The key to avoid rampant destruction by Japanese beetles is to get them at the larvae stage of their life cycle under ground, before they begin to immerge as adults in early June. Milky Spore is not a chemical pesticide, but simply spores of beetle grubs that will spread when Japanese beetle grubs are present in the soil. Infected beetle larvae will die and decay releasing billions of new spores into the soil continuing the cycle until no Japanese beetles remain. One application can remain viable in the soil for many years. Resistant to weather conditions and wont be affected by fertilizers or harm food crops, humans, pets, fish, bees, birds or other animals. A 10 oz can will treat 2000 sq. ft. and has no expiration date if kept sealed and dry.