My three favorite uses for DE are to kill the squash bugs in the garden (which even my Guinea Fowl won't eat). Works great if you just sprinkle 1/2 cup all around the base of each plant. It has to be repeated once a week, or after heavy rain or watering.
I do have chickens and I sprinkle liberally in the chicken house, including the roosts, nesting boxes, walls, and floor. Good on their favorite dust bath areas as well.
The third one is for anyone building a new home or remodeling an older one: sprinkle DE inside the wall cavities, around the tops of the foundation/sill plate, and under and behind the kitchen and bathroom cabinets. No bugs...ever...in your home. Before I knew about DE, I used Boric Acid inside the walls. It works, but not forever. I don't know why, humidity may reduce the effectiveness of Boric Acid (Roach Pruff). And some people have issues with using Boric Acid at all. Boric Acid will kill plants, apparently. DE has worked in my 20 year old vacation cabin which is usually empty. No spiders, no ants, no roaches, and the little bit I sprinkle on the window sills keeps the inevitable flies under control as well. It used to go by the name of "stone flour" or "rock flour". Great stuff. I question the effectiveness of mixing it in liquids or eating it. The "sharp edge" quality is gone once it is wet. So don't think you can mix it in a pump sprayer and spray your plants. A "garden duster" is perfect for it, though. I have dusted it in crawl spaces, in the garden, in the chicken house, in the attic, etc. When I need to clean out an area like an attic, I try to dust it a week ahead, No surprise spiders running around when you move boxes!
I use this duster:
It's a little more expensive, but the dust can be focused on a specific area rather than just out into the air all around.