Saving America’s Iconic Butterfly from Extinction
Researchers estimate that twenty years ago about one billion monarch butterflies formed black and orange clouds as they swarmed southward from the Eastern Rocky Mountains of North America and traveled up to 3,000 miles to Central Mexico’s Oyamel fir forests. Another million overwintered on eucalyptus and fir trees in coastal California. Dubbed ‘king of the butterflies,’ the monarch (Danaus plixippus) continues its annual migrations, but its numbers have diminished greatly over the past two decades.
The U.S. Fish and Wildlife Service estimates that more than one billion monarchs — 90% of the entire population — have vanished in the last 20 years. Primary evidence of the declining monarch population comes from an annual study by Monarch Watch, a research and conservation organization. They evaluate the population of these iconic insects by measuring the number of hectares occupied by monarchs in Central Mexico’s overwintering grounds. Their most recent status report, published in February 2017, shows a 27 percent decrease from last year’s population.
These plummeting numbers have led some scientists to predict that the monarch butterfly is on the verge of extinction. But, as with any debate, there are naysayers, perhaps the most vociferous being Dr. Andrew Davis, assistant professor of ecology at The University of Georgia. In 2011, Dr. Davis wrote an article faulting the measurement tool that has led to such projections, stating that “even though the overwintering population is getting smaller and smaller, once they come northward in the spring they are able to recoup the numbers.” The jury is out, but several valid hypotheses hold sway in the debate over the declining monarch population.
Possible Causes for the Dramatic Decline of Monarchs in Only Two Decades
- Destruction of Milkweed Habitat: As the ONLY host plant, milkweed is essential to the survival of the monarch at each stage of the life cycle. In recent years, female monarchs have found it increasingly difficult to find suitable plants on which to lay their eggs each spring. Once covered in grasslands, the American Midwest was a particularly ideal ecosystem for the monarch, providing an abundance of milkweed and nectar plants. Some scientists base their correlations of the 20-year decline of the monarch with changing land use.
- Fields, once plentiful with milkweed, have been converted to corn and soybean production. A rise in these genetically modified, “Roundup Ready” crops, has effectively eradicated milkweed from the land. Not only farms and fields, but also roadsides across the country have been affected.
- Massive land development has turned fields into skyscrapers and parking lots. For more on the loss of breeding habitats for the monarch, visit the Monarch Joint Venture (“MJV”) website, http://monarchjointventure.org/habitat-loss.
- Reduction of Migratory Monarch Population: Long-term surveys of adult monarchs in the summer months have not shown a decline over time, suggesting to scientists that problems may occur during the butterflies’ transit to Mexico. Several explanations contribute to this theory.
- Changes in climate may be confusing to the monarchs. If temperatures rise above normal in spring, it may throw off their flight patterns; monarchs have been known to leave their nesting grounds for cooler climates before the emergence of milkweed in their flight path. For a complete report on climate vulnerability and the monarch butterfly, visit the World Wildlife Fund website, www.worldwildlife.org/pages/monarch-butterflies-and-climate-change.
- Well-intentioned, but uninformed, humans may be interfering with the migration of the monarchs by planting ‘the wrong type of milkweed’ in their gardens. In an effort to supply monarchs with milkweed, they have planted a widely available milkweed, native to the tropics. This tropical milkweed (Asclepias curassavica) does not die back in warm winter climates, thus encouraging monarchs to stay put in the southern United States rather than continuing their migration to Mexico. This non-native milkweed poses an even graver risk to the survival of the monarchs. Tropical milkweed harbors an ever-present parasite (Ophryocistis Elektroscirrha, “OE” for short) that infects the monarchs, thus weakening them and shortening their lifespan. Most infected insects never complete their migration. For photographs and a comprehensive layman’s discussion of this destructive parasite, visit http://www.wildones.org/wp-content/uploads/2015/04/Biology-Life-Cycle-of-OE-by-Monarch-Watch.pdf.
- Destruction of Monarch’s Overwintering Habitat: Logging, both legal and illegal, has resulted in the destruction of trees on many acres of land in Mexico’s fir and pine forests. Land converted for farming has also led to forest degradation. Water, diverted away from the area for human consumption, has contributed to altering Mexico’s distinct microclimate. Development and pollution in California has resulted in loss of habitat for this western population as well.
