Moths aren't the noisiest of creatures. They actually don't make sounds at all – unless you count thudding against a screen on a summer night. But despite the fact that they don't communicate through sound, some moths have ears.
Why would a moth have ears, if not to converse with other moths? Ears allow moths to listen for the approach of one of their greatest predators – moth-eating bats.
Sound Waves
When bats hunt at night, they use sonar, or sound waves, to find their prey. The sound waves bats send out are too high-pitched for us to hear, but they're heard loud and clear by moths with ears.
Bats are incredibly adept at avoiding even tiny obstacles like twigs – and at honing in on prey – by listening to the echoes that bounce back from these solid objects. Moths with ears can detect this skillful predator even from a distance – and try to get away. Moths without ears, on the other hand, are more likely to become dinner.
Hunting
Here's how you can conduct a test to see whether moths in your neighborhood have ears. The only equipment you'll need is a set of keys. After you've spotted some moths fluttering around a light or screen, jangle the keys nearby. In addition to the jangling, the keys will emit high-pitched sound you can't hear – much like the sounds predator bats make when they're hunting.
Moths with ears will dive away from the sound, as if to escape a hungry bat. Moths without ears won't react at all. But at least this time, they won't be dinner.