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Honey bee dysentery and water

Dysentery in honey bees is one of those unfortunate terms that results in nothing but confusion and misconception. It’s right up there with the word “organic” to describe food grown without manmade fertilizers and pesticides. If you apply the traditional meaning of organic—which, with a few exceptions, refers to chemical compounds containing carbon—then the large majority of chemicals used in conventional agriculture are definitely organic, including all those pesticides. No wonder people get confused.

In humans, dysentery refers to a condition caused by a pathogenic organism, but honey bee dysentery refers to a form of diarrhea caused by too many solids in their feed. To add to the confusion, honey bees also get diarrhea from pathogenic organisms such as Nosema, and it appears just like the other kind. If you feel confused, you are not alone.

Excess water is often blamed for honey bee dysentery, but the condition is actually caused by too much bulk in the honey bee intestine. You can compare it to a human eating too much fiber. During the winter, when honey bees cannot take cleansing flights due to the cold weather, the amount of solids stored in their intestines continues to increase. These solids come mostly from the honey they eat. Some honey has more solids than others and, typically, dark-colored honey has more solids than light-colored honey.

Since bees can only retain about 30 to 40 percent of their body weight in fecal matter, when the time between cleansing flights is too long, they will void inside the hive or just outside of it. This is what we call dysentery. Although solid material—not water—is the cause of dysentery, it confuses people no end.

For example, here is a statement from the Mid-Atlantic Apiculture Research and Extension Consortium (MAAREC) website: “Dysentery can also be caused by feeding bees anything with a high water content in the early spring.” This is a true statement. But to see why it is true, you have to look at how they qualify their words. They are not saying that water causes dysentery; they are saying too much water fed in the early spring may cause dysentery.

Why is this true? It is true because by early spring the honey bee’s gut is loaded with solids. It is probably approaching its limit of 30 to 40 percent of the bee’s body weight. So if the bee drinks a lot of water, the solids may absorb some of the water and push the bee over its 30 to 40 percent-by-weight capacity—sort of like the straw that broke the camel’s back.

Nevertheless, water all by itself does not cause dysentery. This may seem like a subtle point, but if the bee’s gut were empty in early spring (or any other time), the bee could drink quarts of water and not get dysentery.

One final note, although honey bee dysentery is not a disease, it can cause a hive to fail. Colony death may result from stress, diseases promoted by unsanitary conditions, or a breakdown in the internal communication system due to the overpowering odor inside the hive.




Very informative, thanks Rusty. Another common misconception seems to be that dysentery indicates nosema. From what I’ve read dysentery can lead to nosema spreading faster but bees can have dysentery but not nosema.



That’s exactly right; the presence of dysentery could mean nosema is present or not. You need laboratory analysis—or a good microscope—to tell the difference.

Karl Schroeder

Is it reasonable to feed Fumagillin-B as a prophylactic early in the spring and also before bedding down for winter?


It is reasonable if you think you have or may develop a problem with Nosema. As with any drug, overuse may cause resistant strains to develop.


I see the difference between the two. However, I didn’t see a remedy or real recommendation for a remedy.
Did I miss it? Or is this just to let beekeepers know that there is a difference between Nosema and Bee Dysentery?


The point of the post was to explain that excess solids in the diet, not excess water, causes honey bee dysentery. To prevent honey bee dysentery a beekeeper must not feed bees things with too many solids. The only remedy would be to stop them from eating the things that cause dysentery.


So if my bees were loaded with buckwheat honey for winter, that may have contributed to their having dysentery?



It certainly could be a factor. Buckwheat honey is known for having a high ash content.


I’m following up on the dysentery/nosema thread here. Since I lost a couple of hives to dysentery and buckwheat honey may have been a factor, but the possibility of nosema has not been ruled out. I’ll assume that I shouldn’t give the honey from these two colonies to any other bees I have now, or to new colonies created in the spring. I need to find out whether this honey is a nosema spore source. How do you suggest I do this?
And by the way, this is/you are a fantastic resource.



