Cicadas are so loud, they cause fiberoptic-cable interference.

Wired reveals a very strange insect-monitoring device called DAS, or “distributed acoustic sensing,” normally used to track vibrations made by seismic shifts and volcanic eruptions. But Princeton geologists found that cicadas are so loud with their late-summer rattle calls that the vibrations actually affect the laser-light traveling inside fiberoptics:

n the spring of 2021, Sarper Ozharar—a physicist at NEC Laboratories, which operates the Princeton test bed—noticed a strange signal in the DAS data. “We realized there were some weird things happening,” says Ozharar. “Something that shouldn’t be there. There was a distinct frequency buzzing everywhere.”

The team suspected the “something” wasn’t a rumbling volcano—not in New Jersey—but the cacophony of the giant swarm of cicadas that had just emerged from underground, a population known as Brood X. A colleague suggested reaching out to Jessica Ware, an entomologist and cicada expert at the American Museum of Natural History, to confirm it. “I had been observing the cicadas and had gone around Princeton because we were collecting them for biological samples,” says Ware. “So when Sarper and the team showed that you could actually hear the volume of the cicadas, and it kind of matched their patterns, I was really excited.”

Add insects to the quickly growing list of things DAS can spy on. Thanks to some specialized anatomy, cicadas are the loudest insects on the planet, but all sorts of other six-legged species make a lot of noise, like crickets and grasshoppers. With fiber optic cables, entomologists might have stumbled upon a powerful new way to cheaply and constantly listen in on species—from afar.