I’m really glad that on the study guide for the Texas Master Beekeeper Apprentice Level Study Guide that they put honey bee diseases as the first section. It’s really upsetting to study all of the various things that can wreak havoc with our precious hives, so I’m eager to plow through this and get on to studying more about these fascinating creatures.
Next on our hit parade of bee maladies is the dreaded Nosema. There are many different species of Nosema (different strains affect different insects), but only two that affect honeybees. Nosema Apis, and Nosema Cerana. The latter has only affected European honeybees only recently. Cerena is more damaging and kills bees faster than Apis.
Nosema is a disease of the gut. It’s the result of a microsporidian parasite that gets ingested by the bees and damages their digestive ability. It’s generally always around, but the hive can run into trouble during the times of year that conditions are ripe for Nosema to build up inside the hive and therefore more readily become ingested by the bee population.
Besides a generally sluggish colony just not doing well, signs you can keep an eye out for when thinking of Nosema include a number of things. Bees crawling around on the ground in front of the hive can suggest Nosema. The condition known as “K Wing” where the two sets of wings spread out and suggest the letter “K” on top of the bee is also something to watch for. Probably the biggest and most obvious tell tale sign for Nosema is fecal staining on the outside surface of your hive. It looks like brown or yellow drips. The bees get dysentery as they are infected with Nosema. Nosema seems to peak in late winter when the bees haven’t been able to take cleansing flights out of the hive and the spores just build up and build up.
The only way to absolutely diagnose Nosema conclusively is with a microscopic examination.
Here is a good video on the subject.