Does vinegar kill flies?

Yes! It does. I discovered this by accident actually. As an alternative to Windex, we have been using vinegar cleaner in a spray bottle... and one day I was buzzed by a pesky housefly, and after spraying it with one mist... it dropped... took 3 steps and died. I was puzzled by this... until I started to spray any housefly I see with vinegar cleaner for the past 5 years... same result.. they walk about 3-5 steps... buzz a little, and die instantly. There must be something chemically going on within the fly with vinegar, but YES, it's a great non-toxic, clean way of instantly killing a housefly.