I am still pretty fresh to the gardening thingy, so I am sure there are better ways. Last year I used a masonry jar with ice in it that I just tapped them into. They roll off the leaves as their defense mechanism right into the jar. It stays cold enough with the ice so they can't fly away while I collect them in the morning. I kept it in the freezer much to my wife's disgust. I heard the bait/traps just attract them too much. I also put down alot of the milky spore bacteria in my yard and beds which kills them in the grub stage. This year has been much better than last, but I don't know if is the weather, my milky spore, or what.