Pubic lice are tiny parasitic insects that live in coarse body hair, such as pubic hair. They are yellow-grey and about 2mm long. They have a crab-like appearance, so they are often known as crabs. The eggs appear as brownish dots fixed to coarse body hair. Pubic lice are different from the head lice which some people get on their scalp.
Scabies is caused by tiny parasitic mites. They are smaller than a pinhead and burrow into the skin and lay eggs. A more severe and uncommon form of the condition occurs when there are many mites in the skin. This is called crusted scabies, and can affect older people and people with certain illnesses, such as HIV infection.