Where do lice go? - briefly
Lice usually leave a host by crawling onto another person or dropping off the scalp, where they die if no new host is found. Their transfer occurs only through direct head-to-head contact or shared items such as combs, hats, or bedding.
Where do lice go? - in detail
Lice, as obligate ectoparasites, remain attached to a host for the majority of their life cycle. When an adult female deposits eggs (nits) on hair shafts, the emerging nymphs continue feeding on the same individual. If a host is removed from a contaminated environment—such as during bathing, laundering, or treatment—the insects may temporarily detach.
Detachment leads to three primary fates:
- Transfer to a new host – movement occurs through direct contact, shared bedding, clothing, or combs; lice quickly locate another suitable body to resume feeding.
- Survival in the immediate environment – lice can persist for several hours on fabrics, furniture, or floor surfaces. Their survival time depends on humidity, temperature, and availability of a host; optimal conditions (moderate humidity, temperatures around 30 °C) extend viability up to 24 hours.
- Mortality – exposure to dry air, low humidity, or temperatures below 20 °C reduces survival sharply, leading to death within a few hours.
The life‑stage distribution after host removal reflects these outcomes. Eggs remain attached to hair and are unaffected by short‑term displacement. Nymphs and adults that have left the host either seek another person or succumb to environmental stressors.
Control measures exploit these behaviors. Immediate washing of clothing and bedding at temperatures above 60 °C eliminates any detached insects. Vacuuming and thorough drying remove residual stages from surfaces. Re‑infestation is prevented by minimizing direct head‑to‑head contact and by treating all potential carriers simultaneously.
In summary, lice do not migrate to distant locations; they either locate a new host through close contact, linger briefly on surrounding objects, or perish when conditions become unfavorable. Understanding these pathways informs effective eradication strategies.