The Illustrated Insectopedia - Hugh Raffles (2010)

The Sound of Global Warming


Listen. It’s the sound of global warming. It’s getting even louder …


Close your eyes. We’re in another world. A wet world, watery, echoey, a jungle of pipes perhaps. Or a subterranean cave. We could be in that cathedral of a cave where the Princess’s crippled ship crash-lands in Hayao Miyazaki’s Nausicaä of the Valley of the Wind (his ecofantasy anime of “The Lady Who Loved Worms”), an oversize underground tropical lagoon, an oasis of mysterious life in a prophetic poisoned land.

We could be anywhere.

What are these unearthly noises? High-pitched squeaks and deep groans, the long, low creak of huge doors (that can’t be doors), the electric crackling of rapid-fire static. High-pitched chirps, more chirps, that grating sound, which suddenly fades, that rush of liquid like a wave rolling up the beach. Something drumming, something fizzing, something gnawing, something splashing, something squeaking … something orchestrated. Over there: a detonation. Close by: something heavy raises itself to its feet with a querulous bellow. There are animals in here. What kinds of animals? What are they doing? Polyrhythmic, polyphonic animals chirping in counterpoint, call-and-response. So much activity in here. So much motion. So much rhythm. More clicks, more chirps, more squeaks, more splashes, more echo.

Where are we?


We’re inside a tree. A piñon pine (Pinus edulis). We’re in its vascular tissue, just beneath the outer bark, inside the phloem and cambium. We’re enclosed in a rich sound-world, a world audible only on David Dunn’s CD The Sound of Light in Trees, the one that’s on my headphones.1

The tree we’re inside could be thirty feet tall. That’s big if you’re tiny, no larger than a grain of rice, like the piñon engraver beetles (Ips confusus) that arrive by the thousands to lay their eggs and hatch their larvae in these tough, slow-growing trees, with their much-loved seeds and aromatic wood, that dominate the harshly beautiful pine-juniper landscapes of northern New Mexico.

The piñon engravers are bark beetles, members of the Scolytidae, one of only a very small number of insect families whose adults are able to pierce the outer bark of woody plants. Until a few years ago, they seemed to have reached a kind of compact with the piñons. Attracted by signals from pioneer males, the female beetles gathered on weak and dying trees to bore their tunnels and lay their eggs. Their incursions through the bark interrupted the upflow of fluids and nutrients. The blue-stain fungus they carry further clogged the system. The weak trees capitulated. Their demise thinned the forest yet also strengthened it, the pine population benefiting from the easing of intraspecific competition for light, water, and nutrients. But only 10 to 15 percent of the male beetles’ dispersal flights ended in successful reproduction, and healthy trees had little trouble resisting their advances. The trees pumped resinous sap to seal the wounds in their bark, forcibly ejecting the intruders or trapping them in stickiness. Scented monoterpenes, volatile essential oils dissolved in the resin, neutralized the fungi.2

But the droughts that swept the southwestern United States in the first years of this century introduced a new dynamic. Stressed by lack of water, the piñons produced less resin and found that the increasing sugar concentrations in their cells served only to bring more beetles. Higher levels of monoterpenes in the sap extruded from the engravers’ entry holes attracted even more insects. Cavitation—the collapse of xylem tissue induced by the formation of vacuum bubbles under drought conditions—increased to such an extent that for some trees the acoustic emissions produced by the bubbles’ implosions became “an almost continuous ultrasound signature,” a soundtrack to which, as we will see, the beetles may have been paying close attention.3

While the trees struggled, the unusually warm temperatures helped the beetles (and the fungi) raise their reproduction and general activity rates. The convergence of weakened trees and hyperactive beetles led to a catastrophic die-off of piñon pines in the region. In 2003, the peak year of the crisis, over 770,000 acres of New Mexico forest were affected. Millions of trees died, and no effective ideas emerged in response. Using aerial surveys taken by the U.S. Department of Agriculture Forest Service and studies of a piñon-juniper forest plot at the Los Alamos National Laboratory, researchers from the University of Arizona calculated a 40 to 90 percent mortality of piñons across New Mexico, Colorado, Utah, and Arizona in 2002 and 2003.4 Assuming no similar events occur, it could take centuries for the landscapes to recover.

