What is the life cycle of the head louse?
During their lifetime, a female head louse can lay up to 200 eggs on the hair shaft using a strong glue like substance. The eggs remain firmly glued to the hair near the scalp until they hatch, usually within 7 to 10 days. Young lice (nymphs) reach maturity after 7 to 10 days and once mature, can mate and start to lay eggs. Head lice have a life span of around 30 to 45 days. The life cycle and the short gestation is the reason why one time treatments simply will not work. While you may successfully kill live adult lice, the egg may survive treatment, hatch and begin the cycle over again.
Note: The only way to successfully treat a head lice infestation is to BREAK this life cycle. Although you may be successful in eradicating live adults and nymphs, if you do not remove ALL the eggs, the cycle WILL continue.