Sticky yellow bee droppings are a good thing
If you are keeping bees for the first time you have probably noticed all the fecal droppings—sometimes called frass—that appear out of nowhere on your cars, porch rails, or lawn furniture. These droppings are incredibly sticky and difficult to remove—even modern car washes leave them perfectly intact. They are often round and yellow or, if on a vertical surface, long and yellow.
Since I like to write outside, I’ve had them drop on my keyboard and decorate my screen. The “use and care” instructions that come with laptops warn us to use nothing but a damp cloth on these surfaces, so I know the manufacturers never contemplated living beneath thousands of foraging bees. Water is no match for bee poop. The good news is this: these droppings are perfectly normal and a sign that all is well.
Honey bees work hard to keep their living quarters clean. An individual worker bee will hold her feces until she is well away from the hive. The queen, larvae, and drones have their feces cleaned up by the workers and the result is an amazingly clean area, considering how many individuals live in such a small and confined space.
Winter workers will hold their feces many weeks until the air is warm enough for a brief cleansing flight. Fecal trails can often be seen on the snow not far from the hive, or sometimes even on the roof of the hive. This is also normal and nothing to worry about. But lots of feces at the entrance or on the frames is a sign of something gone awry.
Fecal masses inside the hive occur when the bee can no longer hold the feces because of poor food or a disease organism. Honey bee dysentery is a result of a food source with too much indigestible material in it. Nosema apis is a fungal disease of the honey bee which causes dysentery-like symptoms.
Many sources equate Nosema with dysentery, but they are not the same thing. Bees can have dysentery without having Nosema. For example, sometimes bees will consume the sweet juice of overripe fruit. This substance—high in fiber—can give bees dysentery. But only the pathogen Nosema apis can give them the Nosema disease with dysentery-like symptoms. The only way to tell them apart may be a laboratory analysis.
To complicate matters, there is another closely related disease, Nosema cerane, that can kill whole colonies of bees by causing damage to the honey bee gut without causing the dysentery-like symptoms. Many researchers believe that these diseases are everywhere, but take advantage of bees that are stressed or undernourished, whether from other parasites, monocultures, or pesticides. The best way to keep your bees from contracting diseases like Nosema is to provide good nutrition, adequate ventilation, and a healthful, low-stress environment.