Safe, Natural, and Effective Grub Control What Is Milky Spore? Milky Spore is a naturally occuring microscopic bacteria called Baccilus Popilliae. This bacteria kills Japanese beetle grubs before they become adults. Because it is already naturally found in the ground, this is a safe treatment to use around children and pets and is 100% organic. By applying this treatment, the bacteria will begin increasing each year and reach peak effectiveness about 3 years after the initial application. Once established, Milky Spore is effective for between 10-20 years, depending on environmental factors. When Can I Use It? Milky Spore is best applied whenever the ground is not frozen; late spring through early fall is generally the most effective. Once applied, Milky Spore will survive winter temperatures. How Do I Apply Milky Spore? To apply Milky Spore, the general guideline is to use 1 teaspoon of powder every 4 feet in a checkerboard pattern across the lawn. Milky Spore can also be effectively spread with the Milky Spore Dispenser Tube, which makes covering large areas quick and easy. How Much Do I Need? A 10oz concentrate box like this one will cover 2,500 square feet.