Tiger beetles weaponize sound to ward off bat predators

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In the dead of night, bats and insects are locked in an acoustic war.

Bats send out ultrasonic clicks and listen for the echoes to home in on insect prey. Insects that hear those hunting calls must defend themselves. Some flee. Others send out their own ultrasonic sounds to scramble bats’ sonar. And now, scientists have found a new way that some night-flying beetles use sound against hungry bats. They use it to disguise themselves as toxic moths.

Wildlife biologist Harlan Gough led the research. He works at the U.S. Fish and Wildlife Service in Walla Walla, Wash. He and his colleagues shared their findings last May 15 in Biology Letters.

A graphic tale" with animals drawn around the letters

A brown bat soars through a desert sky at sunset, chasing after a flying green beetle with yellow spots.

But even the biggest, baddest tiger beetles must avoid becoming dinner themselves. And for nocturnal species, that means escaping bats.

Many insects flee when they hear bats’ hunting calls. But some tiger beetles respond to bats with their own ultrasonic clicks.

A man with a beard, wearing a yellow hat and a button-down shirt taps his chin while he thinks. The man is labeled “Wildlife biologist Harlan Gough.” A thought bubble above his head shows bat sending ultrasonic clicks at a beetle, which is sending ultrasonic clicks right back. Gough is thinking, “How do they do it? Why do they do it?”

At night, a lit lamp sits on a tarp out in the middle of the desert. An inset shows a beetle approaching the glowing light, saying, “Sooo pretty…”

On a table, a beetle’s back is tethered to a metal rod. In front of the beetle is a camera, zoomed in on the insect. Behind the beetle is a speaker. Gough stands beside the table, holding a phone, saying, “Incoming!”

The same beetle from before pulls its green and yellow-spotted hindwings back so that they overlap with the translucent hindwings. This creates a “bzzzz” sound.

A gloved hand gently cradles a big brown bat, while a pair of tweezers brings a green tiger beetle toward the bats mouth. The bat’s tongue is hanging out and it’s saying, “Gimme!”

A green tiger beetle flies over a desert landscape under a bright blue sky. A thought bubble over the beetle’s head shows a brown and orange tiger moth. The beetle thinks, “I could be her…”

This hints that tiger beetles use ultrasonic clicks to disguise themselves as tiger moths, so they can fly under bats’ radar.

“If you look at your porch light at night, you see all kinds of insects that…we know can get eaten by bats,” Gough says. “What are some [anti-bat] strategies that other insects use?”

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