Mosquito Dunks© are formulated to release effective levels of BTI for a period of 30 days or more under typical environmental conditions. The floating action of the dunks will ensure that active material is released at the surface as well as gradually settling to the bottom. These dunks may be used in all types of containerized mosquito breeding areas. To prevent dunks from being flushed out of certain treatment sites, they can be anchored using a string tied through the hole in the center or staked in place. Alternate wetting and drying will not reduce their effectiveness.