When a bee crashes into water, it may still be able to swim to safety.
New research from Michigan State University confirms that honeybees can propel themselves across the water’s surface, and their movement is purposeful and directional. They swim toward darker areas — likely using visual cues to locate the shoreline and escape.
Scientists only recently discovered that honeybees can propel themselves across the surface of water, which is a surprising ability for an insect built for flight, not swimming.
The reason bees can move across water is surprisingly simple. The undersides of their wings quickly become wet and can no longer generate lift, but the flight motor keeps firing, creating a hydrofoil-like effect. That force generates waves behind the bee that propels it forward.
The study suggests this little-known behavior may help bees survive encounters with water while foraging.
“We found that bees don’t just move randomly when they’re on water,” said Zachary Huang, associate professor in the MSU Department of Entomology and co-author of the study. “They actually orient toward darker areas, which probably represent land, vegetation or the edge of a pool. That behavior increases their chance of getting out.”
To test this behavior, researchers placed individual bees in a shallow bowl of water with a dark section along the edge. Most bees consistently moved toward the dark area rather than randomly around the bowl, showing a clear directional preference known as skototaxis, which is the tendency to move toward darker visual cues.
“Swimming toward those cues may help bees find a place to climb out and dry their wings so they can fly again,” Huang said.
The researchers also tested whether exposure to thiamethoxam, a commonly used insecticide, affected bees’ ability to navigate while on the water.
Bees exposed to the insecticide no longer showed a preference for dark areas. Instead, they moved randomly around the water surface and took longer routes to reach the edge.
Further analysis showed the exposed bees made significantly more turns while moving across the water, suggesting reduced motor control rather than a loss of visual orientation.
“These bees eventually reached the edge, but not toward the dark section and their movement was much less efficient,” Huang said. “The results suggest insecticides may interfere with the motor coordination needed for this behavior.”
The study also examined mason bees, a solitary bee species. Both male and female mason bees showed an even stronger preference for dark areas than honeybees, and female mason bees reached the edge faster and traveled shorter distances.
The findings suggest the ability to move across water and orient toward darker escape routes may have evolved before bees developed complex societies.
In the wild, bees encounter water more often than people might expect. Some collect water to help regulate hive temperature, while others may accidentally land on water while flying over lakes, ponds or irrigation systems.
The ability to propel themselves toward the shoreline could help these bees survive these encounters.
“Even though only a small fraction of workers collect water, the ability to escape when they fall in could still benefit the colony,” Huang said.
The researchers say the work also highlights how pesticides can affect new bee behaviors that are not studied.
“Most pesticide research focuses on foraging or learning,” Huang said. “But bees perform many behaviors in the real world that we don’t often measure. This study shows that even something unusual like swimming can be disrupted.”
This study was recently published in Communications Biology with co-authors Fang Liu and Wenfeng Li of the Institute of Zoology at the Guangdong Academy of Sciences.
