Frequent Fliers

That old, airy injunction—Pursue your dream—takes on an almost literal flavor when you peer into the world of the lepidopterist. For butterflies can seem like creatures born no less of the mind than of the earth. They are vivid like dreams, and shifting and balky like dreams, and when like dreams they expire, they leave behind an all but weightless residue. In Sue Halpern’s bright new book, Four Wings and a Prayer, the species under scrutiny is Danaus plexippus, the monarch butterfly, which, although a sizable specimen by North American standards, typically weighs less than a gram. Its lipid reserves—the stored fat that fuels its transcontinental flights—are measured by the milligram. We’re in the realm of motes and minims—not far from the world attended by Peaseblossom and Cobweb in A Midsummer Night’s Dream.

Yet these pretty lightweights congregate so densely—in such staggering multitudes—as to bow the branches of the trees they roost upon. They winter in the Transverse Neovolcanic Mountains, some fifty to a hundred miles west of Mexico City, in oyamel pine groves located at an altitude of roughly ten thousand feet. (Smaller winter roosts, for monarchs west of the Rockies, are found in California.) Some of them will have flown nearly two thousand miles, from Minnesota, or perhaps from Quebec, in order to settle there. Among the 165,000 or so known species in the insect order Lepidoptera—which includes both butterflies and moths—there isn’t another species that attempts a journey of remotely comparable magnitude. In the common imagination, butterflies often play the role of pilgrims—wandering souls in life’s garden—but only the monarch initiates an annual pilgrimage marked by such miraculous navigational skills and odds-defying pertinacity.

The mysteries of the monarch’s migration lie at the core of Sue Halpern’s tightly focused book, whose greatest virtue is its clear delineation of the enormous, precarious network of contingencies that arise when so small a creature undertakes so vast a voyage; the monarch’s migration is an elongated chain with any number of vulnerable links. To begin with, there are a host of traditional dangers—drought, fire, predators, storms. In addition, monarchs face a number of imponderable man-made perils that raise the theoretical possibility of the creature’s eventual decimation or destruction: deforestation; transplanted predators, like the fire ant; land development, with its discontinuities of food and shelter; the possibility of poisoning through genetically engineered crops; wholesale climatic change brought about by greenhouse warming.¹

Halpern does a splendid job of giving the big picture of a creature that lives on a bigger scale than other insects. When the monarch is viewed in this way—with the maps and the statistics of its migration before us—we’re beguiled into a realm of pure mathematics. The migratory flights take on the ideal one-dimensional purity of Euclidean lines, and the butterflies themselves the ideal no-dimensional purity of Euclidean points (even more so when you realize that monarchs often fly thousands of feet above the earth, through an ethereal zone, invisible to the naked eye). We’re brought back to geometry in the root sense: earth measure.

The appeal of butterflies is so immediate, and so universal, that any attempt to “explain it” can seem a little fatuous. Any child understands: they’re spectacularly beautiful. And this is a beauty that lingers, or even deepens, the more minutely they’re examined. In Kjell B. Sandved and Michael G. Emsley’s sadly out-of-print Butterfly Magic² we find their wings brought impossibly close—camera turned microscope—and still their beauty holds intact. The scales of the wings become the overlapping pantiles of an Italian villa, a jeweled chain-mail armor, a stained-glass window whose leading has been removed, leaving pure panels of light.

Creatures so beautiful would be alluring under any circumstances, but butterflies additionally offer an unparalleled illustration of life’s capacity for wholesale metamorphosis. Again, any child understands it: this is a present from Mother Nature, a surprise package gift-wrapped in a comely chrysalis. So dramatic a life-passage provides irresistible grist for the moralist and the fabulist, for whom the caterpillar’s seeming death and soaring rebirth naturally raise the possibility of the soul’s resurrection and ascension. The emergence of the butterfly also handily suggests a transcending of coarse appetite, given that the caterpillar’s primary duty is to serve as an “eating machine.” From there it’s a short step to a model of the ideal artist—this creature who first ingests the world (in its larval caterpillar state), then digests the world (in its dormant pupal state), and then skips brilliantly above it, on wings stamped with mysterious runes and glyphs. (The patterns on the wings hold a linguistic fascination as well; like symbols of some remote but breakable code, they can seem no more illegible than, say, Mayan hieroglyphs.)

