Caterpillar Clash: The Budworm Returns

Caterpillar Clash: The Budworm Returns

Choristoneura fumiferana larva. Photo by Jerald E Dewey/USDA Forest Service/

In the spring of 1976, Bangor, Maine, was preparing for war. Douglas C-54 Skymasters, the same four-engine behemoths used during the Berlin Airlift, sat wing-tip to wingtip on the tarmac of the small city’s International Airport. State and federal government agencies had mobilized millions of dollars in public funds for the battle. A cumulative 18 million acres – an area nearly the size of the state of South Carolina – was to be carpet-sprayed with chemical and biological weapons over the coming decade, an overwhelming show of force unlike anything this quaint, quiet corner of New England had ever seen.

Despite these efforts, the death toll would reach the tens of millions, with impacts felt as far away as New Hampshire and Vermont and Manitoba and Newfoundland.

Because the victims were trees, not people, the war hardly generated national headlines. But the carnage, total and absolute, would forever change Maine’s society and economy. Thousands of miles of roads were cut to facilitate huge salvage harvests. Mills retooled to handle the enormous volumes of wood. Jobs were gained, then lost. Fierce public backlash in the wake of salvage harvesting and aerial spraying led to new laws governing forest practices. A new forest emerged.

All of this was, for the most part, the result of feeding by the larvae of a small, nondescript gray-brown moth called the spruce budworm (Choristoneura fumiferana). “Those years were a blur,” recalls veteran forester Gordon Mott on a recent visit to Maine’s Baxter State Park, ground zero during the outbreak. By the end of the 1970s, said Mott, the broad, sweeping flanks of mile-high Mt. Katahdin, the park’s signature peak, were lifeless. From the summit, it looked as if the Maine Woods were dying. “It was a sea of red and dying crowns, everywhere you looked,” he said.

Caterpillar Clash: The Budworm Returns Image Budworm damage in Quebec. Photo by Paul Williams.

Mott, a Yale-educated research scientist who led the “campaign” against the spruce budworm in neighboring New Brunswick during the 1950s, had been called upon by the U.S. Forest Service to monitor and research the 1970s outbreak in Maine. The devastation, the politics, and the side effects of long-since-banned chemical pesticides like DDT, used to combat the budworm, had worn him ragged. “It wasn’t a good feeling to have 6 million acres of DDT [spraying] on my hands,” he said, shaking his head.

Wiry, sharp-witted, and white-bearded, Mott, now 82, is a veteran of two outbreaks – and may soon bear witness to a third.

The budworm is back.

A Hot-Burning Fire

The spruce budworm is a well studied – but surprisingly little understood – native of the Acadian forests of the northeastern United States and Canada. Confusion begins with its name.

The “spruce” budworm actually prefers balsam fir. In the spring, it emerges from hibernation as a larva that feasts on spring shoots and buds, then grows to a fleshy brown, inchlong caterpillar. Depending on availability, timing, and weather, it will also prey on white, black, and red spruces. Regardless of species, the budworm prefers the more luscious, foliage-rich crowns of older, mature trees, though it often attacks younger trees, as well.

The budworm is always present across northern New England in small numbers, though between outbreaks its density plateaus at just five caterpillars per tree – so low that even the most wizened woodsman is unlikely to ever spot one. But every 40 years or so – for reasons still little understood by scientists – budworm populations explode. In just five years, populations skyrocket to 20,000 per tree. Veterans describe the forest as wet and dripping with caterpillar “snot.”

To make matters worse, the larvae pupate and emerge as moths in July and take flight, sometimes sailing with the prevailing winds in vast clouds, then landing like paratroopers in far-off forests. If wind and weather combine for favorable traveling conditions, these airborne invasions can be swift – and devastating.

It is this possibility that alarms many in Maine, including Dave Struble, chief entomologist for the Maine Forest Service. Since around 2006, more than 8 million acres have been infested in Quebec – north and west of Maine and directly upwind. Trees are defoliated, gray, and dying.

Caterpillar Clash: The Budworm Returns Image The devastation left by the last budworm outbreak, when an estimated 20 to 25 million cords of spruce and fir were killed. Photo by Steve Schley/Seven Islands.

