Don't know if you resolved your fly problem with the Turkey pen, but we always had great luck with suspending baggies 1/3 or so full of water with a penny or two in the bag. The "logic/magic" is that the reflection from the water confuses the flies complex eyes and they won't fly past it. We use them on the eaves of the patio and by the dog doors. Its definitely cheaper and less messy than fly bait!