Compared to birds—that other common symbol of the artist—butterflies display a quiet otherworldliness and suitably papery fragility. Even the diminutive hummingbird looks like a big-shouldered brute beside them. In flight, their bodies all but disappear; they become coded, disembodied panels, messages all but stripped of a medium. Or they are like flowers that—having discarded leaves, stem, roots, every earthly thing—have taken wing.

Given this air of fragility, it’s easy to understand the potent mystery of the monarch—that tireless marathoner among the Lepidopterae, who cumu-latively outlives, outflies, and often outclimbs his brethren, in the process extending our assumptions about metabolic and aerodynamic plausibility. How do these creatures that fan out so broadly across eastern North America in the spring and summer, ranging over hundreds of thousands of square miles, later manage to funnel their way back to such a narrow range—some sixty square miles in all—of Mexican roosting places? Theirs is a navigational feat all the more astounding once one realizes that none of the millions of butterflies that depart from Mexico in the spring are among those returning in the fall; rather, it is their offspring, perhaps three or four generations removed, that find their way back to a winter home they’ve never seen before.

David Gibo, one of the biologists Halpern interviews, refers to monarchs as “aerial plankton with a guidance system.” While their “annual two-way migrations are among the most amazing accomplishments of insects,” the feat nevertheless “can’t be that difficult. We’re talking about an insect.” His remark reflects decades of modern research that has demonstrated how creatures that are extremely limited, in terms of neurons, can nonetheless engineer and administer extraordinarily complicated processes. The two million or so inhabitants of a termitary mound, for example, collectively carry out remarkably precise feats of thermoregulation—though none of them obviously has a clue that that’s what they’re accomplishing. (By contrast, nature writers of the nineteenth century often ascribed prodigious intellectual discernment to primitive brains. Thomas Belt, whose The Naturalist in Nicaragua was praised by Darwin as “the best of all natural history journals which have ever been published,” eventually concluded that the ant, among all the animals, ranked “next to humanity” in its reasoning powers.)

If the monarch’s navigation “can’t be that difficult,” the search for an explanation certainly is. Halpern’s interviewees have accumulated and sifted through mountains of observational data, and devised a wide range of ingenious experiments. They have altered light patterns in laboratories in order to get monarchs to “think” they’re in a different time zone. They have tried to correlate monarch census estimates against weather conditions, particularly wind. They have subjected monarchs to strong magnetic pulses as a way of confusing their internal polarity. This sort of obsessive devotion and restless curiosity comes across as heartening—but so does the realization that nobody has yet concocted a plausible account of how the monarch, with its myopic eyes and breadcrumb-size brain, manages to find its way home each year.

We’re used to thinking of various regions as “belonging” to certain writers. Northern Michigan is Hemingway country (even if, the last time I checked, his surname was misspelled on the state plaque that rendered this designation official). The waterways of the East Indies were long ago claimed by Conrad, and the Galapagos Islands are jointly tenanted by the ghosts of Darwin and Melville.

Animals, too, have their proprietary overseers. Bees have found a patron in Maurice Maeterlinck, the Belgian Nobel laureate. Borges established a lasting claim upon tigers, although Blake, on the basis of a twenty-four-line poem, has also staked a permanent share in them. The aging housecat is forever attached to T.S. Eliot, and as for that odd Malaysian mammal the pangolin, it’s hard to imagine any other serious poet, ever since Marianne Moore set her quirky stamp upon it, taking it up as subject.

The literary lord of butterflies is of course Vladimir Nabokov, who in his long life pursued lepidoptery as both vocation and avocation, and whose descriptions of butterfly pleasures are so dauntingly exquisite as to strike dumb any other observer stirred by a first glimpse of a new swallowtail or morpho. In addition to casting a long net, Nabokov throws a long shadow.

