We have done a number of stories about the sad state of the monarch butterfly and how their numbers have dropped from a billion to only 33 million as of a couple of years ago. Biologists in the U.S. have been trying to restore the summer habitat of the butterflies by urging the planting of milkweed, which is the primary host plants for monarch butterfly caterpillars.
We have talked about monarch butterflies before. The orange and black butterflies are often used in school lessons about insect ecology. Monarch caterpillars forage exclusively on milkweed; in the process they acquire foul-tasting chemicals that ward off predators. In late summer, monarchs living in the Eastern U.S. migrate to overwintering grounds in Mexico.