What Causes Flies on Cattle?

This is quite sensible. And is what I've seen with our cows. Two cows eating the same grass will or won't have flies on them in the same amount. Age is one consideration, as in some books, this is a nutrition problem. As a cow gets older, they are needing more nutrients which aren't necessarily available to them to the degree they need. On our farm, especially this year, I've found that the fly problem was kept down better when I was moving the herd every couple of days. This kept hatching flies in different paddocks than the cows. I'm in no favor of non-natural pesticides, as the pests simply build a resistance. On top of that, the back rubs have to be re-positioned regularly and re-charged (re-dosed) every month - too small a dose of chemical means the flies just get something to build up their resistance.

https://plus.google.com/110346021190626938227/posts/2S3q7BXcSyV