I knew who you were talking about before I even opened the thread. What a shame the heat and drought didn't wipe them all out last summer.
There's a wild grapevine coming up at the back corner of my house that's pretty popular with the JB's. I wish they'd kill it. I've tried to at least twice and it's bigger than ever. The base of it is behind a shrub and hard to get to.

I put my thumbnail through one on my blueberries today. I only saw one.

Saw the first ones on Sat June 2nd here in NE Ok

What's the best spray for these little monsters?

I've always used Sevin liquid in the red spray bottle, spraying each beetle I see on my crepe myrtles/roses. Been doing it this way for years and each year there are fewer and fewer of them coming back, plus my neighbors have given up on the beetle traps, so that helps, as well.
Sunny

So far I've only seen two. They don't seem to be visibly damaging anything this year, yet. Keeping a look out though.

Try MilkySpore, it's natural, doesn't harm bees etc. lasts 20 years

http://www.stgl.us/gstore/productcart/pc/viewCategories.asp?idCategory=44

Here is a link that might be useful: MilkySpore

I had very few before the last rain we got but that woke up some more. I have plenty of them now, but not a lot of damage on anything yet.
I didn't buy traps this year. I wasn't looking forward to the smell of a gallon of dead beetles a day. I do think it helped a bit to put the traps back in the field to draw them away from my yard. My white crape myrtle was so pretty last year without the beetle damage for a change.

This is odd - The grapevine by my deck that had so many Japanese Beetles on it a few days ago, now has only one that I could see when I looked at it this morning and there's still plenty of leaves on it for the beetles to eat. It makes me wonder if a flock of birds went after them or something. They've also disappeared from another plant that's a favorite of theirs and I can't think of the name but it has pinkish red flower spikes on it. I didn't see any on my white crape myrtle but haven't checked the others. I hope something has developed a taste for them. I would be very grateful. : )

I wish my chickens could fly; they love them. I tossed a plum that was covered with them into the chicken yard and the ate them before they could take flight. So far, they are not flocking to the blackberries......yet. I try to pick often.

There doesn't seem to be any beetle damage this year here, I'm walking around looking as I type this and checking but there are no signs of them. Last year they made lace out of all the elm trees and wild grapes, but this year, nothing. I've only seen three all sumer and I squashed those. Maybe this is an off year for them. Could be that it has been so dry this spring that they died before they emerged. Who knows? I just know I'm happy about it!

Milky spore does.work but the caveat is that it isn't immediate. It works on the grubs so it might be a year or more until they are completely gone.

Sandy

Persicaria is the plant I was trying to think of. The one I have is 'Firetail' I believe. JB's make lace of the leaves. There still isn't any on mine at all today which has got me puzzled.

The lack of JBs this year is strange -- I patrol the roses and crepe myrtles (of which I have many) a couple times a day and haven't found very many to spray with Sevin. Whatever it is keeping them away, thank goodness. And stay away and never come back. And take the mosquitoes and ticks with you!
Sunny

If you spray Sevin on the vegetables, how long do you wait to eat the produce? I have a few JB and just let them eat whatever they are on. But now I am starting to see stinkbugs and a hoard of striped blister beetles. These have to be stopped. The striped blister beetles have a different behavior from the gray BB. Today they were on celosia nothing else, but they had it covered. If I hadn't gone on my walk around the garden this morning, the celosia would have been totally eaten up. When disturbed they run all over. They have already eaten the leaves off some potatoes, but because it is so dry those potatoes were already looking bad.

Sevin works well to kill Japanese Beetles.
I've never had them in my vegetable garden.
They attack other flowering plants, like roses, altheas, crepe myrtle, four o'clocks, and such.
Recently, they have not been a problem.
I will never use a JB trap again. LOL
That only compounds the problem.

I don't use anything on the vegetables, but never see a JB on them. No stinkbug or blister beetle problem yet.

Sunny

Sunny when you use the red Sevin bottle that connects to the hose, how do you know when it is all used up. I sprayed under the elm so if cicadas emerge it will kill them before copperheads come to feast. I sprayed and sprayed and the bottle still has liquid in it. Does the bottle ever get emptied? I think maybe all that is left is water, but I don't know.

I don't use the hose-end Sevin. I buy the red bottle of liquid with a pump handle for one spray at a time. I would think that if you didn't add water to a mix as you would in a regular hose-end bottle, what was left in the red bottle was Sevin. Perhaps your water pressue is not pumping it out of the bottle well ???
Sunny