One of the earliest insecticides developed were those extracted from the pyrethrum daisy, Chrysanthemum cinaeiriofolium. Flowers of this plant have high concentrations of compounds known as pyrethrins, highly active insecticides but ones with very short persistence. Pyrethroids, or synthetic pyrethrins, are insecticides based on the pyrethrins chemistry but modified to produce certain features. For example, most pyrethroids are considerably more persistent and some have miticidal activity. They are highly active against insects and use rates are a fraction of the older organophosphate and carbamate insecticides.
Mammalian toxicity tends to be low as is avian toxicity.
The primary environmental concern has been hazard to aquatic organisms, particularly fish. However, they are not water-soluble and are not considered to pose risks of groundwater contamination. Pyrethroids have been the fastest growing class of insecticides over the past 20 years, and have supplanted many insect control uses formerly done with organophosphates, carbamates, and chlorinated hydrocarbons. Separate formulations allow nursery and greenhouse use. Where trade names are used, no discrimination is intended, and no endorsement by the cooperative extension service is implied.