But everyone knows that similar events, and others unimagined, will occur. And as immediately devastating as was the loss of the piñons to local people and to animals such as the pine-nut-eating piñon jay, the death of the trees is felt most painfully in its etching on the landscape of a new sense of foreboding. The collapse earned its place among the spectacular “natural” events of recent years, whose rawest member is still Hurricane Katrina. The now-famous images from New Orleans revealed a cluster formed from race, class, bureaucratic incompetence, government indifference, and climate. The piñons’ fateful convergence acted on insects, fungi, trees, the insufficiency of expert knowledge, and again, climate. Both events made it starkly apparent that new formations in the age of climate change are unlikely to produce linear outcomes. The future is deeply marked by the inevitable eruption of nonpredictable phenomena on startling scales.5 Forget “homeland security.” Time itself has changed. We know catastrophes are coming, and we know they’ll take us by surprise.


We’re inside a piñon pine in northern New Mexico. All around are engravers, other bark beetles, beetle larvae, and carpenter ants. That drumming is the ants, David Dunn tells me when I call him in Santa Fe. The detonations are cavitation events. That creaking is the tree swaying in the wind.

The Sound of Light in Trees is a soundscape, a “sonic environment.”6 It aims to tune us in to the aural dimension of our everyday world, to create what the anthropologist and soundscape pioneer Steven Feld calls “a sonic way of knowing and being in the world.”7 The piñon environment is not one we can ordinarily perceive through sound. We need transducers—human and mechanical—to convert these inaudible-to-the-human-ear low frequency and ultrasonic emissions into vibrations within our acoustic range.8 Knowing we need transmutation and translation heightens the strangeness of the recording, as does knowing that even with such mediation this world remains deeply inaccessible. There is an unusual, somehow troubling quality to this soundscape, immersive and alien all at once, able to convey both the proximity and the indifference of the natural world, to capture that uneasy paradox at the core of the new realities of global warming.

Entering the piñon arouses dormant senses. I close my eyes to isolate the sounds and discover that listening to these insects might not be so different from collecting them. For me, the listening experience resonates with the Japanese neuroscientist Yoro Takeshi’s persuasive argument about the visual experience of finding, capturing, and studying insects. Yoro says that the Japanese conservationists who are trying to ban insect collecting are destructively shortsighted, that it is through collecting that people, particularly young people, learn what it means to sympathize with others and to live among other beings. Like many of the insect people we’ve met in this book, Yoro and his fellow collectors argue that the close attention demanded by this engagement with another life, another tiny life, develops unfamiliar ways not only of seeing but also of feeling, that the close focus on detail disrupts scale and hierarchical certainty, and that these experiences transmute into ethics. The focused attention on another life creates patience and sensitivity in the collector, Yoro claims, an awareness of subtle variations and other temporalities (change can be very slow, movement very fast, lives very short), and leads to an appreciation of differences, perhaps to a new way of being in the world.

This is seeing rather than merely looking, just as the piñon soundscape cultivates listening rather than merely hearing. Within these trees, among these animals, people “shift their thinking about the centrality of humans in the physical world,” David Dunn tells me, and I realize that unlike Yoro, he’s not looking for insect love but for something closer to appreciation or understanding. He doesn’t exclude the possibility that getting up close to insect sounds might also generate anxiety and reinforce antipathies.9 After all, the insects are not the heroes of this New Mexican story.

Two years of recordings compressed into one hour. Sounds from many different trees edited together. Not just a recording but a composition that takes, remakes, and rearranges nonhuman sound. Even though it’s a self-conscious artifact, this kind of soundscape breaks from its precursor tradition of musique concrète, in which found sounds are explicitly manipulated to emphasize and express human intervention.10David tells me that the accent in his work is on “the inherent nature of these things,” that the task is “to reveal aspects in time and space that are inherent in the materials” and to explore through sound the larger phenomena that these beings—the trees, the insects, the people—create and are a part of.

Thirty-five years as an avant-garde musician and sound artist, theorizing, composing, publishing, performing, collaborating, and of course, recording. There are still few ready-made tools. He uses open-source transducer systems of his own design to make low-frequency vibrations and ultrasonic emissions audible. He sends the contraptions to beetle specialists as far away as China. He runs workshops to show children how to make them.

