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Fruit Flies: The Never-Ending Battle For Your Kitchen

Posted in Maintenance

Is your home-brewed kombucha operation attracting fruit flies?  You’re not alone! Many brewers face this issue on a daily basis. Some don’t pay any attention because they may only have 1 or 2. Depending on the area they live in, some brewers might see a lot more. No matter where you are on the scale, I can help.

First off, let’s get the bad news out of the way. If a fruit fly has landed in your tea, you need to throw out the entire batch. I hope this never happens to you. I know exactly how it feels. I was ready to place a new batch of tea into my brewer. Suddenly, a fruit fly swooped in and ruined my entire project. I don’t have any research on the effects, of drinking fly contaminated kombucha but I can confidently say it’s not a safe choice. Especially if you want to share your kombucha don’t give your friends and family infested product. That’s just gross!

Hopefully, you have a backup Scoby in a container otherwise you’ll need to buy a new one.

If you haven’t had any contamination issues but you have a fresh batch tea and fear these critters, I have a technique for you. Get a medium size fan place it 2 – 4 feet away from the glass jar and tea. Turn the fan on and aim it towards the glass jar and brewed tea. Now you can safely pour tea and fruit flies will not be able to swoop in if you turn away for a moment.

That was an effective method for continuing the brew but what about preventative applications? I have an answer for that too. Your own kombucha product can help you attract fruit flies into a trap.

Science lesson alert: Kombucha brewed at home, if following the proper recipe, will undoubtedly contain acetic acid. Depending on how long you let your tea ferment you could have a tiny bit or whole lot in your batch. In fact, if your kombucha sits long enough you can have str ight up kombucha vinegar. Fruit flies (Drosophila melanogaster), are attracted to acetic acid because it helps guide them to food. Not only will the small fly use the fruit for food but they’ll also plant their larvae and continue their cycle of life. Believe it or not, Fruit flies are actually picky eaters. They can only smell fruit when it’s ready to consume they wait for the aroma of the acetic acid that emits from ripened fruit. Scientific research has concluded that fruit flies become intoxicated by this scent.

Acetic acid will serve as bait for these annoying bugs. Just like in cartoons when mice are caught with cheese we’re going to use an acetic acid trap to capture fruit flies.


  • A cup or jar
  • Apple cider vinegar or very sour kombucha
  • Hot water
  • Dish soap
  • Optional: plastic wrap

If you’ve already spent a countless amount of time trying to find out different concoctions that will work besides this method, stop; you’re wasting your time. It’s scientifically proven that fruit flies are captivated by acetic acid and this formula will yield the best possible trap.

Take your cup and fill it up 1/3 of the way with the vinegar or sour kombucha. I think mixing things always works best so I use both to fill my cup. Next, add about 5 drops of dish soap; this will trap them like quicksand but worse they’ll die instantly. Then add two tablespoons of hot water to allow the soap to rise to the surface.

This last step is optional, some have seen better results with it some haven’t. Wrap the top of the cups with plastic, tape up the sides to create a tight seal. Poke dime-sized holes in the plastic wrap. I typically follow this step because I believe the smell becomes more concentrated and the trap lasts longer.

Featured photo courtesy of Katherine Bowman.

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