Past research by Boise State University and University of Florida scientists has shown that some silk moths in the family Saturniidae have a built-in bat decoy: hindwings with long, elaborate “tails” that deflect sonar, creating a misleading target. As bats swoop in for the kill, they often strike these expendable tails and not the moth’s vital body core.
Now, a new study by the team, published in Science Advances and featured in National Geographic, illuminates the bat-driven evolution of these decoys across the silk moth family tree and tests four hindwing shapes in real-time dogfights between bats and moths. The verdict? The larger the hindwings and longer the tails, the better the moths’ chances of escaping bats on the hunt.
“Once we knew that the tails of silk moths deflect echoes away from their body, we were interested in whether there were optimal anti-predator shapes,” said study co-author Akito Kawahara, associate curator at the Florida Museum of Natural History’s McGuire Center for Lepidoptera and Biodiversity at UF. “One of the first things we did was go into the collections and look at specimens. There was a ton of variation in hindwing length, shape, color and twisting. We wanted to analyze these characteristics in an evolutionary framework to see what was happening.”
Kawahara and his postdoctoral researcher Chris Hamilton, one of the study’s co-lead authors, quantified hindwing shape in silk moths, mapping the evolution of this trait across a detailed family tree. Instead of gradual increases in hindwing length and complexity, they noted abrupt shifts in shape, showing that certain wing shapes might be significantly more effective at deflecting bats than others. Four classes of shapes were linked with moths’ ability to escape bat attack: two types of extra-long tails, short tails and long lobes.
These shapes have appeared multiple times in silk moths globally, and nearly identical …