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 flytrap, using very ripe kombucha as “bait”.