We did (bee) hive inspections over the weekend and found weird stuff on the bottom boards of each of our hives. The (very) strange material didn’t look quite like either mouse or bird droppings – we were perplexed. We had put newspaper around the bottom of each of the hives to help with winter insulation – we thought, perhaps, the bees had chewed some of this up, processed it a bit, and then deposited it.
We consulted one of the local bee gurus who diagnosed the material as evidence of Chalkbrood, which results from infection by the fungus Ascosphaera apis. What you see in the photo are the mummified bodies of bee larvae that became infected and then consumed (in part) by the fungus – these were then cast off as a result of hygienic behavior by the hive.
Apparently, fungal infestation of this sort may occur as a response to stress, and I think I might have been the culprit! As I indicated earlier, we plugged air spaces at the bottom of each of our hives with newspaper. I think I might have removed this extra insulation a bit early. We hadn’t noticed anything amiss with the hives over winter. It wasn’t until several weeks ago that I began to notice what I thought were perhaps mouse droppings in front of each hive. Anyway, I think I may have cold-stressed the hives when I removed the insulation. Under these conditions the larvae would have become susceptible to infestation by the fungus. Some have indicated that Chalkbrood may occur when hive ventilation is inadequate.
In any event, all of last week’s hive inspections were otherwise fine – the queens were producing brood (larvae) and good stores of honey were already accumulating in several supers. We’re going to assume that this episode of Chalkbrood has been self-limiting and is now over. Let’s hope.