Mosquito Dunks eliminates problem mosquitos quickly and safely. EPA registered in 50 states. Mosquito Dunks are a biological mosiquito control made of highly selective microbial insecticide effective against mosquitos in a variety of habitats. They are a safe, non-toxic way to kill mosquito larvae before they can mature into biting adults. Mosquito Dunks are formulated to release effective levels of Bacillus thuringiensis israelensis (BTI) for a period of 30 days or more under typical environmental conditions. The floating action of the Mosquito Dunks will ensure that active material is released at the surface as well as gradually settle to the bottom. Each dunk treats up to 100 sq. ft. of surface water for 30 days. Dunks can be broken up to treat smaller areas.