Still, butterflies enliven a wide range of classics, fiction and nonfiction. At the dark heart of Conrad’s Lord Jim glimmers the haunting figure of the entomologist Stein, a “merchant, adventurer, sometime adviser of a Malay Sultan,” who inhabits a world between the shamefully human and the unselfconsciously insectan. Few scenes in The Voyage of the Beagle are so unforgettable as the one where Darwin and his fellow sailors, off the coast of Patagonia, come upon a cloud of butterflies so vast it resembles a warm blizzard:

Even by the aid of a telescope it was not possible to see a space free from butterflies. The seamen cried out “it was snowing butterflies,” and such in fact was the appearance.

Similarly, in his account of the capture of a Malaysian birdwing, Darwin’s co-framer of the theory of evolution, Alfred Russel Wallace, offered an unforgettable image of the visceral excitement—its intensity bordering on nausea—brought on by the hunt for butterflies:

The beauty and brilliancy of this insect are indescribable, and none but a naturalist can understand the intense excitement I experienced when I at length captured it. On taking it out of my net and opening the glorious wings, my heart began to beat violently, the blood rushed to my head, and I felt much more like fainting than I have done when in apprehension of immediate death.

And, down the ages, there are all those winged creatures fluttering wanly through poems, particularly classical Japanese and Chinese verse.

Yet Nabokov, while primarily a prose writer, is eminent even among poets. My favorite butterfly stanza is the conclusion of his “On Discovering a Butterfly,” which was published in 1941, after he found and named a new species:

Dark pictures, thrones, the stones that pilgrims kiss,
poems that take a thousand years to die
but ape the immortality of this
red label on a little butterfly.

The glories of art, of riches and political power, of religion—none is a match for a new variety of butterfly. Even so, in its emphasis on durability the poem suggests that a new species, once discovered, is here to stay. By contrast, what renders much current butterfly research—like that detailed in Four Wings and a Prayer—so poignant is our awareness of perishability amid widespread habitat destruction. Some years ago, I visited a butterfly research station in the Amazon Basin. The operating assumption was not only that unnamed species were steadily disappearing through environmental spoliation, but that we may never be able even to assess the extent of the loss.

If I have a complaint with Halpern’s book, it’s that a number of the characters she encounters remain somewhat sketchy. (I would also have liked a better map of Mexico.) I kept thinking that she, as a portraitist, needed to add a paragraph here, a paragraph there. I felt the lack all the more keenly because her subject abounds in that particularly noble and delightful eccentric, the amateur naturalist.

Anybody who has ever taken a class at a local nature center or done some camping with an experienced guide probably knows just how much imposing, comprehensive erudition often lies hidden behind that designation of “amateur.” A simple walk through the woods with such a person can leave you feeling that you’ve never before actually seen a tree, or peered into a pond. And theirs is knowledge that, obtained without any hope of material gain or social renown, seems both an implicit act of thanksgiving and a pledge, in beleaguered times, of ongoing stewardship and preservation.

Halpern does do a marvelous job with David Gibo, whose yearning to understand monarch flight eventually led him to become a glider pilot. Monarchs “swim through the air,” in Gibo’s eye, and he was determined to swim along beside them, riding those thermal updrafts that make both planes without engines and transcontinental insect flight a possibility. Halpern, though scared nearly out of her wits, gamely decided to accompany him.

I’d often read about how birds and insects ride thermals, but I’d never actually felt hoisted aloft until I read Halpern’s account, beginning when, at two thousand feet above the earth, the glider was disengaged from its tow plane. “Quiet rushed in around us, a whispering quiet, and the plane untensed like a hand gone from fist to open palm, and for the first time since taking to the air we were flying, really flying.” Afloat at such an elevation, the reader comprehends at last the pilot’s goal of crossing the sky “as if the thermals were stones in a stream.”

There’s something faintly mad—gorgeously so—in a scientific quest whose emulation of the flight of a one-gram insect leads to a perilous ascent in a fiberglass plane that must weigh many hundreds of pounds. But there’s also something gorgeously mad (when Mother Nature is viewed not scientifically but poetically) in that stern, queenlike decree that yearly dispatches millions and millions of butterflies on an exodus extending from Quebec to the massifs of central Mexico, with a small army of researchers doggedly in pursuit. The earthbound body—whatever its relative size, and whether biped or hexapod—is summoned away from its temporary perch. Invitingly, imperatively, the sky opens overhead. The horizon beckons.