My husband recently ate at an outside restaurant and noticed a bag of water on each table. The bag was half full of water and tied up on a stand so it wouldn’t touch the table…so it could vibrate and wiggly. He was told it would keep the flies away. So to test the idea, we took a ziplock Baggie and filled it half full of water, made a small hole in the top and ran a kite string thru it. We attached it to the metal “knocker” on our back door. Our dog food on the back porch attracts flies. Guess what? After two weeks, I have only found one fly that slipped thru the doorway when I had it wide open. Kewl, huh?