The Grace and Force of a Butterfly
How the common Monarch can be threatened with extinction
To hold in your hand a Monarch butterfly is to know a way of grace and a force of nature. The Monarch might gently tickle your skin with its proboscis or grab your finger with its spiny legs — these are among the many ways a butterfly can be touching.
But you can neither see nor touch a Monarch’s force of nature — its long-distance migration, which is in many ways a matter of faith. Well, it’s a matter of faith until the moment you learn that the very Monarch you released from your hand one autumn day in Vermont turned up six months later 2,341 miles away at a forest preserve in Mexico.
Weighing less than a paper clip, the Monarch, a female, had left my grasp and flown southbound, crossing rivers and mountains, highways and borders, before being rediscovered by Raul Cruz Gonzalez at a refuge in the town of El Rosario, Mexico. I have never met Mr. Gonzalez, nor have I visited the Monarch wintering preserves in Mexico. Then again, the Monarch had never made the trip there either.
That I released to the winds of fate a gossamer butterfly in my home town, only to have it encountered again so far away in another nation, may be among the most profound of my countless experiences in nature. For millions of people, even those who’ve never literally been touched by this butterfly, the Monarch is one of the best-known and most celebrated insects in the world.
And yet the Monarch is nonetheless imperiled.
In an unusual move last week, the U.S. Fish and Wildlife Service (USFWS) proposed that the Monarch (Danaus plexippus) be protected as “threatened” under the Endangered Species Act. To be sure, the proposal says a lot about Monarchs. I’m interested what it says about the rest of us.
The USFWS’s 55-page ruling is dense with results from decades of Monarch research and conservation planning. Apart from fruit flies, the Monarch may be the most intensively studied insect in the world, resulting in both worthy and flawed science, as well as plenty of controversy, most of which I need not recount for you here. We have other obligations now.
Accordingly, in order to appreciate the debate that will surely ensue about Monarch conservation, and to help us find our way among these amazing butterflies, I’ll set the stage for you with the essentials about how Monarchs live and die among us. I offer this short detour in my essay because I’ve come to realize that too many people do not know enough about this butterfly, and therefore cannot fully understand the fusillade of threats it encounters most everywhere it flies. So, here for you is a year in the life of a migratory Monarch (in only three minutes of reading):
Most of us happen upon the first Monarchs of the year in spring, when the orange-and-black butterflies drift around our farms and gardens and cities, where they sip flower nectar and breed. From that point on, Monarchs produce multiple generations through the summer. A crucial detail is that these spring and summer Monarchs live for an average of two to five weeks as free-flying adults.
And then something unusual happens in the season’s final Monarch generation. To be sure, it proceeds along the routine butterfly life cycle: from egg to caterpillar to chrysalis to adult. But these last-of-the-season adult Monarchs do not live for two to five weeks and they do not immediately reproduce. They instead live for six to nine months — and fly all the way to the mountains of central Mexico or other points south. This is the migratory generation. A distinct western U.S. population leads a similar life, except that those Monarchs migrate to wintering sites along coastal southern California and northern Baja California, Mexico.
Once they arrive at their particular wintering sites, the Monarchs mostly sit around and wait out the winter happening farther north. Surviving on their internal fat reserves, the wintering Monarchs venture out now and then to sip water from streams or melting frost in order to avoid desiccation. (Photo below.) So dense is the concentration of Monarchs at these sites that they turn the Oyamel Fir forests in Mexico a shade of orange visible from aircraft and in some cases satellites.
Finally, in February and March, after months of waiting, the Monarchs break their celibacy, mate at or near the overwintering sites, and begin a journey north. But they don’t make it all the way back. Along their routes, the females encounter milkweed (in the genus Asclepias) and its close relatives — the essential plants on which she lays her eggs. At this point, the migratory-overwintering generation of Monarchs dies off. So it is now up to their offspring (now living two to five weeks) to continue the northbound journey. Reproducing along the way, the Monarchs repopulate most of the U.S. and southern Canada in two or three generations. The crucial thing to recognize here is that since Monarchs don’t exist in any form during winter across much of the U.S. and Canada (not even as egg or larva or pupa), this return flight amounts to a massive annual recolonization of the Monarch, something rarely seen among insects. You’ll see it your backyard among those first Monarchs of spring.
There you have it — the complete life story of a migratory Monarch. A life imperiled. Virtually everywhere it flies — in yards and parks, and especially in migration and at wintering sites — the Monarch butterfly is threatened with a litany of abuse by humans (and other “catastrophic events”), everything from habitat destruction to insecticides to an overheating planet. It therefore warrants the force of U.S. law for its protection.
And yet you may be asking yourself (or asking me): How in the world can one of the most common and adaptable butterflies in North America, an insect of our backyards, chased around and netted by children, be listed as a species “threatened” with extinction? This question will no doubt surface during public debate about the USFWS proposal. And it’s a valid question.
After all, the Monarch butterfly in all likelihood shall not perish from this Earth anytime soon. This decidedly North American butterfly has actually become a kind of expansionist or colonizer, spreading (with human assistance and wind) as far as Australia and New Zealand, and to islands of the Pacific and Caribbean — to 90 countries, islands, and island groups in total. Monarchs have also taken up full-time residence in southern Florida and the Gulf Coast, the southern Atlantic Coast, and the southern Pacific Coast. These are year-round, non-migratory Monarch populations.
