Japanese beetle were introduced in the US in the 1920's when the japanese government gave a bunch of ornamental cherry tree to the US government. There larvae were in the rootballs.The tree's are all around DC now. They're a terrible pest on the east coast. They'll tear your fruit trees up. Fortunately, around here they don't come out until well after the fruit tree's bloom. You can kill them with liquid sevin and I haven't had trouble with my bee's since the blooms are long gone. The biological control is called MIlky Spore, it's the bug that lives in the ground in Japan which is the natural enemy of the beetle. You get the spores for it at garden store and sprinkle it in yard and it protects for years.
You can tell I got a big problem with em :x