How long do lice live without food? - briefly
Without a blood meal, lice typically survive three to five days, extending to about a week only under optimal temperature and humidity. Their lifespan drops sharply once they exhaust stored nutrients.
How long do lice live without food? - in detail
Lice are obligate ectoparasites that rely on regular blood meals to sustain their metabolism. Adult head lice (Pediculus humanus capitis) typically survive for 24–48 hours without feeding, while body lice (Pediculus humanus corporis) can endure up to 72 hours under optimal conditions. Nymphs, which have not yet reached adult size, possess lower energy reserves and usually die within 12–24 hours if deprived of a host.
Several factors influence the starvation period:
- Temperature: Ambient warmth accelerates metabolic rate. At 25 °C (77 °F) survival times correspond to the ranges above; at lower temperatures (15 °C/59 °F) lice may persist slightly longer, whereas heat above 30 °C (86 °F) shortens the window.
- Humidity: Moderate humidity (40–60 %) maintains cuticular integrity, extending survival. Extremely dry air leads to rapid desiccation and death within hours.
- Species: Head lice are less tolerant of prolonged fasting than body lice, which have evolved to survive longer between infestations on clothing.
- Life stage: Eggs (nits) are inert and do not feed; they hatch only when conditions are favorable, typically within 7–10 days. Once hatched, the first instar requires a blood meal within a day to progress.
Physiologically, lice store glycogen and lipids in the fat body. These reserves support basal metabolic processes, but depletion occurs quickly because the insect lacks the ability to synthesize nutrients internally. The absence of a host triggers a decline in activity; lice become less mobile and eventually cease feeding attempts.
In practical terms, removing the host for at least two days eliminates most adult head lice, but nymphs may still survive if environmental conditions are favorable. Extended isolation beyond three days significantly reduces the likelihood of any stage persisting, especially when combined with low humidity and cooler temperatures.