How long can lice survive on bedding without a human? - briefly
Adult head lice can survive on sheets, pillows or other fabrics for up to two days without a host, while younger nymphs typically endure only 24–36 hours. After this period they die from dehydration and lack of food.
How long can lice survive on bedding without a human? - in detail
Lice are obligate ectoparasites; they require a living host for feeding and reproduction. When removed from a person and placed on sheets or other fabric, their survival depends on species, environmental conditions, and life stage.
Adult head‑lice (Pediculus humanus capitis) can live up to 24–48 hours without a blood meal. Under optimal temperature (20‑30 °C) and relative humidity above 70 %, the upper limit extends to about 48 hours. Lower humidity (below 50 %) accelerates dehydration, reducing survival to 12–24 hours. Body‑lice (Pediculus humanus corporis) exhibits similar off‑host tolerance, with reported survival of 2–3 days in warm, humid environments.
Nymphs, which have not yet molted to adulthood, possess less energy reserves and die more quickly. Typical off‑host lifespan for nymphs ranges from 6 to 12 hours under average indoor conditions, shortening to a few hours in dry air.
Eggs (nits) are resistant to desiccation. They remain viable on fabric for several weeks, provided temperature stays above 15 °C. Hatching, however, requires contact with a host; without it, the embryo will not develop.
Key factors influencing off‑host longevity:
- Temperature: 20‑30 °C sustains adult viability; temperatures below 10 °C cause rapid mortality.
- Relative humidity: >70 % prolongs survival; <50 % leads to dehydration.
- Life stage: Adults survive longest; nymphs die fastest; eggs persist but do not hatch without a host.
- Fabric type: Porous materials (cotton, linen) retain moisture, slightly extending survival; synthetic fibers dry faster, reducing lifespan.
Practical implications: Bedding left unused for more than 48 hours in typical indoor conditions is unlikely to harbor live adult lice. Nevertheless, because eggs can remain dormant for weeks, thorough laundering at ≥60 °C or using a dryer on high heat is recommended to eliminate any residual stages. Vacuuming and sealing infested linens in plastic bags for several days also reduces risk.