It was late on a Friday night, and Haripriya Mukundarajan was trying to record the annoying buzz of a mosquito’s wings.
To fight mosquitoes and the diseases they carry, you need to know where they are—which species, in which places. Everything else flows from that. A lot of labor goes into trapping, counting, and identifying the insects, but Mukundarajan figured there might be an easier way. Mosquitoes give themselves away through the vexing whine of every wingbeat. If Mukundarajan could find an easy way of tracking that sound, perhaps she could develop an easy mosquito-detector. So there she was in her lab at Stanford, with her mentor Manu Prakash, conducting the world’s unlikeliest recording session, with high-performance microphones that they had borrowed.
And then her cellphone rang.
The chiming made her wonder whether the phone could pick up a mosquito’s buzz, so she put in the cages, and found that it recorded the insects just as well as the fancy studio microphones. “We realized that people everywhere are walking around with mosquito detectors in their pockets,” she says.
A mosquito’s buzz reveals not only its presence, but also its identity. Each species seems to hum at its own distinctive pitch, and Mukundarajan and Prakash have shown that cellphone recordings are good enough to classify these insects. They’ve essentially created Shazam for mosquitoes. “I tell people there are 3,500 species of mosquitoes and they laugh,” says Prakash. “To them, it’s just a mosquito. We need to change that if we’re to fight these diseases properly.”