Fred,
If you could add your location to your profile that might save you and others from have to ask/answer.
I've got an American Hornbeam that has been severely attacked by Japanese beetles this year. I've used granular (thanks John) and spray systemics to control them. But, I often and still see them on the leaves chewing away. The consolation here is that there's also a ton of them lying dead on top of the soil, so the chemicals seem to be doing the trick.
Since the beetles have been pretty bad the last several years I've been placing "beetle bags" in different areas in the woods behind my house. That might be helping some, but there's still a swarm of them on my hornbeams, Japanese maples, Satsuki azaleas, etc.
It might be beneficial for you to find out for sure what is affecting your trees and find a measure for them. Or, just rotate sprays for a few weeks using different chemicals that are safe for your trees.
Keep us updated on your fight!
