How long can lice survive without food? - briefly
Adult head lice survive approximately seven days without a blood meal, whereas nymphs endure about four to five days. After this interval, they die from dehydration and nutrient deprivation.
How long can lice survive without food? - in detail
Lice are obligate ectoparasites that require regular blood intake to maintain metabolic processes. In the absence of a host, an adult head louse can persist for approximately 24–48 hours, after which physiological functions deteriorate and death occurs. Nymphs, being smaller and having lower energy reserves, survive for a shorter interval, typically 12–24 hours without feeding. Environmental conditions influence these limits: temperatures between 20 °C and 30 °C and relative humidity above 50 % extend survival by reducing desiccation, while colder or dryer settings accelerate dehydration and mortality.
Key factors affecting survival without a blood source:
- Metabolic rate: Higher temperatures increase metabolic demand, shortening the period of viability.
- Humidity: Adequate moisture prevents water loss through the cuticle; low humidity leads to rapid desiccation.
- Life stage: Adults possess larger fat reserves than immature forms, granting them a modestly longer starvation tolerance.
- Species variation: Body lice (Pediculus humanus humanus) can endure up to 5 days without feeding under optimal conditions, whereas head lice (Pediculus humanus capitis) have the shorter limits described above.
In practical terms, removal of an infested person from a contaminated environment eliminates the food supply, and the lice population will collapse within two days for head infestations and up to five days for body‑lice infestations, provided that environmental conditions are not exceptionally favorable for moisture retention. Continuous monitoring and cleaning of bedding, clothing, and personal items are essential to prevent re‑infestation from surviving individuals.