What are lice intolerant of? - briefly
Lice cannot survive temperatures above 50 °C (122 °F) and die within minutes when exposed to sustained heat of 40 °C (104 °F). They are also eliminated by insecticidal agents such as permethrin or pyrethrin and by environments with very low humidity.
What are lice intolerant of? - in detail
Lice are highly sensitive to extreme temperatures. Exposure to heat above 45 °C (113 °F) for a few minutes destroys both eggs and adult insects. Conversely, prolonged contact with temperatures below -5 °C (23 °F) also proves lethal, as the cold freezes bodily fluids and disrupts metabolic processes.
Chemical agents that damage the nervous system or dissolve the protective waxy coating of the exoskeleton are effective deterrents. Commonly used substances include:
- Permethrin‑based formulations, which interfere with nerve transmission.
- Dimethicone, a silicone oil that suffocates the parasite by blocking spiracles.
- Malathion, an organophosphate that inhibits acetylcholinesterase activity.
Moisture levels influence survivability. Lice thrive in a humid environment; relative humidity below 30 % accelerates desiccation and leads to rapid mortality. Dry conditions strip the insects of essential water, compromising cell integrity.
Physical removal methods rely on mechanical stress. Fine‑toothed combs applied to wet hair generate friction that dislodges nymphs and eggs. Repeated combing at short intervals reduces the population by preventing re‑attachment.
In summary, lice cannot endure high heat, severe cold, specific insecticidal chemicals, low humidity, or sustained mechanical disruption. Each factor compromises vital physiological functions, resulting in swift elimination of the infestation.