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 an excess of water in their intestines. To add to the confusion, honey bees also appear to get diarrhea from pathogenic organisms such as Nosema, but that is probably just an unfortunate correlation. If you feel confused, you are not alone.
Although excess water is often blamed for honey bee dysentery, the condition may ultimately be 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. But since solid material—not water—is what we see, the cause of dysentery 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 like a sponge 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.