Wine flies.. or thunder bugs? Wine flies have visible wings and one body will turn an entire 5 gallon bucket to vinegar rat's piss. Thunderbugs are like little puncutation marks ! and can swarm in millions. They take refuge indoors when the air is opressive, hence the name thunderbugs. They are OK, and will go as soon as the thunder has passed. Wine flies won't and are a pain in the arse. So always cover your wine properly.

LTS