ambience: Dogbane Tiger Moth
You might think of a moth as a silent insect, but some of them can make noise, and scientists think that they do it to keep away bats. I’m Jim Metzner and this is the Pulse of the Planet, presented by DuPont. We’re listening to the sounds of a Dogbane Tiger Moth. It can vibrate a part of its body in much the same way that a cicada does. Normally, the moth sound is too high pitched for humans to hear, so we’ve slowed the recording down thirty-two times. But at its actual speed, the moth sound is in the perfect range for bats to hear. “Bats locate insects by echolocation.” Gilbert Waldbauer is an insect expert at the University of Illinois. “The bat makes a very high-pitched sound and this sound bounces back off insects flying in the air, and a bat, which has very sensitive ears, can pick up the echoes from the insect flying through the air.” Most insects will try to escape a bat by flying away, but certain types of moths take a different approach. “When these moths hear a bat, they do not take evasive action, they make a sound that is at the same pitch as the bat’s sound.” Here’s the sound, again at slow speed, of a big brown bat, and now here’s the clicking sound that the Dogbane Tiger Moth makes in response. ambience: Bat & moth The moth sound appears to be a defense, to keep the bats from eating it. One theory is that the noise interferes with the echolocation signals the bat needs to find its prey. But Gilbert Waldbauer thinks that it’s more likely the moth sound reminds the bat that it really doesn’t like the way that this particular insect tastes. “As a matter of fact, if you try to feed one of these moths to a bat in captivity, the bat will spit it out and then try to get rid of the taste of the moth.” ambience: Dogbane Tiger Moth Pulse of the Planet is presented by DuPont, bringing you the miracles of science, with additional support provided by the National Science Foundation.