How long does it take for lice to be born? - briefly
Eggs hatch in approximately 7–10 days after being laid, and the emerging nymphs reach adulthood after an additional 5–7 days.
How long does it take for lice to be born? - in detail
Female head lice deposit 4‑6 eggs per day, securing each to a hair shaft near the scalp. The eggs, called nits, are cemented with a proteinous glue that hardens within minutes.
At normal human body temperature (≈37 °C) the embryonic development inside the egg requires 7–10 days. Lower ambient temperatures extend this period, while temperatures above 38 °C can shorten it slightly. Humidity influences the glue’s durability but has minimal effect on embryogenesis.
When the nymph emerges, it undergoes three molts. Each molt interval lasts about 1–2 days, resulting in a total nymphal phase of roughly 5–7 days before sexual maturity is reached. Adult lice become capable of laying eggs after an additional 1–2 days.
Typical timeline
- Egg deposition → embryonic development: 7–10 days
- First molt: 1–2 days
- Second molt: 1–2 days
- Third molt: 1–2 days
- Mature adult ready to reproduce: 5–7 days after hatching
Overall, from egg laying to a reproducing adult takes approximately 12–14 days under optimal conditions. Variations in temperature and host hygiene can shift these intervals by a few days.