Monarch butterflies were my guides across the Great Basin last fall. I followed these beautiful migrants for thousands of miles across the West to see the land as they saw it, feel their urgencies, surrender to their compass. By doing so, I also hoped to solve a mystery that has perplexed lepidopterists for many years: Where do western monarchs go for the winter? The conventional wisdom is that all monarchs west of the Rockies winter on the California coast. But I suspected that some of them might sail south through the Great Basin to Mexico where the much more abundant eastern monarchs cluster in radiant orange masses every winter.

Beginning in Canada, I tracked monarchs down the Columbia River, then up Hells Canyon and along the Snake River. Whenever I saw a monarch in flight, I would track it for as long as I could on foot, while the butterfly floated on the wind. When I could no longer keep up, I watched it through binoculars until it vanished and took a compass reading on the direction it was headed. Then I would drive in that direction searching for likely monarch resting and nectaring spots along the way. I came into the Great Basin after spotting two butterflies heading southeast from the Snake River Plain in a direction that would take them directly over the Bonneville Salt Flats.

The chase was on!

When I saw trees at a rest area on I-80, I stopped to camp. The trees—14 robust Russian olives in seven watered planters—might make a suitable monarch roost. That night I re-read a passage from Edwin Way Teale’s Autumn Across America which had inspired me to come this way: “Three monarch butterflies drifted by, then two more appeared in sight—five monarchs winging their way across the desert on their long migration south. More than fifty barren miles of salt and alkali lay between them and the southern boundary of this desolate, plantless waste.”

My chances of duplicating Teale’s sighting seemed vanishingly small. But as soon as the sun hit the trees the next morning, I got up and walked out on the salt flat so I could watch the grove with the sun at my back.As the sun rose higher, the saline pallor of the place threatened to bleach out everything that was not already white. I watched for an hour. I was thinking about breakfast when a monarch fluttered up from the largest tree.

The monarch drifted on the breeze. Then it glided around in spirals, gaining altitude. At 50 feet or so it flew over me. I saw through its backlit wings. They looked like tiny amber windows. Suddenly a barn swallow appeared and I briefly feared for the monarch.Birds aren’t supposed to eat monarchs. The milkweed plants on which they are born and which provide their first food also provide them with a defense against predators. Their early diet of milkweed makes them distasteful. But birds have to learn this. The swallow made one investigative pass but then veered away. The butterfly continued to spiral for a minute or two longer, letting the sun warm its flight muscles. Then, just three minutes after arising, it began flapping hard and fast, making forward as well as upward progress to the south. It stopped at about 100 feet to spiral up again on a current of warm air rising from the ground as the sun beat down on the salt flat. At around 150 to 200 feet the monarch began flying southeast at a moderate clip—flap-flap-flap-glide, flap-flap-flap-flap-glide. I watched it through binoculars as it passed over a train chugging eastward across the dried brine, raised up in bumps and warts and folds that sparkled like sugared donuts. I followed it for about a mile before distance and spontaneous tears of gratitude for Ed Teale and the guiding hand of chance blurred my vision of the receding speck of bright orange. I marked its trajectory on the salt flat, a steady bearing east-southeast at 120 degrees.

A truck driver watched me taking bearings from the shade of his rig. Later, he sidled up, watched me cooking oatmeal on a picnic table.

“What’s that supposed to be?” he said.

“Oatmeal,” I said

“How do you make it?” he asked

“Put oats in water.”

“Huh.”

He didn’t ask about my lines of stones and compass, though I knew he wanted to. I felt a little bad about not being more forthcoming. But while the shivers of this experience were still reverberating, I wanted to write up my notes, not natter. I wanted to eat my hot oatmeal, not talk about it, and to conjure with Teale on the monarchs’ course across the flats, the continent.

As I was leaving the rest area, I gave my cans to an elderly Japanese-American couple who were gleaning aluminum from dumpsters and barrels. It seemed that everyone out here was searching for something. Sometimes it is as concrete as aluminum cans, twenty cents a pound. It might be as simple as a conversation on a long haul, and still be denied; or as illusory as the painted lures of the casinos just across the state line in Nevada. And then some of us, maybe the neediest of all and the best rewarded on this morning, seek something from following the wings of creatures compelled to wander continents.

If we all have anything in common, perhaps it is the indifference of our quarry. Here on the Bonneville Salt Flats, Ed Teale had found that “it is easier...to accept the message of the stars than the message of the salt desert. The stars speak of man’s insignificance in the long eternity of time; the desert speaks of his insignificance right now.”

I had found a monarch crossing the Great Basin headed southeast toward the Colorado River and Mexico. I would follow its direction until I reached the border and saw monarchs headed south into Mexico.

The spectacle of millions of monarchs completely blanketing the forest is one of the grandest wildlife spectacles anywhere. Tourists flock to most popular roosting groves in Mexico and along the central California coast. But it is a kind of nirvana I prefer to share with no one but the monarchs.I have experienced such ecstasy among the monarchs in Mexico. And I experienced it once again on this trip when I camped at Morro Bay on my way home from the border.

At first light I saw dark clumps in the tall eucalyptus trees above me but I wasn’t sure if they were monarchs or leaves. A squirrel climbed a tree as I looked up. It leaped from one limb to another and suddenly set off an explosion of golden particles into the sunbeams filtering through the trees. In that instant I saw more monarchs than I have seen on this whole trip. With no means of making a detailed estimate, nor knowing the extent of the colony, my rough impression put the number here somewhere under ten thousand. As ever when I am among the monarch masses, it was almost impossible to pull myself away. Finally I did, with promises to return soon. The monarchs did not notice.

