I've seen them eat just about anything. Right now, my roses, virginia creeper, and most perennials are lace. Bee balm is covered with powdery mildew, and they seem to stay away from that.

Yes, my neighbor two doors down grows elderberries (I'm in Michigan). When I was last in his yard checking out the shrubs a couple of seasons ago the elderberry were covered in Japanese beetles, so much so that I wondered if they acted as a lure away from my own garden because I don't have much of a problem with them. I pick off one or two J beetles from my pole beans a couple times a week.

Thank you, Maureen. You just saved me some heartache.