It rips through high g-force turns with ease, stops on a dime, hovers, and switches directions mid-flight in the blink of an eye. This isn’t a new drone prototype for the military; it’s a flying machine engineered by nature: the blowfly. Don’t laugh. Insects are nature’s smallest and most agile pilots. However, scientists are hard-pressed to pop the hood and study the insects' flight mechanics in action. The blowfly, for example, beats its wings 100 times per second, which makes it incredibly difficult to observe and take accurate measurements. However, using an imaging technique called microtomography, scientists from the United Kingdom employed a new approach to studying the anatomy of flying insects. The scientists stitched together X-ray images of a blowfly beating its wings to create a three-dimensional video. And the detailed visualization has finally allowed scientists to understand why blowflies are such nimble creatures.
Catching a Fly
Diagram of the experimental setup,showing the direction of the wind stimuli (white arrow) and rotational stimuli (yellow arrow). Courtesy: PLOS Biology The blowfly’s secret to flight wasn’t a complete mystery to scientists. They knew, from previous studies, that a large group of muscles inside the insect’s thorax power the wings. Additionally, 13 pairs of tiny steering muscles that attach to sclerites, or plate-like sections of the thorax, help the insect turn and perform technical maneuvers. Some of those steering muscles are as thin as a human hair; and although scientists could surmise their role in insect flight, they’ve never seen them in action.
Microtomography allows scientists to take multiple X-ray cross-sections of a living creature and combine them into a 3-D model (the same technology, used at a larger scale, in medical CT scans). To capture the blowfly’s beating wings, researchers increased the resolution of the technique, and tethered the blowfly to a rotating table. The imaging setup allowed the researchers to take ten evenly spaced snapshots of the blowfly’s wing beat. Stitching together the images resulted in the video below. The blue, green and yellow muscles are the blowfly's steering muscles.
Researchers found that the 13 pairs of tiny muscles independently expand and contract to alter the amount of space between the plates of the blowfly’s thorax. By distorting the shape of the thorax, the orientation of the beating wings is changed. Researchers concluded that these minute distortions help the fly turn, and give the insect its agility in the air. They published their findings Tuesday in the open-access journal PLoS Biology.
Scientists hope to use microtomography to image more creatures with similar biomechanics. The findings may inspire new designs for micromechanical flying machines: Just think, a drone that's as difficult to swat as a pesky fly.
Image credit: Tomas Krist/Shutterstock