Katydids are well known for their vocal prowess, with males communicating with distant females by rubbing their wings together.
But Supersonus, a newly identified genus of insect that comprises three recently discovered katydid species, is in a class by itself. All three species produce the animal kingdom’s highest pitched mating call, according to a new study.
The call hits notes of 150 kHz, thanks to a structure in its right wing that vibrates like a drum, acting as a kind of speaker. The calling frequencies used by most katydid species range between 5 kilohertz (kHz) and 30 kHz.
Humans, meanwhile, can only hear up to about 20 kHz. (Also see “World’s Loudest Animals—’Power Saw’ Cricket, More.”)
Discovered in the trees of Colombian and Ecuadoran rain forests, the three kinds of newly discovered katydids have unusually small wings—they’re less than a millimeter long. As in consumer electronics, the smaller the speaker, the higher its frequency. (See “Urban Grasshoppers Sing Louder.”)
Study leader Fernando Montealegre-Z discovered that the katydid songs’ reach record frequencies by taking high-speed audio of their calls and then slowing down the sound so that they could be heard by humans.
The sound of the call is akin to the sound of a “bouncing ball, like a ping pong ball,” said Montealegre-Z, a biomechanics expert at the University of Lincoln in the United Kingdom. He published his findings Thursday in the journal PLoS ONE.
Move Over, Jiminy Cricket
Other than keeping tabs on potential mates, the katydids’ high-pitched calls help them avoid becoming someone’s dinner, said Montealegre-Z whose research was supported by a grant from the National Geographic Society Global Exploration Fund, a regional grant program for residents of Northern Europe.
Their tiny wings are too small for flying. By singing higher than most animals can hear, the bugs can have private conversations without worrying about eavesdropping predators, which are mostly bats.
Though bats can hear sounds of 150 kHz, the authors noted, the extreme frequency of the new katydids’ calls means they can’t travel very far, so it’s not likely that a bat would pick them up.
Naomi Pierce, a biologist at Harvard University who was not involved in the study, agreed that these “private channels” likely allow the katydids to escape detection by a predator. (Also see “Moths Jam Bat Sonar, Throw the Predators Off Course.”)
“Increasingly we have the tools to measure these things … We’re finding what you call secret channels that animals can use to communicate with each other” and find mates, she said.
The katydids may help humans develop better technologies, Montealegre-Z said. His team wants to study the new katydids’ wings to see how they might inspire miniature audio technology. And studying the animals’ ears—which have to be incredibly sensitive to pick up each other’s ultrasonic calls—may aid in developing more sensitive microphones, he said.