Mosquito Dunks take care of mosquitoes before they're old enough to bite! If you have standing water you can't get rid of, such as in a bird bath or water garden, simply add Mosquito Dunks to kill mosquito larvae. Dunks are formulated with BTI, a bacteria that's toxic to only mosquito larvae. Safe for other wildlife, pets, fish, and humans. Dunks kill larvae within hours, and last for up to 30 days. USEPA labeled for organic gardening. Package contains 6 Mosquito Dunks.