The Popular Fly Myth That You Should Try Yourself Before Fully Debunking

Flies can be extremely annoying. When you're indoors, it's often easy enough to swat them away with a flyswatter and get on with your day. But if you're enjoying some time outdoors on your porch, patio, pergola, or wherever else, they're a little harder to keep under control. There are plenty of reasons why your yard might be swarming with flies, but what about solutions? Well, there's an suburban legend about keeping these insects away that could help: It requires a kitchen storage bag, water, and some pennies. 

This isn't the first time we've told you to use pennies around your lawn — burying them can give your soil some copper. As for this hack, start by grabbing some kitchen storage bags that zip tightly — you don't want any leaks. Then, get yourself a handful of pennies, divvy them up between the bags, and top them off with water. It doesn't seem matter exactly how much water to use, and there's no exact amount of pennies one should use, so do what you think fits and works. Zip the bags closed and hang them in areas where you don't want flies concentrating. Situating them around your porch is a good bet, and it may help keep them out of the house, too. 

While this hack may seem too simple to work, it appears that folks living in the South swear by it as a working fly repellent. Then again, "MythBusters" debunked the claim that water bags repel flies — though the crew didn't use pennies. It's possible that people who try this trick only think they see fewer flies. But there is a good reason why these annoying insects might avoid hanging bags of water and shiny pennies.

There are a few reasons why a bag of pennies in water may work to keep flies away. One is the way flies' eyes work. They're made up of a bunch of different lenses, which help them see seemingly everywhere all at once — they can detect even the slightest movement. These compound eyes are susceptible to changes in light and reflection because they can perceive the polarization of light. Sound confusing? Your shiny bag of water and pennies might confuse the flies as well, when it reflects the sunlight. The insects can't figure out what they're seeing, so they fly off elsewhere.

Of course, this isn't the only theory. Some people believe flies are spooked by their own reflection in the bag or think it's a body of water and turn away. Others think maybe the pennies in the water look like the eyes of a larger insect or foe, and the flies flee in fright. The thing is, there is no scientific support of this trick, and in some tests, it actually attracted flies.

Flies carry all sorts of bacteria, so keeping them away from food is an absolute must, but it isn't easy. Consider hanging some of these bags from your patio or picnic table umbrella the next time you're dining outside and test the hack yourself. If it doesn't work, you're only out some water and a few sandwich bags — but there are other clever DIY solutions you can consider to keep flies at bay.