Solving the Mystery of the Dancing Honey Bees

For centuries, the meanings of the conspicuous shaking, waggling, trembling, buzzing, and piping behaviors of worker honey bees were deep mysteries. In 1788, for example, a German beekeeper named Ernst Spitzner wrote the following words after watching a bee perform a waggle dance: “Without warning, an individual bee will force its way suddenly in among 3 or 4 motionless ones, bend its head toward the surface, spread its wings… and execute a genuine round dance… What this dance means I cannot yet comprehend.”

Finally, in 1915, a young Austrian zoologist, Karl von Frisch, began to investigate the dances of honey bees. Thanks to his wonderful studies, we know that when a worker bee performs a waggle dance she is sharing information about the location of something important: usually a lush patch of flowers bearing nectar or pollen. But there is another conspicuous, long mysterious dance performed by worker bees: the tremble dance.

Described as “a strange behavior” by von Frisch, the tremble dance became a prime puzzle of honey bee biology in 1923. We see that a bee performing the tremble dance moves her body in three ways, and all at the same time: (1) vibrational—she steadily jiggles her body from side to side; (2) rotational—every second or so, she changes the direction that her head is pointing; and (3) translational—she walks slowly across the comb.

The first time you see a bee walking around on a comb performing the tremble dance, you might suspect that there is something seriously wrong with her, for it does indeed look like her nervous system is malfunctioning, perhaps from pesticide poisoning. It turns out, however, that actually she is producing an important signal that helps her colony take full advantage of a strong nectar flow.

In 1923, von Frisch suggested that the tremble dance gives no information to the other bees, and saw it as a condition perhaps comparable to neurosis. Back then, I accepted his interpretation of this odd behavior. But in 1987, I discovered that the strange-looking tremble was actually a signal that plays an important role in the nectar collection process of a honey bee colony. My aim that summer at the Cranberry Lake Biological Station (CLBS) was to figure out how nectar foragers know whether their colony’s rate of nectar intake is low or is high.

To try to reach this goal, we performed an experiment that involved two colonies; one was a treatment colony and the other was a control colony. Each colony had a population of approximately 4,000 bees, and each was housed in a two-frame observation hive. Both colonies were positioned in the same place: outside one of the classroom buildings at the CLBS. But only one colony received the treatment that increased the search times experienced by its nectar foragers when they got home. This treatment was the removal of most of the colony’s nectar receivers. In effect, we closed most of the “checkout lines” for the nectar foragers in the treatment colony. Then we watched to see if this manipulation discouraged the nectar foragers in this colony from performing waggle dances.

The experiment unfolded over a four-day stretch of good weather in July 1987. On each day, we allowed 15 bees from each colony to forage at their colony’s sugar-water feeder. These 30 bees were eager to gather the sugar syrup we provided. Whenever one of the treatment colony’s labeled foragers arrived home and scrambled into the observation hive, I tracked her and recorded how long she searched to find a nectar receiver and whether or not she performed a waggle dance. I watched 68 return visits and saw that on 73 percent of them the forager performed a waggle dance.

These dances recruited some of their hive mates to visit their feeder, but the recruited bees (recognized as such because they were not labeled) were captured and put in a cage, so the sugar-water feeder never got crowded. We released these bees after we shut down the feeding station for the day. The 15 bees in the control colony also recruited bees to their feeder, and these recruits, too, were caged temporarily to prevent the control colony’s feeding station from becoming overcrowded. We needed the conditions at our two feeders to be as stable as possible—visited by just 15 bees each—throughout each day of the experiment.

Over the next two days, we continued to allow 15 labeled foragers in each colony to make collecting trips to their colony’s sugar-water feeder, while temporarily “jailing” the recruited bees that arrived at their feeders. But while my colleagues were doing this, I was no longer watching the behavior of the labeled bees in the treatment colony when they came into their observation hive.

Instead, I was busy working on removing as many of the nectar-receiver bees as possible from the treatment colony. To do this, I spent each day daubing a dot of lavender-color paint on the thorax of every bee that I saw unloading any of the 15 bees bringing home sugar syrup from the treatment colony’s feeder. At the end of both days, I opened the treatment colony’s hive and I plucked from its combs all the lavender-dotted bees (i.e., most of the nectar receivers in this colony) and put them in a cage with a sugar-water feeder. I needed these bees to stay alive and healthy.

The final day of the experiment started sunny but cool (61°F / 16°C), so it was not until 8:55 that the labeled nectar collectors in the treatment and control colonies resumed their work of bringing home “nectar” from their separate feeders. As soon as the bees resumed their work, I began mine. I recorded two crucial things for each labeled bee (nectar collector) in the treatment colony when she entered the observation hive: (1) how long it took her to find a nectar receiver, and (2) whether or not she performed a waggle dance. Meanwhile, my colleagues recorded how many recruits had arrived at their feeding stations in 15-minute intervals; this information was passed along to me via walkie-talkie.

Soon, it became clear that my removal of nectar receivers from the treatment colony was having strong effects on this colony’s nectar collectors. Now, when these bees returned home, I saw that they searched twice as long as before to find a nectar receiver (average, 21 seconds instead of 11 seconds), and that they performed almost no waggle dances! Three days before, I had seen 11 of these 15 bees perform waggle dances with great excitement, and 23 bees were recruited each hour to the treatment colony’s feeder.

But on the final day, I saw that only 1 of the 15 bees visiting the treatment colony’s feeder performed waggle dances, and only 3 bees were recruited to its feeder each hour. At the same time, it was clear that the 15 bees visiting the control colony’s feeder must be dancing wildly inside their hive. A colleague reported that lots of new bees (more than 40) had appeared at her feeder in the first hour, just as they had back on the first day. This observation was important, for it showed that there was nothing about the weather that was causing the weak dancing by the bees visiting the treatment colony’s feeder.

Watching at the observation hive that housed the treatment colony, I saw why its 15 labeled nectar collectors were no longer dancing excitedly: they were no longer getting “mobbed” by nectar receivers when they got home. Instead, they were experiencing difficulty finding bees willing to receive their loads of sugar syrup. Four times, I saw a labeled nectar collector give up looking for a nectar receiver and regurgitate her load of sugar syrup straight into a cell. I was astonished. Never before had I seen a nectar collector do this. But what really gave me a mental jolt was seeing that 3 of my 15 labeled nectar collectors (20 percent) started to perform tremble dances shortly after they entered the observation hive. I wondered, were these three bees issuing calls for more bees in their colony to function as nectar receivers? It sure looked like it.

That evening, when I entered into my notebook my “Summary and Conclusions” for the day, I wrote the following: “Noticed trembling dances by returning foragers. These bees did this after returning w/ nectar but had a hard time getting unloaded… Is trembling a signal to increase the number of [nectar] receivers?” I knew we had stumbled on something important. In 1989, I described our findings in detail in a 19-page paper titled “Social foraging in honey bees: how nectar foragers assess their colony’s nutritional status.” Despite its dry title, this paper is one of my favorite scientific reports, because our two-colony experiment showed us how a nectar forager tunes her motivation to produce waggle dances (or tremble dances) by noting whether it is easy (or hard) to find a bee keen to receive her nectar.

Several years later, in 2000, when a colleague, Dr. Susanne Kühnholz, and I were interviewing Professor Martin Lindauer in preparation for writing his biography, he told us that Karl von Frisch always suspected that the tremble dance is an important signal—not a symptom of neurosis—and that he (KvF) had once told him (ML) that he would award a prize to whomever succeeded in deciphering the message of the tremble dance. Alas, Karl von Frisch died in the summer of 1982…nine years before the summer of 1991, when my helpers and I performed the experiment that solved this long-standing mystery.

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Text from Piping Hot Bees and Boisterous Buzz-Runners: 20 Mysteries of Honey Bee Behavior Solved by Thomas D. Seeley. Copyright © 2024 by Princeton University Press. Reprinted by permission of Princeton University Press.