A minor disease caused by a fungus, chalkbrood is mostly associated with stress. There still isn’t much information on what to do about chalkbrood, Paradoxically, reports indicate hive populations remained high, even though some bottom boards were covered with chalk-like dead carcasses (mummies). Actually, this may be a good sign; it shows the bees were cleaning out the fungus infection as it developed.
Good hygenic behavior is considered desirable in bee stocks, to keep disease to a minimum. Although it remains an enigma, some generalizations are in order concerning chalkbrood.
1. It occurs mostly in colonies expanding during the summer (spring in Florida).
2. It rarely kills a colony, but will weaken it, leading to a reduction in honey surplus.
3. It is promoted by certain conditions, dampness, susceptibility of bee stock, inadequate nutrition, other diseases or conditions (queenlessness, laying workers, chilled brood).
4. It is spread mainly by beekeepers.
5. It appears that requeening with resistant bee stock is the most likely way to permanently clear up the symptoms.
See some examples of chalkbrood infestation via youtube.com.