Within the last few weeks, horse flies have EXPLODED in swarms in west TN. For some reason, my chestnut gelding is their target, and he is being harassed non-stop. I apply fly spray daily and feed apple cider vinegar, but is anyone really having any luck beating the flies? I am going through fly spray like water, which gets expensive... does anyone have any home recipes for fly spray that actually works? Or even a bottled fly spray that works?