I live in town.There is a 5 acre piece of land next to me that was setting idle,so a farmer put cows on it.I use to see maybe 1 or 2 horse flies per summer,but now they are thick.We had about 7 or 8 of them after us last evening.They came as the cows approached and most of them left with the cows too.If they are from the cows,can the farmer do something to keep them down? I have no experience of any kind with cows.weg