How long do lice and their eggs live? - briefly
Adult head lice survive about 30 days on a host, while their eggs hatch in roughly 7–10 days under optimal conditions.
How long do lice and their eggs live? - in detail
Lice complete their development in three stages: egg, immature form, and mature adult.
Eggs, commonly called nits, are cemented to hair shafts or clothing fibers. Under optimal temperature (≈30 °C) they require 7–10 days to hatch. In the absence of a warm host, the embryo can remain viable for up to 10 days, after which desiccation renders it non‑viable.
Nymphs emerge from the eggs and undergo three molts. Each molt takes roughly 2–3 days, so the transition from hatchling to reproductive adult lasts 9–12 days. During this period the insects feed frequently on blood, gaining the size and physiological maturity needed for mating.
Adult lice survive on a host for about 30 days, during which a female can lay 5–10 eggs per day, producing a total of 50–150 eggs in her lifespan. If removed from the host, adults may persist for 24–48 hours, depending on humidity and temperature; they die sooner in dry, cool conditions.
Key points for each common species:
- Head lice (Pediculus humanus capitis): egg viability 7–10 days on the scalp; nymphal development 9–12 days; adult lifespan ≈30 days on the head, up to 48 hours off‑host.
- Body lice (Pediculus humanus corporis): eggs laid on clothing, hatch in 7–10 days; nymphs mature in 9–12 days; adults live about 30 days on a human, survive 2–3 days without clothing.
- Pubic lice (Pthirus pubis): eggs hatch in 6–10 days; nymphal period 9–12 days; adults live 30–40 days on the host, survive up to 48 hours when removed.
Understanding these time frames informs effective treatment schedules, which must target both live insects and unhatched eggs within the full developmental window.