I was transferring from my brew kettle to my fermenting bucket over the weekend and suddenly a big black fly was buzzing around me. I frantically waved at it while holding the siphon tube and trying to not waste my wort onto the deck. I was very concerned at the thought of the fly landing in my wort and what impact it would have on the beer. I could only think that it would be devastating since flies live such nasty lives. What do you suppose would happen if one landed in my wort? Would it be grounds for dumping the batch? If that fly was sitting on some pile of dog crap prior to landing in my wort I would think the bacteria transferred would be a very bad thing.
No it would not be grounds for immediately dumping the batch.
You would want to pitch your yeast ASAP such that the yeast would became the dominant microorganism.
The acidic environment and alcohol produced by the yeast would generally inhibit or kill the bad bacteria.
If the fly didn’t do a touch and go, it should be strained out of the wort by the siphon.
Bugs in beer is usually a personal preference and most of the time people end up dumping as opposed to waiting.