How long after infestation do lice start laying eggs? - briefly
Female head lice begin laying eggs roughly five to seven days after they hatch, so the first nits appear about a week after the initial infestation. Typically, observable egg deposition occurs within 7‑10 days of colonization.
How long after infestation do lice start laying eggs? - in detail
After a head‑lice infestation, the female becomes capable of producing eggs only after she reaches adulthood. The developmental sequence is:
- Egg stage (nit): Laid by an adult, incubates for 7–10 days before hatching.
- Nymph stage: Newly emerged lice resemble miniature adults but are sexually immature. They require about 7 days of feeding and molting through three instars to become reproductive.
- Adult stage: Once the nymph matures, the female can lay eggs. This typically occurs 5–7 days after the nymph’s final molt.
Consequently, the first eggs appear roughly 12–17 days after the initial contact with an adult louse. The timing may vary with temperature and host hygiene; warmer conditions accelerate development, while cooler environments delay it.
A mature female lays 5–6 eggs per day, reaching a total of 70–100 eggs over her 30‑day lifespan. Eggs are attached to hair shafts close to the scalp, making detection easier during the second week after infestation. Early treatment should therefore target both live lice and nits before the first oviposition occurs.