Moths’ Rippled Forewings Create ‘Decoy Echoes’ So Bats Can’t Find Them

A new study has found that the ripples in a moth’s forewings are actually part of an elaborate defense system against the echolocation of bats.

Moths are common prey of bats and they’ve used other forms of sonic decoys to prevent being detected by echolocation in the past. However, a new study conducted by researchers with the University of Bristol has revealed that forewing ripples also serve has a successful decoy.

According to the National Park Service, bats produce sound waves with their mouths that bounce off objects and return to the bats’ ears. They use this process to pinpoint the exact location of insects to feed on – like moths.

Photo: Wikimedia Commons

As a means of defense, moths have evolved to include natural mechanisms to protect themselves from echolocation. For example, according to Smithsonian Magazine, luna moths may develop long hindwings that reflect a lot of sound. The hindwings attract the bats to that specific part of the wing, possibly preventing the more vulnerable body of the mouth to be targeted during an attack.

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However, researchers discovered an even more effective means of protection against echolocation with large silkmoths. Those moths, such as the Atlas moth or the ailanthus silkmoth, have evolved to develop rippled and folded tips on their forewings which act as an effective means of defense.

Photo: Wikimedia Commons

Researchers used ultrasonic sound at different frequencies to see how it reacted to the moth’s forewings. They wanted to see how well the forewings might reflect the sound waves to get an idea of what would happen if targeted by a bat.

As it turns out, the ripples and folds in that part of the wing did reflect sound back – but it released the sound back into the environment 180 degrees around the wing.

Photo: YouTube/World at Large Official YouTube

The reflectiveness of the forewings ended up being more effective at sonic defense than the longer wingtips of the luna moths.

It’s incredible what nature is capable of producing. Watch the video below:

You can learn more about the rippled forewings and the decoy echoes they produce in the study here.

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