Although the surfaces of the water look flat to the
human eye, for the tiny creatures they appear as huge walls of water
called menisci that must be climbed to get to where they want to go.
John Bush and David Hu at the Massachusetts Institute of
Technology (MIT) in the United States used a high-speed video to
show exactly how three species of gravity-defying insects do it.
"The ability to climb menisci is a skill exploited by
water-walking insects as they seek land in order to lay eggs or
avoid predators," they said in a report in the science journal
Nature.
Millimetre-sized insects cannot scale the walls of water with
their usual movements so they assume a rigid body position and form
dimples on the surface of the water which create forces that suck
them up the slope.
The scientists compared the action to water being sucked up a
thin tube by the force of its own surface tension.
"Meniscus climbing is an unusual means of propulsion in that the
insect propels itself in a quasi-static configuration, without
moving its appendages," the researchers said.
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