If you have any pickle jars you can poke holes in the lids with a big nail and put a few garlic cloves in the jar with a little bit of water. I noticed that the mosquito repellent (Mosquito Barrier) smells like garlic also attracts flies like crazy. If you're not grossed out by the mass execution/still living ones you could dump them and start over or just get a new pickle jar and start over or just keep going until the jar fills up...that's pretty gross though. I also put Bronco spray on my dogs and it works for them...that might work around your area as well. Detract them from one place and attract them to another with a trap? I'm not sure how far away from the problem area you can start but slowly just hang the trap further and further and shortly, you won't have a problem.