Butterfly People

by William R. Leach

  Butterflies bonded with one another or with other species to protect themselves against environmental dangers, proof of which came for Edwards when he studied diverse butterfly nests, called hibernacula, woven by many larvae working together in behalf of a community of caterpillars. For months on end, in Coalburgh, he watched the nest building of a lovely black, white, and red nymphalid, “the Baltimore checkerspot” (Euphydryas phaeton); he may have been the first naturalist to piece together its life history, for many years considered unknowable in its entirety.73 Edwards began studying it in 1868 after a Fraser boy in Coalburgh brought him several pupae from near the Fraser house, which, henceforth, Edwards called “Fraser’s swamp.” The boy had found the butterfly’s favored food plant, Chelone, with hundreds of black larvae clustered about the stems, eating them down to the water level. From that point on and for the next fifteen years, Edwards paid regular calls on the swamp to see the caterpillars erect their nests, some rather large and filled with many occupants, divided into groups or squads, each caterpillar executing different tasks. At night, after closing up the exits and entrances, “to keep the spiders out,” the caterpillars “stayed within the nest.” On the third molt, they stopped spinning in preparation for hibernation, which would last from August to the end of winter. Edwards was convinced that the caterpillars spun their webs because “they anticipated storm[s] and were providing against [them],” and that their web-building habits could be found nowhere else in the butterfly world.

  Much debate over Edwards’s claims in entomological circles preceded the publication of the baltimore checkerspot’s portrait in his Butterflies of North America. Both Alpheus Packard and Scudder argued in print against his idea that the baltimore was unique in its nest-building habits, the tone of their criticism so sharp as to offend thin-skinned Edwards. “The inference was plain,” Edwards wrote to Scudder, “that I was an ignoramus in these things, and did not begin to know anything.”74 Scudder remained firm, publishing in volume 3 of The Butterflies of the Eastern U.S. and Canada a plate illustrating the nests of several species. On the other hand, his own life history of the baltimore checkerspot cited Edwards freely and uncritically, recognizing the obvious excellence of the portrait. Edwards wrote with wit and eloquence about this insect. “How do these creatures communicate with one another?” he asks at the very end of his account. Does one “master” caterpillar oversee and coordinate the work of the web, or do all the caterpillars have “something akin to the knowledge and judgment of far superior beings which leads each one to see what is needed, and to do it without compulsion and without conflict or interference from others? I wonder if all is really harmony; if some do not shirk their duties; if there be not bickerings and fightings and larvicides! Let us hope not. They seem to dwell in peace, and we will assume that they do, and go to them for a lesson as to Solomon’s ants or Sir John Lubbock’s wasps.”

  Edwards observed another gregarious pattern in the butterfly world: the partnerships or symbiotic relationships a few butterflies formed with other insects, protecting them from parasitoids, those predatory “fiends” that fed off of their hosts until they died. One such bond existed between the spring azure—or Lycaena pseudargiolus, to use Edwards’s Latin name for one of his favorite butterflies—and ants.75 After Theodore Mead found the larva in 1876 and Edwards himself the food plant (rattleweed, or Crotolaria retusa, an aromatic flower), Edwards wrote up a full life history for the Canadian Entomologist, a trial run for his 1884 portrait in volume 2.76 In both versions, he related how, on a walk along the edge of a wood near his home, he had seen ants scurrying over the tops of the rattleweed where several blue butterfly larvae were feeding. The ants ran up and down, “caressing” the larvae—behavior the larvae “no way resented, not even withdrawing their heads from the buds they were excavating”—and stopping to “linger about the last segment” of the caterpillar, tapping it gently like the “thrumming of a piano.” Edwards thought that this segment might have an organ of some kind that emitted a sweet liquid the ants found irresistible. He was not sure. Again and again, for five or six years on warm summer days, Edwards looked for rattleweed or dogwood (also a blue butterfly food plant), taking a “hand glass” with him, until, on a bright June late afternoon, he saw on the hill behind his home, radiated in light, ants on rattleweed feeding on two tubes on the twelfth segment of the caterpillar. “The ants fastened greedily on the tubes. I saw sometimes two put their heads onto them and drink to the last morsel,” he reported.77 Edwards sent some larvae to Joseph Lintner, in Albany, and Hermann Hagen, in Cambridge, for their analysis; both confirmed what he had seen. “The greatest discovery I have made this year,” he told Henry Edwards in 1877, “is that of the ants attending larvae of Pseudoargiolous.”78

