Pyrethrum

Definition

A natural insecticide consisting of dried, powdered flower heads from Chrysanthemum cinerariifolium (Dalmatian chrysanthemum) and C. coccineum, containing six esters known as pyrethrins that rapidly paralyze and kill insects on contact. Pyrethrum acts as a broad-spectrum neurotoxin against arthropods, with low mammalian toxicity and rapid environmental degradation, making it valuable for indoor pest control, livestock protection, and mosquito abatement programs. The term also persists as a common name for plants formerly placed in the obsolete genus Pyrethrum, now classified under Chrysanthemum or Tanacetum.

Etymology

From Latin pyrethrum, from Greek pyrethron (feverfew), from pyr- (fire), perhaps referring to the plant's pungent root or fever-reducing properties; the insecticidal application developed from traditional uses of these plants.

Example

Pyrethrum-based space sprays are deployed in aircraft cabins and food-processing facilities to control adult mosquitoes and filth flies without leaving persistent chemical residues.

Synonyms

• pyrethrum powder
• Dalmatian insect powder

Related Terms

• pyrethrin
• pyrethroid
• Insecticide
• contact insecticide
• knockdown effect
• Chrysanthemum cinerariifolium
• mosquito control
• Integrated Pest Management

Usage Notes

Distinguish pyrethrum (the natural plant-derived product containing mixed pyrethrins) from pyrethroids, which are synthetic analogs with modified structures and greater persistence. Pyrethrum is valued for its rapid 'knockdown' effect and minimal residual activity, but breaks down quickly in sunlight, limiting outdoor agricultural use. Some insect populations, notably certain strains of house flies and mosquitoes, have developed resistance through enhanced detoxification. The obsolete genus name Pyrethrum (formerly applied to feverfew and related species) should not be confused with the commercial insecticide product, though both derive from the same plant sources.