Like many people in the Southwest in those years, David sat and stared at the piñons near his home. He watched their green needles turn to reddish brown, then drop. He thought about “the materiality of their world,” the wood, the impedance, the possibilities. He took the piezoelectric transducer disc from a Hallmark greeting card, glued it to a gutted meat thermometer, pushed the apparatus into the bark of the dying piñon, and angled it to pick up the vibrations. One per tree. Less than $10 each.


Technology can bring us closer to the world, David Dunn tells me. Perhaps, he continues, the rich and complex soundscape accessible through a pair of headphones approximates the sensory experience of other forms of life, with their distinctive ambient sensitivities.

Among the best known of his numerous recordings is “Chaos and the Emergent Mind of the Pond,” a twenty-four-minute composition that discovers in the sounds of aquatic insects in North American and African ponds “a sonic multiverse of exquisite complexity.”11

Listening to the pond with two omnidirectional ceramic hydrophones and a portable DAT recorder, he hears a rhythmic complexity altogether greater than that in most human music, patterns comparable only to the most sophisticated computer compositions and the most complex African polyrhythmic drumming.

The sounds can’t be arbitrary, he decides. These animals are not simply following their instincts. “The musician in me cannot help but hear more.” In fact, the musician in him understands human music as a parallel expression to these sounds, as the expressive modality that brings people closest to the ways in which other forms of life communicate. Music suggests organization, not simply sound, and he hears the pond “saturated with an intelligence emergent from the very fullness of interconnection.” He begins to hear the pond as a kind of superorganism, a transcendent social “mind” created from the autonomous interaction of all the life within it, terms not dissimilar to those used by complexity theorists to describe the nest colonies of the eusocial insects (ants and termites, some bees and wasps, some aphids and thrips).

As I read these ideas in the liner notes for “Chaos and the Emergent Mind of the Pond,” I start to understand that the soundscape is more than a recording, more even than a composition. It is also a research method, one that flows easily from a principle of wholeness. The soundscape encounters its piece of the world as a totality. In this, it’s quite unlike scientific investigations that begin their search by isolating individual elements. The method is different, and not surprisingly, the outcome is different too. Something else surfaces. Let’s not stay deaf to its music.


“For a long time,” David Dunn told me, “that was enough.” He composed soundscapes to sensitize his audience to the acoustics of the natural world, to stimulate the recovery of older, lost sensitivities, and to offer more intimate relationships with other life-forms. But climate change changed that too. The dying forests posed the question of responsibility with new urgency. Like many in the midst and wake of disaster, he found himself wrestling with the desire to do something effective, something, as he put it, “to diminish my own sense of tragedy and depression.”

The piñon die-off was no anomaly. As temperature zones have shifted in the past decades, insects have shifted with them. Swift, numerous, and astonishingly adaptive, beetles, mosquitoes, ticks, and others have taken advantage of new conditions and newly expanded habitat ranges with spectacular results. One widely publicized effect is the unwelcome appearance of insect-borne diseases in unexpected latitudes and altitudes (Lyme disease in Sweden and the Czech Republic; West Nile virus in the United States and Canada; dengue fever as far north as Texas; malaria in the East African highlands).12 Another is the unprecedented deforestation that’s struck the boreal forests of Siberia, Alaska, and Canada, the coniferous forests of the southwestern United States, and the temperate forests of the Midwest and Northeast.

The details vary, but the dynamic is well established. Confronted by regional increases in winter and summer temperatures, decreases in precipitation, and the reduction in the duration of freezes, plants and insects have fallen out of step—despite often having co-evolved for millennia. The animals adapt at a rate far more rapid than that of the trees. The beetles accelerate: they eat more; they develop faster (some species move to adulthood in one year rather than two); they reproduce quicker and survive longer. Their numbers explode.

The same conditions of higher temperature and lower rainfall stress the trees. As drought intensifies, their metabolism breaks down, and their defenses weaken. Their established strategy—the migration of populations out of the higher temperature zones over generations—is simply too slow. Temporalities are out of joint. The forest comes apart. The trees are overwhelmed long before they can escape to a place less hospitable to the insects.

