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Combating Fruit Flies


(excerpt from Tim Vandergrift’s wine blog) 

It’s fresh flower time, and for winemakers that means one thing:  the inevitable return of our sworn enemy – the common fruit fly. Minute little flying monkeys of doom, they’re hard to exclude from your winemaking areas, and while they’re easy to kill, by the time you’ve swatted one, thirteen more have materialized out of thin air, looking for a free meal!     The reason why we need to be concerned over the little monsters isn’t just that they’re unsightly and chewy when you discover one inside a mouthful of Chardonnay.   No, it’s their other name we need to think of, “Vinegar Fly”.  The little blighters are filthy with acetobacteria, the organism that turns our delicious alcohol into vinegar.  How to combat ’em?  First, understand that they don’t eat fruit:  they eat mainly yeast.  When they smell carbon dioxide and alcohol, they think it’s a piece of rotting fruit where they can lay eggs and get a delicious meal. When they smell a fermenting carboy, it’s their equivalent of a Vegas buffet ten thousand miles long! You’ll need to wipe up every single little tiny spill of wine or juice immediately, and sulphite the area to prevent any residue from getting a yeast film.   You can set up a wasp trap (available from hardware stores).   Make sure to fill it with the magic formula:  apple cider vinegar with a couple of drops of liquid dish soap in it.   Or you can check out natural pyrethrin-based insecticides: they’re made from plant oils, are mostly safe and can be used in food prep areas.  Never use any other kind of insecticides around wine or food prep areas!   Spray your winemaking area well just before you leave for the day and sweep up the little corpses next morning. 

Note from The Vintner: Keep in mind that it is always recommended that you use a proper food grade primary pail that has a locking lid to pair with a bung and airlock. Old style primaries that are designed to keep the lid cracked open will fill with fruit flies once they discover your pail. Also – the Canadian Government made changes to food grade plastic standards in 2008 as they banned BPA’s. If your Primary is getting old or scratched, it may be a good time to get a fresh one.

If the first time you notice the flies they are already in your airlock – this does not necessarily mean that they are in your wine or beer! Your airlock is designed to let gas out, while not allowing air or fruit flies in. This is your reminder to set your apple cider vinegar and soap cone traps (everywhere) and sanitize your work area. Also, sanitize, rinse and prep a new airlock, then switch the contaminated one out in one quick move. Please call us for advice if you are unsure in any way!

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