As do I but I also live close to a lake and lots of Horse property. It seems as if the Horse fly, even bigger than the Deer fly, is a relitive. It also seems that the Female fly of both species needs blood to produce its young or lay eggs. When I attempt to climb out of our valley I pass through a zone where the little beasties live. It seems as if they can fly faster than 10 mph but maybe they don't like to put out the effort to chase you much faster than 10. They never get me coming downhill but most often do goi uphill. I have been told they respond to darker clothing and they are attracted to Carbon Dioxide. When climbing I am breathing like a freight train and of course expelling co-2. Doubble whammy as they say. I can't remember even seeing any Deer flys very far from Lake Hughes but I do remember seeing some Horse Property out by Quartz Hill.