We've had flies from an unknown source in the kitchen for a few weeks now. I keep meaning to buy a real fly swatter since dish towels are only partially effective. Don't know their source but one got into the fridge the other day and I closed the door and let it die and I still haven't scooped up its carcass. If it helps to know, I don't even HAVE kids (just dogs and out-of-town company). It sounds like you've turned a major cleanliness and tidiness corner - kudos!