They can cause other health risks by spreading such diseases as West Nile virus, encephalomyelitis viruses and equine infectious anemia.
For those who prefer not to use insecticides for horse care, especially on foals less than 12 weeks old, try feeding your horse ACV and make up your own vinegar based natural horse fly spray that you can rub or spray onto your horse's coat as needed:
Best Horse Care Tips for Natural Fly Protection
· Eliminate insect breeding sites as much as possible.
· Cover manure piles and dispose of them often.
· Remove daily from stalls and pens all manure, wet straw, and waste hay then spread thinly or compost in
a covered pile.
· Eliminate standing water that can collect in such places as cans, old tires, discarded bedding and wet organic material.
· Stable horses at sunrise and sunset which are peak feeding times for black flies, no-see-ums and mosquitoes.
· Install overhead stall fans to interfere with the insects flight.
· Place fine mesh screens in all windows. (60 Squares/in2)
· Use fly masks, bonnets, body sheets and other clothing that does not allow the flies to reach the skin.
· Let your horse's mane and tail grow so that he will have extra swishing power.
· Keep horses away from standing water.
· If you don't mind having Muscovy ducks around the barn, they will remove adult house flies more than 30 times faster than the most efficient commercial devices.
***I got this information from www.apple-cider-vinegar-benefits.com
I hope I got it right, at any case it had apple cider vinegar benefits in it.