Moths strike out in evolutionary arms race with sophisticated wing design

Ultra-thin, super-absorbent and extraordinarily designed to detract attention, the wings of moths could hold the key for developing technological solutions to survive in a noisy world. As revealed in a new study published today in PNAS [date tbc], researchers from the University of Bristol have discovered the precise construction of moths wings that have enabled the species to evade its most troublesome predator in a 65 million-year-old evolutionary arms race. Using an array of analytical techniques, including airborne cross-sectional imaging, acoustic-mechanics and refractometry, the team from Bristol's School of Biological Sciences found that the very thin scale layer on moth wings has evolved extraordinary ultrasound-absorptive properties that provide stealth acoustic camouflage against echolocating bats. What makes the team's discovery even more remarkable is that they have identified the first known naturally occurring acoustic metamaterial. A metamaterial traditionally describes an artificial composite material engineered to display physical properties that surpass those available in nature. Naturally occurring metamaterials are extremely rare and had previously never been described in the world of acoustics. Earlier this year, behavioural acoustics and sensory ecology expert Dr Marc Holderied and his co-researchers reported how deaf moths had evolved ultrasound absorbing scales on their bodies that allowed them to absorb 85 per cent of the incoming sound energy that bats use to detect them.