If you’ve ever lived in the south, you’ve probably seen this strange sight on your neighbor’s porch, local BBQ stands, or at the farmer’s market. A plastic bag full of water and a few shiny pennies stands out like a sore thumb, so why would anyone hang it from their doorway or window? The answer is as simple as it is annoying, flies. Those buzzing pests that come out in force every summer can be a real pain, but there’s a cheap and safe alternative to pesticides and fly paper.
To keep flies away from your living space, simply find a zip-loc bag and a few shiny pennies. Fill the bag about half way with water, drop in the pennies, and then hang the whole thing somewhere in the sun. How does this keep flies at bay? There are multiple theories, and they all relate to a fly’s eye and how it perceives light.
According to the myth debunking website Snopes, “The most common theory is that flies bases their sense of direction by where sunlight is coming from, and their complex eyes are overwhelmed and confused by the multi-directional refracted light produced by the bags, causing them to fly off rather than hang around.”
Some people swear by this method while others have no luck at all. The important thing to remember is sunlight. Just dropping a bag full of water by your trash can wont do anything to keep those pests away, but in sunlight the water acts like a prism. Some users insist that the pennies aren’t even necessary and that a bag of clear water is all you need.