Yes, j. beetles are fond of japanese maple leaves. I picked several off some of my green varieties last night. I have heard of heavy infestations but so far I have been lucky. Have not seen them on the red leaf variety I have. When I'm in town, I try to check my trees every evening for JB's this time of year.

I've never had a problem with them on my japanese maples. Maybe because I have too many other things in the yard they like better. I've seen an occational one or 2 on my maples, but for me their favs are crape myrtles, cherry trees, and hibiscus.

I've picked one or two beetles off my largest (3.5') JM tree this spring but they definitely prefer the roses that are nearby. Probably the only good thing about their appetite for the rose bush.

I had multitudes of Japanese beetles on my large Temukeyama last year, and they thoroughly enjoyed every bite, but it came back quite well.