A quick check under the Varroa screen of Colony 17 showed that the bees are building comb. There were shiny wax platelets in a shower where under where they've clustered. There is also evidence that they're cleaning out other parts of the hive. I found 2 dead wax moth larvae and some other detritus.
It's still too soon to see whether they do have a Queen in there. I tried the 'knock test' -- to see whether they remain agitated after a knock on the side of the hive -- but it was inconclusive.