The gypsy moth, Lymantria dispar, is one of North America’s most devastating forest pests. The species originally evolved in Europe and Asia and has existed there for thousands of years. In either 1868 or 1869, the gypsy moth was accidentally introduced near Boston.
― US Forest Service
The video of InSight’s first flyover has the ardor of a Hudson River School painting—Elysium Planitia as landscape fades in as a sweeping volcanic desert, a Sahara in raw sienna and yellow ochre rolling like waves beneath the alien spacecraft. A vision rendered from an orbiter, it is a rare glimpse of a place that, at its closest, is 33.9 million miles away.
When InSight lands, a mathematical choreography of parachute, legs, and touchdown, it lands in a puff of umber dust, its feet clapping Mars like a chalkboard eraser. A camera lens, a bit boogered over with sediment, blinks open and we greet Mars, a sight that never fails to elicit the adolescent thrill of speculative fiction. Even without Orson Welles manning the radio, there is a War of the Worlds echo in our subconscious—Martian will always be the conjoined twin of alien invader.
As NASA’s 4th active lander on the red planet, InSight was designed to be as optimistic as its NASA siblings—Opportunity, Spirit, and Curiosity—but it will not roam. Short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (surely a few high-fives were thrown around when they figured that one out), Insight will root itself to the regolith and deploy a trio of instruments calibrated to detect heat, marsquakes and orbital wobbles—the “fingerprints of planet formation” within a bedrock studded with hematite blueberries. Because Mars was made up of the same stuff as earth, scientists hope that clues obtained from the mission will illuminate ideas about the Earth’s own process of creation, how both planets formed and where their paths diverged At least, that is the plan.
The Earthlings always have plans. On their Martian agenda are the addition of three more landers and two more obiters to the goulash of hyper-engineered robots and satellites. In 2020, the European Space Agency’s ExoMars Mission will direct a life-seeking rover toward a landing site in the Oxia Palus quadrangle, north of Ares Vallis and west of Trouvelot’s Crater. Named after artist-scientist Étienne Léopold Trouvelot, the Martian impact site measures 150 km across and is wind-scoured into pits, pedestal craters, and eroded hills. Dark eolian drifts swell around bright yardangs like invasive wintercreeper. According to scientist K.S. Edgett, Trouvelot’s crater contains “landforms [that] are among the most Earth-like features seen anywhere on Mars.”
In our popular imagination, Mars has been Earth’s dark doppelganger, some parallel world and potential habitat, a vessel for life since 19th century astronomers imagined Martian canals as a dying civilization’s attempt at recusing their home planet. In 1881, Trouvelot wrote, “Is this planet, which is certainly constituted very nearly like our globe, and seems so nearly fitted for the wants of the human race, inhabited by animals and intelligent beings?” One of our first encounters with the red planet was through Trouvelot’s eyes—an 1877 drawing of a round thing swathed in vapors like a snail shell. Based on first-hand observations through Harvard Observatory’s 15-inch refractor, the poster-sized image was the eighth plate of Trouvelot’s celebrated chromolithographs of planets, stars, and zodiacal lights. Plate VI depicts, with uncanny precision, the rugose pores of the moon’s Mare Humorum. Because of his contributions to science, The International Astronomical Union (IAU) named a lunar Trouvelot Crater in addition to the one on Mars. It is smaller, less eroded, and can be found in Mare Frigoris, a cold sea that never was.
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It seems fitting that Trouvelot has a paired set of cosmic craters as namesakes. He was the kind of person who could not be corseted into a single field of knowledge. His Da-vincian career coupled entrepreneurship with art, embraced entomology alongside astronomy, and evolved from home-grown sericulture to scientist at Harvard College Observatory. Born in 1827 France, a day after Christmas, he produced an outpouring of writing, photographs, and scientific papers on topics that ranged from insect antennae to the structure of the sun. His legacy, however, was his art—his work was “known to all students of celestial science” and by the time of his tragic and controversial death in 1895, he was considered to have been “the most famous astronomical draughtsman at the time.”
It was color—the violet nebulas, the purplish-blue of Saturn’s rings, the holographic rainbows of falling stars—that fascinated him; but neither hue nor intensity could be reproduced in photographs of his time. Astrophotography was only just beginning to emerge in the mid-19th century and at best, astronomers could only produce monochromatic glass ghosts of celestial phenomena. Drawings therefore represented the most accurate portrayals of astronomical objects and events, and Trouvelot strove to translate what he saw through the lens of Harvard Observatory’s 15-inch refractor. Believing that “a well-trained eye alone [was] capable of seizing the delicate details of structure and configuration of the heavenly bodies,” he combined precision mapping, time-lapse techniques, with his “rare artistic ability,” as described by astronomer Solon Baily in 1931. The result of his painstaking effort was 7,000 astral illustrations that were scientifically faithful as well as aesthetic. Astronomer and popular science writer, Camille Flammarion, credits Trouvelot for “giving to Science the most beautiful series of telescopic drawings that exist.
