I live in Toronto, very close to TBG. Last year, the JB’s destroyed a whole wall of climbing hydrangea, and this year looks like it’ll be the same. They’re eating the only miniature rose I have (got rid of all the roses last year and now are attacking my raspberry patch. The suggestion of squishing them sounds incredibly naive. there are thousands at any given moment, and they reproduce in instants. Please suggest a practical, effective way of dealing with them! Also, raccoons have been attacking the lawn, although I’ve checked for grubs and can’t see them. could it be the grubs of the JB? Thank you.
I also have a garden filled with things that Japanese beetles adore and I share you frustration. 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. As you suggest controlling the adult by squishing is a bit gross and time consuming. I have found 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.