A synthetic derivative of the chrysanthemum flower that kills insects on contact

Nature · Published 30 September 2026 Swipe more like this →

In short: Discovered in 1972, permethrin is a potent insecticide that mimics natural compounds found in chrysanthemums. While it serves as a vital medical treatment for human scabies and lice, its broad-spectrum toxicity makes it a double-edged sword, capable of incapacitating beneficial insects and posing severe risks to domestic cats.

Permethrin belongs to the pyrethroid family, a class of synthetic chemicals engineered to replicate the insecticidal properties of natural pyrethrins. Its development, led by Michael Elliott at the Rothamsted Experimental Station, addressed the inherent instability of earlier natural analogs when exposed to light and air. By substituting specific molecular structures, researchers created a compound that is both photo-stable and highly effective at disrupting the nervous systems of arthropods. It functions by interfering with sodium channel currents in neurons, leading to delayed repolarization, paralysis, and death.

The chemical's utility is vast, ranging from agricultural crop protection to the disinsection of aircraft and the preservation of woollen textiles. In human medicine, it is a World Health Organization essential medicine, widely used as a topical cream for scabies and lice. Despite its efficacy, its status is increasingly complicated by resistance. In some European studies, scabies has shown resistance in nearly 75% of cases, forcing clinicians to rely on alternative treatments. Furthermore, while it is generally safe for humans and most mammals, it is highly toxic to fish and aquatic life, and its use in agriculture remains controversial due to its indiscriminate impact on honey bees.

The most notable biological exception to permethrin's safety profile is the domestic cat. Because cats metabolize the compound significantly slower than other mammals, they are uniquely vulnerable to poisoning. High-concentration products designed for dogs—sometimes reaching 45% to 65%—can be fatal to cats even in small doses. Clinical signs of toxicity in felines include tremors, convulsions, and hypersalivation, requiring immediate veterinary intervention. While permethrin remains a cornerstone of modern pest control, its long-term persistence in indoor environments and the emergence of resistant pest populations continue to challenge its role in global health and agriculture.

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