As beekeepers there are a number of diseases and pests for us to worry about.  Some of these things are present in our hives all the time and simply raise their ugly heads when the bees are stressed in one way or another.  Nosema is one such disease.

Here’s the information discussed at a recent meeting of the Puget Sound Beekeepers.

The Basics

  • Caused by a spore forming protozoan and affects all adults.
  • Like many diseases it’s present in low levels in most every hive but not a problem unless hive is weak or otherwise stressed.  This could be from another disease, a week queen or a variety of other causes.
  • Strong colonies with plenty of honey, good venting and young, vigorous queens will likely be OK.
  • Ventilation is especially important to combat this disease.


  • If adult bees look like they aren’t doing well, with either crumpled wings, not flying or just look “sick” it may well be nosema.
  • May also see lots of dead bees in front of the hives if your hives are good about cleaning out dead bees.


  • There is no natural treatment on the market currently.
  • Fumidil B fed in sugar syrup is the most common way to treat this disease.
  • If feeding sugar syrup late you can cause moisture problems so make sure the hive is vented properly.
Again, nosema is a disease that usually isn’t a problem for a strong, healthy hive.  Be a good beekeeper, keep your hives strong and healthy and you likely won’t have to worry too much about this in your apiary.
Have you had problems with nosema?
Photo by Stephen Ausmus via the USDA

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