So i'm new to beekeeping, 1st year went ok till winter hit. I'm in upstae NY. Loss 3 hive from possible mites or cold or both( lesson learned, i'm fully educated on mite treatment now) . This spring i'm starting with 2 new nucs and 2 splits from a friend, everything is going good. I have built a long hive that will hold 30 frames. Due to my feeding of sugar syrup last year i'm not sure what leftover frames have nectar honey and what frames have funny honey, so i'm using my long hive as a robbing station to empty these frames. After about a week I checked on the long hive to see the progress, There were massive amounts of bees inside, buzzing louder than my nucs. I also noticed some of the frames had been bridged with wax. I viewed few frames and they don't look like a typical robbed frame, but it looks like an active hives frame. I'm boggled by this. I did look deeper thinking I had a swarm move in but I see no signs of eggs or larvae. I put everything back together and closed up the hive. What do you guys think? My other hives are not smaller so no swarming there.