Small beetle poses threat to Midwest ash trees


CAMPTON TOWNSHIP, Ill. -- After watching her stately ash trees lose leaves and sprout mysterious green shoots, Rebecca Mathewson discovered a tiny metallic green bug snared in a spider web hanging off one of the sorry trees.

She promptly trapped the culprit in a jar and sent it to the proper authorities (the U.S. Department of Agriculture), setting off an investigation by agriculture officials here. They deemed Mathewson's the first emerald ash-borer beetle ever found in Illinois. The insect, deadly to trees, has threatened millions of ash in the Midwest in recent years.

As surveyors searched neighborhoods around this township about 40 miles west of Chicago for telltale signs of the beetles - thinning leaves, tiny holes in the trunks of ash trees, and leafy shoots growing from their bases - officials began trying to identify the size and scope of an infestation they fear could destroy many of the approximately 131 million ash trees in this state, and perhaps more elsewhere.

It did not look like "a menacing bug at all," Mathewson, 45, said. "Initially, you would think it was just a little grasshopper. But if you remember in biblical times, they had grasshopper plagues."

Despite its innocent appearance, the emerald ash-borer, native to Asia, has destroyed about 20 million trees in Michigan, Indiana and Ohio and led to the quarantine of about 15,000 square miles of land since it was first identified in the United States four years ago, according to the U.S. Department of Agriculture.

The initial identification was made in Detroit in 2002, where agricultural officials speculated, the insect might have arrived in the cargo hold of a ship. Michigan quickly issued a quarantine prohibiting the removal of wood or nursery stock from ash trees. Nevertheless, the beetle turned up in Ohio and Maryland in 2003 and in Indiana in 2004.

In Mathewson's neighborhood, a quiet subdivision with large houses and meticulously landscaped yards called the Windings of Ferson Creek, 19 trees have been identified as infested since her discovery early this month.

More than a dozen tree surveyors and four tree climbers explored more than 16 square miles around the subdivision and found no additional infested trees.

But officials said the affected area could be much larger. Trees often appear healthy while the beetles destroy them from the inside out.

"If you didn't know what you were looking for, you would never see it," said Mark Cinnamon, supervisor of the bureau of environmental programs at the Illinois Department of Agriculture. "It's really hard to see what's wrong with the tree until it's too late." Recently, Jim Senechalle, one of a team of tree surveyors, peered through binoculars and tramped across lawns in pursuit of infested trees.

"First of all, we like to tell the people we're here," said Senechalle, a plant and pesticide specialist with the state's agriculture department, as he and a colleague approached a house to tell residents what they were doing. "Hopefully, they don't have dogs." Other potential search hazards included rain and animal droppings.

Curious neighbors asked questions as basic as, "What's an ash tree?" and what should be done about poison ivy in front of one woman's house. (She showed them the rash on her legs to prove it.)

Ash trees are sturdy and commonly used in flooring, baseball bats and furniture construction. They make up about 20 percent of the trees in the Chicago area but just 5 percent of the population in the infested suburban area west of the city.

Sizing up one plot, Senechalle said, "There's no ash around here, which I guess is good." But walking near a densely wooded area in a neighboring subdivision, he said, "I'm not sure how that wooded area is going to get surveyed at this point."

The emerald ash-borer's small size and concealed destruction make it more difficult to identify than another exotic pest, the Asian longhorned beetle, which destroys several types of hardwood trees and was found in the Chicago area in recent years.

Larvae chew through the bark and feast on wood underneath, weaving serpentine paths that cut off the flow of water and nutrients. The adults bore out of the bark in the summer and die after two to three weeks, leaving their eggs on the bark. Trees usually die two to four years after infestation.

Of the emerald ash-borer, Senechalle said, "The only good thing you could say, if you could say there's a good thing, is it only kills ash trees."

For now, officials say they do not know how many trees might be felled by the emerald ash-borer beetle. But they fear it might have been skulking here much longer than anyone realized, perhaps as long as six years. Eventually, officials will set a quarantine area, barring people from removing any ash trees from a certain radius, and the infested trees will be cut down.

"It is hit or miss, and it would be very easy to miss it," Senechalle said of the surveying process.

To Mathewson, who said she adored her two ash trees even now, in their fading moments, the prospect is crushing. "Every time I think of it, it's heart-wrenching to me how many trees are going to be gone," she said.

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