Another for the "so that's what those are for!" file...

From the Proceedings of the National Academy of Sciences of the United States of America

Moth tails divert bat attack: Evolution of acoustic deflection

Significance

Bats and moths have been engaged in acoustic warfare for more than 60 million y. Yet almost half of moth species lack bat-detecting ears and still face intense bat predation. We hypothesized that the long tails of one group of seemingly defenseless moths, saturniids, are an anti-bat strategy designed to divert bat attacks. Using high-speed infrared videography, we show that the spinning hindwing tails of luna moths lure echolocating bat attacks to these nonessential appendages in over half of bat–moth interactions. Further we show that long hindwing tails have independently evolved multiple times in saturniid moths. This finding expands our knowledge of antipredator deflection strategies, the limitations of bat sonar, and the extent of a long-standing evolutionary arms race.
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