It can take as long as 2 to 3 weeks or longer for a person to notice the presence of head lice or nits. Lice live for around a month and can lay up to 130 nits in their lifetime or 4 to 8 per day once they reach maturity. The eggs take around 7 days to hatch, and 7 to 10 days to grow into mating, egg-laying adults. An adult louse lays 4-8 eggs per day and lives for about 10-12 days. From being laid to dying, a louse life-cycle is around 30-35 days.

Baby lice are extremely small but can be seen with the naked eye. They look like a spec with legs! Adolescent lice have a semi-translucent body and are double the size of the baby louse. Adults are larger again and are brown to black in colour with head, body and legs clearly distinguishable.

The life cycle of the head louse has three stages: egg (nit), nymph (baby and adolescent) and adult. Stages of the lifecycle:
1) Egg (nit) is laid on the hair shaft.
2) Nymph emerges from eggs laid on day 0.
3) Nymph moults for the first time.
4) Second moult.
5) Third moult.
6) Adult male and female lice mate.
7) Female lays first eggs two days after mating and can lay four to eight eggs per day for the next 16 days.
8) Louse dies.