The gestation period for nits, or baby lice that have yet to hatch, is seven to 10 days. After the gestational period ends, nits take 10 days to mature into adults. An adult louse can remain attached to a host for up to 10 days.
Nits do not hatch at temperatures less than 69 degrees Fahrenheit. When attached to a host, a louse's total lifespan, from incubation until death, can be up to one month. Because lice's sole food source is human blood, their lifespan is shortened to approximately four days at 74 degrees Fahrenheit or two days at 86 degrees Fahrenheit if detached from the host.