In 2012, the New York Public Library staged Heavens Above: Art & Actuality, an exhibition that paired Trouvelot’s work with contemporary images from NASA. Viewed 130 later, Trouvelot’s hyper-realistic images exude a hypnotic luminescence—each print, from the tumultuous storms of Jupiter to the cochineal carmine outbursts of the sun seem touched by some inner light, as though the paper was not just lit from within but set ablaze.
. . .
We might well be bowing before the “prince of observers,” as Emma Converse, pioneer of astropoetics, once called him, but for the wriggling caveat in his legacy. Among his credits is the accidental importation and release of Lymantria dispar dispar—the very hungry gypsy moth caterpillar that is steadily and voraciously devouring its way across North America. Since their introduction in the 1860’s as part of a sericulture experiment gone awry, the invasive insect has defoliated almost 100 million acres of forest, triggering a cascade of ecological fallout. Despite the deployment of aggressive suppression and eradication techniques by local and national agencies, drought conditions precipitated by recent climate change have turned hardwood forests into larval nurseries for the past several years. The summer of 2018 was particularly bad—across the eastern half of the United States millions of dark, hirsute caterpillars ascended into deciduous canopies, glutting themselves until, in many places, only skeletons remained in high heat of August.
The main challenge of the gypsy moth is that it has not only proved itself to be a fecund nightmare of resiliency, but that it so easily colonizes new territory. Its indiscriminate pallet (it considers over 500 species of plant to be fair game) and the equal opportunity egg laying of females (they will glue their clutch on trucks as well as trees) have thwarted a legacy of attempts to lasso the organism to a single region. Because of this, forest management turned long ago toward defensive strategies aimed at curtailing the insect’s invasion into uninfected regions. Two decades ago, Congress funded the Slow-The-Spread (STS) program which, in cooperation with the USDA Forest Service, addresses the bigger picture of the pest.
To enter into a Sisyphean war against a spineless moth, tenacious and seemingly invincible, requires perhaps a sense of humor. In a Slow-The-Spread logo, a cartoon caterpillar attired in hoop earrings and head scarf leers over the arc of eleven states poised at the leading edge of the blight. Its expression, as it rends a white oak leaf, is pugnacious and a bit punk rock, as though it were saying, “just you try to stop me.”
Knock over a full bucket of paint and you will see a momentum akin to the spread of the gypsy moth. In an animated composite of quarantine maps, STS depicts the insect’s annual expansion across the United State for the past century. Like any good gif, the image staccatos forward before returning seamlessly to its start. By 2007 (the past decade is omitted from picture), Maine through Minnesota is claimed as moth territory, but in a flash, the world is reset and for a second, we glimpse the ground-zero splash around Trouvelot’s home in Medford, Massachusetts.
The gif’s whole scene plays out in an and alarming color as the moth moves west—a hot phlox pink—a pink for barbies, pop stars, or dead starlets, a beach rose pink, valerian pink, loosestrife pink, pink as a Maui sunset pink, pink as a river dolphin pink, pink as a nudibranch, a sweet-sixteen pink, a millennial pink, a Martian sky pink, a Laguna de Peña Hueca pink—a pink like the first color of life on earth.
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Exiled after the December 1856 coup-de-tat in France, Trouvelot arrived in New England, a man of many skills, but of little means. Though his new country too was teetering on the brink of Civil War, his relocation was a vast improvement when compared to the political persecution, censorship, and imprisonment that many politicized republicans like himself faced in France. In contrast, Massachusetts offered Trouvelot an environment of opportunity, allowing him to exercise his talent as an artist and lithographer—a then new and in-demand technology—to establish himself. Furthermore, his proximity to Harvard College and the Swiss-French working under the prominent Swiss born naturalist, Louis Agassiz, provided him with community, intellectual exposure, and work as a research assistant, gathering squirrel’s nests, birds, and insects for their collection.
Despite the rarified condition of the silk industry, silk retained its je ne sais quoi for Trouvelot. Almost immediately after moving to Medford, Trouvelot began to experiment with caterpillars and sericulture, the raising of silk worms. Perhaps it was a self-awareness of his abilities that fueled Trouvelot’s ambition for upward mobility. Intelligent, skilled, and marked by an “exceedingly experimental nature, he sought success with the rebellious confidence of an impresario. Fortune by any means promised stability and some measure of independence, and silk, by John Adam’s account “could turn a farmer into a capitalist.”
