We Tried The DIY Penny Trick To Keep Flies Away, But Did It Really Chase Them Off?

Flies aren't just irritating when they buzz around your face, as they can also carry a whole host of nasty bacteria and spread diseases like dysentery, cholera, tuberculosis, and even leprosy to humans. Their bad table manners make them horrible guests at any dinner, picnic, or outdoor party, where they will land on food and regurgitate whatever they feasted on earlier. An intriguing old DIY suggests that you can deter flies by placing pennies and water into almost any clear container, whether it be a sandwich bag, plastic cup, mason jar, or wine glass. But could pennies and water really deter such persistent insects? Many experts think not. 

"There is no credible scientific evidence to suggest that this type of methodology works for ridding one's house from flies," certified entomologist and exterminator Scot Hodges told Fox News. "I have visited properties that have had the penny-filled bags and flies, so my observation is that this is not something that can be relied on." The fact-checking site Snopes confirms that this hack has been largely debunked, and according to some experiments, the shimmery water may even attract more flies to the area. Still, considering how many people still swear by this trick to get rid of flies, we decided to test it out for ourselves to see if our pesky flies would actually buzz off.

Some believers in the DIY say that the pennies shimmering in the water should mimic the reflective eye of a bug — one much larger and scarier than the flies. Seeing this giant, twinkling bug eye, the flies shouldn't dare to come near you or your food for fear of being snatched up and eaten by the predator bug. Another theory suggests that the flies will be confused by the bright, shiny pennies refracting in water because it hurts their complicated little eyes. Either way, the flies should choose to avoid the area and hang out elsewhere.

This handy penny trick only requires about three supplies: pennies, water, and a clear container. We decided to try using both a clear mason jar and a plastic sandwich baggie, just in case one worked better than the other. We also gathered about 10 shiny copper pennies — the shinier, the better, in theory. While pennies are typically used, dimes, nickels, quarters, or nearly any other shimmering objects, even aluminum foil or jewelry, are sometimes utilized instead.

Putting together the DIY trick was remarkably easy. We simply dropped about five pennies each into the jar and baggie, then added water. To help us truly test the DIY, we also decided to create a tempting scene for the local flies. We set aside a small plate of unguarded food just for the flies on a picnic blanket. It seems that nearly any food can attract the pesky critters, but we baited our plate with a few different options including a sliced orange, cheese, some grape jelly, and fresh spinach. It didn't take long at all for a little fly visitor to hop onto an orange slice, so we knew our bait was effective. 

Some sources recommend hanging the deterrent from a tree or nearby awning, but having them on the table or blanket is supposed to work, too. In our case, we simply set the water-filled jar and sandwich baggie on either side of the bait plate on top of the picnic blanket. We also started a stopwatch to see how long it would take for our fly friend to return, if he returned at all.

After about five minutes, our fly returned to the scene, and he brought a friend with him! The two flies landed on our picnic blanket for a moment, seeming to pause and think about the pennies while they sat rubbing their hands together. Within a few seconds, they happily hopped right back onto the juicy orange slice. We tried adding a few more pennies to the jar, but the flies didn't budge. Even when we held the plastic sandwich bag above the plate, the shiny pennies seemed to have no effect on the fearless little flies.

Unfortunately, we'd have to call this fly-repellent DIY a failure in our book, agreeing with the experts who said that it didn't really work. Since two flies returned after we brought the penny containers out, it's possible that the trick even attracts more flies! Why do so many people still swear by this strange DIY? One explanation could be a confirmation bias, in which people set up the containers, wait a few minutes, and then feel excited when flies don't immediately return. Believing that it worked, these folks may be more likely to share the rumored hack on the internet, whereas those whose DIY failed wouldn't feel such a desire to share. Either way, we'd recommend saving your pennies on this one.