How Moths Hover

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How moths hover, described in reports in BBC News 18 April 2013 and Journal of Experimental Biology (JEB) doi: 10.1242/jeb.087494. The study of insect flight often involves experiments using tethered insects in a flight arena. Scientists have noted that these tethered insects tend to make exaggerated movements of their abdomens. Jonathan Dyhr, a biologist at University of Washington, and colleagues Kristi Morgansen from Department of Aeronautics and Astronautics, University of Washington and Noah Cowan of Department of Mechanical Engineering, Johns Hopkins University, set out to see if the movements were simply a response to being tethered, or a means of controlling flight. To do this the research team placed a hawkmoth in a flight arena surrounded by a display of LED lights, which were used to create a moving pattern to give the moths the sensation of tumbling forward or backwards. They found the moth would bend its abdomen upwards or downwards as the direction of the pattern changed in order to stay in a steady position relative to the pattern.

Using the data from high speed photography taken during the test flights the scientists constructed a computer model of the effect of the movements on flight control. According to JEB the model indicated: “First, flexing the abdomen shifts the moth’s centre of mass to counteract the rotation. In addition, this causes the thorax to bend, re-directing the aerodynamic forces produced by the wings and so correcting the loss of stability. So, while the wings are still central to keeping insects aloft, it seems that the abdomen also plays a key role in flight control”.

Dyhr told BBC that moths were “incredibly good at hovering”, and explained: “A moth can really precisely control movements (and remain) in one place, because it's trying to feed from flowers”. The researchers are studying insect flight to “distil the biological principles of flight control”. Dyhr told BBC news that it was really rewarding to answer this fundamental question. He went on to comment: “We got to collaborate with engineers and use really unique methods to answer very basic biological questions”.

BBC

Editorial Comment: Dyhr is right – moths are incredibly good at hovering, especially when you consider flowers do not stay completely still while the moths drink nectar from them. The fact that moths feed in this way reminds us they had to get hovering right in the first place, or they would not be able to get enough nutrients and energy to keep flying. This means the moth wings and body had to have the right structure, and the moth’s brain had to have the right circuits to control them, as soon as moths tried to feed in this way. It is a good thing for biologists to collaborate with engineers to find answers to biological questions, because engineers know that functioning systems do not come about by chance random processes, and this is a lesson evolutionary biologists need to learn. Functions such as flying and hovering, require understanding of the laws of physics and properties of materials and the application of information to make use of these. In other words, they require a creator. No wonder the God of creation states bluntly that men have no excuse for ignoring His work. (Romans 1:20) (Ref. Lepidoptera, aerodynamics, flight, insects)

Evidence News 3 July 2013

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