Some of it depends on what kind of flies you are dealing with.
You can use pesticides, but they are toxic and require repeated spraying.
I suggest using fly traps, combined with fly parasites, if you are not using any poisonous sprays on your property (sprays will kill the fly parasites, too).
I hang disposable fly traps by my dog kennel and it's made a big difference. Ditto with hanging them near corrals where our cattle and horses are.
Starting early in the season gives you best results, but you can make a difference now.
I use the disposable fly traps. The bait stinks, but attracts the flies. In lieu of commercial bait, a piece of meat in the bottom of the trap, works, too.
I just found some fly traps that are designed to fit the neck of a gallon milk jug. I think those should work well for us. I HATE emptying thousands of putrid flies out of a reusable trap!
If you know the owner of the cows, you might talk to him or her about setting up a fly rub. Fly rubs have pesticide in them, usually mixed with diesel fuel, and when the flies scratch on them, the insecticide rubs off on their hair, which repels and helps kill flies - and makes the cows more comfortable.
> I have a herd of 20 beef cattle in
> a pasture that adjoins my yard. I
> live in southeastern NC. The flies
> are unbearable around my house.
> Any advice?