How do lice and nits reproduce? - briefly
Female head lice lay eggs—known as nits—by cementing them to hair shafts close to the scalp. The nits hatch in about a week, producing nymphs that mature into reproductive adults within roughly ten days.
How do lice and nits reproduce? - in detail
Lice reproduce through a strictly sexual process. Adult males locate receptive females by detecting pheromonal cues emitted by the female’s cuticle. Mating occurs on the host’s hair or body surface and lasts only a few minutes; the male transfers sperm directly to the female’s reproductive tract. After copulation, the female stores sperm in a spermatheca, allowing her to fertilize successive batches of eggs without further mating.
The female deposits eggs—commonly called nits—by cementing each one to a hair shaft or clothing fiber with a proteinaceous glue. Attachment occurs within 1 mm of the scalp or skin surface, ensuring the developing embryo remains at a temperature optimal for growth (approximately 32–34 °C). A single female can lay 6–10 eggs per day and may produce up to 300 eggs over her lifespan.
Egg development proceeds as follows:
- Incubation period: 7–10 days, during which the embryo undergoes segmentation and organogenesis within the protective shell.
- Hatching: The nymph emerges by breaking the operculum, a small cap at one pole of the egg.
- Nymphal stages: Three successive molts (instars) occur over 9–12 days. Each molt requires a blood meal to provide the energy needed for growth.
- Maturation: The final molt yields a sexually mature adult capable of reproduction after an additional 5–7 days.
Environmental factors influence the cycle. Relative humidity above 50 % and temperatures near the host’s body heat accelerate development, while low humidity can desiccate eggs and reduce hatchability. The entire life cycle—from egg to reproductive adult—typically spans 20–30 days, allowing rapid population expansion on a suitable host.
Male lice reach sexual maturity earlier than females, often within 5 days post‑molting, enabling them to seek out newly emerged females promptly. This timing, combined with the female’s ability to store sperm, maximizes reproductive efficiency even when male encounters are infrequent.
In summary, lice employ a direct mating strategy, females lay adhesive eggs close to the host’s skin, and the offspring undergo a defined series of molts before attaining reproductive capacity, completing a life cycle that can generate several generations within a single month.