How do lice eggs die? - briefly
Lice ova are eliminated by exposing them to temperatures above 122 °F (50 °C), applying pediculicidal chemicals that penetrate the shell, or physically removing and crushing the nits. Without these interventions, the eggs remain viable until they hatch.
How do lice eggs die? - in detail
Lice nits perish when their protective shell is compromised or when environmental conditions become unsuitable for embryonic development. Chemical agents, such as permethrin, pyrethrin, malathion, spinosad, or dimethicone, penetrate the chorion and disrupt neural pathways or desiccate the egg, leading to embryo death. Physical removal—combing with a fine-toothed lice comb—extracts nits from the hair shaft, preventing hatching. Heat treatment, including hair dryers set to high temperature or specialized steam devices, raises the temperature of the egg above the lethal threshold (approximately 50 °C) and denatures essential proteins. Freezing, achieved by applying cold packs or exposure to sub‑zero temperatures for a sustained period, damages cellular membranes and halts metabolic processes.
Environmental factors also contribute to nit mortality. Low humidity accelerates desiccation of the egg, while excessive moisture can cause swelling that ruptures the shell. Ultraviolet radiation from sunlight can degrade the chorion’s structural integrity, impairing embryonic growth. Natural predators, such as certain fungi (e.g., Metarhizium anisopliae) and entomopathogenic bacteria, infect and consume the eggs, though these are not commonly employed in routine treatment.
Effective eradication strategies typically combine methods:
- Apply an FDA‑approved pediculicide that contains a proven ovicidal ingredient.
- Follow with meticulous combing to extract residual nits.
- Repeat treatment after 7–10 days to target any eggs that survived the first round.
- Maintain hair hygiene, avoid sharing personal items, and wash bedding at ≥ 60 °C to eliminate any displaced eggs.
Understanding the mechanisms that cause nit death enables selection of appropriate interventions and reduces the risk of reinfestation.