How quickly do lice and nits reproduce? - briefly
Female head lice start depositing about six eggs per day roughly one week after becoming adults, and each egg hatches in 7–10 days. The newly emerged nymph reaches reproductive maturity in another 7–10 days, completing the life cycle in about three weeks.
How quickly do lice and nits reproduce? - in detail
Head lice (Pediculus humanus capitis) complete their life cycle in roughly three weeks under optimal conditions. An adult female deposits 6‑10 eggs (nits) each day, attaching them to hair shafts close to the scalp. The eggs require 7‑10 days to hatch, a period that shortens with higher ambient temperatures (around 30 °C) and lengthens in cooler environments.
After emergence, the nymph passes through three developmental stages, each lasting about 5‑6 days. During each stage the insect molts once, becoming progressively larger and more mobile. By the end of the third instar, roughly 14‑18 days after the egg was laid, the nymph reaches adulthood.
Adult lice live for 30‑40 days on a host, during which a female can produce 300‑400 eggs if uninterrupted. Reproduction therefore proceeds at a rate of approximately 6‑10 new eggs per day per female, resulting in a potential exponential increase of the population within a month.
Key timing points:
- Egg incubation: 7‑10 days
- Nymphal development (three molts): 5‑6 days per stage, total 15‑18 days
- Time to first reproduction by a newly emerged adult: 1‑2 days after the final molt
- Total cycle from egg to reproductive adult: 21‑28 days
Environmental factors such as temperature, humidity, and host grooming habits can accelerate or delay each phase, but the baseline timeline remains consistent across most infestations.