This thread is a year old. I'd suggest that you take the plunge, next time, and start a new thread. It will generate a lot of response, I'm guessing. I wouldn't treat your run for mites that you have not seen. IMO, if it ain't broke, don't spend money trying to fix it. NOt to mention the damage the insecticide will do to the soil life. As far as putting your chicks in the coop, the recommendation is that when they are fully feathered, they no longer need heat. But, even so, they will need to be hardened off, just like you would need to harden plants off. Are you using a heat light, or a heating pad to brood them? Check out Blooie's thread regarding heating pad brooding. If you have means to give them a little heat in the coop, they should actually do better in the coop than they will staying in a brooder in the house. You could also make them a huddle box for the coop: simply a box with a decent sized opening for them to get in, put lots of nice bedding in it so they can cuddle there and stay warm. The sooner you get these 2 groups together, the better they'll get along. Expect some initial squabbling. But if you do it when you put both groups into the coop, the new territory should make the introduction go well. You'll just have to supervise initially. I like to give treats when introducing groups of birds. Enjoy. Do you have adult birds? If so, my response needs modification! In that case, you can still move them out, but put a fence between adults and babies. Check out Azygous "panic room" with integration portals.