It’s a warm August night in Los Angeles.
My glass of gin and tonic is dripping in the heat as my roommate Melissa and I sit on our apartment’s balcony to toast the newest additions to our household. Earlier tonight, we were delighted to find a surprise on Melissa’s most recent spontaneous plant purchase of narrowleaf milkweed: two monarch caterpillars.
The black, yellow, and white stripes were instantly recognizable, even on their small bodies. One caterpillar is larger than the other, and has more vibrant stripes, but they both have long black antennae, bent part way up like they’re trying to catch radio waves. I begin doing what I do best — fervent research — fueled both by my affection for these particular caterpillars and the urgency of the suggested related search terms of “near extinction,” “dying off,” and “sharp decline.”
For the next several days, our lives revolve around the caterpillars. Male and female caterpillars are indistinguishable at this stage, but we decide nonetheless that our companions need names and assign them indiscriminately. The larger one, who we name Bruce, begins ravenously plowing through the milkweed, so we buy another plant. It takes a few days for the smaller one, Bitsy, to catch up and do the same, at which point we buy two more plants. The small table on our balcony holds four huddled milkweed plants, two growing larvae, and a whole lot of their droppings, which is called frass. We have to brush it out of the way to make room for our gin glasses, but our evening communes are still full of delight.
As we sit above the hum of street sounds, we marvel at Bruce and Bitsy’s suction cup feet, their lengthening bodies weighing down the milkweed leaves, and how they look almost dog-like when their heads stretch into a sort of snout. Twice for Bruce and three times for Bitsy, we watch them fade in vibrancy then find their abandoned exoskeletons in suspended animation the next day. Monarch larvae go through five of these molts before they’re ready to pupate, or form the chrysalis where they’ll undergo metamorphosis.
Two weeks later, when we enter the window of when my internet research tells me Bruce might be ready to pupate, we watch him as much as we can. Even once we’re fully stocked on milkweed and have enough to get Bitsy through her final molt, I stop by a native plant nursery nearby to scope out their selection. I tell the owner about our caterpillars and ask how a butterfly could have found the single scrawny milkweed plant on our urban apartment balcony on which to lay her eggs. In lieu of an answer, he smiles and asks one of his own. “Isn’t it amazing?” Of course, I agree. And we’re not even at the most amazing part yet.
The next evening, Bruce is gone.
Like a mother who has lost her child in the supermarket, my heart races as I examine each leaf of the milkweed, even though he would be hard to miss. After a few frantic moments, Melissa finds him, but not on the milkweed —he’s across the table on the citronella plant.
“You don’t belong there!” we scold, deeming ourselves intelligent enough to question Bruce’s internal programming, the same programming that led his mother to our milkweed in the first place. After more internet exploration — “Monarch caterpillar not on milkweed?!?”— we discover that this is another step in the monarch lifecycle. Bruce is searching for a place to pupate, and he’s found it. His rear is affixed to the leaf with sticky silk. By the next morning, he’s hanging upside-down in the “J-shape” that signals imminent pupation.
Somehow, in my time as both a student and teacher of biology, I never learned how a monarch chrysalis is made. I’ve heard people use the phrase “enters the chrysalis” or “builds its chrysalis,” but neither are accurate. The chrysalis is inside the caterpillar. After hanging in the J-shape for about a day, the caterpillar shimmies off its exoskeleton, leaving behind a light green blob that settles into a beautiful ovoid shape with a pointed top. Bruce’s chrysalis, which we return to after a long workday, is jade green with a rim of gold and looks infinitely more like a piece of jewelry than what it really is: an insect larva's insides. When it comes time for Bitsy to pupate, we watch her explore the whole table before eventually returning to the milkweed to shrug off her exoskeleton.
Bruce’s chrysalis, which we return to after a long workday, is jade green with a rim of gold and looks infinitely more like a piece of jewelry than what it really is: an insect larva's insides.
For over a week as both monarchs transform out of sight, our evenings on the balcony are lonely. But we receive one consolation. Without anything to go on in our larval stage assessment, we still somehow correctly sexed both Bruce and Bitsy. Our female, Bitsy, is inside a chrysalis with a tiny vertical crease near its top, but Bruce’s is smooth.
