Anyone on these boards use wormer as their main fly control? We don't usually worm our mature cows, but last summer, we had a few that looked to need worming. I treated about 20% of the cows with generic ivermectin pour on and within 2 days, the flies were gone and stayed gone for about 6 weeks. Since then, when the flies get heavy, we treat a few of the sorrier looking cows and it seems to be working well. For those of you who like to worm your cows yearly, you could treat 25-30% of the herd at a time and control flies through the summer without any extra costs strictly for fly control. Anyone see any problem with this?