  But what sort of adaptation, wondered Edwards, was this bonding? Surely the blue butterfly was not doling out sweets just to be kind to ants. There had to be an adaptive purpose. A letter from August Weismann broached a simple suggestion: “Observe what enemies the larvae have. It is conceivable that there are such enemies as are afraid of ants.” Sure enough, when Edwards looked around with his magnifier, he spotted at least “three species of parasites about these larvae,” then, a fourth, an ichneumon fly, which, he learned from Ezra T. Cresson, at Philadelphia’s Academy of Natural Sciences, was adapted to attack the larvae only “at the last two stages.” Ordinarily, these parasitoids took no prisoners, but in this case, the ants stopped them in their tracks. On one June day, “in the woods,” Edwards watched as an ant defended a caterpillar:

  I saw a mature larva on Rattle-weed, and on its back, facing the tail, stood a large ant. At less than two inches behind, on the stem, was one these [ichneumon] flies, watching its chance to thrust its ovipositor into the larva. The fly crawled a little nearer and rested, and again nearer, the ant standing motionless, but plainly alert and knowing of the danger. After several advances, the fly turned its abdomen under and forward, thrust out the ovipositor, and strained itself to the utmost to reach its prey. The sting was just about to strike the extreme end of the larva, when the ant made a dash at the fly, which flew away, and so long as I stood there, at least five minutes, did not return.

  So here was the secret to the blue butterfly’s immunity from the evil one: a valiant centurion was prepared and determined to beat off all barbarians.

  Will Doherty discussed this symbiosis in his 1886 work “A List of Butterflies Taken in Kumaon” (the Kumaon is a mountainous region in northern India near Tibet), two years after volume 2 of The Butterflies of North America appeared, writing that he knew of only one other naturalist who had observed the relationship, Frederic Moore in his 1880 Lepidoptera of Ceylon. Doherty was unaware that Edwards had done anything on the subject, although Edwards knew of Doherty’s work, having heard about it from Lionel de Nicéville, an expert on Indian lepidoptera and the resident curator of the Natural History Museum in Calcutta (later the Indian Museum). Doherty had much to say on the subject, including discussion of the eleventh segment of the lycaenid larva, with a “tubercle exuding a viscid juice.” “It exists in all the Lycaenidae known to me,” he declared. “It is peculiarly attractive to ants, which at all hours surround the poor caterpillar and, by stroking and tickling it with their antennae, induce it to yield up this sweet liquid.” He added another fascinating detail: that the ants pick up the caterpillar and “deposit” it, he wrote, “in an open space just within the mouth of their nest, whereupon the latter immediately attaches itself to the bark and commences its transformation. I have counted as many as thirteen chrysalids so attached in one nest at the foot of a kind of babul tree. All were uninjured and produced perfect butterflies. The instinct which induces the ants to preserve these caterpillars in their nests, thus sacrificing a large present supply of food to the possibility of a future supply of sweet juice they are so fond of, strikes me as one of the most remarkable things in nature.”79

