@AmpBenzScientist No one is sure if it could even work. You're better off using a water trap that breaks surface tension with an attractant. This can be done with dish soap with a citrus scent often without any thing else added.
@AmpBenzScientist I was suggesting something with a pleasant smell and non-toxic. Folks used to powder fly cap mushrooms in milk in the days before petrochemicals. That's toxic and smells horrible. :3
@AmpBenzScientist I should note the coke was to kill the flys... but I have no idea if that would work. I do know caffeine can dive many insects to have much shorter life spans, and of course nicotine is very deadly to them. But it's best to use something not deadly to people and pets imho.