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Nosema apis and ceranae

Educate Yourself, then Test Your Bees

To Determine if You Should Treat Your Colony


Please keep in mind our objective: to help you determine if you should treat your colony for Nosema with Fumagellin-B.  Fumagellin-B is an effective treatment, but it is quite expensive and has a limited shelf life. And like some other antibiotics, it’s tough on a digestive system so treating a colony that isn’t infected is not in the best interest interest of you OR your bees.  These instructions will NOT prepare you to publish a scientifically accurate paper. 


Let’s get started on a reliable method to test your bees for two serious threats: Nosema apis and the more recent addition, Nosema ceranae.  As with almost all beekeeping topics, there are different approaches and theories and the recommended approach tends to change over time.  Before you prepare to test your bees for Nosema, you really need to study the characteristics of the fungal parasite.  Please study the article at    and other reliable sources for scientific reports of the organisms.


When you have the basics under your belt, we suggest that you read Randy Oliver’s first recommendation for testing for Nosema from Part #13:

That article has a number of helpful photos and testing suggestions, links to additional resources, and updates to the original article that Randy included as his scientific observations suggested modifications to his testing methods.


Randy Oliver’s Part #16 from his Scientific Beekeeping web site suggests examining a smaller number of individual bees to sample the percentage of individuals infected with Nosema instead of the previous method of examining a sample of infection from a combined slurry of 15-50 bees.


Our club has a high quality microscope to observe the samples if you don’t wish to purchase a microscope for your own use.  Using the club microscope  your own, the experienced members of our club recommend this method:

  1. Collect a sample of 20-25 bees from near the top of your hive if possible. Seal them in a sturdy ziplock plastic bag.  Collect nurse/worker bees and perhaps a drone.  Why is it ­NOT a good idea to sample the queen for Nosema???

  2. Put your bees in the freezer to humanely kill them.

  3. When you’re ready to test, dump your bees on a white plastic tray or non-absorbant paper plate.  Carefully count 15 bees and put them back into the plastic bag.  The remainder of your bees MAY be examined individually.

  4. Remove as much air as possible from the bag before you seal it tightly.  

  5. Using a round glass jar that is shorter than the length of the bag, mash the 15 bees inside the plastic bag.  (Avoid the edges of the bag and you’ll be less likely to split the seams of the bag.)  Keep rolling until you don’t hear any more crunching of bee parts.  

  6. Filter the bee “juice” through cheeze cloth or a course filter to remove as many bee body parts as possible.

  7. Add 1ml of water for each bee.

  8. Stir the mixture well and then quickly place a drop approx. 3/16” in diameter on a microscope slide.  (if you put too much slurry on the slide, you will make a mess of the table of the microscope.  If your drop is too big, touch it with the corner of a piece of paper towel to absorb some excess.) Place a cover slip on top of the drops and tap it lightly with your finger. If you see liquid on the outside of the cover slip, dab it with a paper towel.  Clean is good.

  9. Examine the sample with a 400 power compound microscope.   Be careful with this step because you must be careful not to damage the precision lenses on the microscope!  If you’re unfamiliar with the microscope, ask for help.

  10. On the club microscope, the two dials near the back of the scope focus the device by raising and lowering the stage.  The knob closer to you is the coarse focus - the knob furthest from you is the fine focus.  Turning the top of the knob away from you will raise the stage.

  11. The two small knobs on the right hand side of the stage move the slide forward/back, right/left. 


  13. Twist the dial with lenses so the shortest lens is above the hole in the stage and the dial clicks into place.


  15. Count the oval-shaped spores in your field of view.  Divide by 10 and multiply by 2.86 million.  This is the approximate number of spores/bee.

  16. The recommended threshold for treatment is 5 million spores/bee.

  17. If you suspect you have a Nosema problem, you may want to check individual bees using Randy’s method from Part#16.


Please let us know what you find with your bees!

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