Pyrethroids - Insect Insecticides
Pyrethroid Insecticides
Pyrethroids are chemicals that kill insects, including mosquitoes. They can be an important tool in helping to prevent the spread of West Nile virus. Mosquito control professionals mix pyrethroids with water or oil and apply it as an ultra low-volume spray that kills flying adult mosquitoes. Pyrethroids are also using in commerical and residential insect sprays, such as our PEST-O-MINT product.
When used properly, pyrethroids have been found to pose very little risk to human health and the environment. If you want to reduce your exposure to pyrethroid spray, stay indoors during spraying and for about 30 minutes afterwards.
What are pyrethroid insecticides and how are they used?
Pyrethroids are a group of man-made pesticides similar to the natural pesticide pyrethrum, which is produced by chrysanthemum flowers. Although more than 1,000 pyrethroids have been made, only a few are used in Australia. These include permethrin (Biomist®), resmethrin (Scourge®) and sumithrin (Anvil®). Pyrethroids are found in many commercial products used to control insects, including household insecticides, pet sprays and shampoos. Some pyrethroids also are used as lice treatments applied directly to the head and as mosquito repellents that can be applied to clothes.
How are pyrethroids used in adult mosquito control?
Most pyrethroid mosquito control products can be applied only by public health officials and trained personnel of mosquito control districts. Mosquito control professionals apply pyrethroids as an ultra low-volume (ULV) spray. ULV sprayers release very tiny aerosol droplets that stay in the air and kill adult mosquitoes on contact. Pyrethroids are often mixed with water or oil and applied at extremely low rates.
What happens to pyrethroids after they are sprayed?
After spraying, pyrethroids settle onto the ground and flat surfaces. Because pyrethroids are mixed with water or oil before being applied, the amount of residue left on surfaces is very small. Pyrethroids are broken down by sunlight and other chemicals in the atmosphere. Often, they last only one or two days in the environment.
Pyrethroids are not easily taken up by the roots of plants because they bind to the soil. Because of this, pyrethroids usually do not get into groundwater and do not contaminate drinking water supplies. Pyrethroids are eventually broken down in the soil.