There's been some discussion on using Milky Spore to control grubs, so here's WIKI:
After researching this on the web, the consensus of the extension programs is that Milky Spore controls Japanese Beetle grubs only. Various vendor websites claim that it controls the other grub species as well, but I have not found cooperative extension research that confirms this.
http://www.ladybug.uconn.edu/WhiteGrubs.htm
In my little corner of South County, RI, 90 % of the grubs are Oriental Beetle. Maybe 4 % are Asiatic Beetle, and 4 % are Japanese Beetle, and 2 % covers the rest.
I'd like to try Milky Spore to control the Oriental Beetles, but I can't find any scientific research to back it up. If someone knows of a scientific study of Milky Spore and Oriental Beetles, I would like to hear about it.