Head lice are tiny, parasitic insects that live in human hair. They stay close to the scalp for warmth and feed on blood several times a day. When fully grown, they are about the size of a sesame seed – up to 3mm long – and are grey/brown in colour, although they may appear darker in people with darker hair. 

Lice can’t fly, jump or swim, but they do walk around the scalp, holding strongly onto hair shafts as they go. Each louse has six legs with claws to help it grip onto the hair. 

The number of lice that may be present on an infected individual varies, but usually there are around 30. Head lice only live on humans, not on pets or animals, and do not carry diseases.

It’s important to note that head lice infections have nothing to do with dirty hair or hygiene and they are only picked up through head-to-head contact.

Did you know?

Head lice are not hereditary but several members of a family can be infected at the same time.