  Edwards may not have been the first to note this romance between ants and blue but
terflies (indeed, two Germans had observed it one hundred years earlier than either Doherty or Edwards), but he was the first to have it fully depicted, in a magnificent color plate by Peart and Bowen showing not only the tubes on segment twelve but every other feature of the butterfly’s life history—food plant, egg, pupa, and larvae in their various molts. And he may have been the first to understand the character of the symbiosis: “The ant saved the larva, and it is certain that Ichneumons would in no case get an opportunity to sting so long as such a vigilant guard was about. It seems to me that the advantage is mutual between the larvae and ants, and that the former know their protectors, and take satisfaction in rewarding them.”80 This life history beautifully revealed the butterfly people’s conviction that an understanding of butterflies required knowledge of how they related to other animals, or, to quote Scudder, of how they made “friends and associates” out of other species.81

  How eye-opening it must have been for ordinary, educated men and women to have found out that several butterflies, once understood as species, separate and distinct, were really the same species at different seasonal times or in different geographies. Or that you could not know the identity of any one butterfly simply by inspecting the adult insect; you would need to examine all the forms it took throughout its life. Or that evolution could be glimpsed—in Scudder’s and Edwards’s portraits of the red-spotted purple, viceroy, tiger swallowtail, and related species—through the wings of a butterfly. Nature was not only a violent and fierce place full of devouring flies and wasps but also a vast reserve of strategies and maneuvers to aid butterflies and other animals in their battle for survival. Nature was a destroyer and a protector in equal measure. At the same time, the achievement of the butterfly people invites further speculation. Why, for instance, did they—both Americans and Europeans—see so much protective resemblance and mimicry in the natural world when, before the 1850s, the subject had never come up except in relation to human behavior? For thousands of years, no one had scrutinized the rest of nature and seen what Bates, Wallace, Müller, or Scudder now saw. Certainly, the spread of interest in natural history throughout the middle classes, to say nothing of the scientific revolutions themselves, with their new ways of seeing and observing, had a pivotal impact, as did Darwin’s theory of evolution, an influence noted by Scudder in 1889 and, ever since, by naturalists. Another likely cause may have been the increase of travel and exploration by Westerners throughout the tropics, from the eighteenth century onward, step by step exposing people to a staggering variety of beings never known before, and, in particular, to mimickers whose numbers far exceeded anything found in colder climates.

  The invention of photography, in the 1830s in Europe, may also have had an influence; by the 1850s it had spawned thousands of studios, where people went to sit for their portraits, promoting a new fascination with the human image. If people could mimic themselves—make copies by machine, as it were, that might outlast them and assume an independent life—could nature not “photograph” species so that one might look like another, with a similar aim in mind? In a brief 1888 essay, “The Origin of Ornamentation in the Lepidoptera,” Grote used the word “photography” to express the effect produced when “wing patterns” were “reproduced in some species exactly, and in some whole families in the style of a rougher copy.” All arose, he said, from a single “primitive band produced by an outside process, the effect of light and shade on the wing itself.” “Under the murky skies of the Carboniferous the colors of the insect remained dull. Upon this plain wing, the first shade or marking may have arisen by a process comparable to photography, the action being produced by the same chemically acting ray of light.”82

  Yet another condition, paralleling and shaping all the other conditions, may help to explain why so many were ready to find protective trickery everywhere. By the 1830s, industrial capitalism had changed England, and after the 1840s—especially with the expansion of the railroads—much of the United States, into a market economy. Dependent on expanded educational access for all peoples, marked by great innovation and invention, but nearly unregulated and unchallenged, capitalism altered the character of human destiny.83 Before such a revolution, most people belonged intimately to local places, usually in agrarian settings, and did not readily circulate; to quote the historian Karen Halttunen, “All reacted on each other in a hundred ways” and “knew each other by innumerable means.” But as capitalism converted both land and labor into fungible commodities, mobility replaced rootedness as a hallmark of human relationships, and millions of human beings migrated to growing cities for employment, to encounter people they would otherwise never know and often had reason to fear. The only clues to the identity of others beyond the immediate neighborhood would be visual, and many began to worry that city dwellers could not be “trusted,” that they hid behind masks or dissembled to get what they wanted. An entire literature grew up around this concern, climaxing in the United States in Herman Melville’s great novel of 1857, The Confidence-Man: His Masquerade.84

