And speaking of critters. I discovered something accidentally a few years ago. If you kill a mouse in a mouse-trap and forget to check, after it's been dead for a while you might have gigantic flies. There is some kind of fly that hangs around dead things and I've been very wary whenever I've seen them.
While I've been wasting my afternoon on the computer, I've heard a buzzing in the window. Then I went downstairs for something that I honestly can't remember what it was now, I heard it again. I opened our French doors and let out a small bird sized fly - only to discover another one on the wall.