I hate Japanese beetles on my roses! - Ask Extension
Japanese beetles started attacking my roses about 3 years ago. My lawn service company started doing grub control applications in May, but they still ...
Knowledgebase
I hate Japanese beetles on my roses! #913128
Asked August 07, 2025, 4:13 PM EDT
Japanese beetles started attacking my roses about 3 years ago. My lawn service company started doing grub control applications in May, but they still come back. I've used various pesticides from The Home Depot to try to control the beetles. I tried a procedure recommended by the Farmer's Almanac this year which was to cut off all roses and all buds as they start to appear for a period of about 4-6 weeks. But now that I've let the plants bloom, the beetles have reappeared. I go out every morning and spray with pesticide or Neem oil and then cut the affected part of the rose bush off. I asked my lawn guys about a Fall application of grub control and/or milky spore, but they don't think it's necessary. I have never used the beetle traps as most resources recommend against them. Do the pesticides just kill beetles on the plant or will the substance, if sprayed on all the leaves and buds, discourage the beetles? Any other suggestions? Many thanks.
Larimer County Colorado
Expert Response
Hi Michele,
First, you wouldn't want to use insecticides now on your roses, as they can harm other beneficial pollinators, especially if they are blooming. Second, milky spore is not a proven control option. Third, while you treated your lawn, your neighbors may not have and Japanese beetles can move up to a mile or more because they can fly.
The best controls are to hand pick - this was proven by research at the University of Kentucky. Hand picking in the morning and evening, when beetles are sluggish, and throwing them in a bucket of soapy water can drastically reduce beetle populations in your landscape. You can even knock them off into the bucket.
There are products that you can use that JUST affect adult Japanese beetles, such as Beetle Gone and BeetleJus. You can buy these online. They do not kill the beetles, but prevent them from feeding and cause them to die within a few days. They are also unable to mate at the time. These are biocontrols specific to only affecting JBs. These products are expensive and break down in UV light, so need to be reapplied every few days. You would spray them only on your most prized roses.
Traps generally encourage more beetles.
Unfortunately, the JB are here and will remain here. There will not be a chance to do widespread eradication, so adjusting your gardening practices, planting plants that are not desirable, and doing what you can in your own garden will be the most effective options. The adults are only present for a few weeks and they should be on the decline going forward.
Continuing to treat your lawn for grubs is also suggested.
First, you wouldn't want to use insecticides now on your roses, as they can harm other beneficial pollinators, especially if they are blooming. Second, milky spore is not a proven control option. Third, while you treated your lawn, your neighbors may not have and Japanese beetles can move up to a mile or more because they can fly.
The best controls are to hand pick - this was proven by research at the University of Kentucky. Hand picking in the morning and evening, when beetles are sluggish, and throwing them in a bucket of soapy water can drastically reduce beetle populations in your landscape. You can even knock them off into the bucket.
There are products that you can use that JUST affect adult Japanese beetles, such as Beetle Gone and BeetleJus. You can buy these online. They do not kill the beetles, but prevent them from feeding and cause them to die within a few days. They are also unable to mate at the time. These are biocontrols specific to only affecting JBs. These products are expensive and break down in UV light, so need to be reapplied every few days. You would spray them only on your most prized roses.
Traps generally encourage more beetles.
Unfortunately, the JB are here and will remain here. There will not be a chance to do widespread eradication, so adjusting your gardening practices, planting plants that are not desirable, and doing what you can in your own garden will be the most effective options. The adults are only present for a few weeks and they should be on the decline going forward.
Continuing to treat your lawn for grubs is also suggested.
