If you can pet them. lay down beside them, etc...go to TSC or any tack store, and you can buy any number of fly spray products for horses. It comes in spray bottles, Years ago, I bought a gallon of a concentrate. The label is gone, but I think it was called Malathion, or something like that. It was for spraying dairy barns stables, etc, and can be used on cattle. I just mix a little in this hand-held, 1 quart, pump-up sprayer, and spray my horses every day with it. I also have a few game chickens and 2 guineas that hang around the barn. They keep the turds scratched apart, looking for pieces of corn that passed through, and they eat all the maggots in it. This does a lot to help hold down the flies, too. And hang a few fly strips in that run- shed you have, too.