When checking out the hive, I noticed some strange looking little things on the bottom board near the entrance. They are pictured on the right.
You can tell just by looking at these little pods that they are not a healthy part of a bee colony, but were they pests or intruders dispatched by the bees? Or were they dead bees from an early part of the life cycle?
Curse of the Mummy!
Well, it didn't take me long to discover that these are the mummified remains of bee larvae, showing the signs of a fungal infection called chalkbrood (owing to their chalky appearance).
The fungus is called Ascosphaera apis. Apparently it is ubiquitous, but normally only becomes a problem for bees when the colony is stressed, and when weather conditions are cool and damp. Both of these conditions existed for our colony: we'd just introduced the nuc to the hive a week ago, after transporting the nuc from the suburbs into town during a long, traffic-congested ride. Then the weather became unfavorable, and with the relatively small size of the colony, it seems likely the workers struggled to keep the brood warm enough.
Chalkbrood strikes only the larvae, gradually consuming them until they are totally encased in white filaments called hyphae which give them their chalky appearance. They are not yet contagious at this stage, but the black ones are actively releasing spores.
In the picture on the right, you can see a combination of healthy sealed cells where bee larvae are pupating (metamorphosing from larva to adult), open cells with eggs (the "black" looking cells with a tiny white dot or "segment" in the bottom), and larvae in open cells with chalky or black appearance.
Chalkbrood are found in open cells because the disease strikes during the larva stage, and cells aren't capped until the larva is ready to pupate. Workers eject the chalkbrood from the comb, dropping them on the bottom board, where they are gradually pushed toward the front and out of the hive.
These mummies began appearing on Friday, 6 days after we installed the bees in the hive. Bees are eggs for the first three days, and larva from days 4-9. So it's up in the air as to whether the infected larvae are ones that were already larva when the colony arrived, or larva from eggs that were laid and hatched after we installed the colony. If the problem persists beyond this weekend, I think it will be safe to say chalkbrood is infecting larvae that started as eggs laid after we installed the colony.
Inspecting the Hive
We opened the hive yesterday afternoon to inspect it, and after some effort we found Queen Hazel. She seemed active and healthy. Unfortunately we also found plenty of chalkbrood yet to be ejected. But there were also capped cells, honey, and some larvae cells without chalkbrood. We didn't spot any eggs, but frankly, we're not used to doing this work yet, and we may simply have missed them.
There is no known chemical treatment for chalkbrood, so treatment options are cultural: removing the stress, better weather, making sure the bees' nutritional needs are being met, and requeening if necessary.
I think we've mostly met these conditions (other than requeening, which isn't something we want to do right now). We're feeding both sugar syrup and a pollen substitute/supplement. The weather is vastly improved. These should reduce stress on the colony. We are guardedly optimistic that this chalkbrood problem will clear up on its own soon.