Finally, we see Bruce’s chrysalis darken. But no, it’s not actually dark — it’s transparent, and we can see black and edges of an orange wing showing through. It’s almost time for Bruce to emerge, but we both have to go to work. We say our morning goodbyes, but this time they are more heartfelt and urgent than they have been during the uneventful past week. We’re probably going to miss his emergence, and once he’s gone, he’s gone.
Mere seconds after quitting time, I give my coworkers a wave and race home. I drop my bag by the front door and jog through toward the balcony. Before I even get to the door, I see him, transfigured, through the window. A monarch butterfly as large as my hand is perched on a citronella leaf, where a thumbnail-sized chrysalis dangled mere hours before. He hasn’t flown away yet, and my heart leaps.
We both gasp and sigh as he slowly opens his wings and closes them again. They are vibrant orange with beautiful black markings, including a dot on each hindwing that confirms he’s a male, and his thorax is black with audacious white polka dots.
With shaky hands, I FaceTime call Melissa and gingerly open the balcony door. She answers with, “Is it happening?” and I reply by flipping the camera around to show her. We both gasp and sigh as he slowly opens his wings and closes them again. They are vibrant orange with beautiful black markings, including a dot on each hindwing that confirms he’s a male, and his thorax is black with audacious white polka dots. I keep my eyes glued to him, but he doesn’t try to leave. Once Melissa’s home and we’ve sufficiently marveled at him in his final form, he flits to her shoulder, climbs to the top of her head, and propels himself off the balcony and onto our tree-lined street. We lose sight of him almost immediately among the branches. A few days later, I returned from work to another empty chrysalis — Bitsy had left us too.
Though I can breathe deeply that I did enough to keep Bruce and Bitsy alive to adulthood, I’m troubled by the bigger picture.
Although the western population of monarch butterflies has been declining since the 1980s, the most catastrophic loss was in the winter of 2018 to 2019, a single-year drop of 86%. Why that happened, we don’t fully understand, but conservation biologists estimate the monarch population west of the Rocky Mountains to be 1% of what it was in the 1980s. That’s as if going from a full box of cereal down to three spoonfuls. Knowing this deepens my appreciation for the two monarchs on my balcony, but I can’t wrap my head around such a staggering loss or what it means for the monarch population in the coming years.
Conservation biologists estimate the monarch population west of the Rocky Mountains to be 1% of what it was in the 1980s. That’s as if going from a full box of cereal down to three spoonfuls.
In 2019, scientists at the Xerces Society for Invertebrate Conservation suggest an appropriately terrifying name for what is happening to the western monarch population: they are in an “extinction vortex.” At some point, a population becomes so small that normal environmental factors and variation will inevitably decimate their numbers to the point of extinction. That tipping point is called the “quasi-extinction threshold,” and two years prior, a group of conservation biologists out of Washington State University estimated the monarch’s threshold to be right around where its western population currently stands: 30,000. The next few years will tell us if they were right or wrong.
Interestingly, the eastern population of monarchs is much further from extinction, in part because it’s always been larger to begin with. Though the two populations were long believed to be genetically distinct, molecular biologists from Emory University recently disproved that theory: the two groups breeding on opposite sides of the Rocky Mountains have near-identical genomes, likely due to mixing while both groups overwinter in Mexico and coastal California. The same study also found, however, that the populations have different flying patterns. Eastern monarchs are slower with more stamina while western monarchs are the butterfly equivalent of sprinters, but research into why this might be and what effects it could have on survival is still ongoing.
If the western United States were to lose only monarchs but otherwise remain unchanged, it is easy to assume that the ecosystem would find a way to rebalance. But it doesn’t work that way. Because they are relatively fragile and very well-researched, monarch butterflies are the “canary in the coal mine” for other pollinators. If their numbers are dropping, other important insect species are likely not far behind, threatening the survival of both natural and manmade food systems. It’s important that scientists determine the causes of this long-term decline, not to mention potential solutions, before more species are affected.
In researching community science initiatives for monarch conservation, I came across the Xerces-funded Western Monarch Count program (the U.S. Fish and Wildlife Service and San Diego Zoo provide the rest of the financial support). I reached out to the volunteer coordinator for my region, Richard Rachman, a graduate student researcher at Cal State Northridge. He became concerned with monarchs’ decline because of their importance to Southern California’s ecosystems. “Not only are butterflies great pollinators, but for some species their larvae — the caterpillars — are an important food for young birds.”
