Life Span. Nits, or lice eggs, can live for up to 10 days but will need to feed on human blood after hatching. Adult lice can live for up to one month on the head of a human but die within two to three days without body contact.ead lice are very small insects that live on the scalp, which is also where they lay their eggs. They survive longer when on the scalp, but how long can head lice live without body contact? 1  How to Break the Lice Life Cycle. 2  How to Use Dawn to Kill Lice.