Human head lice don’t live very long at all. Their entire life cycle is only about 30-35 days. The adult lice needs human blood to survive. They suck blood and feed about every two to three hours off the scalp of the head. If they come off the scalp, should that happen, they die within 24-48 hours. Adult lice do not like to come off the scalp. They need the heat and humidity of the human scalp to survive. They also need the human scalp and hair to lay their eggs on the hair shaft very close the scalp where it is nice and warm and nice and humid so their eggs can hatch. When those eggs hatch, the adult lice can them immediately get on the scalp and feed on the blood. Adult females lay 80 to 90 eggs during their 14-17 day lifetime so about 5-7 eggs per day. Their eggs take about 8 to 9 days to hatch. Infestations will continue literally for years if you don’t seek treatment so we recommend that you seek treatment and make sure you find out if you have a case of head lice or not.