Mosquito Dunks 6 per card is a larvaecide that kills mosquito larvae only. It is deemed organic by the USEPA. Dunks are harmless to beneficial insects, pets, birds, fish or wildlife. Kills within hours and lasts for up to 30 days. Each Dunk covers 100 square feet of surface area. Perfect fo Koi ponds, hydroponic systems, animal water troughs, bird baths, rain barrels, etc. Place Dunks wherever there is standing water or standing water will accumulate.