Milky Spore timing - Ask Extension
I live in Loveland. When should I administer Milky Spore granules to preven Japanese Beetles this year.
Thank you
Knowledgebase
Milky Spore timing #928514
Asked April 15, 2026, 4:06 PM EDT
I live in Loveland. When should I administer Milky Spore granules to preven Japanese Beetles this year.
Thank you
Larimer County Colorado
Expert Response
Hi Tom,
Unfortunately, milky spore is very ineffective against Japanese beetle and controlling larvae. The effectiveness is only 2-3%.
Instead, use acelepryn, which is sold as Scotts GrubEx. You can apply this granular product NO EARLIER THAN mid-May. In a typical year it would be end-of-May to early-June.
Use a push-type spreader set to the correct settings. This product will provide year-long control of all white grubs, including chafers, Japanese beetle, cranberry girdler, and June beetles.
After application, water the product in with 1" of water (rain! or irrigation).
Unfortunately, milky spore is very ineffective against Japanese beetle and controlling larvae. The effectiveness is only 2-3%.
Instead, use acelepryn, which is sold as Scotts GrubEx. You can apply this granular product NO EARLIER THAN mid-May. In a typical year it would be end-of-May to early-June.
Use a push-type spreader set to the correct settings. This product will provide year-long control of all white grubs, including chafers, Japanese beetle, cranberry girdler, and June beetles.
After application, water the product in with 1" of water (rain! or irrigation).
