Nits are head lice eggs, they are very small, about the size of a knot in thread, hard to see, and are often confused for dandruff or hair spray droplets. Nits are laid by the adult female at the base of the hair shaft nearest the scalp and are firmly attached to the hair shaft. They are oval and usually yellow to white. Nits take about one week to hatch. Eggs that are likely to hatch are usually located within ¼ inch of the scalp.