Head lice are only about the size of a sesame seed (3-4 mm) when they are fully grown. Their 6 legs end in hook-shaped claws which they use to tightly grasp the hair.
They are transparent. This makes them difficult to detect in the hair. Once they have fed, head lice turn brown-red. They lay their pearly-white eggs close to the scalp. In some cases, you can find dead eggs, which are brownish in colour or empty egg cases, also known as nits, that are white and look a bit like dandruff.
The eggs hatch after 7 days. These ‘baby head lice’ are called nymphs. After 10 days, nymphs become mature adults ready to lay eggs.
Adult head lice live about 30 days. In that time, female head lice can lay 200 to 300 eggs.