How quickly do lice hatch? - briefly
Pediculus humanus eggs usually hatch in 7–10 days when temperature is near 30 °C and humidity is adequate. Warmer, more humid environments can shorten this period slightly.
How quickly do lice hatch? - in detail
Lice eggs, known as nits, develop within a narrow time frame after being laid by the adult female. The incubation period typically lasts between 7 and 10 days, depending on species and environmental conditions.
- Head lice (Pediculus humanus capitis): Eggs hatch in about 7‑9 days at room temperature (20‑25 °C). Higher temperatures accelerate development, while cooler environments extend it.
- Body lice (Pediculus humanus corporis): Similar hatch time, 8‑10 days, with temperature as the primary variable.
- Pubic lice (Pthirus pubis): Eggs require roughly 8‑10 days to emerge, also influenced by ambient heat and humidity.
Key factors affecting the rate of emergence:
- Temperature: Each increase of 5 °C reduces the incubation period by roughly one day.
- Humidity: Relative humidity above 70 % promotes faster hatching; low humidity can delay it by a day or more.
- Egg placement: Nits attached firmly to hair shafts receive more stable conditions, leading to consistent development times.
After hatching, the nymph undergoes three molts over 5‑7 days before reaching adulthood. Consequently, a full life cycle from egg to adult spans approximately 14‑21 days under optimal conditions. Understanding these timelines is essential for effective treatment planning and preventing reinfestation.