How quickly do head lice reproduce? - briefly
A female head louse deposits about 5–10 eggs per day; the eggs hatch in 7–10 days, and the nymph matures into an adult in roughly 9–12 days, completing a reproductive cycle in about three weeks.
How quickly do head lice reproduce? - in detail
Head lice (Pediculus humanus capitis) complete their development in three stages: egg, nymph, and adult. An adult female deposits 5–10 eggs (nits) each day, attaching them to hair shafts near the scalp. The incubation period for an egg lasts 7–10 days, after which the embryo hatches into a nymph.
Nymphs undergo three molts before reaching maturity. Each molt requires approximately 3 days, so the transition from hatchling to reproductive adult takes 9–12 days. Consequently, a single female can become capable of laying her own eggs within three weeks of her own emergence.
Reproductive output per female averages 50–100 eggs over her lifespan of about 30 days. Under favorable conditions—temperature around 30 °C (86 °F) and regular blood meals—population growth can be exponential: one fertilized female can generate roughly 10 new adults in a month, each of which will soon begin oviposition. In a fully infested head, the total number of lice may double every 7–10 days during the early phase of an infestation.
Factors influencing the rate include:
- Temperature: higher ambient temperatures accelerate development; lower temperatures prolong each stage.
- Blood availability: frequent feeding is required for egg production; prolonged periods without a host halt reproduction.
- Host grooming: mechanical removal of nits or lice reduces the effective breeding pool.
Overall, the life cycle from egg to egg‑laying adult spans about three weeks, and a mature female can lay up to ten eggs daily, allowing a small infestation to expand rapidly within a few weeks if untreated.