A fly buzzes past your head and lands nearby; you snatch a flyswatter or roll up a magazine and approach it gently – and you strike!
But no matter how fast you are, the fly is almost always faster and it usually manages to avoid your wallop and escape unscathed. (Is it trying to annoy you ?!)
Flies have many customizations that give them increased speed, maneuverability and perception, making them very, very good at detecting and avoiding even the fastest swats. And new evidence shows that flies’ modified hindwings play an important role in launching them quickly ̵
Related: 7 amazing ninja skills
Houseflies (Domestic fly) belong to the order Diptera or true flies. Diptera flies have modified hindwings that have evolved into small, sticklike structures with a button at the end called the limp. Their vibrations help the insects stabilize their bodies during flight by detecting body rotations and transmitting information to the wings.
Flies in the Diptera subgroup Calyptratae, which includes houseflies, also vibrate their halter as they walk, but scientists did not know why. In a study published January 13, 2021 in the journal Proceedings of the Royal Society B: Biological Sciences, researchers examined Calyptratae flies to see if limping oscillations affected their transition to air and directed additional sensory input to help coordinate movements in the wing and leg muscles.
Using high-speed cameras to capture captured and free-ranging laboratory-flying flies during launch, the researchers recorded footage at speeds of up to 3,000 frames per second. They found that Calyptratae flies launched about five times faster than other flies; their start required an average of approx. 0.007 seconds (7 milliseconds) and only one wingbeat.
“None of the Calyptratae had a launch duration longer than 14 milliseconds [0.014 seconds], “the researchers reported. In comparison, launching non-Calyptratae flies took about 0.039 seconds (39 milliseconds) and required about four wingbeats, according to the study.
The researchers then anesthetized the flies and removed the lameness that all Diptera flies have. Calyptratae flies lacking these knotty structures took much longer to become airborne, but the take-off time was not affected in non-Calyptratae flies without lameness. Stability during takeoff also started with removal of dumbbells, but only in Calyptratae flies.
For example, Calyptratae insects known as battleflies that attempted to escape launch without their halter “always resulted in a crash landing,” the researchers reported.
“This indicates that for Calyptratae flies, limping inputs are necessary for a quick and stable start,” said lead study author Alexandra Yarger, a postdoctoral researcher at Imperial College London. Yarger conducted fly research with Fox Lab in the Department of Biology at Case Western University in Cleveland, Ohio.
Being able to escape predators is a big plus for an animal, and Calyptratae flies are extremely successful; with approximately 18,000 described species, they make up approx. 12% of Diptera diversity, Yarger told WordsSideKick.com in an email.
“When performing an escape start, there will always be a trade-off between speed and stability, but Calyptratae seem to have found a way to repel some of the loss of stability through the use of their halter,” Yarger said. “The halter allows the Calyptratae to perform faster and more stable escapes than many other flies.”
In a moment
Halteres are not the only secret weapon in a fly’s elusive arsenal; when a fly is airborne, it can perform maneuvers that would be the envy of a fighter pilot. Fruit flies can change course in less than 1/100 second – approx. 50 times faster than an eye can blink, WordsSideKick.com previously reported. In experiments, perfectly adapted wing flaps generated enough force to quickly propel the flies away from a predator while in the air.
“These flies roll up to 90 degrees – some are almost upside down – to maximize their strength and escape,” said Florian Muijres, who studied biomechanics in flight at the University of Washington in Seattle and now at Wageningen University & Research in the Netherlands. told WordsSideKick.com in 2014.
Flies also have unique vision, which helps them plan their leaps away from a threat. About 200 milliseconds before launch, fruit flies use visual input warning of imminent danger to adjust their posture and determine the direction that will put them in safety, researchers wrote in 2008 in the journal Current biology.
In fact, their improved perception juggles up to six times more visual input in a second than humans can, reported the BBC in 2017.
Animal brains perceive the passage of time by processing images at speeds known as “flicker fusion speed”, a term that describes how many images flash into their brains per second. Second. Roger Hardie, professor emeritus of cellular neuroscience at the University of Cambridge in England, implanted electrodes in the light receptors in fly eyes to measure their flicker fusion rate and calculated it to be 400 times per second; the average flicker fusion rate for humans is around 60, according to the BBC. This means that movement you perceive as “normal” moves like slow motion to a fly.
With all these built-in benefits, it’s no wonder the fly you’re trying to swim can escape. One approach that can improve your chances, however, is to direct your swat toward a place where the fly is likely to go, rather than where it rests, said Michael Dickinson of the California Institute of Technology in Pasadena The independent in 2011.
“It’s best not to hover the fly’s starting position,” Dickinson said. “Say a little forward to predict where the fly will jump.”
Then you can also just leave the fly alone, Yarger added. “They have as much right to survive as any other animal,” she said.
EDITOR’S COMMENT: The article was updated at. 13.35 ET on January 13 to include quotes from the lead researcher and video of experiments.
Originally published on WordsSideKick.com.