Waterlily beetles flit over ponds too quickly to follow with the naked eye — you might spy them resting on the surface, but try to spot their departure and you'll be left staring at a series of spreading ripples, with the insect long gone.
Now, scientists have discovered the secret behind the beetles' "now you see me, now you don't" performance. Using high-speed cameras, they revealed that waterlily beetles use their wings to skim across the surface of the water like tiny skiers.
Using this "water flight" technique, they travel at astonishingly fast speeds, zipping 1.6 feet (0.5 meters) in just a second — comparable to a person moving at 311 mph (500 km/h). [Watch the Vanishing Beetle in a Slow Motion Video]
Waterlily beetles' bodies measure about 0.2 inches (6 millimeters) in length, and they live in ponds, streams and lakes across North America. But study co-author Manu Prakash conducted his initial filming of the elusive insects in his kitchen. Prakash, an assistant professor with the Department of Engineering at Stanford University in California, filmed the beetles as they skittered over plates filled with water, explaining in a statement that working with them in the lab was difficult because they were hard to find when they got loose.
Ready for takeoff
The scientists found that the beetles performed a precise set of movements to prepare for their water flight. First, the beetle would lift each leg and then set it back down. Immediately before takeoff, it elevated its middle pair of legs above the water, angling its body to point upward. The beetle would flap its wings a couple of times to unfurl them, and then beat them strongly in a figure-eight pattern to move forward, never losing contact with the water.
While waterlily beetles aren't the only insects that skim over water, not all of the other skimmer species can fly. As waterlily beetles are capable of flight, they may prefer "skiing" as a more efficient foraging technique, the researchers suggested.
But it wasn't all smooth sailing for the beetles — the researchers observed that the rapid wing motions also generated ripples in the water that were sizable enough to guarantee a rough ride, which study co-author Haripriya Mukundarajan of Stanford University's Department of Engineering compared to traveling over a street riddled with potholes.
"Although these potholes are being generated by the insect itself," Prakash added.
The findings were published online today (March 2) in the Journal of Experimental Biology.