Bats and fireflies swoop in front of high-speed cameras. Researchers watch. They want to know: Why do fireflies flash? Are they sending a message to predators?
We already know fireflies flash to attract mates. (And some females flash to trick male fireflies—then eat them!) But some experts guessed the beetles may also flash to warn creatures that want to eat them.
The researchers meet in a dark flight room at Boise State University in Idaho. There, they introduce western bats to fireflies. The species have never met before. And it isn’t a cordial first meeting! The bats dive down for dinner. But they get a bad taste in their mouths. They shake their heads and spit. After a few tries, the bats avoid the glowing bugs. Good defense, fireflies!
Next, the researchers do the hard part. They hold fireflies under a microscope. They paint the beetles’ abdomens black. The fireflies must still be able to fly normally. But all the light must be covered by the paint.
The researchers release the darkened fireflies into the room with the bats. The bats cannot see the fireflies’ night lights. In the end, the bats eat 40 percent of the darkened bugs, and none of the glowing ones. The lights have “taught” the bats not to eat glowing fireflies. “Don’t eat this bug!” the flashes say. “It tastes bad!”
But eventually, the bats learn to avoid the darkened bugs too. It just takes them twice as long. How do they learn when they can’t see the fireflies’ lights? (Bats aren’t really blind. That’s a myth!)
Bats can learn to say “no” to firefly snacks using two senses: vision and sonar (sound). Hunting in a dark room, the bats used sonar to steer clear of blackened fireflies after they associated the bad tasting bugs with the firefly flight pattern. Fireflies fly slowly. They don’t dart back and forth like they’re scared. Why aren’t they scared? Because they taste so bad no bat would want them! Other icky-tasting insects fly that way too—so bats may recognize the warning sign.
What did the researchers learn in the end? Bats figure out their food fastest and best using both ears and eyes.
