Here in the mid-west we have a real challenge with Japanese beetles that will eat away at your plants, shrubs and flowers. An efficient way to collect them, while minimizing the number that may escape is to fill a cup water, hold the cup beneath them and just tap then or the plant gently and they fall right in. See below. You can then just leave them in there until they die – they can’t escape. I did this twice a during the summer and it really did seem to control the numbers and the damage.