Why Honeybees are Good at Grooming
Honeybees are pretty good at what they do, gathering as much as 30 percent of their body weight in protein-rich pollen to bring back to the hive per foraging trip.
But it gets awfully messy. When bees prowl around a flower, perhaps drinking nectar for immediate energy, pollen falls all over them and sticks to the hairs that cover their bodies — even their eyes.
They use their legs to clean off most of the pollen and fill structures called pollen baskets on their rear legs.
Their grooming process is efficient. Researchers at Georgia Tech found that a bee could shed about 15,000 pollen grains in two minutes as it brushed itself clean. Guillermo J. Amador, David L. Hu and colleagues recorded the behavior on video because they wanted to learn more details about how the bees clean up regularly. They reported their work in Bioinspiration & Biomimetics.
Dr. Hu’s lab in the mechanical engineering department of Georgia Tech concentrates on biological processes that may have engineering applications. One of its subjects is how different animals keep clean. So they study the structure of things like cat tongues and eyelashes.
Insects are interesting because, Dr. Hu said, they operate on a different scale from humans. When we want to create things that we can clean, he said, “we make surfaces that are very smooth — like car smooth.” The same is true of our countertops. And that’s largely because we use water.
But for something the size of a bee, water doesn’t work so well. “When insects get into water,” he said, “they can’t get out because of surface tension.” So nature has come up with other solutions. “Nature,” as Dr. Hu puts it, “doesn’t do smooth.”
But it does hairy very well. So a bee uses hairy legs to clean a hairy body and eyes. Dr. Amador and Dr. Hu concentrated on the eyes, which a bee needs to clean in order to see clearly.
They used several techniques to study what the bees were doing and how much pollen they were getting rid of. One of the techniques used backlighting to silhouette bees and pollen grains so computer software could recognize and count the black dots against a light background. Dr. Hu said the technique was inspired by Pig-Pen, the Peanuts character who was always accompanied by a cloud of dirt particles.
They also used a bee leg, removed from the bee and attached to a small motorized apparatus. Dr. Amador, now a researcher at the Max Planck Institute for Intelligent Systems in Stuttgart, Germany, said that different spacing of the hairs on the leg and the eye turned out to be important, a bit like cleaning a hairbrush with a comb. You wouldn’t use a brush to clean another brush with exactly the same kind of bristles.
There are a number of ways the information might be useful. We can turn the hose on a car, but not on sensors, microchips and microrobots.
As for the smooth surfaces humans are so fond of, Dr. Hu was reassuring.
“We’re not going to have hairy tabletops anytime soon,” he said, “or hairy cars.”
- Story by James Gorman, The New York Times
- Photo by Candler Hoobs, George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology