Bugs fly high in the sky on an insect superhighway

You probably don't have a second thought when a butterfly flutters before you. But the butterfly just may be using your backyard as an exit ramp from a kind of insect superhighway high above your head -- miles above... as high as mountains. Scientists have learned that some three billion insects, from butterflies to spiders (using their webs as hang gliders), float over us on any given .6-mile plot of air, hoping, of course, to land in a promising place so they can maybe find a good dinner and date. After all, life is an adventure.