Mosquito Dunks. Kills mosquito larvae for 30 days! These have been used by professionals for years. Will NOT harm people, pets, wildlife or fish. Once a month place wherever water accumulates around your home – you’ll be rid of mosquitoes for the whole season. Each Dunk will treat up to 100 sq ft of surface water regardless of depth. May also be broken in half to treat smaller areas. Great for use in water gardens, flower pots, bird baths, rain gutters and decorative ponds!