Though the species is native and has been documented as far back as the sixteenth century, it’s viewed as an enemy combatant in Maine, explains Struble, because much of the northern third of the state is dedicated to growing trees for paper and lumber production. During the most recent outbreak, Maine’s spruce and fir stocks were so savagely struck that even The New York Times took notice, predicting a severe timber shortage in Maine and fingering the budworm as the culprit. An estimated 20 to 25 million cords of spruce and fir were killed between 1975 and 1988, more than a decade’s average harvest in Maine. Ken Stratton, a former state forester, told the Times: “This is a very serious situation. Some people are going to be hurt.”

The ferocity of the outbreak led to an equally ferocious response. With millions of acres – and millions of dollars worth of timber – at the front lines, industry aligned with state and federal government to initiate the largest, most expensive spray program in the United States. Synthetic chemical pesticides, including trichlorfon, carbaryl, and fenitrothion were broadcast-sprayed across Maine’s forests – notoriously wet forests that are crisscrossed by streams and rivers and dotted with pristine lakes and ponds. Rising costs and public protest eventually led to a sharp decline in public funding and a swap to Bt (Bacillus thuringiensis), a more targeted biological pesticide with lower toxicity to humans and wildlife.

“We were the bad guys back then,” acknowledges Pat Flood, a former operations manager and forester for International Paper. “And we were making things worse.” Flood, now a Maine senator, arrived in the state shortly after the outbreak subsided, but oversaw much of the subsequent harvest – and was in the midst of the public relations skirmishes that followed.

“Initially, we built roads for salvage. But we needed to justify the capital expense. So we cut more and more. Everything became bigger. Bigger harvests. Bigger sawmills. More demand. Once you learned how to move that much volume that quickly, it began to feed on itself,” he said.

New mills, manpower, and money – the cogs of the war machine – created a business boom and an environmental backlash. More roads also meant more “eyes” in the woods – and increasing public scrutiny. New, more restrictive laws, including Maine’s Forest Practices Act, which regulates clearcutting, soon followed. (In the early 1980s, 80,000-100,000 acres of forest were being clearcut each year in Maine. Today, about 15,000 acres a year are clearcut. Industrial landowners opted instead for smaller, partial harvests, as dictated by new laws. While more aesthetically pleasing, they spread the cutting, and roads, across a much larger footprint, according to records kept by the Maine Forest Service. Even paper-making changed dramatically. Instead of making newsprint the traditional way, with spruce and fir pulp, mills retooled to use hardwood species unaffected by budworm.

“The budworm changed everything,” says Struble.

The forest products industry has since downsized, though it remains a larger part of Maine’s economy than that of any other state. In 2013, forest products generated $8 billion in total value to the state’s economy, including 38,789 jobs – too many to ignore, says Maine State Forester Doug Denico.

Today, the industry is bracing for the worst.

“We have had no choice but to blow the whistle and get people alarmed,” said Denico. “If this outbreak isn’t as bad as it could be, great; but if it is, then we’ll be ready.” A long-time forester for Plum Creek, one of the largest landowners in Maine, Denico recalls the previous outbreak all too well: “There wasn’t a green needle left. The forest was dying.”

Caterpillar Clash: The Budworm Returns Image If spruce budworm arrives, there is unlikely to be another state-wide government response. This time around there are wood pellet and biomass markets to supply if smaller trees need to be harvested. Photo by Dave Sherwood.

Together with researchers at the University of Maine and landowners, the Maine Forest Service is putting together a blueprint for a more thoughtful, measured response – ahead of the budworm’s arrival. But there are still more questions than answers.

Is the forest of today more, or less, vulnerable to a budworm outbreak? Is spraying the best approach? Can the markets handle the sudden influx of wood that might result from an increased harvest? In this day and age, is any level of spraying economically, or politically, feasible? Who will fund the response? What role should the state play? What lessons can be gleaned from past outbreaks?

Then And Now

To the untrained eye, the forest along Baxter State Park’s winding Perimeter Road seems peaceful and timeless. There is no hint of the war that took place here just four decades ago. But to the professorial Mott and his wife Ginny, who both spent years here researching the previous outbreak, these forests are a textbook in budworm biology.

In 1970, this corner of Baxter, only recently protected, was much like the rest of the Maine Woods: a vast, largely uninterrupted swath of mature spruce and fir dotted with bow-legged moose, pristine brook trout ponds, and surprisingly few roads despite its proximity to Boston and New York. Weak markets through the middle of the twentieth century, difficult access, and rudimentary logging equipment limited harvesting to only the biggest, most valuable trees. Maine Forest Service records showed nearly 130 million cords of standing spruce and fir across the landscape in the mid-1970s – much of it in big, mature trees that were more than 60 years old. It was, says Mott, an almost perfect feeding ground for the largest budworm outbreak on record.

