Cass County uses a number of synthetic pyrethroids to control adult mosquitoes. Pyrethroids are synthetic chemical insecticides that act in a similar manner to pyrethrins, which are derived from chrysanthemum flowers. Pyrethroids are widely used for controlling various insects. Permethrin, bifenthrin, and sumithrin are synthetic pyrethroids commonly used in mosquito control programs to kill adult mosquitoes.

• Permethrin has been registered by EPA since 1977. It is currently registered and sold in a number of products such as household insect foggers and sprays, tick and flea sprays for yards, flea dips and sprays for cats and dogs, termite treatments, agricultural and livestock products, and mosquito abatement products. Cass County utilizes permethrin adulticides in all ULV applications including aerial applications.

Cass County has 17 truck mounted foggers that are calibrated to apply ultra low volume(ULV) spray. Our ULV trucks put out droplets around 20 microns in diameter or 0.0008 inches across (about the width of a living cell). These droplets are in the air for about half an hour and travel up to 300ft. Cass County Vector Control currently uses an application rate of approximately 0.0035 lbs per acre of permethrin, or about 0.4 grams of active ingredient per "average" household yard. Compare that to a single can of common household pesticide used in backyards for control of mosquitoes and flying insects; each contains about 1.7 grams of permethrin and other similar active pesticides - about what a Vector Control truck would put out over an acre of land. In contrast, application rates for certain agricultural products such as apples can be up to 0.4 lbs of permethrin per acre of crop (181 grams per acre). 

Cass County's current adult mosquito control material inventory:

 http://www.epa.gov/pesticides/health/mosquitoes/pyrethroids4mosquitoes.htm#pyrethroids

http://npic.orst.edu/pest/mosquito/mosqcides.html