ne monarch butterfly flies by. Then another, and another. As they fly, the butterflies seem to float' in They make beautiful shadows" on the ground below. They seem to be ruwhere. In fact, there are so many butterflies that the groups look like beehives in the trees. And when they fly, the sound of 150 million monarchs' wings creates a soft sound, as though it is raining. People say Mexico is the only place in the world where you can hear the sound of butterflies' wings moving.