Once established in your lawn, Milky Spore kills the Japanese beetle grub for 15 to 20 years. It begins working immediately as soon as it is applied when grubs are feeding. Each grub that dies from Milky Spore decays and releases 3 billion new spore. Once all of the grubs are destroyed, the spore will remain dormant but viable in the soil until new grubs come along even years later. Won't harm beneficial insects, animals, pets, or man. Safe for use around wells, ponds, and streams. Harmless to birds, bees, and fish. Recommended by Master Gardeners. Use 3 times a year for 2 years with applications in the spring, summer, and fall. For use in lawn spreaders. May be applied anytime of the year as long as the ground is not frozen. For control of the Japanese beetle grubs. 20 lb bag. Treats 7000 sq ft.