Its been 25 or 30 years since I used the stuff, so I forgot a few key points. Looks like since I started using the stuff, they have changed how they process DE for pools. It is now heat treated and won't work for bugs. The real deal irritates your skin, so they now process it to stop that. Good for you in the pool, not good for killing bugs.

The good news is that food grade DE does work, go figure. The same folks that sell the Dustin Mizer also sells the right kind of DE:
http://www.earthworkshealth.com/products.php

To use properly do like Ernie says. Blast the underside with water, then apply the DE and this willmake it stick.