Gerald, I know you've had a bunch of responses but I thought I might chime in here as well. I have seen what you described , "bees on the underside of sbb". I have seen this on newly established hives that, in my opinion, which parallels what Michael Bush said, are bees that are confused, and just didn't make it back into the hive. They of course want to be in the hive but didn't quite make it in because of them not quite understanding that the sbb is indeed a barrier. The squares allow lots of ventillation and odors to permeate through. In their need to get inside, they frantically wound up where they thought they might get in. Now, also, the reducer could have had something to do with this. Hope you removed it by now. Also, is this a package install? Sory if I didn't see this referred to or not earlier. If so, was wondering why you were treating for mites already? I would allow them to get situated, stress free, before doing any treatments, unless they were overrun with mites when you got them.