“Today, we’re dealing with a forest that is drastically different in age and composition from any previous outbreak,” explained Mott as he bumped his Subaru wagon along the gravel road. This is Mott’s first lesson of the day: Less mature softwood means less food for the budworm. “An outbreak will likely be much less severe this time than last,” he said.

Maine Forest Service data confirm Mott’s observation: Spruce and fir volumes have dropped by nearly half statewide since the early 1970s, to around 70 million cords. And the trees are younger, often by 20 years or more.

Farther down the road, along Nesowadnehunk Stream, once an important river-driving thoroughfare, Mott pulls off the road and he and Ginny admire healthy stands of mixed yellow birch, paper birch, northern white cedar, sugar maple, red maple, balsam fir, and red spruce. “There’s far less continuous conifer now than prior to the 1970s and 1980s outbreak, and much more mixed wood,” he observes.

Lesson #2: Spruce and fir, when mixed amongst hardwoods, are more resistant to budworm, which tends to thrive only in areas where its favorite foods are most concentrated.

Mott points out other subtleties along the way, easily overlooked by the layman. He is eager – even exuberant – to share his hard-earned wisdom. On a shady, north-facing slope, he enters a pickety thicket of softwood – dense, dark, and seemingly impenetrable. He grabs a young fir tree and offers it as a hint of what is to come.

Fir, explained Mott, was a minor component of the precolonial northern forest, but decades of “cherry-picking” the most economically viable species of each logging era – from mast white pines of the mid-1800s to the old-growth red spruce the late-nineteenth century – has left plenty of growing space for the much more tenacious and competitive fir, long considered a “weed” but now more common in the remaining softwood stands than spruce. Since the last outbreak, the fir, despite being more susceptible to the budworm, has outcompeted the spruces and is now dominant in many of the remaining softwood stands – for the first time ever.

Lesson #3: More fir means the budworm isn’t going away.

This, says Mott, is likely as true inside Baxter State Park – where spraying was less vigorous and no logging took place following the budworm – as it is outside, on private lands, where vast acreages were protected with chemical pesticides before nearly a decade of intensive salvage harvests.

Which brings Mott to Lesson #4: There is no single cure-all, no one perfect solution or management approach.

“I’ve been around long enough to know better,” he said.

To Spray, Or Not To Spray

With millions of dollars’ worth of timber on the stump in Maine – and many questions still unanswered, landowners, policy-makers, and environmentalists are already on edge. Fear of the unknown, explains Lloyd Irland, a former Maine state economist who helped direct the state’s massive spray program in the 1970s, contributed to the intensity of response last time.

“This time, there will be a much better-informed forest community,” said Irland, who, in 1987, helped to draft a “time capsule” document to ensure that lessons from the past outbreak wouldn’t be lost. “We’ve already had three or four hundred people together in a room talking about budworm – before we even have brown needles on trees in Maine. That’s an extraordinary difference.”

Like military veterans for peace, Irland, Denico, Struble, and Mott, and others who lived through the 1970s outbreak, take the threat seriously – but this time, their approach is tempered by experience and wisdom.

Caterpillar Clash: The Budworm Returns Image Some 18 million acres was treated for spruce budworm during the late 1970s and early 1980s in Maine. Photo by Jerald E Dewey/USDA Forest Service/

No one envisions a broad-based, state- or federally-funded spray program like last time – and all agree there’s no money, or political will, for it anyway. “We aren’t recommending the state get involved with a spray program, except to monitor what goes on and work with the pesticide control board to ensure that landowners use appropriate pesticides” said Denico.

Even pesticides have changed dramatically in the past 50 years. Mott recalls the anguish he felt when a Canadian fisheries biologist approached him with a handful of writhing salmon parr – victims of a DDT spray program he’d helped lead in New Brunswick. This time, he advocates careful, small-scale spraying with Bt, the much more benign, narrow-spectrum organic pesticide.

The landscape has also changed. Today, a more diverse group of landowners, including NGOs like The Nature Conservancy and the Appalachian Mountain Club, as well as private investors, logging contractors, and a few remaining industry landowners, have created a checkerboard of management practices – one likely less uniformly susceptible to a budworm outbreak – and less likely to unite behind a single strategy. “Our recommendation will be to let landowners individually, or collectively, do battle themselves,” said Denico. “Any spray program will be much more targeted.”

