Summer, open windows, warm air… and the inevitable guests—flies. As soon as you air out the room, these pesky insects are right there. They circle, land on fruit, nibble on your food, and become especially active just when you’re about to relax.

You’ve probably tried everything: fly swatters, scented sachets, chemical sprays, sticky tape, ultrasonic devices, and even “folk” methods like lemon on the windowsill. But let’s be honest, flies seem to ignore most of our efforts.

There’s one unusual yet popular method many have heard of: a transparent bag filled with water and coins.

It sounds strange, but the idea is this:

Flies have complex vision—their eyes are made up of many tiny lenses, making them very sensitive to light and reflections. If you fill a transparent bag with water and drop a few shiny coins inside, the light will refract and reflect in different directions. This “shimmering” effect is thought to disorient insects and deter them from approaching windows or doors.

How to make this design:

-Take a clear, heavy-duty bag.

-Fill it with water a little more than halfway.

-Place 3-5 shiny coins inside.

-Tie or close the bag tightly.

-Hang it near a window or front door.

This method requires no chemicals, is odorless, and is completely safe for the home.

It’s important to understand that there’s no scientific evidence supporting this method’s effectiveness. It “works” for some, but not for others. It’s more of a folk life hack than a guaranteed solution.

If flies are truly a nuisance, it’s best to combine this method with proven measures such as mosquito nets, a clean kitchen, sealed food items, and insect traps.