A Bug's Life

When we got home yesterday from a night away, we found our kitchen all a buzz....not with activity but with the winged flapping of a pile of flies. GROSS! They were congregated in the window in the kitchen as well as the downstairs bathroom. In no time my grossed out cries had Garret ushering them into the after life! But I cant stop wondering how they got in?! We found ants last week so i bought some traps, but I dont want to use fly paper like we are living on a farm. Im hoping that G smushed the really fertile ones so they wont be leaving any fly babies behind...