I absolutely hate it when a fly gets in the house, especially when I'm cooking and have food out. I have figured out a way though, to make eradicating them once they get in a bit easier. In our living room, there is a bay window with curtains hung; a sheer set which is usually set closed, and the thicker ones mostly left open. As light gets through, it attracts the flies that get in the house. So I'll open the sheer curtains just a bit in the middle. The fly gets in there and buzzes around the window, partially trapped. In there they're easy pickins with the fly swatter.