The result has been a catalog of destruction. Since the early 1990s, spruce bark beetles have caused the death of 4.4 million acres of Alaskan boreal forest. In the same period, the mountain pine beetle has moved into 33 million acres of forest in British Columbia and caused major damage in Montana, northern Colorado, and southern Wyoming. Long-term predictions are suitably apocalyptic. One North American scenario envisions a continent-wide invasion of bark beetles radiating from British Columbia to Labrador and down into the forests of eastern Texas.13

David and his collaborator, the University of California physicist James Crutchfield, an expert in nonlinear complex systems, describe the mechanism at work here as a “desynchronization of biotic developmental patterns.”14 They investigate it in a new project imagined through the logic of the soundscape, a scientific inquiry symbiotic with The Sound of Light in Trees that doesn’t so much look at climate change as listen to it.

For several decades, research on insect behavior has been dominated by chemical ecology, the study of the effect of chemical cues on ecological interaction. In his fascinating account of a life among insects, Thomas Eisner, pioneer and undisputed giant in the field, documents the discoveries: the bombardier beetles that spray scalding benzoquinones when threatened; the female Photuris fireflies, which procure defensive chemicals by consuming male fireflies of a different genus; the beautiful female moth Utetheisa ornatrix, which discriminates among sexual partners according to the finest calibrations of pheromonal scent; the defensive toxic-vomit response of sawfly larvae and grasshoppers. The stories seem infinite, and so, too, Eisner makes clear, do the opportunities for further research.15

Chemical ecology has proved to be an overwhelmingly fertile field for insect studies. In particular, tremendous energy has been funneled into work on three classes of compounds: pheromones, which influence the behavior or physiological development of members of the same species (for example, in mating or aggregating); allomones, which act on members of a different species to the advantage of the producer (for example, defensive toxins, such as the bombardier’s spray); and kairomones, which affect members of a different species to the advantage of the receiver (for example, those monoterpenic pine resins that inadvertently attract parasites or predators to a wound).

The explanatory power of chemical ecology is unquestioned. Its descriptions of the intricacies of insect life are quite amazing. Nonetheless, David Dunn tells me, it has done little to slow the advance of bark beetles through the northern forests. Its primary pest-control tools—pheromone traps (which decoy the beetles or disrupt their behavior) and pesticides—have proven ineffectual or impractical. Despite hundreds of research papers and untold millions of dollars in research funds, the beetles march on.


Listen. They’re coming through loud and clear. Those squeaky chirps are the piñon engraver beetles. The female has a small, hard comb (the pars stridens) on the back of her head, which she grates against a scraper (the plectrum) located under the front edge of her prothorax. The male makes sounds too, but no one is sure how.

The range of sound-making organs in bark beetles is substantial. And so are the uses to which all the noise is put. Think of the Scolytidae as social insects. Not in the same way as eusocial insects, like the honeybees, with their elaborate nests and sharp divisions of labor. Social in a looser sense: they live in groups; they coordinate mass arrivals on target trees; they arrange spacing to ensure that they don’t settle too densely; some occupy their nests collectively. Such complex cooperative behavior presumes communication.

Research on bark beetle interaction has focused largely on chemical signaling; sound has been regarded as ancillary.16 Symptomatically, there is still nothing published on how bark beetles hear or what kinds of auditory organs they possess.17

But what if—as Dunn and Crutchfield propose—bark beetles are attracted to vulnerable trees not only by the aggregation pheromones of the male pioneers and the kairomones released in the wounded trees’ resin but also by bioacoustic cues, such as the internal explosions of gas bubbles during cavitation events? Could we provisionally assume that, like many butterflies, moths, mantises, crickets, grasshoppers, flies, and Neuroptera, bark beetles, too, may have hearing in the ultrasonic range? The rich ultrasonic sound-world of the piñon pine suggests as much, as do recent studies indicating that hearing among insects is far more widespread than previously assumed.18

Indeed, after spending time inside the piñon alongside the animals and scaled to their world, it becomes more and more inconceivable that so little research is being done on beetle bioacoustics and that the intensely interactive sounds inside the tree are arbitrary. Reviewing the piñon soundscape, Dunn and Crutchfield discover that “a very diverse range of sound signaling persists well after the putatively associated behaviors—host selection, coordination of attack, courtship, territorial competition, and nuptial chamber excavations—have all taken place. In fully colonized trees,” they write, “the stridulations, chirps, and clicks can go on continuously for days and weeks, long after most of these other behaviors will have apparently run their course.” What does this mean? Their inference is careful but important: “These observations suggest that these insects have a more sophisticated social organization than previously suspected—one that requires ongoing communication through sound and substrate vibration.”19

