Even though summer is our favorite time of year, we do have a few complaints about what the season brings. While we don’t much mind the heat and humidity, the one thing that sends us indoors faster than an Olympic sprinter is the bugs—especially the flies!

We’re sure that you are already well aware of the fact that there are plenty of store-bought and homemade items that can stave off these pesky winged creatures, but many of them don’t come with the most pleasant of odors. In fact, if you can’t stand the smell of citronella or spray-bottle chemicals then you are pretty much out of luck!

That’s why we are sharing a hack with you today that will allow you to ensure that all of your porch side cocktail hours, barbecues, and late-night reading sessions are fly-free zones—and the best part is you probably already own all of the materials you’ll need to make your own.

All you need to get started is a heavy duty freezer bag, some table salt, lime juice, pennies, and water. When you combine the items just so, the see-through hanging device will literally turn into a fly’s worst nightmare.

Because this trusty doo-dad needs a light source to do its magic, it’s best to keep it near an outdoor lamp or lighting fixture so that you can keep the flies away both during the day AND at night.


Why flies hate these hanging bags

Even though most insect repellants are based on emitting odors that bugs hate, the inspiration behind building this type of “fly frightener” has nothing to do with scent—for them, the repulsion is connected to their sight.

According to research compiled by How Stuff Works, entomologists agree that throwing a certain amount of shiny coins in a water-filled bag creates an inhospitable sight for flying insects. Just think of it as being the complete opposite of an oasis—once a fly spots the shiny coin and water combo, they’ll want to get as far away as possible.

What the insects are seeing in the bag is an example of light refraction, something the human eyes can handle, but for insect’s eyes, it’s a completely different story.

close-up view of a flyJacob Martin via Flickr

Let’s look at the common housefly, for instance. These pests are actually born with a pair of large “complex eyes” which contain 3,000 to 6,000 “simple eyes”. Experts liken their view of the world as being that of a mosaic pattern. Pretty cool, huh?

Since their sight is skewed, their sense of direction is tied to light sources, like the sun or a flame. When a housefly catches a glimpse of a contraption like the hanging water bag, they automatically get confused by the refraction, and they go on their merry ways.

Now that you know all about why bugs hate this trusty DIY contraption, it’s time for you to learn how to build your very own. Just click on the video below to get the full tutorial for yourself, and get ready to say “goodbye” to those pesky flies for good!

What do you think of this insect hack? Have you tried this before? How do you keep flies away from your porch or deck?