There are as many suggestions for dealing with this pest as there are weeds in the garden. One that is particularly popular is baiting. Homemade or store bought baits are placed in the garden to catch and kill the beetles. Photos show some pretty impressive (and disgusting) numbers of beetles in these traps. I have no doubt, they are an effective means to catch beetles. Still, I don't bait.
My theory is that beetle traps can actually make the situation much worse by luring even more beetles onto your property. Instead, my method is simple. Catch em. The kiddos can be enlisted for this task. Current going price on a beetle head is a dime. They were a nickle on the first day they hatched due to large quantity. When we catch them, we stick them in a bug hotel with stuff to munch on, because we are dorks and feel bad squishing them. OK sometimes we also feed them to the toads. Most of them go in the bug hotel though.
Japanese beetles don't bite, but they feel creepy when you catch them. They have claws on their feet that don't hurt at all, but you definitely know you have a beetle in your hand. There are a couple of tricks to catching them. Early morning or late evening are the easiest, because when they are cold, they are less likely to fly. These beetles have a trick where they roll on their side and off whatever they are hanging onto. If they are on a huge tomato, good luck finding them once they roll off. That's why when I go to nab on, I place one hand under the leaf and then go to grab it. Most of the time they roll right into my hands. It's handy to have your container right there because once they unfurl their legs from the rolling, it feels ICK!
This seems like a lot of work, but am/pm beetle scanning after the first day only takes a few minutes. They seem to pick a few favorite plants and you'll find 90% of them hanging out there. There year for me, they have been on the peppers, the fugly bush and one tomato plant on the patio (Persimmon-of course). They only seem to be eating the peppers and whoo boy a few missed beetles can do a LOT of damage!
Catching them early is the key. We made a huge dent in the numbers the first day they appeared. Tonight I only plucked three. There have been less and less everyday. Beetle feet are creepy but I'll take them over a stinky beetle trap any day, especially if I only have to deal with the feet for a few days.