How long does a louse live? - briefly
Adult head lice typically live around 30 days on a human host, while body lice survive a similar period but may persist up to two months under favorable conditions. Without a blood meal, they die within one to two days.
How long does a louse live? - in detail
The lifespan of a head louse (Pediculus humanus capitis) varies with environmental conditions and life stage. An adult female typically lives 30 – 40 days, during which she lays 6 – 10 eggs each day. Eggs (nits) hatch after about 7 – 10 days, giving rise to nymphs that undergo three molts over roughly 9 – 12 days before reaching maturity. Body lice (Pediculus humanus humanus) follow a similar schedule but may survive up to 2 months under favorable conditions.
Key factors influencing survival:
- Temperature: Optimal range 30 °C – 32 °C; lower temperatures extend development time, higher temperatures reduce longevity.
- Host availability: Continuous access to a human host sustains feeding; lack of blood meals shortens adult survival to 1 – 2 days.
- Hygiene and treatment: Insecticidal shampoos, lotions, or manual removal of nits can truncate the life cycle dramatically, often eliminating adults within 24 hours.
Typical timeline for a single generation:
- Egg stage: 7‑10 days.
- Nymphal stage: three instars, total 9‑12 days.
- Adult stage: 30‑40 days (head louse) or up to 60 days (body louse).
Understanding these intervals enables effective control strategies, such as timing pediculicide applications to coincide with the emergence of newly hatched nymphs, thereby preventing the maturation of subsequent adults.