Passing through the village of Cayucos, I spied a garden full of purple lantanas brimming with monarchs. Trying to look unobtrusive, I commenced catching them with forceps and tagging them. All along I had applied the tiny numbered adhesive tags to monarchs' wings, in hopes of one or more recoveries that would confirm my hypothesis.

As dusk came, the air cooled and the monarchs left the garden one by one. I reached to tag one last butterfly nectaring intently on an orange blossom. But I watched it too long, drunk on the pleasure of it all and the sweet scent that had also beguiled the monarchs. The butterfly grew restive, I reached, missed, and it flew off. To where? I’ll never know.

Then I realized that elegant butterfly, a pale orange oval rimmed by a citrus streak and hemmed in black and white, burrowed into one simple white blossom, might be the last live monarch I would see until next spring’s migration.

Danaus plexippus is the Latin name for the monarch species. Monarchs are members of the Danainae subfamily, commonly known as milkweed butterflies because their catterpillars feed solely on milkweed plants. Milkweed is found over much of North America. But monarchs can’t survive a frost. So in order to exploit the abundant milkweeds of the north, they evolved the most remarkable insect migration in the world.

To envision the life cycle and migration of the monarch, let's begin in the fall, with a monarch ready to emerge from its chrysalis. The pale green pellet, studded with gilt knobs, has turned the color of molasses. Just before it splits open, the casement goes transparent and the pattern of the butterfly can clearly be seen, but in miniature. The pupal skin breaks away and the adult butterfly, its abdomen bloated and its wings crumpled, tugs itself out into the air. Hanging upside down, it pumps fluid into the veins of its wings, which expand to their proper shape, as its abdomen shrinks to its slender form. When the wings dry, the leading vein stiff like a kite's strut, the butterfly lifts off into the breeze for the first time.

As the milkweed that nurtured it so far withers and its pods burst in silky explosions, the monarch deserts the fields and meadows of the north and sails southward. In a good monarch year, as this has been, great hordes of orange butterflies push with the weather along many of the same flyways used by the departing birds of fall. By day, adroitly exploiting thermals, they may fly thousands of feet into the sky, then glide for many miles before dropping again to nectar on sunflowers, goldenrod, or rabbitbrush. They will need the fat converted from nectar to get them through the winter. Sometime around the Day of the Dead, Nov. 2, they reach their destination in Mexico or on the California coast.

Each spring, around the equinox, the monarchs reverse the flow, and spread north again. Now they are interested in sex. Increasing day-length has changed their chemistry. Males aggressively take down females and fertilize their eggs. From here, chance and weather conspire with twin drives to disperse and find milkweed. As they wing northward, the females leave their eggs on milkweed plants they find along the way, From those eggs will spring minute caterpillars bearing their genes. They will gobble milkweed at a rapid rate, molting four times, until they are black-,yellow-, and ivory-striped. From a fifth molt, after a few weeks, will come the jade jewel box of the chrysalis, where we began.

I crossed the Sierra Nevada and headed north. I had seen the monarchs at play in their winter homes and now I too wanted to get home before winter came. But I decided to cut through the Great Basin to see if I might cross paths with any monarchs stragglers headed south a little late.

I followed the Truckee River to Pyramid Lake. I’d imagined searching the shore for monarchs. But it was dark when I got there and I decided to press on. I slept in my car when I got to the Black Rock Desert. It was cold when I woke and I didn’t expect to find any butterflies there. So I headed north again to Surprise Valley, where I still harbored a small hope to be, well, surprised. But by the time I got there I had given up on the monarchs. I decided to leave the Great Basin here instead of continuing north to the Warner Valley wetlands.

Crossing the Warner Mountains on Fandango Pass, I spotted a stand of showy milkweed, the first I had seen in days. I stopped to look it over. Some of the leaves were green, but looked frozen. And then, yes! I couldn’t believe my eyes, There was a monarch chrysalis! I wanted it to be alive. It was still green and gold, but not the beech-leaf spring green of the one I had found when I began this quest in Canada. The gilding of this chrysalis was almost the gold of my wedding ring, but like it, a little tarnished. Finally, I had to admit that this pupa was the sarcophagus that chrysalides are frequently likened to—dead, and darkening. But frozen almost certainly, just last night.

So I might have seen a cinnamon-colored wind sailor blowing past me down in Surprise Valley under the triple rainbow I saw earlier in the day. A few degrees warmer, a little more sunshine, and this straggler might have flown today. Whether it could have made it to any winter sanctuary this late is an open question. Surely the last to leave do not always make it, just as the first to arrive here in spring can be victims of late frosts and storms. But this poor pupa nonetheless linked the trip home to the trip out, the Columbia River to the Great Basin to the Sonoran desert to the rest—but which rest? I imagine that a monarch would probably go to the California coast from here. Yet it is not that far east of here to the Great Basin flyways where monarchs steered me southeasterly—pointing me, if not leading me, all the way to the border—where I found monarchs southing into Mexico, west of the Continental Divide after all.

This monarch is indeed linked to all the others. And if it won’t join them in the winter clusters, it has at least taught me again that quality Robinson Jeffers described in “November Surf” as “the dignity of room, the value of rareness.” The astonishing monarch masses Jeffers knew in Carmel, that I knew just days ago at Morro Bay, can never do the same.

I loved them there in their shimmering thousands, but maybe I came back inland in order to regain that rarefied company in which I have been traveling all these weeks, when every individual truly counted — as this one frozen chrysalis surely counts, beyond measure.

Robert Michael Pyle is writing a book about his journeys with monarchs for Houghton Mifflin.