Interestingly, I have a colony that is in a poor place. I can't find the records for the colony and the marking on the queen has worn off....so shes got to be at least 3 years old. Last year produced a good surplus and fed well and strong into the autumn.
Very small colony now vs the others adjacent which are rapidly expanding even with the variable weather conditions and.
But no sign of disease, no chalk brood, no spotting in the small brood pattern. No K wings and mite drop non existent.
I'll look into this Nosema thing a bit more...but the existential question is do I leave them to it, unite, add brood from another hive, feed (they have bee candy on them from February) while the other hives go from strength to strength.