In what form are mosquito larvicides used?
Typically, breeding areas are treated with granular or floating “briquet” insecticides. The most commonly used active ingredients are two kinds of bacteria (Bti and Bacillus sphaericus) and an insect hormone mimic called methoprene. A conventional insecticide called temephos also is used under certain conditions where Bti and methoprene have limited effectiveness. The surface of breeding sites is sometimes treated with oils or other surfactants.