I noticed a bunch of fruit flies in my airlock this morning, how disgusting! Anybody else having problems with these little buggers? I solved the situation by using an iodophor solution in the airlock, they dont like that odor! Hopefully no contamination got into the fermentor.
That happened to me when I fermented at my friends house. Luckily, the beer turned out great. I think it has something to do with humidity. If not, it must be something to do with living in a remote area because my buddy lives out in the country where theres lots of wildlife and vegetable matter everywhere
fruit flies are attracted to CO2 so the belching airlock is like a landing light for them. They aren’t good at swimming though so the liquid should prevent anything nasty from happening to your beer.
That being said fruit flies are amazingly good at squeezing through tiny tiny openings and if there is a way they will likely find their way into your beer so beware! nothing might come of it at first but let that beer at just a little o2 and you may start to get some vinegar growth. This is assuming a fly actually got into your beer which is unlikely.
They definitely can’t swim through air lock. They definitely can infect your beer if it is not absolutely air tight. I’ve had them sneak past bucket lid seals. In your case, most likely nothing to worry about.
You should be okay but that’s why airlocks come with lids!
At what point would you all be concerned with a fruit fly caused infection? I had one little demon fruit fly crash into my rehydrated yeast this weekend and instantly drown I pulled him out, but pitched the yeast anyway. I had no other yeast option other than bread. Its a Saison fermenting at 75. Fermentation was active in only 3 hours.
Surprisingly, the fruit flies are avoiding my carboy.
Exactly the purpose of an airlock - keep bugs out.
So you knowingly pitched a vinegar fly into your wort? Sorry, but there’s no way I would do that! They’re covered with acetobacter.
Just one fruit fly will instantly give a funky taste to a glass of beer. I drink from a lidded stein in fruit fly season.
One fruit fly isn’t a guarantee you’ll get contamination. Its certainly fruit fly season, I have a few glasses of vinegar/wine/dish soap and have captured hundreds of the little suckers.
But acetobacter requires oxygen, so assuming fermentation starts quickly and oxygen is kept out after - one fruit fly probably won’t have an effect. I’m suspicious about one fruit fly turning a glass of beer funky. That one might be all in your head. There just isn’t enough time for acetobacter to turn beer unless it sits for a few days.
This.
Thanks. I’m hoping it was a “clean” fruit fly! This thread definitely has me inspecting all my equipment and rethinking my processes.
I’m not saying it’s a big concern, but I wouldn’t do it. That fruit fly would, at the very least, be in my head right down to the last pint. I certainly wouldn’t repitch the yeast!
And I have noticed an off flavor halfway through a beer only to discover a fruit fly upon further inspection. My wife and several friends have also noted this phenomenon.
I fish them out of my glass frequently and haven’t noticed any funky tastes. Lately there’s been about two per pint that land in my glass particularly if I’m sitting in the yard. Maybe I need to drink faster.
I’ve been at wineries with open fermenters - fruit flies everywhere - thousands of them!! It would probably gross most wine drinkers out! They were not selling vinegar and the wine won awards.
Or drink from a lidded stein! 
I’d use the yeast. You will out compete any funky if it’s a starter. I probably wouldn’t reuse the yeast.
As far as “one fruit fly getting in your beer causing an off flavor” … I’m just gonna say that has to be in your head. There is no way a beer can get infected that fast. I’d be willing to do a taste test with you to see if you could pick out the “funky” beer.
I think that the odds of infection from one fruit fly prior to fermentation (assuming sound sanitation practices) are slim to none. The competition for O2 by the yeast would likely win out.
As far as tasting acetobactor. I think the taste threshold for acetic acid is roughly 150-200ppm. So imagine the effects of one fruit fly in your beer. I can’t imagine that it would noticeably sour your beer. Perhaps stranger things have happened, but…
I bottled some mead in clear nip-sized bottles for a competition last weekend and while packaging them for shipping I noticed a tiny ant floating in one of the bottles. I doubt it will affect the taste, but it might have turned off a judge at the table.
Funny, these bottles were rinsed after first use, rinsed again after storage, sanitized in starsan, drained well and put into the freezer before filling from a keg. I can’t figure out where the little guy had a chance to get in there.
Ants are tasty. They have a nice kick from the formic acid in their abdomen. It would probably compliment a lambic quite well.