In the 19th century, the town of Medford, Massachusetts was a ship building town, devoted to brick, tar, and farm. The Mystic River ran black and rummy through its heart dividing it in two—the west side was wide open with cultivated farmland, while the east side bordered deep hardwood forests. Trouvelot had settled at 27 Myrtle Street in a compact home that seemed, in Trouvelot’s eyes, to lend itself toward experiments in silk culture. Situated at the very eastern edge of the town, the working-class neighborhood was surrounded by woodland and brush, offering acres of wild, untouched stands of red and white oak; red, white and sugar maple; birch, peeling and green; and a forest floor of fern, lady’s slipper, and rare squawroot. Trouvelot’s home stood by an 8-acre thicket of smaller scrub oak, which would have resembled the abandoned stands of mulberry trees once grown to feed the domestic silkworm, Bombyx mori.
By Trouvelot’s arrival in the mid-1800’s, sericulture had declined precipitously in the United States. In the 1830’s, the thriving American silk industry, which began in the 1600’s, had experienced an economic boom and bust, comparable to that of the Dutch Tulip-mania, when a variety of mulberry tree, exploded in price. After the speculative bubble burst, a blight tore through orchards in 1844, decimating the industry to such an extent that many abandoned their caterpillars and cocooneries in favor of simply importing the raw fiber from China.
Despite this collapse, the romance and economic possibilities of silk still entranced an ardent minority, as L. P. Brockett writes in his 1876 history of the silk industry, “There have, however, not been wanting advocates of the lost art who have urged its restoration with much of the old enthusiasm and a formidable array of argument and figures.” Furthermore, as a Frenchman, Trouvelot had a unique connection to the material—under the direction of the French Government, colonists in Louisiana had successfully produced so much silk during the Revolutionary War that, according to Brockett, they were able to “to supply the high country (probably Georgia, and the western parts of South and North Carolina).”
With the Civil War threatening cotton supplies, Trouvelot sensed opportunity. But in contrast to the fat, demanding Bombyx mori species that fed exclusively on mulberry leaves, Trouvelot’s idea of using a native American silk worm offered a promising alternative.
In his notes and publication in Society of Natural History, Trouvelot hinted at years of great difficulty. The task of getting to know a wild species and then coaxing it to bend its lifecycle for agricultural means was enormous. As far as he knew, no one had ever attempted such a feat. Yet his persistence paid off. By 1866 Trouvelot had succeeded in raising an enormous colony of Telea pholyphemus in the brush behind his home. Across the seven acres, no fewer than a million lime-green and fuchsia spotted caterpillars were feeding on oak branches, gut thrusting through an enclosure blanketed by an expanse of protective netting. Trouvelot had subjected these insects to a host of experiments to test their mettle. He subjected cocoons to freezing, suffocation, and dissections, yet over and over again, the beautiful brown and lavender moth survived, as though in defiance of the dead silk industry.
Though the endeavor established him as an expert entomologist, for Trouvelot, the whole ordeal was something beyond scientific inquiry. According to Robert J. Spear in The Great Gypsy Moth War, Trouvelot never referred to his project as a “field laboratory.” Rather, he spoke of his culture as an “infant industry;” if these moths could succeed in becoming a viable replacement to Bombyx mori, he would be rewarded with both wealth and acclaim. Had he been pure scientist, his forward-thinking approach would have garnered its own recognition, yet the promise of great profit glimmered in his mind—a commercial motivation that steered him toward the fateful decision to further tinker with nature.
In 1867, Trouvelot had also published two papers describing a method of hybridizing moths. By making use of the insect’s natural pheromones, he found that he could force separate species of moth to mate. Should such a paring producing viable young and perhaps a hybrid variety could improve upon the quality of silk. The Polyphemus moth produced a silk thought to be inferior to B. mori, and while hardier, was still susceptible to disease and predation.
In 1866, Trouvelot returned briefly to Paris and connected with entomologist Muriel L. Guberlet. There he placed a mysterious order to have the eggs of a European variety of silk worm sent to his Medford home.
