We get those monster horse flies too on our property.

The bite is VERY painful and when they are around we all carry wooden swatters. We just cut the ball and rubber band from the old paddle ball game.

Its kinda hard to run from them when you are in waist deep water trying to catch some smallmouth. The paddle works great but its almost impossible to hit them until they land on you.

In my area, the hotter it gets the more abundant they become. Repellents seem to have NO effect at all on stopping them and they are very fast.