Animals

Tiger beetles weaponize sound to ward off bat predators

Some beetles’ ultrasonic clicks sound like toxic tiger moths, warning hungry bats away

A beetle affixed to a tether hovers in front of a dark grey background

New experiments where tiger beetles flew while tethered in place (one pictured) reveal one clever way these insects ward off bat predators.

Geena Hill/University of Florida

By Maria Temming and JoAnna Wendel

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.

illustrated text reads "Wild Things: A graphic tale" with animals drawn around the letters
Text: Beetles vs. Bats: An ultrasonic battle . Written by Maria Temming. Illustrated by JoAnna Wendel. Image: A brown bat soars through a desert sky at sunset, chasing after a flying green beetle with yellow spots.
Text (above image): In the insect world, tiger beetles are fearsome predators. They’re super fast and have huge jaws for snapping up ants and other insects. Image: A green beetle scuttles across the ground after two fleeing ants. The beetle is saying, “Lunch!” The ants say, “Oh no!” and “Run!” Text (below image): But even the biggest, baddest tiger beetles must avoid becoming dinner themselves. And for nocturnal species, that means escaping bats.
Text (above image): Bats hunt by echolocation at night. They chirp out “ultrasonic” clicks too high-pitched for humans to hear, then listen for the echoes to locate prey. Image: Three bats chase insects through the sky at night. A full moon illuminates the bats, insects and the landscape below, dotted with cacti. The bats’ echolocation calls are illustrated as yellow rings that spread out from their mouths, toward the insects they’re chasing. Text (below image): Many insects flee when they hear bats’ hunting calls. But some tiger beetles respond to bats with their own ultrasonic clicks.
Text (above image): That got wildlife biologist Harlan Gough curious. Image: 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?”
Text (above images): To find out, Gough and his colleagues captured 19 species of tiger beetles from southern Arizona. Twelve were active only during the day. Seven came out at night. Image (top): During the daytime, Gough stands out in a desert landscape. He swipes a net at a swarm of beetles, saying, “Come here, little beetles!” Image (bottom): 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…”
Text (above image): In the lab, the researchers tethered each beetle to a metal rod so they could watch it fly in place. Then, they played echolocation clicks over a speaker to mimic a hungry bat swooping in. Image: 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!”
Text (above top image): When beetles fly, they lift their outer forewings away from their beating hindwings. Image (top): A beetle lifts a pair of green and yellow-spotted wings, labeled “forewings,” up and away from its body. This allows a pair of translucent, labeled “hindwings,” to spread out from underneath. Text (above bottom image): But nocturnal tiger beetles pulled an unusual maneuver. “Right as they hear the bat sound, they go, ‘Uh oh!’ and they swing their [forewings] rearward,” says Gough. The beetles’ beating hindwings smacked their forewings, producing ultrasonic clicks. Image (bottom): 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.
Panel 7: Text (above image): At first, the scientists thought tiger beetles’ sounds might be a warning to bats that the beetles contain nasty-tasting chemicals. But captive big brown bats eagerly gobbled up all these species. Image: 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!”
Text (above image): “I think we can throw out the idea that tiger beetles are chemically defended against bats,” Gough says. But maybe beetles’ clicks were just meant to make bats mistake them for toxic tiger moths — which also make ultrasonic clicks. Image: 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…”
Text (above image): When the team compared tiger beetle clicks with those of toxic tiger moths in Arizona, the researchers found the clicks’ length, pitch and other features were a lot alike. Image: Gough sits at a table with a laptop, whose screen shows two similar-looking sound waves: One from a moth and another from a beetle. Gough is saying, “Wow, talk about ultrasonic camouflage!” Text (below image): This hints that tiger beetles use ultrasonic clicks to disguise themselves as tiger moths, so they can fly under bats’ radar.
Text (above image): Gough suspects such acoustic trickery may be common in the night sky. Many insects have ears tuned to bat calls, but little is known about how they use their ultrasonic sense. Image: A kid wearing a red sweatshirt looks up at a glowing porch light at night, which is swarming with insects. Text (below image): “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?”

Power Words

More About Power Words

acoustic: Having to do with sound or hearing.

bat: A type of winged mammal comprising more than 1,400 separate species — or one in every four known species of mammal. (in sports) The usually wooden piece of athletic equipment that a player uses to forcefully swat at a ball. (v.) Or the act of swinging a machine-tooled stick or flat bat with hopes of hitting a ball.

beetle: An order of insects known as Coleoptera, containing at least 350,000 different species. Adults tend to have hard and/or horn-like “forewings” which covers the wings used for flight.

biologist: A scientist involved in the study of living things.

chemical: A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

colleague: Someone who works with another; a co-worker or team member.

echolocation: (in animals) A behavior in which animals emit calls and then listen to the echoes that bounce back off of solid things in the environment. This behavior can be used to navigate and to find food or mates. It is the biological analog of the sonar used by submarines.

insect: A type of arthropod that as an adult will have six segmented legs and three body parts: a head, thorax and abdomen. There are hundreds of thousands of insects, which include bees, beetles, flies and moths.

maneuver: To put something in a desired or necessary position by using one or more skilled movements or procedures.

metal: Something that conducts electricity well, tends to be shiny (reflective) and is malleable (meaning it can be reshaped with heat and not too much force or pressure).

moon: The natural satellite of any planet.

nocturnal: An adjective for something that is done, occurring or active at night.

pitch: (in acoustics) The word musicians use for sound frequency. It describes how high or low a sound is, which will be determined by the vibrations that created that sound.

predator: (adjective: predatory) A creature that preys on other animals for most or all of its food.

prey: (n.) Animal species eaten by others. (v.) To attack and eat another species.

sound wave: A wave that transmits sound. Sound waves have alternating swaths of high and low pressure.

species: A group of similar organisms capable of producing offspring that can survive and reproduce.

swarm: A large number of animals that have amassed and now move together. People sometimes use the term to refer to huge numbers of honeybees leaving a hive.

toxic: Poisonous or able to harm or kill cells, tissues or whole organisms. The measure of risk posed by such a poison is its toxicity.

translucent: The property of letting light through, but not being transparent. Usually, things viewed through a translucent material (such as frosted window glass) appear as hazy shapes with no detail.

wave: A disturbance or variation that travels through space and matter in a regular, oscillating fashion.

A version of this article appears in the April 1, 2025 issue of Science News Explores.

Citations

Journal:​ H.M. Gough et al. Tiger beetles produce anti-bat ultrasound and are probable Batesian moth mimics. Biology Letters. Vol. 20, May 15, 2024. doi: 10.1098/rsbl.2023.0610.

About Maria Temming

Maria Temming is the Assistant Managing Editor at Science News Explores. She has bachelor's degrees in physics and English, and a master's in science writing.

About JoAnna Wendel

JoAnna Wendel is a freelance science writer and cartoonist in Portland, Ore. She loves to make comics about all types of science, but she especially loves drawing planets, invertebrates and sea creatures. When she's not drawing, JoAnna is probably reading, hiking or hanging out with her cat, Pancake.

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