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Fruit Flies in Kombucha

Fruit flies in kombucha…they’re not a match! Here’s how to keep those pesky fruit flies away from your kombucha projects (and what to do if they get inside).

You may have noticed that fruit flies seem to be attracted to kombucha (maybe even more so than we are!). They’re attracted to the smell of fermentations (like rotting fruit, garbage, and of course kombucha), so you may find them hovering on top of your first fermentation jar.

Is it okay for fruit flies to be sitting on top of your jar? Yes. But is it okay for them to be inside your jar? Nooo.

So if you’ve noticed a few (or many 🙋🏼‍♀️) fruit flies hanging around your kitchen, you’ll need to take some precautions to make sure they don’t slip into your kombucha.

3 traps used to catch fruit flies

Reduce the number of fruit flies

The first step in keeping fruit flies out of your kombucha is to reduce the total number of fruit flies as much as possible. Make a few fruit fly traps and nestle them around your kitchen. These will attract and kill the fruit flies. Here are three fruit fly traps that work well for us:

Funnel over vinegar (or kombucha): Add a bit of vinegar, kombucha, or even some rotting fruit to a tall glass. Set a funnel over the glass. The flies will be attracted into the glass, but won’t know how to get out.

Vinegar (or kombucha) + dish soap: Add vinegar to a small dish, then add a drop of dish soap. The soap will reduce the surface tension so the flies sink (a sad way to go, but sometime’s you gotta do what you gotta do for your brew).

Adding dish soap to vinegar to catch fruit flies

Plastic covered cup: Pour your smelly substance into a glass, then cover it with plastic wrap. Prick holes in the top with a fork so the flies can get in (they won’t be able to find their way back out).

Poking a hole in plastic wrap covered cup to catch fruit flies

Store bought fly traps: While these homemade traps all work well, I’ve also had success by hanging a sticky strip next to our kombucha vessel.

Keep flies out while brewing

While your kombucha brews, the number one thing you can do to protect it from fruit flies is to ensure it is covered with a proper cloth.

While cheesecloth is the conventional recommendation, some cheesecloths are not finely woven and can leave gaps for fruit flies to sneak in. To prevent these sneaky buggers, use one of these as the cloth covering for your first fermentation:

  • Tightly woven cheesecloth, folded over itself a few times
  • Coffee filter
  • Few layers of paper towels
  • Tea towel
  • Cotton t-shirt

Keep flies out while bottling

So what if you need to bottle your kombucha and there are kombucha-thirsty flies hovering everywhere? Here are a few tricks I use nearly every time I bottle.

Work quickly: If there are just a few flies, simply work quickly. Take off your cloth covering, pour the kombucha into a ready-to-go jug or bottles, then quickly replace the cloth covering. I typically don’t let my vessel be exposed to open air for longer than 20 seconds (trust issues, much?).

Use a fan: Point a fan at your work space. The fruit flies won’t be able to fly through the strong wind (i.e. your wind shield ⚡️).

Vacuum: If there are many flies sitting on top of your brew, use the hose attachment of your vacuum and suck up all the flies around your brew.

Fruit flies got in my kombucha. Now what?

You opened the top of your first fermentation and noticed a dreaded fruit fly inside. Now what? Well there are two camps of people on this: the squeamish and the brave.

Let’s start with the squeamish. I fall squarely into the squeamish category (especially after having seen a video sent to me from a reader of a fruit fly maggot in her kombucha). For people like us, just throw it all away. The fly may have laid larvae, and you’ll never be able to get the thought of maggots out of your head. Just accept, toss it out, clean your supplies, and move on.

For the brave, you can salvage your kombucha. If your SCOBY is fairly large (more than an inch), it is unlikely that the fruit fly was able to penetrate very deep into the kombucha. Carefully remove the SCOBY and peel off the top layer. Rinse the bottom layer very well then add it back into your vessel.

After a week, exam the brew well for any traces of larvae. If you still see traces of an infestation, throw it all away. But if you don’t see anything, you should be fly free!

Annnnd now that I’ve thoroughly infiltrated my brain with images of fruit flies and maggots, I’m going to go look at pictures of kittens. Happy brewing!

4 thoughts on “Fruit Flies in Kombucha”

  1. Thanks, this is really helpful! We had a cloth over ours and the flies/larvae still got in. Should we store our scoby hotel with a tighter lid?

    • Try using a more tightly woven cloth (or a few layers). Also be sure not to keep the cloth cover off for too long when adding or removing the SCOBY. A tighter lid isn’t recommended though, because you need that airflow.

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