How quickly do lice reproduce on a human? - briefly
Female head lice begin laying eggs within 24 hours of attaching to a host; each female produces about 5–6 eggs daily, which hatch in 7–10 days, allowing the population to double roughly every week. Consequently, a noticeable infestation can develop within two weeks of initial contact.
How quickly do lice reproduce on a human? - in detail
Lice complete their life cycle entirely on the human scalp. An adult female lays 5–10 eggs (nits) each day, attaching them to hair shafts close to the scalp. The incubation period for an egg averages 7–10 days, after which the nymph hatches.
Nymphs undergo three molts before reaching maturity. Each molt requires approximately 2–3 days, so the transition from hatch to reproductive adult spans roughly 9–12 days. Once mature, females become fertile within 24 hours and resume egg production.
Under optimal conditions—adequate temperature (30 °C ± 2 °C), humidity (50–70 %), and a steady blood supply—a single female can generate 30–40 viable offspring within a month. Population growth follows an exponential pattern; if no control measures are applied, the number of lice can double every 5–7 days after the first generation emerges.
Factors influencing reproductive speed include:
- Temperature: lower than 20 °C slows egg development; above 35 °C reduces egg viability.
- Hair length and density: longer, denser hair provides more attachment sites, facilitating higher egg retention.
- Host grooming: frequent combing or washing removes nits, interrupting the cycle.
Effective management requires disrupting one or more stages of this rapid cycle—removing eggs before hatching, eliminating nymphs before they mature, or killing adult females to halt egg laying.