Honeybees can't swim, and when their wings are wet, they can't fly, either. But Chris Roh and other researchers at the California Institute of Technology found that when bees drop into bodies of water, they can use their wings to produce little waves and slide toward land-like surfers who create and then ride their own waves.
As with many scientific advances－Isaac Newton's apple or Benjamin Franklin's lightning bolt－Dr. Roh's experiment began with a walk. Passing Caltech's Millikan Pond in 2016, he observed a bee on the water's surface producing waves. He wondered how an insect known for flight could push itself through water.
Dr. Roh and his co-worker, Morteza Gharib, used butterfly nets to collect local Pasadena honeybees and observed their surf-like movements. The researchers used a wire to restrict each bee's bodily movement, allowing close examination of their wings. They found that the bee bends its wings at a 30-degree angle, pulling up water and producing a forward force. Bees get trapped on the surface because water is about three times heavier than air. But that weight helps to push the bee forward when its wings move quickly up and down. It's a tough exercise for the bees, which the researchers guess could handle about 10 minutes of the activity.
The researchers said the surf-like movement hasn't been documented in other insects and most semiaquatic (半水生) insects use their legs for propulsion (推进力), which is known as water-walking. It may haveevolvedin bees, they predicted.
Dr. Roh and Dr. Gharib have imagined many practical applications for bees'surfing. One plan is to use their observations to design robots able to travel across sky and sea. "This could be useful for search and rescues, or for getting samples of the surface of the ocean, if you can't send a boat or helicopter," Dr. Gharib said.
