I've never had a fly problem either in the coop or run and I've never had an odor problem, either. The girls are fed fermented feed which seems to help that. I still don't have an odor problem but I have begun to notice flies in the run only. Nothing about my housekeeping has changed. I have pine shavings and straw on the floor of the coop and all is well in there. The run is dirt and I usually put in straw. They rake through it, it brings up bugs, and then I top it off with more straw when the first batch is beginning to disintegrate. The other day I put pine shavings in the run because that's what I had on hand. WHOA! That evening I've got flies all over the pine shavings! Funny thing is that the shavings were in one half of the run as the girls hadn't had time to scratch it over the entire run and the flies were only on the half of the run where the shavings were. Anyone else had that same problem? It's the same brand shavings I've always used. Guess I'm going back to straw.