Despite the uncertainty, he tells me that we do know for sure two causes for western monarchs’ steep decline. The first and major one is habitat loss, both of milkweed for caterpillars and of flowers for adult butterflies. The second is insecticides, which take out other insects as collateral damage in pest control. The silver lining is, these rather direct factors also means that there are straightfoward solutions to counter the decline.
So, since monarch caterpillars are adapted to only eat milkweed, does more milkweed magically solve the problem? Not so fast, says Emma Pelton, the Conservation Biologist of the Endangered Species Program at Xerces and the lead author on the 2019 study. In a recorded presentation, Peloton points out that although monarch caterpillars enjoy both native and non-native milkweeds, some non-native species, specifically the attractive tropical milkweed (Asclepias curassavica), actually confuse monarch butterflies and disrupt their migration. Because evergreen plants like tropical milkweed don’t die back in the mild SoCal winter, they also provide a breeding ground for protozoan parasites that could weaken monarchs and even kill them. Therefore, apart from native milkweed, Pelton recommends native nectar plants for monarchs to feed on as adults. Pacific aster, purple sage, western coneflower, cobwebby thistle, and others will thrive in Southern California while supporting monarchs locally and along their migratory route. Furthermore, until scientists create targeted insecticides, Pelton advises caution when purchasing plants that may have been treated with pesticides.
When Rachman, a botanist by training, rattles off other native plants Southern Californians can put in their yards, my heart sinks a little. I don’t have a yard, and neither do millions of other Southern Californians. Before I bring this up, though, Rachman beats me to it: “By the way, anyone can have native plants on their balcony or tiny patio or anywhere. They’re not just for rich white people. They’re for Angelenos. You have a national park on your balcony. I want to recognize that.”
“By the way, anyone can have native plants on their balcony or tiny patio or anywhere. They’re not just for rich white people. They’re for Angelenos. You have a national park on your balcony. I want to recognize that.” — Richard Rachman, Regional Coordinator (Los Angeles County), Western Monarch Project
It’s good that native plants can be added to sprawling backyards and apartment balconies alike because if western monarch recovery is possible at all, it will take a huge effort. Some monarchs are migratory while others are residential, and it’s the migratory subset, which faces more variable food and shelter, that has been recently decimated. They used to travel in huge clouds, and now their groups are less than a percent of their past size. It’s easy to lose hope, but while their population is tiny, ours is not. “There’s strength in numbers,” says Rachman in the 2021 Monarch and Milkweed Conference. “You yourself did not put the monarch butterfly in this situation, and you yourself are not going to save them alone. But as a collective, we can do so much better.”
I think of the two butterflies that first spread their wings on my balcony. If our milkweed plant hadn’t been there, or if I hadn’t made early morning trips to the nursery for more milkweed, would Bruce and Bitsy have had a chance at survival? There’s no way to know whether our monarchs were residential or migratory—will they stay nearby, occupying the same airspace I do, or will they shake the Los Angeles smog off their wings and fly south toward Mexico?
And I think of another monarch: the one I haven’t written about yet. A third caterpillar appeared while Bruce and Bitsy were pupating, and though we provided milkweed aplenty, it never reached the same size as its predecessors. It went into the J-shape looking much too small, and instead of shedding its exoskeleton to expose its chrysalis, it shriveled and died. We didn’t even manage to name it before monarch season fluttered to the ground and made way for fall.
Once Melissa and I confirm there are no other living monarchs in any stage left on our milkweed, including checking the underside of each leaf for white conical eggs, we clean up. We brush the frass from the table and pluck the half-eaten dry leaves off the milkweed. We scrub at the reddish-brown spots on the table below the successful chrysalises where fluid seeped out as the butterflies emerged. And we adjust our routines to stop slipping out to the balcony every chance we get.
Rachman tells me about another boon to the monarch conservation effort: milkweed is a ruderal, meaning it is incredibly resilient after disturbances. “We bring all of our experiences into conservation. We’re up against a lot, but we’re ruderals too.” The next few years’ monarch counts will tell us if we’ve done enough to stop monarchs from spiraling toward extinction. My own milkweed plants have already started to grow new leaves on their caterpillar-stripped branches.
Next summer, I’ll be ready.
This story has been corrected to reflect the fact that monarch caterpillars are generally mildly toxic to most species if ingested, but not birds.
