I said all I know about dealing with jap beetles, but will be on the lookout for stink bugs, don't know if DE will work on them or not, worth a try. Ususally a multi-pronged attack (minus the traps which are not good for me) is the most effective. Last year the beetles were evident well into September. That's what will make the stink bugs harder to fight.
With the beetles, if I dig and find the light-colored, fat grubs, I throw them in the street or squash them, but that won't make much of a dent overall for sure.
We live in the country so while I can deal with the local Japanese beetls, there’s no way to get all of them.
I put up the traps every year and the first year here caught a TON of them. Not so many in the following years.
The traps keep them away from the plants, otherwise, I wouldn’t do them.
I’ll deal with the stink bugs as I find them and will be stocking up on good DE, not the heat treated stuff I read about upthread.