Can I use milky spore to prevent recurring problems with Japanese beetles in my lawn?
–Beth Thomas, Morton Grove A: Milky spore disease can reduce the number of Japanese beetle larvae feeding on your turf grass. But adding the bacterial spores to your soil is a process, not a one-time treatment. Milky spore disease affects only Japanese beetle grubs, but not white grubs, which also are common in Illinois lawns. For it to work, you must have a large number of only Japanese beetle grubs. For best effect, the soil temperature when you apply must be just right, between 60 and 70 degrees. While some grubs can be killed following the first application, in our area, it usually takes up to five years for the bacteria to spread and reach levels high enough to provide control, and the progress is affected by soil temperature each year. In the meantime, you can’t apply any other grub-killing insecticide. The process takes time because the Japanese beetle grubs have to ingest the bacteria for the number of spores to increase. When the number of spores in each grub becomes high eno
