Ask the Gardener: What's the Best Way to Get Rid of Japanese Beetles?

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Ask the gardener is a column in which local readers send in questions about your garden, lawn, trees and more. 

This week's question: What is the best way to get rid of Japanese Beetles that are eating my plants and flowers? Do those bag traps really work?

Joe Krygiel, manager at in O'Fallon, answered the question:

The bags work, but if you put them in the wrong spot, they can do more harm. Ideally, you want to put them up and away from the parts you're trying to protect.

Is there anything else you'd suggest?

A good contact killer called Sevin (Dust).

Are there certain kinds of plants the beetles favor?

They favor roses, crepe myrtles, Rose of Sharon and anything in the fruit tree family.

Have Japanese Beetles been an issue in this area?

This year, they haven't been as big of a problem. I'm not sure of the reason. They should start to wind down soon, because it's nearing the end of the adult life cycle. The adults go back in the ground, lay eggs and die. The beetles start as grub worms in the winter, so you can also treat for those.

Boot July 03, 2012 at 02:01 PM
Thanks for posting this. I'm very happy to learn that those beetles won't be terrorizing my rose bush all summer long!
Brynn Palmer July 03, 2012 at 06:47 PM
If you don't want to risk killing the good bugs (Lady Bugs, Praying Mantis etc.) by using Sevin Dust, you can pull them off and by hand drop them in a bucket of hot water with a little bit of bleach added. They don't move fast so it's easy. You can also apply Milky Spore a couple of times a year which kills the larve.
George Newell July 03, 2012 at 06:49 PM
You can kill the grubs in the soil with milky spore organism. It is not toxic to humans or pets. You would have to research a source, Adult beetles could still fly into your garden so this would not completely eliminate the problem.
Kalen Ponche July 03, 2012 at 10:40 PM
Thanks for all the responses! It's nice to know there are some options out there that won't hurt good bugs!
Fred Oompahloompah July 03, 2012 at 11:39 PM
I have two traps. I had to order the traps two seasons ago but had to order the bait and faremones that attrack them online this year because the nurseries and hardware stores do not have them in stock. These are very effective in capturing the jap beetle (I captured them by the thousands) but you have to dispose of them in away that kills them and they are very hard to kill. The instructions come with the traps and it is a nasty, smelly and disgusting process that they recomend. I found it easier to dump them into a siplock bag, seal it and cut off their air supply then dispose of them in the trash. They are more then just annoying like a fly or nat. They destroy crops and flowers. Gardening can be a every expensive hobby and most often we are not farmers so the cost of this far exceeds the produce that we bring to the table.


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