I had to do some reading and check with a couple sources to verify what I thought about this. But the consensus is that honey, although it may possibly contain some Nosema spp spores, is not considered a problem. The spores are everywhere. You can compare it to the common cold in humans. The virus is everywhere. Contracting the virus is more or less the result of a weakened immune system than the presence or absence of pathogen, since the pathogen is always present. Bees will be exposed to many more spores from infected bees which accidentally make their way into the hive, come in contact with other bees in the field, or leave spores on flowers where they are nectaring. Any spores in the honey will not germinate and reproduce–it is not the right environment for them. If it were me, I would go ahead and move the honey into the next colony without a worry. I don’t know how to test honey for Nosema, but you can send some of your dead bees to a lab for analysis. Check with your state extension service for details.


This is good news! When I originally started my search into what had happened w/my bees and had come up with the possibility of nosema, the reading I did led me to believe that I had to destroy the infected equipment. I had a stack of boxes filled with honey and beautiful brood comb waiting by the burn pile for a “burn day”. I am so glad to have waited this out.
Thanks very much.


Hey Rusty,

After careful consideration I think I see two common events that lead to the death of 8 of my colonies. Dysentry due to pollen substitute mixed in the candy boards and shrews.



Don’t you know you’re supposed to tame your shrews?

Seriously, don’t leave me hanging. Tell me about shrews. This is all new to me. What did they do?

About candy boards, I never add pollen substitute until after winter solstice when brood rearing begins. Did you add it earlier, or is the solstice too early for your area?? Really interested.


We think we lost a hive this winter to dysentery. Is it ok to harvest the lost hive’s honey? What signs do I look for if it is bad? I poked my finger in one of the comb and it seemed really watery. But it could have just been built up condensation. We seem to have a separate issue with that too.



Honey bee dysentery is not caused by a pathogen, it is caused by a diet high in solids. In any case, the honey is perfectly safe to eat. The bees don’t cap the honey until it is at the proper moisture level. If the combs were really hot when you poked your finger in, the honey may have seemed runny. Or perhaps you poked your finger in uncapped cells? That would be different. Bring the honey to room temperature and then try again. Also, maybe you can borrow a refractometer and measure the moisture level.


Hi, Rusty,

I lost a hive to dysentery this winter and would like to hear your thoughts on whether feeding the bees solid sugar over the winter could have contributed to their illness. When the winter is very long and very cold, the bees go through more fuel without the opportunity of a cleansing flight. Do you think adding sugar to the hive as extra food was a mistake?



If anything, plain sugar protects against dysentery because it is extremely low in ash. In fact, it’s lower than honey. Ash is the stuff that collects in the honey bee’s gut and causes the dysentery. It’s like eating fiber. For some numbers and an explanation on this see, “Is organic sugar better for bees?


Thanks for your reply, Rusty. I read recently in an old-timey source that if the honey hasn’t cured properly by late fall, i.e., too high a water ratio, this can cause dysentery. Your thoughts?

I just can’t figure out why the dysentery set in. If there is something I did or didn’t do I’d like to know so that I can prevent it from happening again.



I don’t think it’s the uncured honey because, like the post explains, unless their guts are already filled with solids, the water won’t make much difference. People see watery dysentery and think it must be caused by too much water, but that’s just not true.

My guess for cause would be the type of honey. Some honey, especially darker ones, are much higher in solids than the lighter-colored ones. If the bees eat a lot of honey that is high in solids and have few days for flying, dysentery will set in.

It probably was nothing you did. Some beekeepers take out the darker honey before winter, but that’s a lot of work for something that may never happen.

Elisabeth Gillmore

Hi Rusty,
I have noticed bee poop on the hive lid and around the hive entrance. I am worried because I saw a honey bee with deformed wings trying to fly outside of the hive. Do you think it could be Nosema? I would like to send samples to a lab but I have no clue where to send them and how much it will cost. I installed a new package of bees last month and have been feeding them sugar syrup with honey bee healthy. I am a new beekeeper so any information would be greatly appreciated.



