Just when everything seemed fine it took a wrong turn. I started 2 packages last May. Both were fine going into winter. They both were in 2 deeps and a medium left on full of stores. I checked on them throughout the winter by eye and ear and they were fine. During these warmer days early in spring they were out flying around like normal. I made a quick inspection last week and looked in bottom 2 deeps w/o pulling frames and they had good amounts of bees in both hives. I finally had time I could do a deep frame by frame inspection today. When I opened up the one hive it looked ok until I got into the bottom deep. There were no capped brood, no larva, no eggs, no dead bees, nothing?? I am just baffled. Looks like they just up and left. The other hive was doing good with capped brood, larva, and eggs. I just observed bees bringing pollen into this empty hive within the past 2 weeks. Also had top entrances on these hives which has led to some robbing by the other hive it appeared. It looks like there are still bees left from this hive in there but was hard to tell with apparent robbing going on. Any ideas what happened??