I got an email a while back that said to put 5 or 6 pennies in a ziploc filled with water and hang it close to your door, outside. Here is a copy of the information. Don't know if it works, but what have you got to lose.???
Fill a ziplock bag with water and 5 or 6 pennies and hang it in the
> problem area. In my case it was a particular window in my home. It had a slight
> passage way for insects. Every since I have done that, it has kept flies and
> wasps away. Some say that wasps and flies mistake the bag
> for some other
> insect nest and are threatened.
Regarding the science behind zip log bags of water? My research found that
> the millions of molecules of water presents its own prism effect and given
> that flies have a lot of eyes, to them it's like a zillion disco balls
> reflecting light, colors and movement in a dizzying manner. When you figure
> that flies are prey for many other bugs, animals, birds, etc., they simply
> won't take the risk of being around that much perceived action. I moved to a
> rural area and thought these "hillbillies" were just yanking my city
> boy
> chain but I tried it and it worked immediately! We went from hundreds of
> flies to seeing the occasional one, but he didn't hang around.