Beekeeping is rife with confusing terminology that can baffle even experienced beekeepers. Honey bee dysentery is a perfect example.
In humans, dysentery is a contagious illness caused by bacteria that are associated with unsanitary conditions. But in honey bees, dysentery is not caused by a pathogen. Instead, it is the result of an excess amount of fecal matter in the honey bee’s gut. It’s not a disease, but simply a condition.
Honey bee dysentery is a problem that colonies encounter in winter when the outdoor temperature does not allow them to fly. Waste products accumulate inside a bee until she has no choice but to empty her intestines, regardless of where she is. Sometimes she may exit for a quick flight, but because it is too cold to go far, she defecates on or near the landing board. This accumulation may be your first sign of a problem.
A colony with dysentery is unpleasant for both the bees and the beekeeper. Even though the dysentery was not caused by a disease organism, a hive full of bee excrement leads to the unsanitary conditions. The bees try to clean up the mess and, in the process, they spread any pathogens that were carried within individual bees. In addition, the smell within a soiled hive may mask the scent of the pheromones that are vital to communication between bees.
Nosema and Dysentery
To add to the confusion, honey bee dysentery is frequently confused with Nosema disease. Nosema apis is caused by a microsporidian that produces severe diarrhea in bees. It, too, occurs mostly in the winter and is indistinguishable from dysentery. Lots of folks assume their bees have Nosema apis, when they actually do not. The only way to know if a colony has Nosema is to dissect some bees and count spores under a microscope.
In recent years, a new wrinkle in diagnosis appeared when a separate disease, Nosema ceranae, became common. Unlike Nosema apis, Nosema ceranae is a summer disease that does not cause diarrhea to accumulate in a hive. The important point to remember is that Nosema and dysentery are separate conditions that you can’t distinguish without a laboratory analysis.
No-Fly Days and Honey Bee Health
For now, let’s assume your soiled hive tests negative for Nosema. You would like to prevent this condition in the future, but how? Why do some colonies get it while others overwinter without a hitch?
Like most other animals, honey bees have an intestine that moves food from the stomach to the anus. It can stretch when necessary, which expands its capacity. In fact, a honey bee can hold 30 to 40 percent of her body weight within her intestine.
In warm weather, bees can empty their intestines while foraging. In winter, they need to go on periodic, short “cleansing” flights. Afterward, they quickly return to the hive and join the winter bee cluster to warm themselves up. But sometimes winter can be unrelenting, providing very few days warm enough to fly.
Ash in the Honey Bee Diet
As you know, food has varying amounts of indigestible matter. We humans are encouraged to eat lots of fiber, which helps keep things moving through the digestive tract. This is exactly what honey bees need to avoid in winter. When a honey bee eats excess solids, they must be stored within the bee until the next cleansing flight.
Solids in the bee diet are in the form of ash. Technically, ash is what’s left over after you completely burn a sample of food. Ash is made of inorganic materials such as calcium, sodium, and potassium.
Honey, which is the main diet of winter honey bees, has variable amounts of ash, depending on what plants produced the nectar. The difference between honey types explains why one colony may get dysentery while a neighboring colony did not—they simply collected nectar from different sources.
Honey Color Matters
Darker honey has more ash than lighter honey. In chemical analyses, darker honey consistently shows higher levels of vitamins, minerals, and other phytochemicals. In fact, all the extra stuff inside dark honey also makes it more nutritious. But in the winter months, these extras can be hard on the bees. As a result, some beekeepers remove the dark honey from their hives before winter and give them lighter honey instead. The darker honeys can be used for bee feed in the spring when the bees are flying.
When it will be used for winter feed, sugar should also be as ash-free as possible. White sugar has the lowest ash, while darker sugars such as brown sugar and organic sugar have much more. A typical sample of light amber honey has about 2.5 times as much ash as plain white granulated sugar. Because of the way it’s processed, some organic sugar has 12 times as much ash as light amber honey. The exact numbers vary with the manufacturer, but lighter is better when it comes to bee feed.
Climate Makes all the Difference
How much attention you need to pay to winter feed depends on your climate. Where I live, it is not unusual to get a 50+ degree day in the middle of winter. On a day like that, the bees will make quick flights. If you have snow on the ground, you can easily see how important those flights are.
The fewer flying days you have, the more important the quality of winter feed becomes. For a beginner, this will be hard to determine, but you may be able to find historical records of daytime temperatures on the Internet. If you have a good flying day once every four to six weeks, you probably don’t have to worry about dark honey in your hives. If you won’t have a flying day for three or four months, a little planning may prevent a problem with dysentery.
A Note About Water
You will sometimes hear that excess water causes honey bee dysentery, but water by itself will not cause dysentery. However, too much water in the early spring may push bees over their limit. If the bees haven’t been outside, and if they are approaching the maximum amount of waste they can hold, the gut material may absorb part of the water, exceeding the bee’s ability to carry it. That is one reason why many beekeepers prefer to feed sugar cakes or bee fondant rather than syrup in the early spring.
You can help your bees avoid dysentery by adding upper entrances, removing dark honey, and carefully selecting winter feed. Just remember to tailor your management to suit local conditions.
Have you had a problem with honey bee dysentery in your area? If so, how did you handle it?