  It would be a mistake to overemphasize economic culture as causal in matters of scientific change. Human mimicry is not of the same order or the same kind of disguise found in nonhuman nature. People who “mimic” others might act intentionally and, often, unethically; animals behave unintentionally and never unethically, as Scudder carefully pointed out in his essay “Mimicry and Protective Resemblance.” There is “no intention in the case so far as mocker and mocked are concerned.” But as Scudder also implied, naturalists may have begun to employ such words as “mimicry” and “trickery” because the words—as well as the reality—had become such an intrinsic part of the everyday life of human beings. He warned of the dangers of employing this discourse, because it tended to obscure what was actually going on in nature. “ ‘Imitation’ and ‘mimicry’ both imply intention,” Scudder wrote, “but the limits of our language compel us to use figurative speech; we have no word to express unconscious mimicry.” At the same time, reliance on this language may have actually helped open the eyes of naturalists to mimicry in nature; after all, it did exist, if not in the same degree or in the same way.85

  It is a curious thing that whenever Scudder and others put together the “lists of enemies” that butterflies had to deal with in order to survive, they failed to mention human beings. This is especially notable for Scudder, whose books were big, and whose lists covered birds, wasps, spiders, numerous other animals, the weather, glaciers, and floods but omitted people. How far had these naturalists come, if they had come at all, from the earlier Humboldtian outlook that affirmed a wholeness of nature strong enough never to break apart or fragment? Did they believe that humans had no harmful impact on other species?

  The proof of human harm was growing, and if it hadn’t worked its way into the lists, all the butterfly people suspected it was happening. They believed, for instance, that the Xerces blue, a pretty little lycaenid butterfly found only in and around San Francisco, had vanished as a result of habitat destruction caused by development. Although the theory was later proved incorrect (the insect was seen still flying in the 1940s), many butterfly people, drawing on their own experience, judged that the Xerces blue had disappeared, including Strecker, who was told about it by Hans Hermann Behr, a resident of San Francisco.86 Strecker feared the erasure of what he called the “paradisiacal spots” that had given rise to much of butterfly life, yet year after year, as large-scale farming advanced around Reading, Pennsylvania, such spots were “becoming more rare,” he lamented. “It has cut me to the soul many a time to see just such places burnt over, strewed with lime and ploughed up to raise wheat to make bread, to keep the worthless souls in the worthless bodies of worthless human beings which live and die without leaving the slightest vestige of a footstep ‘on the sands of time.’ ”87 Strecker told amateurs how to kill butterflies, but, just like Grote, he knew the value of the totality of life out of which the butterflies came. Save one and you save the other.

  In Genesis I
–II: An Essay on the Bible Narrative of Creation, written in 1880, Grote bemoaned the “American conceit that he who has the most money is a great man.… We value Science chiefly for what it will bring in money and comfort. The results are that our industrial enterprises take the form of monopolies, our lands are falling into the hands of fewer owners, and we are wasting our natural resources.” Ten years later, he concluded that “everything degenerates at the hand of man,” a paraphrase perhaps of Rousseau’s “everything degenerates in man’s hands,” although Grote did not acknowledge its source in Émile.88 Sounding a bit like Strecker, Scudder mourned, in an excursus titled “Local Butterflies,” that “our cultivations have made much havoc with our butterflies, for as one spot after another, is brought under drainage, the plants become for that locality extinct and with them butterflies depending on them for food.” And in another excursus, “The Spread of the Butterfly in a New Region,” he described the “influence of man, and particularly of civilized man,” who “is everywhere upsetting the arrangements of nature, directly or indirectly exterminating all forms which cannot endure his presence or withstand the baleful influence which follows in his train.” In yet another reflection, “The Best Localities for Collectors,” he noted “the rapid and wholesale changes wrought upon the face of the land by our irreverent civilization,” which have despoiled “the sanctity of certain special spots passed down by successive generations of butterfly hunters.”89