Last year I didn't have to deal with them, one of the critters chewed off the bottom of the (full) bags and there wasn't a beetle left to be found. But normally I tied the bag shut with a twist tie, put it in a heavy duty ziplock and tossed them in the trash.

When I used the traps, I would dump the day's catch into an empty spaghetti sauce jar and put it in the sun. The beetles would be dead in about 10 minutes. I'd leave them until the next day to make sure they were cooked through (to make sure any eggs inside were dead), then spread them around the planting beds. Spread out like that, I could not smell them. That's some good slow release nitrogen for the plants!

Alex

And some delicious irony to boot!!

My friend feeds them to her chickens. I bury them.

A few days ago I discovered that the fish in our pond LOVE Japanese beetles. I knock the beetles off into a jar and dump them into the water in one big wriggling lump. The Sunnies swarm like Pyrahnas as they gobble them up. Satisfying to watch.

I put them in compost and cover them up. They attract earthworms like you would not believe. In 2 months they are totally converted to soil.