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!
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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.
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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.
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Order a Gardens Alive catalog.They have a good selection of natural pest control options.