Pubic lice (phthirus pubis) are also known as crabs and pediculosis pubis. They are tiny parasitic insects that live in coarse body hair, most commonly pubic hair. They can also be found on the eyelashes, eyebrows, abdomen, back and in facial hair such as beards or moustaches. Pubic lice are blood-sucking insects and they don't usually live on other animals.
Adult pubic lice are about 2mm long (smaller than a match head) and are a yellow-grey colour. They have six legs, but the two pairs of back legs are much larger and look like the pincer claws of a crab (they use them for grasping hair), hence the nickname crabs.
The females lay very small eggs, which are smaller than a pinhead, and glue them to the base of hairs. The eggs hatch after 6-10 days. The empty eggshells are known as nits and look like a white oval dot in the hair. Female lice live between one to three months and during that time can lay up to 300 eggs. Numbers can therefore grow quickly if not treated. When lice are present in large numbers, it is known as infestation.
Pubic lice affect only humans. They can affect people of any age, but are most commonly found in young adults.
Sexual contact is the most common way of spreading pubic lice, and you are more likely to get them if you or your partner have multiple or casual sexual partners. Pubic lice can be caught by close contact (non-sexual) with someone who has them, for example by hugging or kissing someone with an infested beard or chest hair. It may be possible for pubic lice to be spread by sharing clothing, bedding and towels.
Lice can live for up to 24 hours off the body. However, because pubic lice depend on human blood for survival, they will rarely leave the body unless there is a close body contact with another person.
