Hungry bats whipping through the blackness to gulp down insects may have driven moths into daylight—creating what we know as butterflies—suggest Canadian researchers.
The idea springs from their discovery of butterflies that have ultrasonic ears, explains Jayne E. Yack of Carleton University in Ottawa. Night-flying, tropical butterflies of the superfamily Hedyloidea have on their wings ears sensitive to high frequencies, Yack and James H. Fullard of the University of Toronto report in the Jan. 20 Nature.
Such ears can detect an incoming bat's echolocation pulses in time for the insect to try zigzagging out of death's way. Many moths have evolved such ultrasonic hearing, but researchers hadn't detected it in butterflies, Yack notes.