Itching occurs, especially at night, in the pubic hair area.

Seeing the lice. The lice are small (up to 2 mm long), and can just be seen with the naked eye. They are squat in shape and, with a magnifier, you can see that all the legs emerge close together from the front of the body, and the middle and hind legs have large pincer-like claws giving the ‘crab’ appearance. They use their claws to grasp hairs close to the skin surface. They hardly move except at night, when they slowly transfer their grip from one hair to another.

Nits, which are the egg cases, can be seen attached to the hairs. The female lays the eggs in a hard brown shell, which she attaches to the hair on the surface of the skin. As the hair grows, the egg case will be further up its shaft, so the position of the nits on the hair gives you an idea of how long you have had them. After about 8 days the eggs hatch, and the empty egg case appears white and is easier to see.

Rust-coloured specks may be seen on the skin – these are louse faeces.

Blood specks may be seen on underwear.

• Crab lice - main page
• What you can do and what your doctor can do
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