It is difficult to resolve Trouvelot’s entomological practice and his work as an astronomer without imagining him like a chameleon, one eye trained toward the minuscule world of his caterpillars, and the other raised skyward toward some unthinkable height. But like a true polymath, Trouvelot worked simultaneously in multiple fields—sericulture, map making, lithography, star gazing, and art. Such inclinations were supported by his association with Harvard University. At that time, natural science was finding form and definition in academia and revolutionary ideas in evolution and technology were blooming among scientists and amateurs alike. Space exploration too was expanding at an astronomical rate. Harvard Observatory had acquired the largest astronomical telescope in the nation—a fifteen-inch Boyden refractor, and suddenly the previously unseen terrains of faraway planets were emerging with startling clarity.
Trouvelot days revolved around the nursing of his brood, the watering, feeding, sweeping of waste, and the chasing away of sparrows and cuckoos from his precious culture. But his nights were devoted to his 6-inch telescope. Deep in the rural Medford, with the steady sound of chewing bovine and silk worm alike, Trouvelot peered into the sky and sketched the details of the moon, the wings of nebula, and ribbons of auroras snaking across the celestial dome. By 1872, his drawings and observations earned him an official place in the observatory, where he was asked by director Joseph Winlock to “represent, as nearly as possible, the most interesting objects in the heavens.” Perhaps it was this opportunity to peer into the heavens with such incredible magnification that forced his astronomical occupations to the forefront. That same year, Trouvelot moved from his Medford home to yet another quaintly landscaped house on 99 Garden Street, blocks from the Harvard Observatory.
At some point during this time, he had allowed his carefully tended hoard of caterpillars to succumb to disease and collapse, and one wonders at the reason for abandoning a near decade long project. Was the allure of the space so completely absorbing that it eclipsed all else? Or perhaps, after so long an effort, had Trouvelot just tired of the endless work needed to grow silk worms? Or was it the need to block out some great accident?
Regardless of the motive, the work at the observatory offered unearthly riches which Trouvelot met with fervor. A whole world expanded before him, demanding the laser keen rigor of his eye. Trouvelot peered through the great lens and carefully recorded every infinitesimal detail in his logbook. Later he would bend over his thick sketchbook, which he had meticulously designed, and finish his observations, his hands stained and dusty with ink and pastel. Trouvelot provided the earliest account of dust storms on Mars. He saw the dead oceans, channels, haze, and fog. He imagined, perhaps, life.
In a way Trouvelot’s work paralleled the19th century paintings of the west, images that were shimmering mirages of sun-drenched prairies, luxuriant waterfall lights, and sloping hills crowded with docile bison. It was all seduction really, art claiming land as though it was tame, reclining, and inviting.
Of life on Mars, Trouvelot wrote,
“So far as observation goes, Mars seems to be a planet well suited to sustain animal life, and we may reason from analogy that if animal life can exist at all outside of the Earth, Mars must have its flora and fauna; it must have its fishes and birds, its mammalia and men ; although all these living beings must inevitably be very different in appearance from their representatives on the Earth, as can easily be imagined from the differences existing between the two planets. Although all this is possible, and even very probable, yet it must be remembered that we have not the slightest evidence that it is so; and until we have acquired this evidence, we may only provisionally accept this idea as a pleasing hypothesis, which, after all, may be wrong and totally unfounded.”
After Trouvelot’s 1866 visit to Paris, almost a quarter century passed before the gypsy moths emerged from the undergrowth to invade the human. By 1890, Medford and surrounding towns such as Winchester, Malden, Melrose, Stoneham, and Wakefield were blanketed by a thick voracious army of caterpillars to which they had no defense. Gardens were destroyed, orchards decimated, and ancient shade trees withered to bark and bones. Though teams of men were made to combat the caterpillars, girdling trees with wide belts of tar, poisoning them with arsenic, burning them in buckets with kerosene, and later, entire bushes with a cyclone burner, it seemed nothing could stop the spread.
For almost a decade, Massachusetts summers were marked by furred trunks, the peppering frass of caterpillar droppings, and the echo of crunching mandibles in the canopy, a percussive drumming like summer rain. Later, their pupae crowded the knots and branch crotches like handfuls of ripe mulberries. When the adults emerged, clouds of male moths flickered through the air ground like cherry blossoms. The pale, flightless females remained on the trees mating, laying eggs, and dying in days. During the silent part of their metamorphosis, one could see how well the gypsy moths had trashed the place. A season of infestation left towns littered with the refuse of their life—caterpillar guts, moth corpses, and vacated pupae. In the forests, millions of trees were polka dotted from root to crown with dusty yellow thumbprints made up of eggs and the coat of insulating hair that would protect them like saffron mittens through another winter.
