I am looking for advice re: how to keep bees, ants, flys from overtaking my hummingbird feeders. I have tried everything I can think of to discourage these intruders, but what works for one (cotton balls keeps bees away, but not flys and duct tape inside out keeps ants out, but only until it dries up) doesn't work for others. Any help is greatly appreciated. Thanks in advance! Judy