Bottom line. I could pick them off at will. That is, until a new breed of fly appeared around late July. Smarter, faster, smaller. Like when those German Messerschmitts first showed up during the war. These little bastards seemed to know what I was going to do before I did it. Jab, jab, right hook. I couldn't touch them even with my new state-of-the-art fly swatter from Bed Bath and Beyond.
I think I'll just let them eat until they get fat and dumb.