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 loud and clear to 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.

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.