http://en.wikipedia.org/wiki/Diatomaceous_earth

It is often sold a 'ant killer powder' or 'crawling insect killer or dust' most hardware stores or green houses will carry it. It is mechanical so it isn't a poison, crawling insects cannot crawl over it. They dehydrate or abrade them selves to death. I'd almost feel bad about it but we are speaking of mites here.... Nothing is too bad for them. It is old school for sure, back before chemical treatments were so common.

thanks Mike, I think... LOL. It isn't intentional. Working in a university has the perk of auditing any class I want.