I heard a remark put down to an old cowman. "Why would you worry about heeol flies? Keeps the cows bunched up so the bulls can find the ones in heat!"
I have quite a little buckbrush in my southern pastures and this was always traditionally summer pastures. I was going to have it sprayed as it seemed like I would have more grass for cattle to eat. Never could get a sprayer to come and do it, tho'. One day I rode down to check on the cattle and they were all yearling steers. The heel flies were out and really aq pain. When I found the steers almost everyone was lying down in the buckbrush, rolled up on top of their feet. Their tails were busy, but they seemed pretty comfortable. Since then, the buckbrush don't bother me at all.
I've been told and noticed for myself that horned longhorn cattle, will graze into and a lot closer around brush then other cattle. I know that they browse more. Must be why I like them!
I think I posted this before, but if you move your cattle at least a half a mile to fresh or different pastures. every 4 to 6 days, you can get ahead of anf beat most of the fly problems.
I read a book sometime back, by a man who was of a tribe up in Montana. He grew up on the families ranch that was run by his grandmother. The tribe is one where the women traditionally have the power in the family and are considered the landowner. He told of his grandmother telling him that before they came and fenced all of the country, the great spirit put all the flies and bugs along the creeks to drive the animals up inot the higher hills to spend the summer months. Then in the fall when the flies and bugs died, the animals would drift back to protection and there would be lots of feed for them to winter on. Made sense to me and I found it interesting.