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Currently (as of 6/25/2018) Funidil/fumigillan is no longer availble on the market so this may be esoteric at this point. Combine that with the latest research that Nosema cerana has displaced Nosema apis and that Fumidil makes Nosema cerana worse, the only people treating with fumidil at this point have a stockpile of it.


There is much info on Nosema as far as the details. I recommend MAAREC or other sites for details of what the symptoms are, what it looks like under a microscope etc. I will not repeat all of that here as that information is commonly available.

Philosophy of Beekeeping

The first issue you need to decide, is what your philosophy of life is as well as your philosophy of beekeeping.

A lot of decisions on equipment or methods or treatments, depend on your personal philosophy of life and your personal philosophy of beekeeping. Some people have more faith in Nature or the Creator to work things out. Some are more interested in keeping their bees healthy with chemicals and treatments. You'll have to decide where you stand on these kinds of things.


If you're the type to take an herbal remedy before you run to the doctor, you probably fall into this category. True organic would be no treatments whatsoever. Some will say this can't be done, but there are many people including me doing it. Many are online and help each other through it. After that there are "soft" treatments like essential oils and FGMO, and then slightly "harder" treatments like Formic Acid and Oxalic acid for Varroa.


If you're the type who runs to the doctor for antibiotics the second you get a sniffle this is probably more your style. Some in this group treat for prevention. IMO the wiser ones treat only when necessary. Most of the recent research shows that treating for prevention has caused resistance to the chemicals on the part of the pests and has done little to help the hive and often hurt them. Chemical buildup in the wax from Cumaphos (Check Mite) and Fluvalinate (Apistan) used for Varroa mites, is suspected to be the cause of high supersedure rates, and known to be the cause of infertility in drones and queens. Fortunately as far as Nosema, it has not built up resistance to Fumidil.

Science vs Art

If you see beekeeping as an art or you see it as a science it will change your perspective a lot. I think it's a bit of both, but since bees are quite capable of surviving on their own and since we really can't coerce them into doing anything, I see it as more of an art where you work with the bees natural tendencies to help them and yourself. Some won't believe anything until it's been proven in a scientific study. Some will go with their own observations.


This is another thing that changes your philosophy on many things. When you have time to spend with the hives and the hives are in your backyard, then methods that require you to do something every week are not a big problem. For instance, when I requeen in my own yard, I don't mind if it takes three trips to the hive to get it done if that improves acceptance. But if it's at an outyard 60 miles away, I want to do something one time and be done. The same is true of the number of hives. If you have only two hives to deal with on a certain issue, you may not mind how complicated it is. When you have hundreds of hives to deal with, you have to have a streamlined system.

Reasons for beekeeping

A lot of your decisions will be guided by this. If you have bees as pets you have a different agenda than if you have them solely to make a living. Some are somewhere in between.

Assuming you have decided where you fit in the realm of beekeeping philosophy we can proceed to some branches in your decision on what to do about Nosema. If you are of the Chemical/Scientific philosophy you should see instructions on how to use Fumidil or Fumagillin. Advice on this is available on the bottle as well as most beekeeping web sites such as MAARC etc. At this point you've made up your mind and should skip the rest of what I have to say as it will be addressed to those of a different mindset and will only offend your view of the world.

If you are still reading I assume you have at least a small interest in the organic side of beekeeping or at least trying to avoid the use of chemicals and antibiotics in your hives. That or you just want to find something to disagree with.


If you want to get a grasp of how necessary it is to give preventative treatments for Nosema, I will point out a few things that may help clarify this for you. First, realize that many beekeepers have never treated for it, including me and I've been doing this since 1974. Not only are there many beekeepers who don't want to put antibiotics in their hives, but in fact many beekeepers in the world are prohibited from using Fumidil by law. I am certainly not the only person who thinks it's a bad idea to put Fumidil in your hive. The European Union, Australia and New Zealand have banned it's use in beekeeping. So we know they aren't using it legally anyway.

