mm long (slightly smaller than the body louse and head louse), and can be distinguished from those other species by its almost round body. Another distinguishing feature is that the rearmost two pairs of legs of a crab louse are much thicker than the front legs and have large claws.
The eggs of the crab louse are laid usually on the coarse hairs of the genital and perianal regions of the human body. Crab lice may also be found on other areas of the body that have coarse and relatively sparse coverings of hair, such as the beard, moustache, eyelashes, underneath the arms. They do not generally occur on the finer hair of the scalp.
The female lays about three eggs a day. The eggs take 6–8 days to hatch, and there are three nymphal stages which together take 10–17 days before the adult develops, making a total life cycle from egg to adult of 16–25 days. Adults live for up to 30 days. Crab lice feed exclusively on blood, and take a blood meal 4–5 times daily.
Infestations of crab lice are known as pediculosis pubis or phthiriasis pubis (which, unlike the generic name of the louse, is spelled with a phth). Infestation of the eyelashes is referred to as pediculosis ciliaris or phthiriasis palpebrarum.
...
Wikipedia