I got some banana boxes out to sew some poultry netting over the top and bottom holes for chicken cages and the flies were thick in them. So I shook them off into another box and fed them to the chickens. They were only about an inch deep in the pile in the box and on the floor of the chicken house. The chickens would tend to stand on the pile and peck around the edge of the pile. I guess on the pile itself they couldn’t see the “fly” for the “flies”.
From Wild Critters