I work on a small farm with a variety of animals. I want to reduce the fly population and don't want to harm the environment. What is the best approach? I take care of cows, horses, alpacas, llamas, chickens, geese, ducks, and sheep (a few of each).
Linn County Oregon insect issues
Manure handling/disposal is key to reducing fly populations. Animals however, will attract flies even with the best control measures.
It sounds like insecticides are not an option so covering/reducing piles of manure, harrowing of pastures to move dung piles around and get them to dry out so they are free of moisture will reduce the ability of flies to lay eggs.
Manure from winter in and around barns are a big source of flies, especially in warmer weather.