In defense of urban shade

Beetles threaten trees in Worcester

The USDA assessed maple trees yesterday at Worcester’s Kendrick Field as they searched for infestation by Asian longhorned beetles (above). Eradicating the pest may require cutting down thousands of the city's trees. (Chris Christo/ Worcester Telegram & Gazette)

WORCESTER - The woman with the wide-brimmed hat aimed her binoculars at a splotch of sap dripping from a branch, a potentially ominous sign for this aging maple and thousands of others in the area.

As she scanned the park's other trees, Diane Leonard, a plant protection officer sent by the US Department of Agriculture, said the sap might indicate the maple has been infested by Asian longhorned beetles, which were recently discovered here and present a dire threat to the region's trees.

Leonard was part of a team of city, state, and federal inspectors who began searching Worcester's Greendale and Great Brook Valley neighborhoods yesterday for signs of the beetle, which has devastated trees in parts of Chicago, New York City, and central New Jersey.

"Once you've seen the damage they can do, you know there's a need to respond quickly," said Tom Denholm, director of the USDA's Asian Longhorned Beetle Cooperative Eradication Program, who came in to oversee the search for the destructive insects.

Over the next three weeks, six two-person teams will comb the neighborhoods, seeking egg-laying scars, leaves changing color prematurely, and the signature quarter-size holes that the beetles bore into their hosts. Inspections will also take place on private property.

All infested trees will be cut down, and many in the surrounding area may also be removed in an effort to prevent the beetles from spreading.

Ken Gooch, the incident commander from the state Department of Conservation and Recreation, said officials are not sure how long the beetles have been in the city. The black-and-white insects are believed to have initially come to the United States from China in wooden shipping pallets.

The beetle spends much of its life inside trees, and that makes chemical sprays difficult to use in combating it. It is known to affect trees such as maple, birch, horse chestnut, poplar, willow, elm, ash, mimosa, hackberry, sycamore, and mountain ash.

In Worcester, the beetles threaten about 19,000 public shade trees, 90 percent of which are the highly vulnerable maples, said City Manager Michael V. O'Brien in an interview as one team looked for beetles in the city's Kendrick Field. He estimated the trees at risk have a value of at least $40 million.

"Right now, it's too early to tell how many trees will have to be removed," said O'Brien, who expects it will take about five weeks to know the extent of the infestation.

In New York, officials have removed more than 18,000 trees. New Jersey has lost more than 20,000, and Chicago cut down 1,550 infested trees. Because lightly infested trees are hard to identify, trees deemed at risk of hosting the beetles may be cut down as a precaution.

In addition to the public eradication campaign, the Greater Worcester Land Trust has called on volunteers to help survey 800 acres of forested land around Worcester.

Anne Lewenberg, a spokeswoman for the Land Trust, said trained volunteers will be sent to assess every tree in the targeted area before the first frost appears.

"We need as many people as we can get," she said.

David Abel can be reached at dabel@globe.com.