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Maybe you're getting them, flashes of orange and black in your backyard garden, or around the flowerbeds bordering your neighbor's home, in the Fallow Fields, or even amid the landscaping at Wegmans in DeWitt. They are the famous royalty of the world lepidoptera: the monarch butterflies. And they are on the move.
After all, it is early October, and these fragile, striking insects are on their way back to the homes of their ancestors, far to the Southwest. Arguably America's favorite bug, these Danaus plexippus (named for the mythological king of Egypt and descendant of Zeus) are not the same butterflies that you may have seen coming into their progeny, the fourth generation of an annual life cycle that began earlier. in the high Sierra Madre mountains of central Mexico.
Some of this is a familiar, classic study in insect propagation and metamorphosis: Monarchs mate, the female lays eggs, then a distinctive striped yellow, black and white caterpillar hatches. Feeding for the next two weeks on the milkweed plant where it originated, the sated caterpillar then spins itself into a chrysalis and, after a serious, 10-day transformation, emerges as an adult monarch.
Then things get complicated. Since they are cold-weathered, their "winter-over" habitat in Mexico's Michoacon Hills (and California's Pacific Grove for those west of the Rockies) provides the requisite climate where millions hibernate until February. Summoning the last of their strengths, these butterflies then, the larvae eat, the eggs, and their evolutionary mission completed, die. This reproduce-and-die cycle will be repeated by March and April and then through the United States, with steadily moving northward, with two months to six weeks.
The fourth, and final generation, however, is injured. With increased life spans of six to eight months, this is the final strain that you have not seen in your late-blooming flowers. and pollinating your garden. And, when the time comes – around mid-September and beyond hereabouts – heading home.
Watching monarchs fly their fortitude and their daunting mission. At 2.5 to 2.75 grams they seem weightless, wafted by the ficklest of breezes, and driven by four gossamer, dappled wings that beat in short bursts at 300 to 720 beats per minute, a lower rate than most other butterflies.
And their flight pattern, swoops and rises, can seem erratic. But by riding thermals, or warm updrafts, and coasting at speeds estimated to be anywhere from 8 to 25 mph, and replenishing their energy along the way, these peripatetic vagabonds manage to cover 2,500 miles back to the winter home of their great-grandparents.
Even more mysterious is the monarch's guidance system, an unexplained ability to somehow navigate an unfamiliar course of thousands of miles, arriving at a refuge they have never seen.
Like many other species, however, monarch butterflies are feeling the negative pressure of human activity. They have a history of milk production, milkweed, pesticide and herbicides.
"Monarch butterfly populations are declining due to loss of habitat," according to Chip Taylor, director of Monarch Watch, a research and support facility at the University of Kansas. "To ensure a future for monarchs, conservation and restoration of milkweed needs to become a national priority."
Karen Oberhauser, an entomologist and educator at the University of Wisconsin and director of the UW Arboretum, cites "the risks posed by global climate change and pest control practices to monarch butterflies" as significant factors in the threat to the species. Noting that monarch population numbers are lower than they have been, and that those numbers fluctuate, Oberhauser reiterates Taylor's point.
"The loss of breeding habitats, areas that have milkweed that the larvae eat and nectar plants that the adults also affect the ability of the population to rebound from fluctuations," she emphasized. The migration itself is described as a "threatened phenomenon," due to habitat loss and drought. As a result, some estimates suggest monarch "over wintering" population losses in the tenfold range during the last decade. A 2015 study estimates has 1 billion population drop since 1990. Other factors include predation and car strikes.
Not all the news is bad, however. The Mexican habitat, where hundreds of millions of monarchs were spent, was expanded by the government to 62 square miles in 1986 and further added in 2000. And there is great concern and support in the scientific community. Monarch Watch director Taylor has described the 2018 migration as "promising," with favorable conditions for monarch population growth "better this year than any year since 2001."
Oberhauser's signature curriculum, Monarchs in the Classroom, is designed to educate students and teachers on biodiversity, especially to monarchs. For the rest of us, the monarchwatch.org website offers updated information on monarch activity, support and conservation (like cultivating milkweed) and monarch-butterfly.com details the monarch's vital information. The 2002 book by Sue Halpern, Four Wings and a Prayer (Penguin Random House), lacking in current statistics, offers a hands-on, comprehensive overview of the lives of Danaus plexippus, and the efforts to preserve them.
By now the bulk of the northeastern monarchs have passed through Central New York on their way to cluster in the fires of the Sierra Madres and sleep the winter off. And then begin their annual odyssey once again. A close encounter with a monarch fluttering is an enduring picture of the changing of seasons, and a paradigm for the cyclical nature of their fragile existence.
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