Drosophila

[acm28]

Hi,
I'm a newbie so the answer to my question may be obvious but for the sake of conscience I'll leave the question here anyway...

I have some bottles finishing their second fermentation (priming) and today I remembered to take a look at them and noticed that I had some friends there (drosophilas, better known as fruit flies and largely responsible for vinegar...). There weren't many, maybe 5 or 6 (about 4 of them resting on top of 3 of the bottles), when I saw them there around the bottles I got a little worried and decided to see if anyone could clarify if there was a risk of them contaminating the my beer (although it is already bottled) and/or they lay eggs
or if they are there just because they were attracted by some compound that came out of the bottle (I don't know if this is possible but I would like to know) (and, of course, I hope that's what happened)

(I read somewhere that drosophilas are attracted to alcohol and so I think it's worth mentioning that the beer in question is a Belgium Tripel beer)

I would appreciate any kind of help/clarification on this issue (and I apologize for any errors in writing English)

Thanks

 

[fluketamer]

drosophila dont make vinegar they are attracted to vinegar . which is produced when fruit rots via acetobacter and lactobacillus and others.
this gave them an evolutionary advantage to flies that couldnt detect vinegar.

likely some extra beer on the outside of the bottle left during bottling soured and this attracte dthe flies. the bottles are likely sealed i would hope. if you see something inside the bottle thats another story

 

[hotbeer]

Growing up, I was always told the flies and gnats wouldn't eat or drink to much. And that they'd always leave enough left for me.

If anything attracted them, it's on the outside of the bottles unless you didn't seal them well enough. And if you didn't seal them well enough, the other results from that will be more worrisome than the flies.

 

[acm28]

I had the idea that drosophilas were vectors of acetic bacteria, but apparently that was a wrong idea, thankfully

Yes, the bottles are completely closed (with caps)
Thank you for your help and I hope you're right (I don't doubt you) and that it's really just traces of beer on the outside of the bottle

When I open the bottles in question, I'll come here and thank you because you're certainly right and I actually have nothing to worry about.
Thank you both once again for the clarification !!!

 

[Deadalus]

You probably spilled a little beer on the outside of the bottle while bottling. After capping, you could give the bottles a quick rinse so they aren't attracted as much. They love to hang around my starters and airlocks.

 

[timeeeee]

Growing up, I was always told the flies and gnats wouldn't eat or drink to much. And that they'd always leave enough left for me.

Omg I love this. Honestly I've found a few in the sediment and still drank it but that's just me lolol

Seconding what everyone else said: Mainly, some beer on the outside is exposed to a lot of oxygen so acetobacter can go to town and turn alcohol into acetic acid (so if you smell around the caps, you're probably noticing vinegar!) which attracts the buddies. I guess it's possible that the caps aren't sealed right but waaaay less likely. Inside the bottles, the lack of oxygen should be preventing your beer from turning into vinegar.

 

[Whisky River]

You probably don’t have anything to worry about from the flies that are there now but please be aware that they can very easily be the cause of your next batch spoiling if they are still around when you are bottling your next batch. Might be worth trying to get rid of them now so they don’t hang around.

 

[acm28]

You probably don’t have anything to worry about from the flies that are there now but please be aware that they can very easily be the cause of your next batch spoiling if they are still around when you are bottling your next batch. Might be worth trying to get rid of them now so they don’t hang around.

Thank you for the warning!!! The most certain thing is that the flies won't harm my next batch since they are where I store the bottles, the "manufacturing" process and the bottling I do elsewhere, so I should be more or less safe... Anyway, I'm going to prevent them and get rid of them as quickly as possible (and keep an eye out to see if they don't appear again)

 

[G_robertus]

I had the idea that drosophilas were vectors of acetic bacteria, but apparently that was a wrong idea, thankfully

Yes, the bottles are completely closed (with caps)
Thank you for your help and I hope you're right (I don't doubt you) and that it's really just traces of beer on the outside of the bottle

When I open the bottles in question, I'll come here and thank you because you're certainly right and I actually have nothing to worry about.
Thank you both once again for the clarification !!!

As far as I know Drosophila sp. are attracted to a range of odours, including vinegar and fruity esters. But they also carry bacteria with them including Acetobacter. That said, many organisms carry loads of bacteria including Acetobacter with them, as you do yourself as well. Closed bottles should be fine though, I tend to see them in summer near my wild ales as well.

 

[acm28]

As far as I know Drosophila sp. are attracted to a range of odours, including vinegar and fruity esters. But they also carry bacteria with them including Acetobacter. That said, many organisms carry loads of bacteria including Acetobacter with them, as you do yourself as well. Closed bottles should be fine though, I tend to see them in summer near my wild ales as well.

Great, I feel much calmer knowing that it happened to you too and that there was no problem.
Oh, okay. I knew that acetic bacteria had many origins, but I thought that in the case of beer, the origin was mainly due to drosophila, but in that case better.

Thank you

 

[acm28]

I just want to inform you that I opened two bottles and that apparently the drosophila are just on the outside (as you said), the beer was great and there was no trace of "contamination" of any kind.
Thank you all for your help

 

[JAReeves]