I make traps. I cut the top 1/4 or so off a water bottle and flip it into the bottle. So that the small opening is pointing down. Tape it together so the only way into the bottle is through the small opening.
Then pour a tiny bit of water, a few drops of soap and a chunk of fruit, usually apple. Set it near the location of the flies.
24-48 hours later, bottle full of flies on the fruit. Give it a swirl and the flies fall into the water and can't get out due to the soap. Then put it back and let the rotting flies and fruit attract more!