You can see that the life cycle of the head louse has three stages: egg, nymph, and adult. Here’s what the CDC says about the head louse wheel of life:
- Eggs – Nits are head lice eggs. They are hard to see and are often confused for dandruff or hair spray droplets. Nits may be found at the base of the hair shaft nearest the scalp (1). They are 0.8 mm by 0.3 mm, oval and usually yellow to white. Nits take about 1 week to hatch (range 6 to 9 days).
- Nymphs – The egg hatches to release a nymph (2). The nit shell then becomes a more visible dull yellow and remains attached to the hair shaft. The nymph looks like an adult head louse, but is about the size of a pinhead. Nymphs mature after three molts (3,4) and become adults about 7 days after hatching.
- Adults – The adult louse is about the size of a sesame seed, has 6 legs (each with claws, yikes), and is tan to grayish-white (5). In persons with dark hair, the adult louse will appear darker. The females can lay up to 8 nits per day. Adult lice can live up to 30 days on a person’s head. To live, adult lice need to feed on blood several times daily. Without blood meals, the louse will die within 1 to 2 days off the human host.