Larvicides are products used to kill immature mosquitoes before they become adults. They can be either biological (such as toxin from specific bacteria that is lethal to mosquito larvae but not to other organisms) or chemical products, such as insect growth regulators, surface films, or organophosphates. Larvicides are applied directly to water sources that hold mosquito eggs or larvae. When used well, larvicides can help to reduce the overall mosquito burden by limiting the number of new mosquitoes that are produced.
An example of a larvicide is Bacillus thuringiensis israelensis (BTI), which comes in products known as mosquito “dunks” or “donuts.” Adulticides are products used to kill adult mosquitoes. Adulticides can be applied from hand-held sprayers, truck-mounted sprayers, or using airplanes. Adulticides, when used well, can have an immediate impact to reduce the number of adult mosquitoes in an area, with the goal of reducing the number of mosquitoes that can bite people and possibly transmit the West Nile Virus. Both larvicides and adulticides are regulated by the U.S. Environmental Protection Agency.