How many days do lice appear? - briefly
Lice become visible approximately two weeks after an infestation, when eggs hatch and nymphs mature. The full cycle from egg to adult usually takes 14‑21 days.
How many days do lice appear? - in detail
Lice become detectable only after a specific interval following the initial contact with an infested host. The development cycle proceeds through three distinct stages, each with a predictable duration.
The egg, commonly called a nit, is attached to hair shafts near the scalp. Under optimal conditions—temperature around 30 °C and adequate humidity—egg incubation lasts 7 to 10 days. During this time the embryo matures but remains invisible to the naked eye.
After hatching, the newly emerged nymph resembles an adult but is smaller and less mobile. Nymphal development requires an additional 5 to 7 days, during which three successive molts occur. Upon completion of the final molt, the insect attains full maturity and begins feeding on blood three times a day.
Consequently, the earliest point at which live lice can be observed on the scalp is approximately 12 to 17 days after the first contact with an egg‑bearing source. Visible signs such as itching, irritation, or the presence of moving insects typically appear shortly after the adult stage is reached.
Key points summarised:
- Egg incubation: 7‑10 days
- Nymphal period (including three molts): 5‑7 days
- First visible adult lice: 12‑17 days post‑infestation
- Observable symptoms (itching, visible insects): within a few days after adult emergence
Understanding this timeline assists in early detection and timely treatment, reducing the risk of a full‑blown infestation.