As we sat in an enclosed patio section of a restaurant, we happened to notice a couple of zip lock baggies pinned to a post and a wall. The bags were half filled with water, each contained 4 pennies, and they were zipped shut. The owner told us that these baggies kept the flies away! We actually watched some flies come in the open window, stand around on the window sill, and then fly out again. And there were no flies in the eating area!