End in Sight for Worcester’s Beetle Battle

USDA's Clint McFarland inspects trees infested with the Asian longhorned beetle, From "Bugged: The Race to Eradicate the Asian Longhorned Beetle" 20120, photo by Stavros BasisOnly 13 Asian Longhorned Beetles were caught within the Greater Worcester quarantine area during all of 2012. That’s significant progress in the four-and-a-half-year fight to eradicate the black-and-white spotted insect that has gnawed its way through tens of thousands of trees in the city and surrounding towns, feasting on maples and other hardwoods over the past decade-plus.

According to Clint McFarland, director of the USDA’s Animal and Plant Health Inspection Service (APHIS) in Worcester, his team has found pockets of ALB infestations in Shrewsbury, Holden, West Boylston, Boylston and Worcester over the past year, but all have been or are in process of being contained.

The key is finding infestations before the mature beetles emerge from host trees. It takes one to two years for the beetles to develop inside the host. If the infected trees can be discovered and removed during that window, the beetle larvae are destroyed.

Lazy Beetles Help APHIS Eradication Effort

And if the beetles emerge, chewing quarter-sized holes through branches and trunks to venture outside? You need to catch them early, before they mate and lay eggs in new host trees. Fortunately, when the mature beetles first climb out of their trees, they don’t travel far.

“The beetles are lackadaisical,” says McFarland. “They would rather walk from one tree to the next than fly. And they tend to return to their home tree.”

The fact that the beetles are coach potatoes has given the USDA a significant edge in the eradication fight. In 2010, for example, when an infestation was discovered in six trees on the grounds of Faulkner Hospital, across from the Arnold Arboretum in Jamaica Plain, McFarland says they found two holes in trees where beetles had emerged. Soon after, they caught the two ALB culprits wandering nearby. The infected trees were destroyed, the site has been monitored since, and he believes that pocket has been contained.

APHIS has surveyed more than 3 million potential host trees within the 110 square miles of the Greater Worcester quarantine zone since McFarland’s team went into action in 2008, and removed about 31,000, mostly in the heavily infected Burncoat neighborhood. That represents about one percent of the surveyed urban forest. Many of those trees have since been replaced with diverse, beetle-resistant saplings.

Pockets of Beetle Infestations Still Remain

Still, the process has been and continues to be a painful one for neighborhoods where trees need to be cut down to halt the beetle’s advance. McFarland says many trees on a 14-acre plot of town land in Shrewsbury near Ireta Road were heavily infested, requiring “complete host removal” with town permission, angering neighbors who have lost their privacy screen. Though the land will be replanted with saplings, it will be years before the landscape regains its lush tree canopy.

McFarland says the goal, whenever an infested pocket is discovered, is to limit the number of trees that must be removed and continue to monitor the site for indications that the beetles have spread. Infected sites are surveyed three times over a period of years to ensure eradication has been successful.

Imidacloprid, the same insecticide found in flea collars and used to treat lawn grubs, has been employed to inoculate endangered trees near an infestation, but only with landowner permission, and with careful monitoring of possible risks to groundwater and soil quality. McFarland says the insecticide is very effective in killing ALB larvae, but the treatment only lasts for a year.

It will take at least another two years of surveillance to find what McFarland expects will be the last infected trees in Greater Worcester, and another decade to be sure the beetles are gone for good.

Infected Firewood Presents Greatest Risk

In the meantime, he says the biggest risk of another outbreak is “human movement”—in particular, when people take firewood that contains beetle larvae outside the quarantine zone. If the wood is infected and left to cure for a year or more, the mature beetles can emerge and start a new infestation in live trees nearby.

“People are trying to be chivalrous. They leave their unused firewood at a campsite for the next person,” he says. “That scares me because it increases the chances of the ALB’s spread.”

The potential consequences of an ALB infestation in the great northern hardwood forests of Vermont, New Hampshire and Maine would be so dire—sugar maples are a beetle favorite—that all three states have enacted programs to confiscate any firewood that people bring across borders and exchange it for “clean” cords.

In Massachusetts, McFarland says, the Department of Conservation and Recreation won’t allow any firewood to be brought into state camp grounds and provides safe firewood, instead. “We need to buy local, burn local,” he says.

Of all the communities that have been devastated by the ALB—in Illinois, New York, New Jersey, Massachusetts and now, Ohio—Worcester has the dubious distinction of having the densest infestation for the number of trees here.

New Jersey is on track to declare eradication soon, marking the successful end of their ALB fight that began in 2002. McFarland looks forward to the day when Worcester can hold its own ALB eradication ceremony.

Until then, the watchwords are continued vigilance and citizen awareness. The Asian Longhorned Beetle may be a lazy bug. But we can’t afford to be, too.

Photo Credit: Image of Clint McFarland by Stavros Basis, from Bugged: The Race to Eradicate the Asian Longhorned Beetle by Producer/Director Emily V. Driscoll

Evelyn Herwitz is the author of  Trees at Risk: Reclaiming an Urban Forest and blogs about ALB prevention and tree stewardship at treesatrisk.com. She predicted the 2008 Asian Longhorned Beetle infestation of Worcester, Mass., in her book, published by Chandler House Press in 2001.

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