When do lice lay eggs? - briefly
Female lice start laying eggs roughly 7–10 days after they emerge as nymphs, depositing about one egg each day. The eggs, or nits, are cemented close to the scalp and hatch after approximately 7 days.
When do lice lay eggs? - in detail
Lice reproduce by laying tiny, oval eggs called nits. Female head lice (Pediculus humanus capitis) begin oviposition about 3–5 days after reaching adulthood, which itself occurs roughly 7–10 days from hatching. From that point, each female deposits 5–7 nits per day for a period of 3–4 weeks, resulting in an average total of 30–40 eggs per reproductive cycle. The eggs are cemented to hair shafts near the scalp, where the temperature remains optimal for development.
The incubation period for nits depends on ambient temperature. At typical human scalp temperatures (≈34–35 °C or 93–95 °F), embryogenesis completes in 7–10 days. Cooler conditions extend this interval, while temperatures above 38 °C can impair embryonic development. After hatching, the newly emerged nymph passes through three molts over the next 9–12 days before attaining full maturity.
Body lice (Pediculus humanus humanus) follow a similar schedule but lay eggs on clothing fibers rather than on hair. Egg‑laying commences 4–5 days after adult emergence, with a daily output of 4–6 eggs and a total of about 30 eggs per female. The incubation time on fabric at room temperature (≈22 °C) is roughly 8–12 days, lengthening in cooler environments.
Pubic lice (Pthirus pubis) initiate egg deposition 2–3 days after reaching adulthood. Each female produces 2–3 eggs per day for approximately 2 weeks, yielding a total of 10–15 eggs. The incubation period on coarse hair is 8–10 days under normal body‑heat conditions.
Key timing points:
- Adult emergence → first egg laid: 3–5 days (head lice), 4–5 days (body lice), 2–3 days (pubic lice).
- Daily egg output: 5–7 (head), 4–6 (body), 2–3 (pubic).
- Total reproductive span: 3–4 weeks (head), ≈3 weeks (body), ≈2 weeks (pubic).
- Egg development to hatching: 7–10 days (head), 8–12 days (body), 8–10 days (pubic) at typical temperatures.
Understanding these intervals is essential for timing effective treatment, as interventions must target both the adult insects and the developing eggs before they hatch.