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Chalkbrood - What is it and how can I manage it?

Chalkbrood is a fungal disease that attacks the brood of a colony and can cause harmful damage if not managed by the beekeeper. Over time chalkbrood can kill a significant amount of brood (mummifying sealed larvae), weakening the colony making them much more susceptible to other disease and pests.

I’d like to ask the forum how others manage this disease in their apiary or hive. For example, what are some key steps to cover as a means of prevention and are there any quick solutions for management?

I think its best to view chalkbrood as a symptom as much as a disease in itself.
All hives have chalkbrood spores. Disease is evident when something else is wrong in the hive either stress (weaher, feed, queen issues) or some other underlying condition. Identify this, fix it and the chalkbrood will go away.


Such a great answer @JimM!

my own experience with chalkbrood mirrors what Jim said. It can be viewed as similar to wax moth or beetles as an issue. It seems it is always there dormant- waiting for the right conditions to take hold. I have observed here in Adelaide that it is a seasonal thing. Last year in spring and summer we had a bit of it in many hives. This year hardly any at all. The best defense against it is to build up strong hives.

I have been told that it is related to chilled brood, so the best way to stop it is to make sure that hives are kept full of bees. That means not putting supers on until the box below is packed with bees, not transferring nucs into bigger hives until they are strong and crowded, taking care with checkerboarding frames and only doing it during good weather and with very strong populations. It might mean moving a hive out of a shady and/or damp position.

A month ago I had a strong hive that had no chalk brood at all. I went into the brood box and found the outer two frames were all honey and pollen. I decided to remove them and also one frame of eggs to donate to a queenless nuc. I checerboarded the new foundation frames into the brood box. Two weeks later I observed some chalkbrood mummies being thrown out of the front of the hive. It seems I went too far breaking up the brood cluster and the brood got chilled allowing the chalk brood to get a hold. In spring I could have down the same without any issue- but things had slowed down and we have had a very cool summer. As that hive is still very strong I expect it will soon recover.

At times a weak brood box with chalk brood would be better off condensed down into a nucleus until it builds back up.

Some people place a banana cut in half length-ways on the top of the brood frames to stimulate cleansing behavior. Others believe it is a gas that the banana gives off that inhibits the chalk brood spores. I have tried it but can’t really say that it helped- it may have I am not sure.

others say that if a hive doesn’t recover over time re-queening may help- as the original queen may have lacked sufficient hygienic behavior.

The good news is that in the end chalk brood generally just disperses if the colony is kept strong.

I completely agree with @JimM’s response above. However, I have some things to add that even seasoned beekeepers don’t always remember. I am sure that @JeffH will be able to add even more comments. In no particular order:

  1. The most common cause of chalkbrood is chilled brood. With a new beekeeper, this may be from them inspecting in poor weather (cold, overcast, windy, wet) or taking too long over the inspection. My suggestion to prevent this is only inspect when the temperature is above about 62°F (17°C) and preferably higher. The number I give is a lot lower than most Australians, but in the UK, if we used the 22°C often suggested, you might only be able to inspect on about 4 weekends per year! It works fine in lower temperatures if it is not windy, wet and you are fairly quick
  2. Wet hives with condensation will chill the hive. Make sure it is dry and insulated in winter, otherwise coming into spring, you may face chalkbrood
  3. Keep your hives strong. If they begin to weaken, condense them down into a smaller space with dummy/follower boards or even moving them to a nucleus box. Bees prefer to be crowded than sparse
  4. If you have more than 10% chalkbrood on a frame, consider removing the frame, or cutting out the affected area if all mummies are close together. Mummies are very hard for workers to remove, and spread infection as they are discarded by the hive
  5. If your queen is older than 2 years, consider replacing her. Queens can be the source of a spreading infection in the absence of other factors

As far as quick solutions are concerned, I don’t think anything sensible is quick, but I am willing to listen to others. I would pursue all of the items above, and if the hive is weak, perhaps try to obtain a frame of capped brood and nurse bees from another stronger hive to boost the worker population.

Just my 2 cents… :blush:

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I agree with what you said Dawn.

On 2 occasions, the only thing that fixed the problem was a new queen. The previous queens were also new, however their progeny didn’t exhibit the behavior required to clean the chalk brood mummies out.

Something to add is doing brood inspections during cool windy weather. Wind can blow directly onto the larvae & chill it. With no wind the honeycomb itself acts as a kind of insulator over a short period of time.

PS. Sorry @Dawn_SD , you said “windy”

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