The men walked around the stump. McFarland stared down at some sawdust and let out a sigh, as if to say, "What next?" The now missing tree had been identified as infested, as had almost all the maples in that part of town. But the cutting and chipping work was not supposed to have begun; whoever had removed the tree was not working for APHIS. The wood was, in effect, a ticking time bomb. Contaminated with beetle larvae, it could become a source for yet another outbreak elsewhere.
Standing beside the two men as they considered the whereabouts of a single tree in a city of trees, I began to grasp the immense challenge of trying to stop an insect from having its way in the world. I thought about all the years the beetle had been in Worcester before it was discovered, years in which wood was moved freely out of the city, in the back of a landscaper's truck, perhaps, or as firewood to be stacked beside someone's cabin in the forests of New Hampshire or Vermont or Maine. I remembered something I had read about the beetle: Chinese farmers, who had watched the insect march across the northern provinces, referred to it as the "forest fire without smoke."
It is no surprise that the beetle's escape from China came via trade. Invasive species have traveled undetected in the ballast of ships, in nursery plants, in crates of fruit, in old tires, even in the wheel wells of airplanes. Life likes to travel, and in the era of globalization it travels at a pace never before known, covering distances never before possible. Thousands of introduced species now prey upon or outcompete native species in the United States. The costs of this ecological upheaval, even in purely economic terms, is staggering—a 2005 Cornell University study put the damage from invasive species at $120 billion per year in the United States alone.
Not long after the Brooklyn infestation was discovered in 1996, the USDA began requiring that solid-wood packing material—the stuff used for shipping crates and pallets—be fumigated or heat-treated to kill the larvae of forest pests. These regulations were applied first in 1998 to Chinese imports and then in 2005 to those from all other nations. The regulations have reduced the entry of the ALB into the country, although, even today, dozens of the beetles are intercepted annually in ports nationwide, and other avenues of entry, such as live plant imports, remain. The protocols established by the government after the Brooklyn outbreak—quarantines, inspections and the destruction of infested trees—have largely succeeded, in part because the beetles disperse slowly on their own.
We have no choice but to fight the insect. The costs of not doing so are enormous—one USDA study puts the potential ALB damage in the United States at more than $650 billion, and that's accounting only for trees in municipalities, not on forested lands. The federal government has spent in excess of $250 million on ALB eradication efforts thus far, and more than $24 million in Worcester. Each known outbreak—in New York, New Jersey, Chicago and Worcester—was discovered in a densely populated area, by an alert citizen, after years of infestation. But what if other infestations are taking place out of sight—near a warehouse in a small town in New Hampshire, perhaps, or behind a lumberyard in upstate New York?
I asked E. Richard Hoebeke, a Cornell University entomologist who has studied the Asian longhorned beetle as long as anyone in the United States, about possible undetected infestations. He talked about the many years the beetle had been invading before it came to our attention. He spoke of the overwhelming number of shipping containers pouring into the country.
"Are there other infestations?" he said. "I'm certain of it. Worcester won't be the last."
Concerned that the beetle might find its way into the Northern hardwoods, I visited the ecologist David Foster, director of the Harvard Forest, a 3,000-acre parcel in central Massachusetts that is the site of long-term ecological research. How might the beetle change the New England landscape? To ask that question, as it turns out, is to invite others—questions about what shaped the land in the first place. By way of explanation, Foster took me into the woods.
Much of the Harvard Forest, like more than half of New England, was cleared by farmers in the 18th and 19th centuries and later abandoned. Not far into our walk we passed a crumbling stone wall that cut a straight line through the woods. It was nearing dusk, and a skin of ice covered the snow. Foster, a tall man with dark hair and the ruddy complexion of someone who spends a lot of time outdoors, took big, crunching steps along the trail. We passed a stand of pines and ducked under some fallen snags, and then we came to level land populated by maples and birch. "Beetle food," said Foster, wryly.
It would seem to be our poor luck that so much of New England contains habitat so well suited to the ALB, but, as Foster pointed out, that is at least in part of our own making. In the mid-19th century, New England's settlers began to abandon their farms—lured by cities and by the opening of the West—and their fields returned to forest. Trees such as birch and maple and pine spread first and farthest, on land that once hosted more hemlock, beech and oak, which are not susceptible to the beetle. "Most people walk through these woods and don't see the human impact," Foster said. "But if we compare the vegetation of these forests in 1600 with the vegetation of today, we see huge changes. There's a tremendous increase in species like red maple, which is favored by the beetle."