OK, I have seen many posts about flies...and lots of them. I too have had a bad experience with them. So, I went to our local feed store...and the reccomended " Dairy Bomb-Z 55" Its made by Durvet. For use on Cattle,Horses,Swine,Sheep,Goats,and in homes, Restaurants,Food Handling plants, Dairies, Milk Houses, Cattle, Horse and Poultry, and Swine quarters. Active ingredients Pyrethrins....0.5% Piperonyl Butoxide, Technical.....5.0% Other ingredients..........94.5% Equivalent to 4.00% (Butylcarbity) (6-propylpiperonyl) ether and 1.0% of related compounds. You can spray htis directly ON the birds for lice...and in the nest boxes, roosts, and walls of the coop...to controll flies, gnats, lice, mites. Just wanted to share my new find. IT WORKS GREAT!!!