Frequently Asked Questions

What are Pyrethroids?

Pronounced “pi-ree-throid,” these ingredients are found in many commonly used consumer home and garden pesticides for treating problems with mosquitoes, caterpillars, ants, spiders, garden worms, wasps, cockroaches, aphids and other insect infestations. They are also widely used in agricultural and professional pest control.

Have I used a Pyrethroid?

Insecticides with pyrethroids are used to control a wide range of insects. Chances are you are probably using a pyrethroid if you have selected a pesticide product intended to control mosquitoes, caterpillars, ants, spiders, garden worms, wasps, cockroaches, aphids and other insects that threaten plants, home or health.

While you won’t see the word “pyrethroid” as a listed ingredient, pyrethroids are contained in products with the following active ingredients (often ending in “thrin”):

  • alpha-Cypermethrin
  • beta-Cyfluthrin
  • Bifenthrin
  • Cyfluthrin
  • Cypermethrin
  • Cyphenothrin
  • d-Allethrin
  • d-phenothrin
  • Deltamethrin
  • Esfenvalerate
  • Etofenprox
  • Fenpropathrin
  • Flumethrin
  • gamma-Cyhalothrin
  • Imiprothrin
  • lambda-Cyhalothrin
  • Momfluorothrin
  • Permethrin
  • Prallethrin
  • Resmethrin
  • Tau-fluvalinate
  • Tefluthrin
  • Tetramethrin
  • Tralomethrin
  • zeta-Cypermethrin

How do I use Pyrethroids?

These ingredients are found in many commonly used pesticides for treating problems with mosquitoes, caterpillars, ants, spiders, garden worms, wasps, cockroaches, aphids and other insect infestations. Always read the labels of each pesticide product to ensure proper use.

How are we exposed to Pyrethroids?

We are potentially exposed to very small amounts of pyrethroids when consuming treated crops or when exposed to products used to control insects around the home. EPA’s evaluation of pyrethroids considers aggregate risks from these multiple sources of exposure, including all anticipated dietary exposures. EPA establishes pyrethroid use requirements that reflect additional margins of safety as required by US law. The EPA determined that pyrethroids do not pose unreasonable adverse effects to human health when used as directed. Skin absorption of pyrethroids and their metabolites is very low. All uses are reviewed and approved by US EPA, European regulatory authorities, and other regulatory authorities around the world based on applicable health and safety standards.

What is the Pyrethroid Working Group?

The Pyrethroid Working Group is a pesticide industry alliance that has come together to ensure that its products are used responsibly and only in keeping with their intended and approved use.

Pyrethroid Working Group actively promotes stewardship of its products among consumers.

To learn more about best practices in the home when it comes to use, storage and disposal of pyrethroids, consumers should please visit

To learn more about PWGs programs for assisting Pest Management Professionals (PMPs) with training and education on best application practices, please visit

The following companies are members of the Pyrethroid Working Group:

  • AMVAC Chemical
  • BASF Corporation
  • Bayer CropScience
  • FMC Corporation
  • Syngenta Crop Protection
  • Valent BioSciences Corporation

Additional Facts

  • Pyrethroids are synthetic chemicals based on naturally-occuring pyrethrins, found in chrysanthemums.
  • Pyrethroids have been reviewed and approved for use by many government regulatory agencies around the world, including the US EPA and EU regulatory authorities.  The use of pyrethroids has been approved in nearly 80 countries globally.
  • Pyrethroids are used globally to protect human health from many infectious diseases carried by pests, including Lyme disease, Zika virus and West Nile virus.
  • Pyrethroids strongly bind to sediment and other natural materials in water bodies, which limits bioavailability to non-target organisms.
  • Pyrethroids protect the nation’s food supply by helping farmers control pests that threaten a wide range of important crops.
  • Manufacturers of pyrethroids promote the responsible use of their pesticides through stewardship programs aimed at growers, consumers and professional pest control applicators.
  • Pyrethroids have been used for over 30 years by homeowners, farmers and commercial pest control operators
  • Pyrethroids are widely used in products for agricultural, vector control (e.g. mosquitoes), animal health, stored grain, home and garden, and turf and ornamental markets.