Costs may also prove prohibitive. In the 1970s, spraying cost $5 per acre or less. Today, that price could be as high as $40 to $60, according to recent figures from similar spray programs in Pennsylvania and Quebec. “Landowners will have to look at their high-value stands and decide how much risk they’re willing to accept,” explained Pat Strauch, director of the Maine Forest Products Council. Strauch acknowledged that his members are on high alert. “It doesn’t matter who the landowner is, this will be a big deal. But, as a whole, I think we’re in a better position this time than last.”

For starters, he said, remaining pulp and paper mills now prefer hardwood to spruce and fir – making the industry less vulnerable to an outbreak. The existing road network, built in the 1970s and 1980s – as river drives ended and budworm salvage ramped up – will keep costs down should landowners need to salvage dying timber. Targeted spraying with biological pesticides like Bt can help buy time. Presalvage in areas where severe outbreak is imminent will ensure that valuable wood doesn’t die on the stump. And many landowners have been purging fir from their ownerships for decades, seeking to favor the less vulnerable spruce.

Strauch has faith that industry can devise new ways to use the abundant fir that could flood the market should trees begin dying en masse, as in the 1970s. “Historically, we’ve been very good at finding new opportunities,” said Strauch, who has been tasked with helping organize the industry response. “The beauty of Maine is that we have markets for everything.” He cites wood pellets and biomass, both of which can take advantage of smaller trees, as two examples.

But Strauch acknowledges that politics could be as big a factor in decision-making as biology or economics. Many environmentalists are already watching. Jenn Burns Gray, of Maine Audubon, and Cathy Johnson, of the Natural Resources Council of Maine, said their organizations – two of the most prominent in Maine – had yet to take a position but are learning. “We’re waiting, and watching, like everyone else,” said Johnson.

Jym St. Pierre, of Restore: The North Woods, an environmental advocacy group, said he and others will keep a much closer eye on any spraying or salvage proposed. “We literally waged a military-like campaign on the budworm back then. In the midst of that war, we swept aside a lot of important environmental issues, saying ‘Look, we don’t have time to think about these things right now,’” he said. “But this time will be different.”

Calm Before the Storm

In Baxter State Park, the budworm has yet to arrive, quiet still pervades, and the din of politics is faint. Pheromone traps, which use sexual attractants to lure budworm moths, are scattered across the landscape here and throughout northern Maine. They have shown a sharp increase in budworm activity in recent years – but still far short of an outbreak.

Mott makes one last stop at Nesowdnehunk Field, a vast spruce and fir “flat” near the cool, wet base of Mt. Katahdin. He forces his way through a thicket of balsam fir spaced tightly as jail bars. A faded strip of flagging flutters from a branch. “I think this is it,” he declares. “Plot #1.”

Caterpillar Clash: The Budworm Returns Image Forester and research scientist Gordon Mott helped lead Maine's war on spruce budworm during the 1970s. The experience has given Mott, now 82, a different perspective on the forthcoming outbreak. Photo by Dave Sherwood.

It’s an old research plot where he and Ginny had studied the budworm’s devastating impact on Baxter’s spruce forest – and its subsequent conversion to fir. Today, it’s hard to tell one bend in the road from another. It all looks the same – miles of fir thickets with almost nothing growing in the understory but clubmosses, club-handled bolete mushrooms, the occasional fir seedling, and a few bracken ferns and pin cherries.

In many ways, acknowledges Mott, it resembles a graveyard. The fallen spruces – the last vestiges of the precolonial old-growth forest – remain only as soft, moss-covered humps on the forest floor, like the headstones of another era.

But Mott isn’t overly sentimental. As a forester, he views budworm as part of the natural cycle, a reality in the Acadian forest no different, really, than wet springs or cold winters. It’s a perspective gained during previous outbreaks.

Lesson #5: “Budworm happens,” he said.

Dave Sherwood is a Maine-based environmental journalist.

This article was supported by Northern Woodlands magazine’s Research and Reporting Fund, established by generous donors.


No discussion as of yet.

Join the discussion

To ensure a respectful dialogue, please refrain from posting content that is unlawful, harassing, discriminatory, libelous, obscene, or inflammatory. Northern Woodlands assumes no responsibility or liability arising from forum postings and reserves the right to edit all postings. Thanks for joining the discussion.

Please help us reduce spam by spelling out the answer to this math question