How many days does it take for lice to hatch from nits? - briefly
Lice eggs generally hatch within 7–10 days under typical temperature and humidity conditions. Extreme heat or moisture can shorten or lengthen this period slightly.
How many days does it take for lice to hatch from nits? - in detail
Lice eggs, commonly called nits, develop under the hair shaft and require a specific period before the emerging nymph breaks free. Under normal indoor temperatures (20‑25 °C or 68‑77 °F), the incubation interval averages 7 to 10 days. Deviations occur when environmental conditions shift: higher temperatures can shorten the cycle to 5‑6 days, while cooler settings may extend it to 12 days or more.
Key variables influencing the timeline include:
- Temperature: each 5 °C increase can reduce development time by roughly one day.
- Humidity: optimal relative humidity (50‑70 %) supports normal hatching; extreme dryness slows embryogenesis.
- Lice species: head lice (Pediculus humanus capitis) typically hatch within the 7‑10‑day window; body lice (Pediculus humanus corporis) show a similar range, whereas crab lice (Pthirus pubis) may take 8‑12 days.
- Egg condition: intact, well‑attached eggs hatch reliably; damaged or improperly cemented nits may fail to develop.
After emergence, the nymph resembles an adult but lacks fully developed reproductive organs. It requires an additional 5‑7 days of successive molts before reaching maturity and beginning egg production.
Therefore, the expected period from egg laying to hatching lies primarily between one and a half weeks, with precise duration determined by temperature, humidity, species, and egg integrity.