I’m guessing the poop is just from bees that are orienting in the area of the hive. If it’s yellowish (and not dark brown) I wouldn’t worry. Deformed wings and Nosema aren’t normally related. The bee with deformed wings may have been in the package that you received. Deformed-wing virus is usually carried by varroa mites, and the hive your bee came from probably had mites. I think you should do a sugar roll test to see if you need to treat for mites, but I wouldn’t worry too much about Nosema.

Information about the Sugar Roll Test is here. I can do a Nosema test if you need it, but you probably don’t.


Hey Rusty,

I have a quick question about dysentery. I’ve seen it in my over-wintered hives, but never in summer. I hived a swarm on June 1st. In 2 weeks they drew out 10 medium frames and the queen is laying well with a good brood pattern. Unfortunately they have a SERIOUS dysentery problem. The hive entrance is filthy, the frame tops are stained yellow, and a lot of the bees in the hive have yellow fecal spots on them. As I’ve said, I’ve seen dysentery in spring and it’s always cleared up by itself. I’ve never seen it this time of year, so I’m not sure if I should worry about Nosema, do a blind treatment, or just wait a while and see if it clears up? On a side note, they seem to be pretty aggressive… Not sure if it’s a symptom of the problem, or just the genetics. I don’t know if the swarm was a wild swarm, or if it came from an apiary. The property owner where I got it didn’t know if there were any beeks in the area. Any thoughts? Thanks


Well, Matt, my thought after reading your first sentence was, “There is no such thing as a quick question about dysentery.” Turns out, I was right.

To begin with, remember that honey bee dysentery and Nosema are not the same. Honey bee dysentery is caused by a diet high in solids when the bees cannot get out for cleansing flights. Nosema apis is a microsporidian that causes the bees to defecate uncontrollably. Nosema ceranae is also a microsporidian but it does not produce dysentery-like symptoms.

One thing is that both honey bee dysentery and Nosema usually produce dark-colored spots, not yellow, and it usually smells really bad. Yellow is usually a sign of healthy bees, but of course they shouldn’t be messing the inside of the hive.

Nosema apis isn’t as widespread as it used to be. It seems to be getting replaced by Nosema ceranae. But I think I would test for Nosema anyway, just because I don’t know what else it would be causing the problem. If you can’t test yourself, you can send samples to a number of the bee labs. Most will do it for free.

Other than that, I don’t know what would cause your symptoms. I would like to know what you find out.


I occasionally notice a spot or two of what I guess (?) is dysentery on the hive – very infrequently. The landing board, etc is all clean. It’s just that I find a spot or two on the side of the hive, ‘once in a blue moon’. Bees seem fine, so I’m guessing that as long as one is just talking a spot or two on the hive that everything should be okay?


That’s where I was concerned. These occasional spots look brown to me?



They are yellow at first, but when they oxidize, they turn brown.


Hey, quick question. I am keeping bees in Guatemala right now and the highest quaity sugar is unrefined brown sugar. It’s a hot part of the year so they can be out foraging all day. Would that make it okay to feed them with brown sugar syrup because they are going to be able to poop whenever they want? Or is it still bad for their insides? Even the closest thing to white sugar isn’t that unrefined.



I think as long as they are flying it will be okay. The high ash content of brown sugar is considered a problem when bees are confined to the hive. That said, I have no experience with it.


I am a brand new beekeeper. I am in the Chicago land area. I just installed a package of bees in my top bar hive on Saturday evening. 3 days ago. I have a window to look in. There are a few streaks of brown in the hive. I know the bees came from California. Should I be concerned at this point? How much is too much for dysentrey? I am feeding sugar water and brood patties now. They do not have any comb. Its a new hive. Weather is still cool here too. There were a few out yesterday. It was low 50s and sunny. The rest were clustered in the corner of the hive. Any suggestions?



I wouldn’t worry just yet. As soon as they get out to fly they will probably be fine. Do you have starter strips or something on the bars? Has the queen been released? It is sometimes hard to get them started in a top-bar hive, but starter strips or a bead of wax on the bars really helps. Honey bee dysentery is not a disease but due to a poor diet or confinement. It usually clears when the sun comes out.