Parasites, Diseases, and Viruses, Oh My! Now What?

Tracheal Mites live in the bee’s respiratory system and have become less of a problem with the use formic acid and thymol based treatments for control of Varroa Destructor Mite. These treatments are also effective in treating the tracheal mite, mostly eliminating them. Symptoms include: bees appearing to be disoriented, unable to fly and disjointed wings. Bees are unable to get out to forage, leading to a large number of bees found throughout the day at the hive.

Nosema weakens the immune system of the honeybee leading to increased colony death. It is a problem in winter because bees are not getting out of the hive often to defecate, increasing the risk of spread within the colony. You may see LOTS of bee poop all over your boxes. Don’t confuse normal cleaning flights with Nosema. To prevent Nosema keep your colony strong and healthy, replace old comb and make sure there is good drainage and ventilation in your bee yard. Find more information here.


American Foul Brood (AFB): AFB is extremely contagious. Spores contaminate a hives by drift, robbing, tainted equipment/ tools. They infect and destroy larvae and once the cells are capped larvae turn brown. You will note a rancid smell, spotty brood pattern and sunken perforated cappings; inside the cell you would find melted looking brown remains of the larvae. You can check for suspected AFB by sticking a toothpick into a cell and stir the larva and pull the toothpick out. If it has a ropey appearance, more than 2 cm there is a good chance it is AFB. Because of the infectious nature it is recommended that all equipment be burned or wooden ware be scorched to disinfect before using again. AFB must be reported to the state inspector. More in depth information can be found here.


Sacbrood Virus (SBV) can be seen and easier to identify. Capped brood will have pin sized holes in it. Pupae have underdeveloped heads. The infected larvae will die and become dark and brittle. It will be easy to remove from the cells. SBV is transmitted via contaminated food, feces or during mating. You can try removing infected larvae and re-queening but as of today there are no known treatments to get rid of SBV directly.

Deformed Wing Virus (DWV) can be seen as well and looks as the name describes. Adult bees infected with the virus show no visual signs. It is the most common virus found in a colony and is transmitted by the varroa mite. The bees are unable to perform hive duties or forage and the bees do not survive long. It is transmitted by contaminated food, feces or during mating. The queen can pass the virus to her offspring. Prevention and treatment is mite management.

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