Do My Honey Bees Have Nosema?

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Do My Honey Bees Have Nosema?

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Barbara from Massachusetts asked:

Inspecting one of my hives I found what I believe is Nosema. Is there any treatment now as too cold for liquid? This has been a weaker hive going in to winter but was hoping they would survive.

Rusty Burlew answers:

Honey bee dysentery is often confused with Nosema disease, so when beekeepers see feces on or near a hive, they automatically think the worst. But several recent papers have reiterated that dysentery is caused by an excess of moisture in honey bee feces. It may occur simultaneously with Nosema or not, but the two conditions are not related.

Dysentery is caused by excess moisture in the bee feces, and it becomes a problem when the bees are confined in the hive due to cold weather. If they can get out for a cleansing flight, they can get rid of the watery feces and return to normal. If not, they may end up defecating in the hive, a situation that leads to unsanitary conditions that can spread disease from bee to bee.

Excess moisture in the diet of confined bees may result from foods such as dilute syrups or uncured honey. Although bees need water to digest honey and syrup, too much becomes a problem in the wintertime because of the time span between cleansing flights.

The only way to know if your bees have Nosema is to have them tested by a lab. Oftentimes you can have it done by your local agricultural extension service or at a university. If you belong to a bee club, it may have someone who can test a sample for you. Most master beekeepers, for example, are trained to do it and have a microscope for the purpose. The test requires about 20 older bees which can be found in a place away from the brood nest, like on the lid or top bars. If you find someone to test it, ask them what they prefer as a sample.

That said, there is no currently available treatment for Nosema disease. Most colonies recover on their own, although some do not. Good management practices, including rotating old combs out of the hive, seem to be the best prevention. Still, a test can be good for your peace of mind and will help you understand what condition you are dealing with.


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