Japanese Beetles


I had an infestation of Japanese beetles last summer that attacked my roses. Is there anything I can do now to prevent an onslaught of the pests. If they return can I do anything else besides pick them off the flowers and drown the (*&^%$ things? I have a bee and butterfly friendly garden and don’t want to harm them


Thank you for contacting Toronto Master Gardeners about the annoying Japanese Beetle.

The following information on controlling this pest is from a post on our website

“This is a common question posted at this time of year. The Ontario Ministry of Agriculture and Food has a website at the bottom of which there is a lists of plants that are most susceptible to damage by this insect.   To control Japanese beetles you can either control the adult or the larvae. the best method (although still time consuming but strangely satisfying) is to go out in the early morning or in the late evening when they are not as likely to fly around and simply knock them into a small bucket/jar of water (add a few drops of soap) where they drown. You will need to begin this process at the end of June or the beginning of July and continue until sometime in early August. After that, the next method of control is to go after the larva. Nematodes are best applied in August and are watered into the affected area. They attack the larva of Japanese beetle, June bugs and European chafer all of which racoons and skunks like to dig up the lawn in search of. When applying nematodes it is important to keep them refrigerated until you are ready to apply them. Ideally they should be applied on an overcast morning or evening. If the lawn is dry it should be irrigated first with about ½ to 1 inch of water. You should prepare and use the entire pack and water (while agitating) them into the soil. You might need to irrigate the lawn again to “wash” the nematodes into the soil. You can also reference our other responses to this problem at Roses and Grey Grubs in the Lawn

Unfortunately, there currently is no preventive measure to eliminate these annoying pests.

We wish you a beautiful beetleless summer.