Did some maintenance on OBH tonight. Bees had built almost all comb in top 2 frames of 10 frame Bonterra hive, Cold weather seemed to encourage them to build comb at top where feeder was. Noticed queen cells in top of hive even though 6 empty frames at bottom. I think bees sensed hive as being crowded with all action at top of hive. Moved brood frames to bottom of hive with empty frames above. All went well, saw queen safely move between two bottom frames before closing hive up. After letting hive calm down several hours almost all bees in bottom two frames where brood is and not at the top where they had been for past 4 weeks. Hopefully this gets them building more brood comb and working their way up filling frames. Any comments or similar experience would be great to hear. Didn't really want to disturb hive but when I saw queen cells it seemed like the thing to do...