Kills mosquitoes before they're old enough to bite | The only product with bti, bacteria toxic only to mosquito larvae | Lasts for 30 days and treats 100 square feet of surface water | Non-toxic to all other wildlife , pets, fish, and humans | Labeled for organic gardening by the usepa | Use Mosquito Dunks in any standing water including rain barrels, bird baths, tree holes, elevator shafts, planter reservoirs, rain gutters, etc