Fifty pounds of DE is a lot. There are places that will sell a couple of pounds and you can get it by mail if your local feed stores don't have it. Here is some information about DE.

This is the one I use. It's supposed to be an even finer grind, drying up bugs faster. It is feed grade - cattle, dogs, people, I suppose - but you don't want to inhale it (though the really bad stuff to inhale is the pool DE that has a lot of silica in the mix. That's toxic all around, not for animals or plants.) The applicator container (called the 7 oz duster) comes with a long skinny straw (like the one that comes on WD-40)that you use to puff this onto plants. It doesn't take much. All of the Soil Mender products are very good, recommended for organic gardening.

SRS