Ask Wine Wizard

My wine has some kind of flies buzzing around the must. Do I need to throw this batch out?


Ricky Lanier via email asks,

I am following the recipe for tomato wine from the August-September 2002 issue. The recipe says to loosely cover the must in the primary fermenter with a plastic sheet. But after about seven days, I noticed what I call “gnats” buzzing in and around the must. Will I have to throw this batch away? And what should I do to keep this from happening again?

My condolences on experiencing your first visitation by the ever present, but never welcome, Drosophila melanogaster — more commonly known as the common fruit fly. These prolific and pesky little airborne bugs are the bane of not only the home winemaker, but of anyone who has left a peach to rot in the kitchen fruit bowl, whose daughter forgot to take out the recycling or whose compost pile has gotten a little out of hand. Fruit flies are attracted to the aromas of fruits and vegetables, especially those that are rotting or fermenting. Their small size means that they might slip your notice for a day or two . . . until, as you found, your home winery has suddenly become the Drosophila Dating Game. Your primary fermenter is where they all go to raise their fruit fly families and live happily every after for their short, but annoying, lives. What can the conscientious winemaker do? I suggest you first try to stop them from entering your home winery. Install tight screening on windows and doors and make every attempt
Response by Alison Crowe.