From Trouvelot’s Astronomical Drawings, 1871
Veiled Sun Spots (1871) is arguably the most startling and nebulous piece of his lithographic prints. To the layman, the image resembles a wooly tangle of unraveled cocoon rather than a solar event. By Trouvelot’s observation he believed that phenomenon occurred beneath the surface of the sun, as though an energetic happening was writhing, beyond reach. Likewise, the story of how the gypsy moths escaped and established itself in the wild is equally veiled, both by time and memory. Residents of infested areas bore memories that were colored mythic by gross extent of the pestilence.
When bad things happen, it is often the instinct of humans to point a finger. Trouvelot has borne the weight of the calamity and blame for his part in the event. In most articles about the origin of gypsy moths, Trouvelot is described as stupid, reckless, foolish, an amateur, a part-timer, a man who seemed to trip into sericulture as though he slipped on a banana peel. Yet to reduce him so simply is both glib and myopic. An examination of the man and his work suggest far different story.
Though Trouvelot was an autodidact, he was not a casual one. His peregrinations between the stars, insect eggs, and art were far from helter-skelter engagements. Each endeavor was a deep dive, decades of hard work that asked for intellectual engagement and a rare tenacity. Taken as a whole, Trouvelot’s nature remained consistent no matter what project he set himself on—to all his work, he applied his intense powers of observation, uncanny precision, and rich insights. The specificity of his scientific drawings, the precision of his handwriting, the obsessive documentation of his work, and the voraciousness of his intellectual study points to a person unlikely to engage in thoughtless experimentation.
The introduction of the moths was indeed a mistake. But the mistake was not the careless sashay into intra-species moth sex, as it is generally depicted. Trouvelot’s mistake, was neither in execution nor intent, but in ignorance—he failed to recognize the gypsy moth for what it was.
The following evidence opposes the idea that Trouvelot would consciously select the gypsy moth for hybridization. Trouvelot was never alone in his silk experiments. Many others, amateur and entomologist alike, and looked to other caterpillars, other insects, and even spiders for their silk production potential. In those cases, none besides the domestic silk worm were viable options. Gypsy moths were known European pests with toxic silk. Furthermore, the tent caterpillar, a native pest similar to the gypsy moth, was already well known in silk circles for its inability to produce silk. Trouvelot also felt that hybridization could only happen when species were closely aligned—first cousins rather than distant relatives. Unlike the thumb sized adult gypsy moth, Polyphemus moths can grow a wingspan of up to 6-inches, filling a palm, making physical mating not only highly unlikely, but completely improbable. Letters from Trouvelot in 1870 indicate that he had sought to specimens of Bombyx yamamai, a big oak-eating silk moth, more akin to his Polyphemus moths. To arrive at his decision, he had examined countless species for qualities such as silk production to hardiness until it became clear to him that that species was the only choice. Though he himself never got a chance to try his experiment, in the 1950’s lepidopterist Gary Botting, was able to hybridize Polyphemus and B. yamamai to great acclaim. Instead, Trouvelot was left with AN accident.
When larval lepidoptera hatch, the first instar is microscopically small—delicate and ambiguous. True, Trouvelot raised them, he would not have known what they were until it was too late. Unlike the fat smooth silk caterpillars of the Bombyx, he would have seen these grow into an extraterrestrial horror—a body warted with rows of dots, blue and blood blister red, a mad and luxuriant sprout of urticating hairs, and a saffron head, like the meat of a hazelnut splitting the chaff.
True to their name, gypsy moths caravan. And they have spread from Europe to North America in much the same way: by being unnoticed. The USDA Animal Plant Health Inspection Service has issued warnings and downloadable checklists specifically because of this characteristic. They ask residents of infested areas to seek out the egg masses before traveling—to look in barrels, firewood, washing machines, boots, pipes, backpacks, bug zappers, snowblowers, and all car parts. Or in boxes. They hide in plain sight.
Before dying, each fertilized gypsy moth female produces an egg mass. While no bigger than a caramel it contains within it up to 1,000 eggs. When they hatch, the little larvae are only 1/16 of an inch, so small these caterpillars can be dwarfed by a single dandelion seed. Shortly after birth, their silk production kicks in and their glands spin out a strand of silk meant to send them flying. Like a mote, they can be taken up by a thieving breath. Or a cosmic wind—imagine them rise. We are limited by our perspective and our smallness, are only treated to the purview of our insignificant successes and fears. On ground, we might see our local arbors leafy and undisturbed, or we might, by the end of a hot, dry summer, greet a naked empire of stripped trees. Only from space, miles high and weightless, can one see the damage wrought by gypsy moths—a barren stain blooming on a blanket of green.
This view from Landsat 8 shows damage to the forests wrought by gypsy moths. Taken on July 13, 2016. Credit: USGS/NASA Landsat Program.
JENNYMAE KHO 