How to Make a Fruit Fly Trap

Good golly, Miss Molly! Fruit flies love ferments–and the fresh produce that we keep around to create our delicious ferments. Are they as bad at your place as they are at mine? Well, keep reading. Michelle will tell you how to beat them at their own game!

As any preparer of kombucha, sauerkraut, or sourdough knows, fruit flies LOVE the aroma of anything fermenting. No matter how fastidiously clean the kitchen is kept, somehow those tiny little black dots of annoyance find their way to hover in clouds over whatever is brewing.

Fruit flies are a vector of acetic acid bacteria—the bacteria responsible for turning anything alcoholic into vinegar. So while I enjoy vinegar, and I tip my hat in thanks to the little guys for helping it happen, I still don’t want to share my kitchen space with them. They love SCOBYs, and if they have the chance to access them, they will lay eggs and ruin your kombucha. Trust me, there are few things less appetizing than checking on a brewing vessel and finding it wriggling with unwanted guests.

The fruit flies’ appetite can also be its bane, however, because kombucha makes a fantastic fruit fly trap. If you have the following items, you have all you need to enter the battlefield for your kitchen.

  • A bit of plastic wrap
  • Rubber band
  • Toothpick
  • Jar

How to Make a Fruit Fly Trap in Two Easy Steps

  1. Pour two inches of kombucha in a jar.
  2. Cover it with the plastic wrap, secure tightly with a rubber band, and poke lots of holes in the top with your toothpick. They’ll look impossibly small, but trust me—the flies will find a way to fit through.

Place your trap in a viable location—I usually put one right next to my sourdough starter and another right next to my kombucha brewing tank—and let it do its work. The flies will be drawn to the aroma, crawl through the holes, and eventually drown themselves. If you find that your jar is full of flies just hanging out on the inside of the glass, like party-goers at the side of a pool, and you just want them to go away, you can also put it in the freezer to finish them off. Once everything inside is dead, empty your jar outside, give it a little rinse, and, if there’s still flies to reckon with, start the process all over again.

And it Gets Even Better

To make this trap even more effective, pair it with a sheet of fly paper right above for a two-pronged attack. Granted, this does not look very nice if it is near your food-prep area, so find an out-of-the-way spot. I found that putting a setup like this on top of my refrigerator was a great solution during our “lively” summer months.

Some sources have recommended putting a drop of dish soap in the liquid to break the surface tension, but strangely, I have found that my traps were less effective when the soap was included. If you’re managing a fruit fly problem, try both methods and see what works for you!

Happy trapping, and, of course, happy brewing!


This time of year, you do not want to get caught red-handed without enough fermenting supplies. Check out the Fermentools 12-pack so that you are well prepared for the day all the cabbage is ready to harvest from the garden.


Andrew and Michelle are the new owners of a 12-acre homestead in rural America. They are just embarking on this journey that is far removed from their city-life upbringing, so they realize that they have a lot to learn in order to succeed in this new place.Come along with them and read more about what they learn as they make this transition at their blog Simple Life Homestead.

Leave a Comment