Current weather and delay conditions for (GRU) Sao Paulo-Guarulhos International Airport Conditions
Another option is to mix small amounts of apple cider vinegar with the animal's drinking water; consuming this solution is known to change the blood pH of the horse, thus keeping horseflies away. Cider vinegar, coupled with essential oils, is also used in home sprays as the sharp odor may repeal horseflies.
It seems like everyone knows at least one homemade horse fly spray recipe that uses natural ingredients (by natural we mean a recipe that doesn't contain man-made insecticides). Here at CowboyWay.com we decided to take three homemade horse fly spray recipes, and one semi-homemade recipe, and put them to the test.