Louse eggs on the hair very close to the scalp are the primary sign of an active infestation. A female can lay up to 50-150 eggs in its life, but it can lay up to 100 eggs in 30 days. She also glues her eggs, sometimes called "nits", which look like tiny white beads, to hair shafts very close to the scalp (usually about a centimeter or two [half an inch to three-quarters of an inch] from the scalp). Eggs are very small, about the size of a period "." (full stop) in normal printing. Eggs may appear white, yellowish, brownish or greyish, but are almost always lighter colored. An egg normally undergoes a 7-9 day incubation before hatching as a baby nymph.