We have been advised that now is the perfect weather for the fungal disease, CHALKBROOD, to take off in European honey bee, Apis mellifera, hives.  It has been hot and now it is cooler and wet.

Chalkbrood is caused by a fungus, Ascosphaera Apis, and it affects sealed and unsealed brood in a hive.

Chalkbrood is a fast-acting fungal disease which kills brood when larvae eat food infected by chalkbrood spores.

This fungus grows through the infected bodies of larvae by sending fine thread-like growths into the larvae bodies and killing the larvae.

Chalkbrood will weaken a hive, leading to a reduction in honey production and increase susceptibility to other pests and diseases.

Please be aware that Chalkbrood spores can be present in a hive and have no effect on a hive.

Colonies that are weakened by other circumstances such as extreme heat may become susceptible to this fungus.

Chalkbrood is not a disease of Australian native bees.

Information on how to identify and manage Chalkbrood is available from

Chalkbrood disease (bee) – dpi.nsw.gov.au


Chalkbrood is a fungal disease of honey bee brood that infects the gut of the larvae. It is caused by a spore-forming fungus Ascosphaera apis that is consumed along with larval food. Although it can affect workers, drones, or queens it most often occurs in workers and drones. It does not infect humans and has no effect on the quality of the honey or other apiary products. Diagnosis and tests …


Chalkbrood | Department of Agriculture and Fisheries …


Chalkbrood is caused by the fungus Ascosphaera apis and it affects both sealed and unsealed brood. Appearance of infection . At first, larvae are covered with a fluffy white fungal (mycelial) growth that looks like white mould on bread or very fine cotton wool. Larvae become swollen inside the cell. Later, the dead larvae dry out to become hard, white or grey/black chalk-like mummies …


Chalkbrood disease « Bee Aware


A beekeeper will be able to diagnose an infected hive based on the presence of the hard, shrunken chalk-like mummies in the brood and in and around the entrance to the hive. The mummies will be white to grey-black in colour. Infected hives also show a scattered brood pattern or appearance. The cell caps of dead larvae may contain small holes, appear slightly flattened or have been chewed away …