The Unsolved Mystery: Washboarding Behavior in Bees
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When Karl von Frisch decoded the mystery of bee dances in the 1920s (and won the Nobel Prize much later, in 1973), some might erroneously conclude there’s nothing more to learn about these fascinating communal insects.
Of course, nothing could be further from the truth. As proof, consider the unsolved mystery of washboarding.
Often observed at the entrance to hives, washboarding is a purposeful group behavior involving anywhere from a few to several hundred bees engaging in a swaying to-and-fro movement reminiscent of scrubbing clothes on a washboard. They arrange themselves in rows facing the hive entrance, stand on their second and third pairs of legs, and bend their heads and front pair of legs downward. Then they rock rhythmically while fanning with their wings.
Is it cleaning? Is it communication? No one knows. (My husband, always a jokester, suggested the bees are just cheering on their queen: “Everybody do the washboard!”)
Some observations about the behavior:
- It is only the worker bees (never drones) that participate in this behavior. The majority of the workers are between 15 and 25 days old.
- Washboarding starts around 8 a.m., peaks around 2 p.m., and may continue as late as 9 p.m. after the sun sets.
- Bees will washboard more frequently on rough surfaces than smooth surfaces.
- Bees will perform this behavior for hours and hours without stopping.
- Some beekeepers see the behavior frequently; others can go decades without seeing it.
What are some of the theories behind the behavior?
Dr. Norman Gary, professor emeritus at U.C. Davis Dept. of Entomology, postulates “these rocking movements probably serve as a cleaning process by which the bees scrape and polish the surface of the hive.” His theory springs from his observations of how the bees scrape the surface of the hive with their mandibles “with a rapid shearing movement, sliding over the surface as if cleaning it.” He notes how they pick up some material and then clean their mandibles.
Another theory is put forth by Dr. Susan Cobey, geneticist at U.C. Davis and Washington State University. She suggests washboarding bees are in the “unemployment line” during times when foraging is not so good. In the absence of more useful occupations, she speculates the bees are “sweeping the porch.” She also notes “The behavior seems to have a genetic component, as certain colonies perform this, others not in the same yard/same conditions. I tend to see washboarding when the forage is scarce.”
In contrast, H. Storch in his book At the Hive Entrance, noted washboarding was more common in colonies harvesting abundant amounts of pollen. He speculated the behavior is to remove tiny grains of pollen from their bodies where it slipped into the gap between head and thorax, where it causes discomfort.
Katie Bohrer and Jeffrey Pettis of the USDA-ARS Bee Research Lab suggest the behavior has a sanitary component, cleaning places where pathogenic organisms might congregate.
Experienced beekeepers have noticed washboarding tends to happen more frequently in warmer weather. One noted that after a very dry summer with a high collection of corn pollen, washboarding might occur because of neonicotinoids intoxication. Another observed (during good foraging conditions), “With so many landings [at the hive entrance] per day, some pollen is sure to have jostled off. When it’s so precious in the first place, this seems like sensibly conservative and hygienic behavior.” Yet another beekeeper speculates “what they are actually doing is propolising the external area where they gather when the hive is either too hot or over capacity.”
Another observer noted his washboarding bees do not face the entrance, but “washboard in every direction. I took a slow-motion video of it, and [it] is fascinating that the bee appears to be wiping the surface and then placing whatever is wiped on their thorax hairs. The slow motion makes it appear for all the world that the wiping on the thorax is intentional. I assume that the bees are sampling pheromones at the entrance (at the common touchpoint), accumulating them as part of a hive-wide communication/endocrine system of pheromones that is constantly updating. I usually see it in the evening close to sundown.”
In 2017, washboarding was recorded in wild bees lodging in a hollow tree. Dr. James Taulman documented the appearance of the hive entrance over a period of weeks, during which time the entrance became noticeably smoother. His theory is that washboarding behavior is connected with some sort of communication. He speculates two glands — the Nasinov gland and the tarsal gland — might play a role. The Nasinov gland is a pheromone-producing gland in the abdomen of a worker honeybee, functional only in bees of foraging age (10 days old). The tarsal glands are found on the legs of bees and secrete an attractive, oily, colorless “footprint” or “trail” pheromone. Smoothing the surface might help connect and dispense the two pheromones at the entrance to the hive. Both glands are used to attract foragers. Could washboarding bees be playing a function in helping foragers find their way back home more easily?
Because bees did not evolve to live in smooth-sided Langstroth hives but instead in rough natural tree cavities, we must be wary of interpreting bee behavior strictly within the bounds of what would benefit a colony housed in a commercial hive box. Instead, behavior observed in the wild can be assumed to have a survival component to it.
What that component is, of course, is still unknown. For all we know, my husband’s joke about the bees cheering on their queen by encouraging everybody “to do the washboard!” has some merit.
And that’s one of the many reasons why honeybee research is so exciting. There is still so much to learn.
PATRICE LEWIS is a wife, mother, homesteader, homeschooler, author, blogger, columnist, and speaker. An advocate of simple living and self-sufficiency, she has practiced and written about self-reliance and preparedness for almost 30 years. She is experienced in homestead animal husbandry and small-scale dairy production, food preservation and canning, country relocation, home-based businesses, homeschooling, personal money management, and food self-sufficiency. Follow her website http://www.patricelewis.com/ or blog http://www.rural-revolution.com/.
Originally published in the Spring 2023 issue of Backyard Beekeeping and regularly vetted for accuracy.