So I've been researching DE and I thought it would be a good thing to add to our coop for added pest control. I went to a feed and garden store in our area and they were out. The man in charge of that section of the store went off on me. He told me...and I quote...."Food Grade Diatomaceous Earth doesn't work for crap and I'm tired of people recommending it for their d**n chicken flocks!" He went on to tell me to use some kind of a pesticide powder, of which I won't use. I told him my flock is very healthy right now, I was wanting to use it for preventative measures. He laughed at me again and said my flock is probably NOT healthy because I let them free range in a protected section of our yard. I am wondering about all that he told me. I don't want to use chemical pesticides on my flock. I practice very good hygiene in our coop/run/chicken yard. I am very meticulous about checking my hens, keeping their area clean and so on. I don't know why this guy would go off on me. Should I listen to him? What are all your thoughts? I have used DE in my garden sparingly, with protective clothing and mask. I understand the respiratory risks and am very careful with it. This guy at the store told me it would make my chickens blind? Why would other chicken sites recommend using it if it would make them blind? I am sorta confused and any advice someone can offer.