North American walnut sphinx moth caterpillars (Amorpha juglandis) look like easy meals for birds, but they have a trick up their sleeves- they produce whistles that sound like bird alarm calls, scaring potential predators away. At first, scientists suspected birds were simply started by the loud noise. But a new study suggests a more sophisticated mechanism the caterpillar’s whistle appears to mimic a bird alarm call, sending avian predators scrambling for cover. When pecked by a bird, the caterpillars whistle by compressing their bodies like an accordion and forcing air out through specialized holes in their sides. The whistles are impressively loud-they have been measured at over 80 dB from 5cm away from the caterpillar- considering they are made by a two-inch long insect.