Hi Michael and All: >I've requeened lots of chalky colonies. >Sometimes it works, but not very often. That is my experience as well. I think that if you wait until the situation is quite severe that the break in brood rearing is not matched by the worker population which is also decreasing. I think it may be better just to unite the colony with a better one. I have also begun to think that broodcombs with a lot of chalkbrood (especially with the black spore laden mummies) are best destroyed or taken back to the rib and disinfected if they are plastic. This year I went from 200 to 400 colonies. I had the least chalkbrood I have had in years due to a combination of putting honey combs in new brood supers and one of the warmest springs I can recall. The combination of rapid spring buildup and cold nights seems to trigger it. But I agree that breeding hygienic bees is the answer. Regards, Stan