How and where do lice reproduce? - briefly
Lice reproduce by internal fertilization; after mating, the female deposits oval eggs (nits) onto hair shafts near the scalp where they adhere with a cement‑like substance. The eggs hatch in 7‑10 days, and the emerging nymphs mature within another 9‑12 days, completing the life cycle on the host.
How and where do lice reproduce? - in detail
Lice reproduce through internal fertilization. Adult males locate females on the host’s hair or body hair, mount them, and transfer sperm via their abdomen. Copulation lasts only a few seconds, after which the female begins oviposition.
The female deposits eggs—commonly called nits—by cementing them to the surface of each hair shaft or to clothing fibers in the case of body lice. Egg attachment occurs close to the scalp for head lice, near the waist for body lice, and around the pubic region for crab lice. Each egg measures about 0.8 mm and remains firmly glued until hatching.
Key parameters of the reproductive cycle:
- Egg production: 5–10 eggs per day for head lice; up to 30 per day for body lice.
- Incubation period: 7–10 days at 30 °C for head lice; 4–6 days at 27 °C for body lice.
- Nymphal development: Three molts over 9–12 days, each stage resembling a smaller adult but lacking reproductive capability.
- Adult longevity: 30–40 days for head lice; up to 2 months for body lice under optimal conditions.
Environmental factors such as temperature, humidity, and host grooming influence egg viability and nymph survival. High humidity (70–80 %) enhances hatching rates, while frequent combing or washing removes attached eggs, reducing reproductive success.
In summary, lice complete their life cycle entirely on the host or, for body lice, on the host’s clothing, with females laying cemented eggs that hatch into mobile nymphs, which mature into reproductively active adults within two weeks.