Honey Bees
Bacterial and Fungal Diseases
American Foulbrood (AFB)
- Suspect if you see dark brood cells with sunken, punctured caps. Positive "ropiness" test. May notice a foul odor or see dried scales (spores).
- Prevent with good hygiene. Once infected, kill all bees and burn equipment.
American Foulbrood is a highly contagious bacterial brood disease that only affects larvae. You may notice dark, sunken, punctured brood cells and an overall spotty brood pattern. In the later stages, the hive may develop a foul odor. Check for AFB with the ropiness test by inserting a toothpick or twig into the brown pupal mass and slowly withdrawing. If the brown, snotty mass ropes out of the cell at least ½ inch, this is considered a positive test.
Unfortunately once AFB is present, the bees should be killed and the hive equipment burned. Spores can remain dormant 70 years, easily infecting future hives if the equipment is reused. Prevent AFB by using new equipment rather than purchasing used. Clean equipment between hives and cull old comb.
Not related to European Foulbrood.
European Foulbrood (EFB)
- Suspect if you see off-white or brown larvae, which may appear twisted in their cells. They die before their cells are capped.
- Prevent with good hygiene. Can resolve on its own. To treat, can simulate nectar flow, requeen, or treat with antibiotics.
European foulbrood (EFB) is another, though less serious, bacterial brood disease. It’s considered a stress disease, particularly when nectar flows are sporadic. Larvae appear off-white or brown rather than white, and may appear twisted in their cells. Affected larvae die before their cells are capped.
Colonies can recover from EFB infections. Sometimes the issue may resolve on its own if the hive experiences a strong nectar flow. The hive can also be requeened or treated with an antibiotic like Terramycin. EFB doesn’t form spores, so equipment can be disinfected and reused.
Not related to American Foulbrood. May see signs of EFB and chalkbrood at the same time, since they are both stress-related.
Chalkbrood
- Suspect if you see little white mummy or chalk-like brood. May collect on the bottom board.
- Prevent with good hygiene. Can resolve on its own. Ensure there is proper hive ventilation.
Chalkbrood is a fungal brood infection that affects larvae and pupae. The affected brood starts to look like a little white mummy or a little piece of chalk. They later turn black. You may find them collecting on the bottom board as they fall.
Chalkbrood is usually stress-related and often resolves on its own. It’s more common during the spring and when there is high humidity within the hive, so proper ventilation can help. You may see signs of chalkbrood and EFB and at the same time.
Nosema
- Difficult to detect. You may see excess fecal matter within the hive or around the hive entrance.
- Keep healthy hives. Can use antibiotics when necessary.
- Keep antibiotics away from children and pets