A killer beetle: How to check for signs of the emerald ash borer

Three emerald ash borer specimans. The emerald ash borer has destroyed tens of millions of ash trees in the United States. (WTOP/Andrew Mollenbeck)

WASHINGTON – The beetles are returning to America, but no one is fainting in excitement. It’s more like dread.

The emerald ash borer, native to China, has destroyed 100 million ash trees since its arrival in the U.S. more than a decade ago.

First spotted in Michigan, the emerald ash borer has reached the Washington area, where it will soon emerge again.

“The emerald ash borer is considered to be one of the most destructive forest pests,” says Lourdes Chamorro, a scientist with the U.S. Department of Agriculture’s Systematic Entomology Laboratory.

The larvae are the troublemakers, forming galleries in the inner bark of the ash trees.

As they grow, they disrupt the flow of nutrients and water that go up the tree. Leaves fall to the ground, and ultimately the tree dies.

Among other uses, ash trees are the staple of baseball bats, and manufacturers are watching closely.

Louisville Slugger says it has not yet seen an impact on the bat industry, but the company has a contingency plan in place.

“In the event the worst case scenario would become reality, the company is prepared to use alternative sources of timber for (Major League Baseball) bats,” a company news release states.

As for why the emerald ash borer is so destructive, Chamorro says the trees in China co-evolved with the insect and developed defenses.

“The species of ash that we have here are very different, and so they don’t necessarily have the defenses that the trees in China have,” she says.

“When they came to this country, it was basically like an open free-for-all for these beetles,” she says.

She suggests homeowners with ash trees to keep an eye out for signs of the destructive beetle.

The emerald ash borer make a “D” shaped exit-hole in the trees. Additionally, the crown of the tree begins losing leaves and shoots may emerge from the trunk as the tree’s health declines.

Maryland has a firewood quarantine in place for counties west of the Chesapeake Bay to curb the spread of the pest.

And Virginia’s Department of Forestry similarly recommends leaving firewood at home when visiting state parks or campgrounds and to use firewood from local sources only. And a quarantine is in effect for much of Northern Virginia.

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