Idiopathic Brood Disease Syndrome
There is a brood disease going around. Some beekeepers have called it the Crud for lack of a long Latin description. This disease I have seen in over wintered colonies. It looks like a little like AFB, a little like Europeon foulbrood, and a little like Chalkbrood. But really not bearing all the symptoms.
I had two beekeepers stop by last week that had foulbrood but this is different. No shrunken perforated cappings, no roping when punctured with a toothpick and no scale on the comb.
I have heard of several beekeepers having this. My buddy running 200 colonies had it. The beekeepers dusted with Terramicin and it quickly went away.
Looking at the pictures it is plain to see, if your larvae is not pearly glistening (wet looking) white, something is wrong.