One of our most endangered pollinators in not a bee at all, but a butterfly. The monarch—a name nearly synonymous with “butterfly” in North America—is rapidly declining in number.
Like other pollinators, the monarch is exposed to pesticides, urban development, freeways, and modern farming. All of these take a toll. But the monarch is unique because, much like a bird, it makes a yearly migration from north to south and back again. Monarchs from east of the Rocky Mountains overwinter in southern Mexico. Monarchs from west of the Rockies overwinter around Pacific Grove, California.
Unlike a bird, however, the monarch migration spans several generations. In other words, the monarchs that left in the fall are not the same ones that come back in the spring. So how do they know where to go? This is a question that hasn’t been answered.
What we do know, however, is that habitat destruction is vastly reducing the number of monarchs that can survive the transcontinental trip. In Mexico, illegal deforestation is destroying the overwintering grounds that the monarchs have used for untold generations.
In the north, vast numbers of milkweed plants are being replaced by weed-free farms, cities, golf courses, and industrial complexes. Milkweeds in the genus Asclepias are the primary food of larval monarchs. The larvae, known as caterpillars, eat the leaves of the milkweed. These leaves contain toxic compounds called cardiac glycosides that the monarch stores in its tissues making them unpalatable—or even poisonous—to predators.
The monarchs cannot survive without the milkweeds or the overwintering grounds, meaning that the monarch is being squeezed at both ends of its long and arduous migration.
If you live in North America and would like to assist the monarchs you can plant milkweed plants such as Asclepias tuberosa, A. speciosa, A. syriaca, A. incarnata, and A. curassavica. In addition, the monarchs need nectar plants such as purple coneflower, cosmos, joe-pye weed, Mexican sunflower, verbena, and floss flower. And tell your friends. The more voices the monarch has, the greater our chance of saving it.