Flies in the Airlock?!!!!!

I transferred my cider into secondary today and noticed that the airlock on another carboy needed to be topped up. No problem right? Except when I add to it I notice about 10 fruit flies that float to the top of the airlock!!!

Do you guys think the airlock did what it was supposed to do and keep them out or do you think it let them in. It is a darker colored beer so I can't see anything floating around in it. Is there something I can do to test it? I put in a new sanitized airlock on it, but I am not sure what to do. Can someone help?

The airlock did what it's supposed to do, keep those goddamn vinegar making bastards out of your brew. Just dump out the airlock and add more liquid like you already did.

might be a good idea to clean and sanitize it first

You can add a small piece of paper towel and a rubber band to the top of the airlock, after you clean and refill the airlock.

Yeah, you'll be fine. Certain times during the year, I get them in my airlock as well.
They'd have to dive and swim through the airlock liquid to get at your beer.

I wouldn't worry about it. If you used vodka or sanatizer in your air lock I would guess that there would be zero chance of the flys living through 'diving and swiming' to get through the air lock. Even with water, I don't see them making it.

Not to mention, if they did 'dive and swim' under the little cup in the air lock, when they surfaced inside, they would be in a relativly zero oxogen a enviroment. It's pretty hard to catch your breath after swiming, when you surface in a tube full of CO2.

i use vodka in my air lock and have had no problems with insects.
have not done any cider either, but i think the vodka keeps the fermenting wort smell down.
first couple batches i did, i used water in the air lock, and could smell the fermenting wort when walking into the basemet where fermenter was placed.
swiching to vodka leaves no smell in air that i can notice anyway.

Thanks for the replies. I had either vodka or gin in the airlock. Guess I kind of freaked when I saw the flies, but sounds like I should be fine. Thanks again.

I was having the same problem and I used a piece of my wife's pantyhose as a filter. just cut out a section, and yes she did give me a new pair she had, and I attached it with a rubber band. No more flies in my 3 piece airlock. They only really seemed to like the Apfelwein airlock, and not the beer.