Diatomateous Earth (Hope I Spelled that right).  Its basically dirt.  But not really.  What it is is "Diatoms" (A tiny living organism) that died millions of years ago at the bottom of an ancient sea and piled up hundreds of feet thick.  The remains that piled up formed a layer of thier microscopic remains which when mined and screened looks simply like powdered sugar.  Under a microspcope the particles look sharp and kinda spiny (I think).

 Anyway you can handle this stuff with your hands and even eat it if you had a mind to.  BUT if it is dusted evenly in grain will scrape the waxy cuticle off of insects causing them to dehydrate and die.  Simple, effective and once in the grain, lasts forever AND is not harmfull to people so it can be used for human consumption etc.

 Does it work?  I have applied 1 50 lb bag to each 5000 bu bin since I had almost an entire season ruined by bugs one year.  I have NEVER had a bug problem since.

Just rigged up a simple Gandy applicator to a hydraulic motor that runs off the auger tractor.  dusts it on as its augered in.

If you do a search on the www you should find info on it.  I had to have the coop buy it for me and they had to buy a 1000 lb pallet minimum which they wanted me to buy.  I did and have been using it for 6 years - no bugs. 

Found a link to the type I use:

http://www.diatomitecanada.com/fossil-shell-flour-de-food-grain-storage.htm