Head lice are tiny insects that live in hair. Nits are the empty egg cases attached to hair that head lice hatch from.

Head lice are a common problem, particularly in school children aged 4-11.
They’re largely harmless, but can live in the hair for a long time if not treated and can be irritating and frustrating to deal with. Head lice can be difficult to spot, even when the head is closely inspected.

They’re very small whitish or grey-brown insects that range from the size of a pinhead to the size of a sesame seed. The only way to be sure someone has head lice is to find a live louse by combing their hair with a special fine-toothed comb.

Pubic lice (Pthirus pubis) are tiny parasitic insects that live on coarse human body hair, such as pubic hair.

As well as being found in pubic hair, the lice are also sometimes found in:

• Underarm and leg hair
• Hair on the chest, abdomen and back
• Facial hair, such as beards and moustaches
• Eyelashes and eyebrows (very occasionally)
• Unlike head lice, pubic lice don’t live in scalp hair

Pubic lice are spread through close bodily contact, most commonly sexual contact.
Adult pubic lice are very small (2mm long) and aren’t easy to see. They’re a yellow-grey or dusky red colour and have six legs.

Pubic lice are sometimes known as crabs because they have two large front legs that look like the claws of a crab. These are used to hold onto the base of hairs.
The lice lay their eggs (nits) in sacs that are stuck firmly to hairs and are a pale brownish colour. When the eggs hatch, the empty egg sacs are white.

Lice are highly contagious and can spread quickly from person to person.