What is the head lice life cycle?

The average life span of a louse is around 40 days and it estimated that they can lay more than 100 eggs during this time. Lice can only survive on humans: after a couple of days away from the scalp, they will die. A louse lays eggs close to the root of hairs where they will be kept warm by the scalp, and after 7-10 days the baby lice hatch. The eggs remain fixed in place and become more noticeable as hair grows and moves them away from the scalp.

Lice take 9-10 days to become fully grown, feeding on blood. A female louse may begin laying eggs from 9 days after she has hatched. Therefore, in order to break the cycle, lice should be treated within 9 days of hatching to prevent any further hatching.