Government and Non Profit Efforts to Protect Monarch Butterflies
There is a plethora of initiatives by both government and private agencies to monitor and protect the beloved monarch butterfly. Monarch Joint Venture (“MJV”) is a science-based partnership of over 50 federal and state agencies, non-governmental organizations and academic programs, dedicated to conserving the monarch migration in the lower 48 United States. Partners include the U.S. Fish and Wildlife Service, the U.S. Forest Service, the National Park Service, the Xerces Society for Invertebrate Conservation, and Monarch Watch, as well as many local foundations and conservancies, museums, botanical gardens, and more. They offer the general public many ways to become involved: monarchjointventure.org.
Community Efforts to Boost the Monarch Population, One Backyard at a Time
Chances are good that you first learned the four stages of a life cycle—egg, larva, pupa, adult—by observing the life cycle of a butterfly. And, chances are good that the monarch butterfly was one of the very first butterflies you were able to recognize. As an elementary school teacher, my students and I tracked the journey of these brilliant orange and black insects every year with a popular global migration program called Journey North. www.learner.org/jnorth/monarch/migration.
Monarchs and their phenomenal annual migration capture the imaginations of young and old across North America. For this reason, communities are banding together to learn what they can do to save our graceful fluttering friends from extinction. The National Wildlife Federation has a program called the Mayors’ Monarch Pledge, designed to create habitats and educate citizens about the monarchs’ plight. Communities all along the main migratory flyway between Austin, Texas and the Great Lakes are planting roadsides with native milkweed and nectar plants. St. Louis, Missouri and Charlotte, N.C. are both designated sanctuary cities for monarchs. Closer to home, the Loudoun Wildlife Conservancy has initiated a challenge to raise and release 2,000 monarch butterflies this summer in Loudoun County alone. loudounwildlife.org/habitat-restoration.
So, what can you do to help? The simplest answer — “Build a Monarch Way Station.” A monarch way station is simply a garden that has both milkweed plants to feed the larvae and nectar plants to feed the adults.
How to Build a Way Station for Monarch Butterflies
Location: Select a spot that receives at least six hours of sunlight per day.
Size: Scale it up or down to suit your space. Though not ideal, even deck containers may constitute a way station when space is limited.
Soil: Low clay soils are best, as good drainage will help prevent root rot.
Host Plants: It is recommended that you have at least 10 milkweed plants, preferably two species of native milkweed. Since different species mature at different times, you will increase the duration of monarch activity in your yard by increasing the number of species you plant.
Milkweed is essential to any monarch way station as the monarch larvae eats only milkweed. Females lay their eggs exclusively on milkweed plants, tasting the leaf to make sure it is suitable before laying their eggs. A newly hatched caterpillar eats its nutrient-rich eggshell before consuming the leaf, containing a toxic chemical that protects it from predators.
There are many varieties of milkweed, but you must select the species carefully. Most definitely do NOT plant the tropical variety that carries the insidious OE parasite! Choose milkweeds that are native to your area. According to nearby Loudoun County’s website, the top three choices for our area are:
- Asclepias syriaca (common milkweed)
- Asclepias incarnate (swamp milkweed)
- Asclepias tuberosa (butterfly weed)
To learn more about the best species for your area and to purchase plants, visit the Xerces Society website at xerces.org/milkweed/which species to plant.
Nectar Plants: Some sources say that goldenrods and asters are critical for adult monarchs, but there are many colorful options. Annual plants, such as Cosmos, Marigold, and Zinnia are good choices. Perennials include Joe-Pye Weed, Coneflower, Bergamot, and Mountain Mint. As with milkweeds, try to select both early and late season bloomers to attract the monarchs to your site from early summer through fall. Fruit-bearing trees are also welcome additions for butterflies’ all-liquid diets. Consult the North American Butterfly Association for a complete listing of the best butterfly nectar plants in Central Virginia. This list is not exclusive to the monarch, but specifies which plants attract which butterflies. www.naba.org/ftp/ceva.pdf.
There are many excellent guides to help you create a sanctuary for monarchs in your own backyard. To my mind, the single most important stop to make on the web is Monarch Watch.org. They will even provide you with a kit to get you started and walk you through the steps of certifying your garden. Their downloadable brochure, entitled Creating a Monarch Waystation Guide, contains step-by-step directions for the amateur gardener. www.monarchwatch.org/waystations. If you are a visual learner, watch a Youtube video of a monarch habitat created in Waterford, Virginia by Nicole Hamilton, president of the Loudoun Wildlife Conservancy, “How to Create Your Own Monarch Butterfly Rest Stop,” How to Create Your Own Monarch Butterfly Rest Stop | National Geographic.
“Monarch butterfly studies tell a perplexing tale,” www.sciencemag.org/news/2015/08/monarch-butterfly-studies-tell-perplexing-tale