Chilled brood and chalkbrood in honey bees are often confused. Although often classified as a honey bee disease, it is not strictly a bee disease, but chalk brood is caused by a virus. This is caused when bee hives are opened when the weather is too cool, or by condensation forming inside the hive and dripping on the brood.
Chilled brood can also occur when the brood ‘nest’ becomes too large for the available house bees to keep warm enough. Care should be taken not to open hives when the weather is too cool. Do not leave frames exposed any more than absolutely necessary. Replace frames of brood in the same order they were removed to maintain the structure of the brood nest.
Brood killed in this manner turns gray and may resemble another one of the few bee diseases which occur in bee hives, sacbrood.
As with many honey bee diseases there is no real treatment, prevention is the best cure. Effected brood will be removed by bees from the cells as soon as the colony grows stronger and returns to normal.