Thank you everyone. I'm very glad to hear that DE can help with this. The current coop is quite large (built in early 1900's for far more chickens than my 6), so I think I will first DE the floor then cover with another bale if straw. If that is one of the places the flies were coming from, then this should help. I really don't think I would be so bothered by this, except we are still in town and I don't want the neighbors hating the chickens (or us). We've kept chickens for about 10 years, and never noticed this when using the coop and run. The flies must have been a source of food for them, when there was less available to forage. Once we have moved out to our property, I am also planning on using the paddock system, but again the only place with electric (heated chicken watered used in winter) is way at the bottom of our hill, which is our road access and the only place we can see neighbors homes. So, again I don't want to be causing a fly issue for them. If I felt confident that there would be enough forage on the hill (rather thick forest of deciduous trees, many raspberries and roses), and that I would remember to change their water often during the winter (no electric for waterer), then I could paddock them near the house site (work in progress, as earthbag building takes longer than we expected, but looks like it will be liveable by fall). So, if I paddock them at the bottom of the hill near the main road and use an open-bottom mobile coop, perhaps this won't happen on the scale it is happening now. And of course, there are no sidewalks to poop on there. Thank you again.