Along the rivers in the hot plains of Australia where the kangaroos rest in the shadows of the eucalyptus trees and the Kookaburra bird laughs like crazy above the water, the Australian Butterfly sometimes swarms in thousands. These brilliantly colored Pierids are related to our own common white and yellow butterflies that also swarm in great numbers across Iowland roads in summer. The swarming means that some thousands out of millions of eggs laid a couple of months before on the fresh green plants brought by the rains have now come to maturity. But, before they could become butterflies, many millions of caterpillars were eaten by furiously hunting birds. The butterflies themselves swarm forth over the land hunting for new places to lay their eggs where the ephemeral rainstorms of vast dry Australia bring a brief flowering of green life.