Invasion of the Longhorn Beetles | Science | Smithsonian
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Researchers search for Asian longhorned beetles among Worcester's hardwoods. (Max Aguilera-Hellweg)

Invasion of the Longhorn Beetles

In Worcester, Massachusetts, authorities are battling an invasive insect that is poised to devastate the forests of New England

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On a pleasant july evening Donna Massie steered her car into her driveway at the bottom of Whitmarsh Avenue in Worcester, Massachusetts. Her husband, Kevin, and his friend Jesse were huddled beside Jesse's car, a gold Hyundai Sonata, and were peering closely at one of its doors. They were staring not at a dent but at a striking black-and-white beetle, about the width of Donna's pinkie and half as long, with bluish legs and two banded antennas that curved back over the length of its body like the whiskers of a catfish. 

The beetle gently probed the surface of the car with its forelegs. None of the three was much of a bug person, and Donna was decidedly anti-bug, stipulating a death-to-insect policy in her house. Still, the beetle transfixed her. It was larger than any she'd ever encountered, and with its otherworldly colors it was almost beautiful. Before the creature whirled its wings and flew away, Massie and her husband decided that it must be a June bug, albeit a freakish sort.

The insect might have escaped further notice, and evaded authorities altogether, if the Massies had not hosted a cookout two days later in their backyard, where others began to notice the curious beetles. They were hard to miss, creeping along the trunks of the maple trees that fringed the Massies' yard. Their black wing casings stood out starkly against the silver bark. One beetle planted itself on Kevin's pant leg and had to be pried loose. Then Donna noticed something unnerving. Near the base of one maple, she found a beetle sprinkled with sawdust, its head submerged in a dime-size hole in the tree's trunk. It seemed to be eating its way inward. 

The following morning, Donna searched the Internet and identified her backyard visitor as an Asian longhorned beetle, also known by the abbreviation ALB. Her search also turned up a pest alert from the state of Florida that warned of the dangers posed by the insect. Donna began leaving messages with various agricultural authorities.

Patty Douglass, who works for the United States Department of Agriculture (USDA), was in her office in Wallingford, Connecticut, 75 miles south of Worcester, when Donna Massie's call came through. In her position as the plant health director for Connecticut, Massachusetts and Rhode Island, Douglass regularly fields phone calls from gardeners, landscapers and amateur entomologists who believe they've encountered one of the nonnative insects on the USDA's threat list. Nearly all of these calls prove to be in error, as the insect universe is almost incomprehensibly large and varied, and mistakes in identification are easily made. The beetle order alone contains some 350,000 known species; by comparison, the total number of bird species is roughly 10,000.

Massie took a photograph of the beetle with her cellphone and sent it in. The portrait was pixelated, but the beetle's speckled black-and-white abdomen and its telltale antennas were unmistakable. Within 24 hours of receiving the image, Douglass and Jennifer Forman Orth, an invasive species ecologist with the Massachusetts Department of Agricultural Resources, were standing beside Massie in her backyard, staring up at her trees. Douglass spotted one of the insects, confirming with her own eyes a scenario that she and others at the USDA had long feared—an ALB outbreak in New England. She grabbed Massie's arm. "Oh, God," she said. "They're really here."

For most of its history, the Asian longhorned beetle occupied a small, largely unremarkable niche in the forests of China, Korea and Japan. It was not known as a serious pest. In the 1960s and 1970s, however, the Chinese government began to plant enormous windbreaks of millions of trees in its northern provinces in response to erosion and deforestation. These windbreaks were composed almost entirely of poplar trees, which mature quickly and tolerate the arid, cold climate of northern China. As it happens, the poplar is a tree favored by the ALB, along with maple, birch, elm and several other hardwoods. The beetle is unique among invasive forest pests for attacking such a broad array of hosts, which is partly why it is so dangerous.

Adult beetles feed on leaves, twigs and young bark. Females deposit anywhere from 35 to 90 eggs, one at a time, in pits they dig in the bark. When the eggs hatch, ALB larvae bore into the cambium, the tissue that ferries the tree's nutrients, and then they move into the heartwood. Over several years, this tunneling chokes off a tree's supply of nutrients and kills it—a death by a thousand cuts.

In the 1980s, as China's poplar forests matured, the ALB population exploded. Within a few years, hundreds of millions of trees were infested, and the Chinese government had to cut tens of thousands of acres of forest to prevent the beetle's further trespass.

Meanwhile, China, along with the rest of the world, experienced a surge in foreign trade. Since 1970, global sea trade has tripled, and today more than 90 percent of the world's goods travel at least one leg of their journey by ship. The United States went from importing 8 million sea containers in 1980 to more than 30 million in 2000. And most of those products—diapers, televisions, umbrellas—are packed in crates or on pallets made of wood. In the 1980s, pallets of infested poplar began to leave Chinese ports, carrying Asian longhorned beetle larvae. A stowaway on the global shipping network, the insect came into nearly instant contact with warehouses across the world.

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