Jun 17, 2013 - 01:31 PM
Thats how bag fly traps work, they emit a foul odor and attract flies. When the flies go inside they can't out.
The Flies Be Gone has an odor too. The trick is to place it away from the home or building so that the flies are pulled "away" and not attracted "to" the house.
The only fly traps that would not have an odor would be a light trap that attracts the flies with a light, or a glue type trap that attracts the flies with a pheromone.
Bottle flies are the result of something rancid in the area that is attracted them. If they are a continual problem, then Flies Be Gone is your best alternative.