Hey Rich, just saw this in reference to Yellow (or Deer) flies and thought you might be interested.
Trouble w/ Yellow flies (aka deerflies)? Suspend a flat black bucket from a tree limb so it's 3-5 feet above ground, such that the wind can make it move around. Then coat it w/ STP motor oil. The yellow flies will be the only insects attracted to it. Once they land on it, they can't escape.