Diatomaceous earth will take care of the flies in both the house and barn. Make sure it is food grade.
Just put it in a dish. The bugs land on it and the stuff will kill them. I have hear that dawn dish soap and water will work, but you have to spray it on the flies.How would you apply that? We're talking about around window sills mostly...
There is no such thing as a stupid question.Never mind, that was a stupid question.. bugs stole my brain.