The incubation period for head lice is between 6 and 9 days, or roughly one week. After hatching, young lice (nymphs) become adults in about 7 days. These adult lice can live on a human head for up to 30 days.
The scientific name for head lice is Pediculus humanus capitis. They are an ectoparasite, which means they live outside of the host's body. Adult female head lice can lay up to 8 eggs (nits) each day. These nits are difficult to see due to their yellow-white color and minuscule size. While lice can live on a host's head for over a month, they will die within two days if they leave the host.