What is "pyrethrin"

Pyrethrin \Pyr"eth*rin\, n. [NL. Pyrethrum, generic name of feverfew, Gr. ? feverfew.] (Chem.) A substance resembling, and isomeric with, ordinary camphor, and extracted from the essential oil of feverfew; -- called also Pyrethrum camphor.

n. (context organic compound English) Any of a number of naturally occurring insecticides extracted from the pyrethrum plant; unusual in having a cyclopropane ring.

The pyrethrins are a class of organic compounds normally derived from Chrysanthemum cinerariifolium that have potent insecticidal activity by targeting the nervous systems of insects. Pyrethrin is synthetically made by industrial methods, but it also naturally occurs in chrysanthemum flowers, thus is often considered an organic insecticide, or at least when is not combined with piperonyl butoxide or other synthetic adjuvants. Their insecticidal and insect-repellent properties have been known and used for thousands of years.

Pyrethrins are gradually replacing organophosphates and organochlorides as the pesticides of choice, since these other compounds have been shown to have significant and persistent toxic effects to humans. Because they are biodegradable compounds, pyrethrins are now widely regarded as being preferable to pyrethroids, which is the name of a group of synthetic analogues of pyrethrin that accumulate in the environment. Pyrethrins are considered to be low-toxicity pesticides from a human health standpoint.