Mosquito Bits is a microbial insecticide used to kill mosquito larvae growing in water. Mosquito Bits can be used in: water gardens, flower beds, rain barrels, roof gutters, bird baths, tree holes, unused swimming pools, old automobile tires, animal watering troughs, and any other standing water you may have around your property. When the Mosquito Bits are applied to the surface of the water they release a larvacide, which sinks to the bottom of the water where the mosquito larvae are growing. One teaspoon will treat 25 square feet and one tablespoon will treat 75 square feet. A 7 to 14 day interval between applications is recommended. Mosquito Bits are safe and all natural. Due to changes in shipping regulations, we cannot ship this item to California.