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Thursday, July 8, 2010

Asian beetle isn’t here yet

The discovery of the destructive Asian longhorned beetle in Boston, two years after its discovery in Worcester, Mass., has confirmed the need for New Hampshire to keep a vigilant eye for an insect that can lead to the near-destruction of entire forests.

“We are still actively looking throughout the state, and continue to welcome phone calls from people who might have seen one,” said Jen Weimer, forest health specialist for the New Hampshire Division of Forests and Lands.

The Asian longhorned beetle is similar in appearance to the harmless white-spotted sawyer beetle – which, despite its name, has far fewer white spots. The best way to recognize an Asian longhorned beetle is from its long, curving antennae, which have regular black-and-white markings that make them look like dashed lines.

The beetle tunnels through trees, disrupting sap flow and fatally weakening them. It is feared by forestry officials because no biological or chemical control exists and it thrives in a wide variety of hardwood trees. Maple and birch trees are among the species that are particularly vulnerable; if it became established in New Hampshire it could destroy huge swaths of forests.

The only practical response is to chop down and destroy trees that are infected or may have beetles. After the beetle was found in Worcester in 2008, the state cut down more than 27,000 trees throughout several square miles and ground them into chips that are being burned to create power at a biomass plant. Officials there are still searching to see if beetles have spread; if so, more trees will have to go.

The inch-and-a-half-long, shiny, spotted beetles, are native to East Asia. It was first seen in New York City in 1996, having apparently been carried over on wooden pallets with sewer pipes made in China, and has since been found in Chicago, Toronto, some New York State towns and Worcester.

On Tuesday, officials in Boston announced that six red maples bordering a hospital parking lot were infested, and had been cut down. The site is directly across the street from the Arnold Arboretum, which holds hundreds of unusual tree species.

The Asian longhorned beetle doesn’t travel very far or fast on its own. It spreads almost exclusively by riding on wood that is carried by people – both treated lumber, cordwood and bark mulch or plantings.

“What we have heard, so far, is that (the Boston outbreak) is linked to landscape material,” Weimer said.

This travel pattern is why the state has a ban on out-of-state firewood being carried into state and federal campgrounds, although it is not banned statewide at private campgrounds.

It’s also why the state is focusing its surveillance efforts on cities, where lumber, wood pallets, bark mulch and other wooden material is more often delivered for business. Biologists and field specialists are visiting industrial sites, inspecting along railroad tracks, and looking at recent plantings.

Last year, Nashua and Manchester were among the cities targeted by inspectors. Concord, Claremont and Littleton are the main targets this year, Weimer said.

The Asian longhorned beetle is far from the only tree-damaging insect that has state officials worried, and give impetus to a ban on firewood imports.

Concern also exists about:

Hemlock woolly adelgid, which destroys hemlock trees. It has been found in Amherst and a few other places in New Hampshire.

Emerald ash borer, which devastates ash trees. First spotted in Michigan in 2002, it has spread as far east as New York state. Unlike the Asian longhorned beetle it flies well, and its arrival in New Hampshire is all but inevitable.

Beech scale, a tiny insect that carries a devastating fungus under the bark of beech trees. The fungus came to Nova Scotia from Europe in 1890 and has spread as far south as West Virginia. New Hampshire trees appear relatively resistant, as beech scale disease appears to infect only about half our beech trees; other regions have much higher mortality rates.

David Brooks can be reached at 594-5831 or dbrooks@nashuatelegraph.com.