From what do lice die? - briefly
Lice are eliminated by chemical pediculicides (e.g., permethrin, malathion), physical suffocation agents (silicone‑based lotions, dimethicone), extreme temperatures (heat above 50 °C or freezing below –5 °C), and by starvation when the host’s hair is removed. These methods disrupt the insect’s nervous system, block respiration, or deny essential nutrients, leading to rapid mortality.
From what do lice die? - in detail
Lice perish when exposed to agents that disrupt their physiological processes or destroy their protective exoskeleton. The most effective categories are:
- Chemical insecticides – neurotoxic compounds such as permethrin, pyrethrins, and malathion interfere with sodium channel function, causing paralysis and death. Resistance to these agents has been documented, prompting the development of newer formulations that target different neural pathways.
- Physical removal – fine-toothed combs, when used on wet hair with a lubricant, mechanically extract lice and nits, leading to population collapse. Repeated combing eliminates survivors that lack chemical exposure.
- Thermal treatments – temperatures above 50 °C (122 °F) for several minutes denature proteins and destroy the cuticle. Steam devices and hot air blowers exploit this principle, while cold exposure below –5 °C (23 °F) for extended periods also proves lethal.
- Chemical desiccants – substances such as dimethicone coat the insect’s exoskeleton, blocking spiracles and causing dehydration. These agents act without neurotoxic effects, reducing the risk of resistance.
- Biological agents – entomopathogenic fungi (e.g., Metarhizium anisopliae) infect lice, proliferate within the host, and ultimately kill it. Field trials show moderate efficacy, limited by environmental conditions.
- Prescription medications – oral ivermectin binds to glutamate-gated chloride channels, leading to paralysis. It is used when topical options fail or when infestations are severe.
Each method targets a specific vulnerability: neural transmission, structural integrity, moisture regulation, or metabolic function. Successful eradication typically combines at least two approaches to address potential resistance and ensure complete removal of both adult insects and their eggs.