Over the summer, I've noticed a few flies here and there - especially since I have a new, young flock that are still too little to free range in our yard with the 2yr olds, so the flies hang round the run area. So, I ordered some fly predators that finally (took longer than I'd hoped to get them) arrived 2 days ago, and I spread them around the perimeter of the run area and hung the rest in the bag in the coop. The flies in the coop, where I use pine bedding, DE and barn lime, aren't bad at all, I'm glad to say. This morning I sat out there and thought, wow, have those predators been doing their job already? The flies were scarce. However, I just went out to check on the girls 6:30PM on the 4th day of this super heat wave - in the upper 90's and more all week... I HAVE NEVER SEEN SO MANY FLIES at once EVER! This is my 3rd summer raising chickens. There were so many, I could hear them humming in choral unison! There were hundreds hiding in the flowers that hang on the corners of the run! I am especially stressed because my chickens are known illegals now, and I have been trying to keep the area as pristine as possible (for a chicken area anyway) while the city council decides the fate of my girls and my life-giving pastime. City council members and interested folks have been stopping by to visit and check it out, but I can't have people over when the flies are so bad! I keep the run clean with sand and DE on a daily basis. I pick up any leftover food/feed as soon as they lose interest. What else can I do???