So why would you want to avoid Fumidil?

Just how dangerous is Fumidil to your hive? It's hard to say exactly, but of all the chemicals people put in hives, it's probably one of the least dangerous. It does break down quickly. It doesn't appear to have a lot of downsides on the surface anyway. But if you're of the Organic kind of philosophy you're still thinking, why do I want to add antibiotics to my hive? I certainly don't want it in my honey and, in my view, anything that goes in the hive can end up in the honey. Bees move things all the time. Every book I've seen on comb honey talks about the bees moving honey from the brood chamber up to the comb honey supers during a cut-down split. Having an area of the hive that is the only part there when chemicals are applied is a nice idea, but it's a lot like a no-peeing section in a swimming pool.

The issue of danger is how dangerous is Fumidil to people. This is the reason it is illegal in most of the world. It is dangerous to people. It is known to cause birth defects and that is why, although it was developed for people, it was instead relegated to being used in bees.

Microbial Balance

What do antibiotics do to the natural balance of a natural system? Experience with antibiotics would say that they upset the natural flora of any system. They kill off a lot of things that perhaps should be there along with what shouldn't leaving a vacuum to be filled by whatever can flourish. Probiotics have become a big thing in people and horses and other animals now, mostly because we use antibiotics all the time and upset the normal flora of our digestive system. Are there beneficial microorganisms living in bees and beehives? Are they affected by Fumidil? Yes, it's unscientific of me to assume there are without some study to support it, but my experience says all natural systems are very complex all the way down to the microscopic level. I don't want to risk upsetting that balance. We know that yeasts and fungi are necessary to the fermentation of the pollen to make bee bread and without them pollen is not digestible to bees. We know that Fumidil kills fungi and yeasts.

Here is some research that shows that Fumidil disrupts the bacteria that protect the gut of the bee from Nosema

Propping up weak bees

Yes, those with the Scientific philosophy will find that statement offensive. But I know of no better way to say it. Creating a system of keeping bees that is held together by antibiotics and pesticides that perpetuate bees that cannot live without constant intervention, is, in my organic view of beekeeping, counterproductive. We just continue to breed bees who can't live without us. Perhaps some people get some satisfaction of being needed by their bees. I don't know. But I would prefer to have bees who can and do take care of themselves.

Encouraging Nosema?

What other non-organic practices may contribute to Nosema?

While the non-organic group tends to want to believe that feeding sugar instead of leaving honey will prevent Nosema, I have seen no evidence of this. Honey may have more solids and may cause more dysentery, but while dysentery is a symptom of Nosema, it is neither the cause nor is it evidence of Nosema. In other words, just because they have dysentery does not mean they have Nosema. The study referenced above shows that sugar syrup disrupts the bacteria that make up the film that protects the gut of the bee from Nosema.

Many of the Honey Bee's enemies, including Nosema, Chalkbrood, EFB, and Varroa all thrive and reproduce better at the pH of sugar syrup and don't reproduce well at the pH of honey. This, however, seems to be universally ignored in the beekeeping world. The prevailing theory on how Oxalic acid trickling works is that the bee's hemolymph becomes too acidic for the Varroa and they die, while the bees do not. So how is it helpful to feed the bees something (sugar syrup) that has a pH in the range that most of their enemies, including Nosema, thrive, rather than leave them honey that is in the pH range where most of their enemies fail?

Bottom Line

The bottom line is this. You have to make up your mind what your risks are. What you are willing to put in your hives and therefore into your honey. How you want to keep bees. How much you trust a natural system or how much you want to strive for "better living through chemistry"

Nosema ceranae

There's a new kid in town and it looks like from the research it has kicked Nosema apis' butt. Nosema apis is difficult to even find now since ceranae took over. And the worst news for the "treaters" is that Fumidil actuall makes ceranae worse.


So maybe all this talk of fumidil is now a moot point since ceranae took over and fumidil only helps ceranae?

Michael Bush

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Copyright 2008 by Michael Bush

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