They studied the caterpillars’ response to airborne sounds and surface vibrations at high- (2000 hertz) and low-frequency (150 hertz) sounds. The next step was figuring out how they were hearing the sounds, and to do that, the team removed some of their hairs. While that might seem like an odd strategy, many insects perceive sound through hairs that detect how it moves the air. In fact, the team’s caterpillars were less sensitive to sounds after they lost hair on their abdomen and thorax. “And the way it’s always been done is to look at what animals do and learn how animals detect sound.”