I will be trying Cedar Oil this year.
http://www.finegardening.com/item/23...panese-beetles
You can also make a citrus spray by boiling citrus rinds until soft and then spraying the plants. It is short lived and has to be re-applied after rains.
As Beeman stated, beneficial nematodes are supposed to work very well at controlling the grubs in your lawns and gardens. I will be purchasing them this year myself.