I went through all of my hives yesterday and pretty much found what I expected, except for one.

This colony (Italian) was a split created last July. It was built up pretty well to make it through winter, and while it was a relatively small cluster, it seemed to make it through okay. As the bees started flying in late Feb & Mar, I noticed some signs of dysentery on the boxes. I had already started Fumagilin-B on that hive and they seemed to being okay. I left well enough alone until yesterday when I did a complete inspection. Coming out of winter, they were a medium over a deep. When I went through the medium, I was pleased to see capped and open brood about the size of your hand on both sides of two frames (did not see queen). I set that box aside and went into the deep where I found about four frames almost full of brood. Only one problem, nary a bee on the brood and several dead bees that looked like they died midway through emerging. I then noticed about 500 or so dead bees on the SBB, not an outrageous amount, but something to think about and an abundance of shell cappings detritus on the SBB. I'm at a bit of a loss as to what happened, but I do have two theories.

1. The dysentery/nosema really took its toll and the population plummeted so quickly that there were not enough bees to keep the brood warm in those cold nights and thes mall cluster went above them - thus the death.
2. There was robbing from one of my other hives that decimated the population with the same result.

Where do I go from here? Well, I've been noodling on that and the queen seems to be doing her thing with the workers she has, so I'll check it closely this weekend and if I note an improvement, I'll give them another week or two, if not I'll combine with another that's doing a bit better.