Beetles infesting trees in Bay State

Shiny, spotted Asian beetles that attack hardwood trees and are considered potentially more destructive than Dutch elm disease, chestnut blight, and gypsy moths combined were discovered in Worcester last week.

Investigations are ongoing and preliminary, but as many as 15 trees in northwest Worcester have been confirmed to be infested with the Asian Longhorned Beetle, said city manager Michael O'Brien.

A preliminary assessment indicates that the beetle may have been in the area for five years, O'Brien said. Now, officials are working on a more complete tree-by-tree survey of a circular area with a 1.5-mile radius in the Greendale section of the city.

"This is a voracious insect; it really has a potential to be very damaging," said Suzanne Bond, a spokeswoman for the US Department of Agriculture. "It destroys a number of species of hardwood trees, and maples are a preferred species. . . . It really has a potential to damage a number of industries if it were allowed to spread unchecked - maple syrup, lumber, tourism."

The beetle is known to travel in wood packing materials used to transport goods from Asia. This is the fourth such infestation reported in the United States since the beetle was first discovered in Brooklyn, N.Y., in 1996. It has also been found in Chicago and New Jersey.

The beetle is difficult to eradicate because it spends much of its life inside trees, making chemical sprays largely useless. It also is pernicious because of its appetite for a variety of tree species - including maple, birch, horse chestnut, poplar, willow, elm, ash, mimosa, hackberry, sycamore, and mountain ash.

Worcester officials are particularly concerned because the majority of the trees in the city's parks and public ways are Norway maples vulnerable to the beetle's attack.

The female chews out a small, football-shaped cavity in the tree bark and then lays her eggs in the summer. The larvae feast on the inner bark, and then bore deeper into the heartwood of the tree before hatching in the spring, exiting the tree-trunk through a dime-sized hole, according to Michael Smith, an entomologist with the Agricultural Research Service at the USDA who has studied the beetles for 11 years.

The attack can damage the tree's circulatory system and weaken the tree, and O'Brien said it can take anywhere from three to seven years for a tree to die.

Officials will attempt to stop the insect's spread by cutting down infested trees and grinding or burning them. This is the strategy used in the other US cities where the beetles were found.

In Chicago, 1,550 infested trees were removed, and authorities have declared success. In the New York area, 6,200 infested trees were removed, though the beetle has not been contained there, and in New Jersey more than 700 were taken down. Lightly infested trees can be hard to identify, so other at-risk host trees are also cut down - an additional 12,000 in New York and more than 20,000 in New Jersey.

A chemical may also be injected into healthy host trees, which kills the adult beetles that feed on the leaves.

Carolyn Y. Johnson can be reached at cjohnson@globe.com.