All Hail, the Monarchs
Imagine setting off on a journey so essential to your family’s continued existence it takes multiple generations to reach the final destination. Add to this generations-long trek such complications as extreme weather, lack of shelter, sleep deprivation, starvation, and the risk of food poisoning when food is at last found—all obstacles which must be overcome by you, your child, grandchild, and so on, within a set length of time before the objective is reached. Reads like an intriguing plotline for a riveting novel, doesn’t it? Consider it more a biography, if you will, of the majestic monarch butterfly.
With a life story such as this, it’s no wonder the orange-winged beauty has left so many spectators—scientists included—in awe. Unlike other butterflies, the monarch’s seasonal migratory practices make it a truly unique species. The World Wildlife Fund goes as far as saying it’s “the most highly evolved migration pattern of . . . perhaps any known insect.” Traveling roughly 3,000 miles each fall, these pollinators fly south toward the warm coastal climates of Southern California and central Mexico’s Sierra Madre Mountains to escape the cold—a dip too far below 55 degrees Fahrenheit would render them flightless.
Their migration path and winter roost depends on the monarchs’ origin. Those that begin their initial journey from southern Canada, the American Midwest, and eastern states make their winter home in Mexico, while monarchs that reside west of the Rocky Mountain Range travel to sites near Monterey Bay, the surrounding Greater Los Angeles area, and San Diego. Throughout its southward voyage, this “first generation” feeds on nectar-bearing plants, such as the California poppy and common sunflower, storing as much energy as possible in preparation for the lengthy winter ahead. Foraging for various flowering plants along this migration path is imperative to the adult monarch’s winter survival, as nectar provides lipids (molecules that include fats, vitamins, and other beneficial components), which can be stored and metabolized into energy.
While the lifespan of most monarchs is between four and six weeks, for these first-generation travelers, an extended winter allots them six to nine months of life, half of which is spent in hibernation. When the first hints of spring arrive, this well-aged group needs all the nourishment it can gather for its initial stretch north and short-term mating season. During this final crossing, the overwintering generation must lay as many eggs as possible to give its species a chance for survival. The following two to four generations of offspring will continue the northbound migration, mating, laying eggs, and pollinating plants as they feed on nectar—making their important contribution to the circle of life.
According to the U.S. Department of Agriculture (USDA), the monarch is the only butterfly that makes such a roundtrip migration, similar to birds. But unlike migrating birds, monarchs rely almost exclusively on one type of plant for their species’ survival: milkweed. As the name would indicate, this tasty treat—for monarch young, at least—is a wild, weed-like perennial that contains a milky substance known as cardenolides, a toxic steroid that when ingested can cause cardiac arrest in animals. Monarchs are impervious to this toxin. When the larvae eat the plant, they store a toxic chemical compound that is bitter tasting and alkaloid, which is often poisonous to the species’ predators. The bright orange coloring of the adult’s wings serves as a warning sign of this toxin.
There are around 140 milkweed species grown in North America, and of those more than a dozen are California-native plants. Two species are particularly common in the area surrounding the Los Angeles Zoo: narrow-leaf (Asclepias fascicularis) and showy (A. speciosa). Each has a slightly different flower, ranging from white to pale-pink, and a deep purple. And all grow well in the clay-based soil that’s prevalent in the area.
“The plants produce attractive flowers that develop into large, showy seedpods that open and disperse masses of seeds covered in fluff,” says L.A. Zoo Senior Gardener Andrew Lyell. The “fluff” is then carried through the air, planting seeds sporadically across the landscape for future growth. At the Zoo, to help the milkweed along, Lyell occasionally scatters seeds into the wind, awaiting springtime to see where they previously landed. “Near the Rainforest of the Americas, a small group started from one seed,” says Lyell. “Many more plants appeared, and with them came the butterflies, flitting from plant to plant and depositing their eggs.”
Although the perennial is an attractive, easy-to-maintain, drought-tolerant plant, its tendency to grow wild like a weed and move in on less-invasive plants can prove troublesome. Combine this characteristic with its toxicity and it’s easy to understand why crop growers across America would want to do away with the milkweed. Weed-killing chemicals, such as herbicides and pesticides, have all but wiped out the nutrientrich monarch food, and in the process caused a major decline in the brightly winged butterfly.
In 2014, National Geographic reported on a study, spanning ten years of research, which correlated a 58-to-81 percent milkweed-to-monarch decline. And according to the U.S. Fish and Wildlife Service, monarch populations have been reduced by about 970 million across the U.S. since 1990. While these numbers point to a need for growing awareness and especially action, all is not yet lost.
The butterfly is currently under consideration to be included in the federal Endangered Species list (a decision that must be made by June 2019), which would make it the first insect listed. In November 2015, the USDA announced that its Natural Resources Conservation Service is investing $4 million in conservation efforts to help agricultural producers in 10 states with the provisions of food and habitat for the dwindling monarch populations.
Surprisingly, one factor that may benefit the monarch is the longstanding drought that has otherwise plagued the state—as many homeowners are replacing lawns with drought-tolerant native plants, including milkweed. And there’s still much that local gardeners can do to help the species, advises Lili Singer, director of special projects and adult education at the Theodore Payne Foundation for Wild Flowers and Native Plants in Sun Valley.
“Southern California is one of the better locations for growing milkweeds because they all grow well in clay soil,” says Singer. “They love the sun and they love the weather here.” She cautions against buying just any milkweed, especially those that are not native to the area. The trouble with non-native plants is that some species of milkweed predispose caterpillars to disease, to which monarch butterflies have not yet adapted. One such species is tropical milkweed (A. curassavica), also called bloodflower.
If you want to give a boost to these butterflies, the best time to plant milkweed is between March and May, free of fertilizers and soil amendments, watering regularly in the early weeks to help the seed develop. In addition to the three common L.A.-area milkweeds mentioned above, Singer also suggests planting the Indian or woollypod milkweed (A. eriocarpa), which have large leaves and clusters of appealing cream-and-pink petals.
Once established, the plant will hopefully welcome a host of monarchs and in turn the caterpillars that will take their parents’ place in the cycle of life.
Originally published in Zoo View, Spring 2016