Still, as I can attest, what makes a Monarch a Monarch is its annual migration. Despite this butterfly’s haphazard transcontinental abilities, the migratory populations of the eastern, central, and western North America constitute 90 percent of the Monarch’s worldwide range. And those populations face the most proximate and meaningful threats. In the foreseeable future, 60 years ahead, the USFWS puts the probability of extinction of the eastern and central migratory Monarch population at 56-74 percent and at 99 percent for the western migratory population.
Here’s a threat summary (with supporting ecology):
Loss of Milkweed and Nectar Plants — For the northbound recolonization of the U.S. and Canada to work each spring, Monarchs need milkweed on which to lay their eggs and nectar to fuel their flights. Both have been in decline. Nectar availability is particularly crucial during a Monarch’s southbound migration and its ability to survive winter (by converting nectar to fat). A Monarch arriving to Mexico with insufficient lipid reserves won’t survive for its return journey north. (New research, which I’ll write about in a future post, suggests that more Monarchs are now dying on the way to winter refugia.)
Loss or Damage to Wintering Sites — Perhaps the most effective way to kill off a species is to deplete essential habitat where it congregates in huge numbers. In Mexico, this includes illegal logging and agriculture (including for avocados) encroaching on the winter refuge sites. In southern California the threats are mostly urban development, fire, and drought.
Insecticides — What more do we need to say here? Insecticides kill insects. Full stop.
The Climate Crisis — Our over-heating of the planet causes direct and indirect threats to Monarchs, especially at wintering sites. (These aren’t winter condos, after all.) Rising annual temperatures are predicted to make winter sites in Mexico far less hospitable to the Oyamel Fir trees on which Monarchs roost. And more frequent and intense winter storms can drench and then freeze and kill overwintering Monarchs. Sea-level rise and widespread drought are likely to degrade California wintering sites.
In its proposed listing, the USFWS found that the Monarch is “in danger of extinction within the foreseeable future within a significant portion of its range,” which makes it eligible for protection under the Endangered Species Act. This is not a threat of ultimate and irreversible extinction, but rather an extinction of place and a way of life. Or as the writer and lepidopterist Robert Michael Pyle puts it, an “extinction of experience.”
In the end, none of these threats should be surprising. What’s unusual in the case of the Monarch is that the USFWS is proposing to list as threatened a species most of us already know. Monarchs are not abstractions — they aren’t like Snail Darters or Northern Spotted Owls. Monarchs are cosmopolitan — and our companions. They live and die in our backyards. They go where we go. And yet, where we go we too often destroy nature, including butterflies we venerate. That such an adaptive insect is at risk in our midsts says more about us than about the Monarchs.
Perhaps for us there can be redemption. The USFWS is accepting public comments on its Monarch listing proposal and conservation remedies until March 12, 2025. (More on this below.) After that, with the return of the Trump administration, the proposal’s fate, like Monarchs themselves, is uncertain.
On that autumn day near my home in Vermont, when I held in my hand that particular Monarch, little could I know at the time of its fate. And yet a butterfly, weighing less than the breeze, did indeed go on to survive its journey to Mexico. It made the world smaller, bonding me to a place 2,300 miles away and forever strengthening my dedication to people and wildlife and wild places.
In the end, at least for me, that is the way of grace and force from a single butterfly. It is my faith as well.
News, Postscripts, Acknowledgments and an Image Gallery
For Paying Subscribers: My first-of-the-year online meeting with Chasing Nature’s paying subscribers, in January, will be about Monarchs: my experiences with them, yours, and what we can do for their conservation. Stay tuned for news about that.
So how could I know for certain that my Monarch actually flew from Vermont to Mexico? In a community science project, run by Monarch Watch and designed to learn more about the migration, we volunteers affix little stickers with unique identifying codes to their hind wings. Yep, Monarchs fly to Mexico with these stickers, where enough of them are seen and noted for data. Among the more than 1,500 Monarchs I’ve tagged over the course of 25 years, five have been recovered in Mexico, including the female in this essay with tag code CAL189. (One other Monarch I tagged in New Jersey was later found dead in Washington, D.C.)
The USFWS’s 55-page proposal is packed with information (and is a key source for assertions in this essay); but the FAQs at the Services’s Monarch resource page are easier to understand. Good stuff in there.
Ernest H. Williams, a retired butterfly ecologist who studied Monarchs for years and was on the faculty of Hamilton College, reviewed this essay and offered valuable comments. Below are his images of overwintering Monarchs in flight and sipping water from thawing ground frost in Mexico.
I close with my images from the Monarch life cycle.
Beautifully written, as always. Just two things to keep in mind. One, not all Eastern monarchs migrate to Mexico. Some are year-round residents or colonizers northward from the Gulf States and from coastal areas from the Carolinas south. What is at risk is the migration phenomenon, not the species itself, and this is a great departure for classification under the ESA. Two, milkweed is not even close to a critical limiting factor east of the Appalachians. Hundreds of acres go unused every season in MD alone. It's best we treat the Great Plains population as a case unto itself and not generalize nationwide about problems it is (and the West Coast population) is encountering
Wow your photo of a Monarch emerging from its chrysalis is just mesmerizing! And I love learning that it weighs less than a paper clip. 🦋