Recent research by Reginald Cocroft and his associates at the University of Missouri at Columbia raises yet another question. Cocroft has shown that the low-frequency and ultrasonic airborne sounds recorded by David Dunn are actually only one element of an insect’s sound-world. In huge numbers, it seems, insects that live on plants also communicate by the nonacoustic vibration of their living substrate. “Vibration-sensitive species,” write Cocroft and Rafael Rodríguez, “can not only monitor vibrations to detect predators or prey but also introduce vibrations into structures to communicate with other individuals.” By vibrating the leaves, stems, and roots of plants, insects send meaningful signals across significant distances (up to twenty-six feet in the case of stoneflies). Unconstrained by the physical limitations of airborne communication, they can deter predators by producing low-frequency signals that mimic far larger animals. Some, such as leaf-cutter ants, vibrate to call their comrades to a high-quality food source. Others, such as larval tortoiseshell beetles, exchange vibrational signals that coordinate the formation of defensive groups. Still others, including thornbug leafhoppers, generate collective distress signals to summon their mothers when they are under threat. And needless to say, predators eavesdrop on vibrations to locate their prey (a practice that accounts for “vibrocrypticity,” by which some insects “move so slowly and generate so little vibration in the substrate that they can walk past a spider without eliciting an attack”). The diversity of vibrational signalers and signals is “fantastic.”20

Let’s reimagine the landscape of the soundscape. Let’s begin with all that busy, noisy, musical energy and open our senses wider still. And let’s assume not only multimodality but cross-modality—that, like our own, these senses make sense in combination rather than isolation.

Yes, the world of insects is a noisy world, a constant whir of acoustics: drumming, clicking, squeaking, chirping.

Yes, it’s also a vibrating world, so sensitive that even gentle winds can disrupt it and a rainstorm can cause it all to dry up or be drowned out.

Yes, it’s a chemical world, too: a nonstop, impossibly complex, wildly inventive molecular maze of attractants, repellents, potions, poisons, and disguises.

And yes, as we know from von Frisch’s honeybees, it’s a world of direct physical intimacies—touching, palpating, and substance sharing—and a world of visual cues, too.

It’s an intensely interactive world, a landscape across which animals of the same and different species connect and communicate.

Listen. Can you hear it? With the soundscape we take tentative steps into a wider, richer world.


But more than just the sound of life in trees, the soundscape is the soundtrack to an epidemic. These noisy beetles are not merely symptoms of global warming, say Dunn and Crutchfield; they are also its cause. Dunn and Crutchfield see forest dynamics as a cybernetic feedback loop accelerating under conditions of climate change. With their relentlessly successful adaptive population dynamics, the insects drive the system past equilibrium. Decisive in felling the forests and so releasing carbon stored in tree biomass and captured during tree growth, bark beetles become the accelerating motor of what Dunn and Crutchfield call “entomogenic climate change.”21

It is an intriguing insight. But in practice it is likely to make little difference to the Scolytidae and their bark-piercing allies. Already there is little hesitation from any quarter in holding beetles responsible for the deforestation overwhelming so many North American forests, in understanding their behavior as “infestation” and “invasion” (folding these anxieties into persistent fears of human immigration), and in working to eradicate them.

Listen. These sounds provoke complicated responses. The beauty of that rich interior life, the music of the phloem—it is self-contained, indifferent, the soundtrack to catastrophe. These beetles live fully communicative lives, their Umwelt is thoroughly social. These are not the enemies we ought to choose. The biosecurity state, with its traps, its pesticides, its arborists, its public-education programs, and its quarantined counties, is largely powerless. It was Mao Zedong, apparently, who said that where there is repression, there is resistance. He wasn’t thinking of insects. But we should be. As far back as twenty-five years ago, 7 billion beetles were caught in pheromone traps during a campaign to repulse an invasion of European spruce bark beetles in Norwegian and Swedish forests.22 Seven billion, and still they kept coming. Repression is futile. Somehow, we will have to cohabit. Somehow, we will have to make friends.