How long can lice survive without blood? - briefly
Adult head lice typically survive 24–48 hours without feeding, while younger nymphs endure roughly 12–24 hours before dying. After this period they cannot resume activity and will perish.
How long can lice survive without blood? - in detail
Lice are obligate ectoparasites; they require regular blood meals to maintain metabolic function. The duration they can remain viable without feeding varies by species, developmental stage, and environmental conditions.
Adult head lice survive roughly 24–48 hours when detached from a host. Body lice, which inhabit clothing, endure slightly longer, up to 72 hours, because they are adapted to intermittent contact with the skin. Pubic lice (Pthirus pubis) display a similar range of 24–48 hours.
Nymphs, being smaller and less energy‑dense, perish sooner. First‑instar nymphs often die within 12 hours of separation, while later instars may persist up to 24 hours.
Eggs (nits) are the most resilient stage. In a warm, humid environment they remain viable for at least 7 days, sometimes longer, but will not hatch without the appropriate temperature and humidity.
Key factors influencing survival without a blood source:
- Temperature: Ambient temperatures between 20 °C and 30 °C prolong viability; lower temperatures accelerate mortality.
- Relative humidity: Levels above 50 % reduce desiccation risk; dry conditions cause rapid dehydration.
- Species adaptation: Body lice are more tolerant of periods off the host than head or pubic lice due to their ecological niche.
In practical terms, an adult louse deprived of a blood meal for more than 48 hours is unlikely to recover, while eggs may remain dormant for up to a week before losing viability.