We use the big jar type traps with a bait that stinks like rotten meat, catches wasps and flies and we empty them twice a week, they are far enough away from the house and the flies seem to head in the direction of the traps, about another month before they start again here and the horses don't help.
We also have a healthy population of dung beetles that break up horse droppings within 3 days or so, they work really well and deprive the flies of a feed.
Because of my wifes work we are not allowed to have chickens or any other bird or pigs so they are not an option for us.