I use food grade DE and have for years. When we had to care for our daughters horse I gave it to her mixed in her feed. It kept the flies down dramically and she never had worms while she was here for over 1 year. I use it on my dogs and it keeps flies and fleas from bothering them I also sprinkle it outside where they lay. I use it it my garden and paint it on my trees. It has many uses. I read alot about it from an orgainc ranch its called WolfCreek Ranch if you google it he will tell you all about it as he has used it for many many years. He even drinks it himself. Before you turn down a perfectly good natural pest control research it yourself. As with anything else everyone has their own opinion.