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A natural knockdown type Insecticide derived from chrysanthemum flowers. Pyrethrin does not usually kill the insects so they must be disposed of while they are unconscious. It is often used in combination with other insecticides.

Note: The synthetically produced pyrethrin mixture is called Permethrin.

Synonyms and Related Terms

pyrethrins; pyrethrum; pyrenone; pyrocide


  • Toxic by ingestion, inhalation and skin contact. LD50 = 584-900 mg/kg.
  • Persons sensitive to ragweed will be prone to pyrethrin poisoning.

Physical and Chemical Properties

Insoluble in water. Soluble in alcohol, petroleum ether, kerosene, carbon tetrachloride, ethylene dichloride, nitromethane.

Composition C21H28O3
CAS 8003-34-7
Refractive Index 1.5242

Resources and Citations

  • Wikipedia: Permethrin Accessed July 2023
  • G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 643
  • Lynda A. Zycherman, J.Richard Schrock, A Guide to Museum Pest Control, FAIC and Association of Systematics Collections, Washington DC, 1988
  • The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983
  • Encyclopedia Britannica, Comment: "pyrethrum" [Accessed March 26, 2002].
  • J. Dawson, CCI Technical Bulletin, 'Solving Museum Insect Problems: Chemical Control' , Canadian Conservation Institute, Ottawa, No. 15
  • Stephen R. Edwards, Bruce M. Bell, Mary Elizabeth King, Pest Control in Museums: a Status Report 1980, Association of Systematics Collections, Washington DC, 1980
  • Matt Roberts, Don Etherington, Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology, U.S. Government Printing Office, Washington DC, 1982