The Flapping of Bumblebee Wings, at 5,000 Frames per Second

How do insects' wings actually work? We've just gotten a little bit closer to finding out.

A bumblebee at close range (Science/AAAS)

To human eyes, bees appear to float rather than fly: They glide along gracefully, seeming almost to be carried along on currents of air. But if we could look more closely at them, of course, we'd see a more complicated picture: Insects have to work hard to stay aloft, beating their wings at rates that can top out at 600 beatsper second. But that work, at the molecular level, has been something of a mystery to us humans. How do airborne insects actually execute their impressive aerobatics? Do they fly like vertebrates do, using nervous signals and muscle contractions? Or do they have a more specialized mechanism for keeping themselves aloft?
The biophysicists Hiroyuki Iwamoto and Naoto Yagi have just gotten us closer to answering those questions -- at least when it comes to one particular kind of airborne insect: the bumblebee. And they've done that using x-rays. The scientists' goal? To measure the changes that occurred within bees' muscles as the insects were in flight. To do that, Iwamoto and Yagi glued bumblebees down (sorry, guys) to the end of a narrow aluminum tube. The scientists then (sorry again) aimed an x-ray beam at the creatures. And then they read the information provided by the bright spots that formed when the x-rays were scattered by the insects' muscle movements. The scientists then synchronized that information to video footage of the bees moving -- at 5,000 frames per second.
What they got was something like this:
What they got, also, was a tentative conclusion: that bumblebees seem to fly using stretch activation -- the same mechanism that makes vertebrate muscles move. Which you can see, ever-so-slightly, in the video, in extreme slow motion. Bumblebees: They're just like us. Sort of.