Flies and Fermenting Kombucha

You’ve heard the old saying “You can catch more flies with honey than with vinegar,” right? If you’ve brewed kombucha, you know that it isn’t true!

In nature, vinegar (acetic acid) indicates fermenting activity, which signals to scavengers like flying insects that there’s a bounty of rotting food nearby (Yummmmmy)! Because fermentation is really just controlled decomposition (don’t tell your non-fermenting friends, it might gross them out), flies are naturally drawn to most fermenting foods.

What does a SCOBY infected with flies look like?

The best precaution is to cover any open-air fermenting vessel with a breathable cloth (cheese cloth is not recommended because flies can penetrate the loose fibers) and secure it with a rubber band, twist ties or string to keep the cover taut.

Kombucha can be problematic with fruit or vinegar flies due to its strong odor. You could make your own fly trap to distract flies from invading your brew.

Homemade fly trap

Homemade flytrap, using very ripe kombucha as “bait”.


6 thoughts on “Flies and Fermenting Kombucha

  1. Austin Post author

    Great tips. Thank you for giving us your solution!

  2. Againstthegrain

    I should have also mentioned that the tip of the cone shouldn’t touch the vinegar. So proportion the cone length and vinegar level so they don’t meet.

  3. Againstthegrain

    If I have an abundance of ripening fruit on my counter sometimes fruit flies/vinegar flies (i.e., drosophila) set up camp, so I set out a vinegar fly trap (or two, or three). To a very small jar or glass I add about half inch or so of apple cider vinegar (kombucha would work, too). Then I tape a piece of paper into a cone shape, leaving the tip slightly open (or the tip could be cut off, but keep the opening NO larger than 1/8″). The cone is placed on the jar or glass like a lid, with the cone pointed down inside the jar. If I place the jar in a good spot, the aroma of the vinegar attracts the flies more than the fruit does. The fruit flies go into jar for the vinegar, but then they can’t make their way back out very well (yes, eventually they drown in the vinegar, but I don’t lose sleep over that, frankly). Rinse and replenish the vinegar as needed.

    Note that these traps don’t work at all with houseflies.

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