I jumped into this forum from the hosta forum - we hang jap beetle bags & they work pretty well. We have grapevines that they seem to love - they chew & chew until the leaves are just a skeleton of a leaf; I just want them to stay away from my blueberries!

Any info re: how to deal with jap beetles is appreciated.

Before I got my soil in balance I too had problems with Japanese Beetles, but as the soil became healthier and the plants grew stong and healthy they apparently became less atractive to many of the insect pests I once saw. Today I see a few insect pests, including Japanese Beetles, that are easily controlled without the use of organophosphates and more often than not they leave apparently because they do not like my plants.
Those Japanese Beetle "traps" are meant to attract the male beetle to your yard because there is a pheromone that mimics that of an adult female ready to mate, and those males then emit a pheromone that tells any females around that there are males here ready to mate so the females are drawn in creating a Japanese Beetle heaven. Many years ago the researchers from MSU approached my mother about putting one of these traps in our yard to see if there were Japanese Beetles present. Until that trap was put in we had none and after that we had many, every year.

This is going to sound weird, but... I love those damn things! Knock on wood, but around here, all they ever seem to eat are smartweeds, a noxious weed that's infested my garden since year 1 (in particular, the variety is Lady's Thumb). They're the only insect I've ever found that eats that stuff.

I have beetles that eat vines down to webs. I upgraded from soaps/oils to a rapidly degradable insecticide (definitely NOT Sevin). Spray/sprinkle in the evening while beetles are still on, and hopefully by morning they are all dead and insecticide can't kill any good insects anymore. If you spray insecticide on something that has flowers, you will kill butterflies and bees also.

Too bad smartweeds are such a noxious pest, or I'd recommend them to you as a distraction crop ;) I mean, they really, really work!

I wonder if there's any varieties that don't reseed so readily...

Here's a thought.... you could try planting other Periscaria species that aren't so invasive and see if the beetles like them as much as they like Periscaria maculosa. For example, something not suited to your climate.