I am not sure if the spore would be a waste or not. I sometimes buy the bag-a-bug lures,and place them in the far corners of the property. I have read that if you can get/kill the first bunch of jap beetles(the scouts for food) then you will have less coming into your yard. I either pick them and feed the beetles to my hens,or spray non-edbile plants with a mix of water and the dogs flea/tick shampoo. Personally I love seeing the hens gobble them down!
One year when I was removing a lot of grass for garden beds I found tons of grubs. Happen to have a robin close by so I kept throwing them to her. She kept coming back to get the grubs for her babies.
The grubs eat grass roots. The jap beetles love my raspberry and rose of sharon plants.Atleast they are easy to catch compared to the 4 lined plant bug.
Order a Gardens Alive catalog.They have a good selection of natural pest control options.