I used to use Sevin back when I used chemicals, and it was the only one that worked for the beetles. I didn't want to stick my nose near a sevin sprayed bloom any more than one covered with beetles, so I didn't do it much even then. Interesting about the DE though- I may have to try that sometime.
Recently I've heard that about Milky spore, but in the past I had read that it actually spreads in the soil as years go by. I still don't see any grubs (whereas I used to see them with every trowel turn of the soil).