Many moths, including most Noctuoi-dea, Geometroidea, and Pyraloidea, possess ultrasound-sensitive ears, which probably evolved as a defense against echolocating bats. Therefore we would expect moths that are isolated from bats geographically or temporally to be deaf or less sensitive than moths hunted by bats. However, studies of isolated moths living on remote islands or flying at winter have failed to show significant changes in threshold at the frequency of best sensitivity (BF) either in noctuids or in geometrids, although some of the isolated noctuids have increased thresholds at frequencies above c. 40-60 kHz. Perhaps these moths retain good ultrasonic hearing because their form of temporal or geographic isolation is not effective enough. A recent report on degeneration of hearing in some dayfly-ing moths (Dioptinae, Notodontidae) from Venezuela indicates that becoming diurnal may be an effective way of avoiding contact with bats.
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