By DOUG GRAVES

Ohio Correspondent

COLUMBUS, Ohio — It’s been 15 years since the discovery of the emerald ash borer (EAB) in the United States. Native to northeastern Asia, EAB was first detected near Detroit in 2002.

As of last month, EAB is found in 33 states and the Canadian provinces of Ontario, Quebec and Manitoba. The invasive pest has killed more than 35 million ash trees and caused millions of dollars in tree loss. And with around 10 percent of the Ohio tree population being ash, this state has a lot to lose.

It’s a war of man versus bug – and any expert on this invasive beetle will agree the green bug is still winning the war.

“The destructive emerald ash borer has been discovered in the Wayne National Forest in southeastern Ohio, which has led us to decree that the bug is now in all of Ohio’s 88 counties,” said Greg Smith, spokesman for the Ohio Department of Forestry.

“Wayne National Forest spans 12 counties in southeastern Ohio and many of these counties were not originally on the list of counties with the emerald ash borer,” said Kaleigh Frazier, spokesman for the Ohio Department of Agriculture.

“It’s just another non-native pest attacking our forests, and we know it won’t be the last,” said Gary Williamson, timber group leader for the Wayne National Forest.

Even Ohio Agriculture Director David Daniels has weighed in on the issue. “The extent of this pest’s damage is devastating,” he said. “Detection is the first step in responding to this insect through quarantines, to limit its spread.”

The EAB was first detected in Michigan on June 2, 2002, in Ohio on Feb. 12, 2003, and in Indiana on April 21, 2004. Other states in this region have been affected too, including Illinois, Kentucky, Iowa and Tennessee.

“The insects kill ash trees by boring tunnels under the bark to lay eggs,” Smith explained. “The tunnels disrupt the water flow up the trunk so the trees are deprived of water. The bug can kill an ash tree in three to five years.”

The EAB has a one-year life cycle, with adult beetles typically living an average of three weeks. Most female borers lay 30-60 eggs, but an older female may lay as many as 200.

Eggs are laid in furrows in the bark and after hatching, the larvae chew through the bark and live in the phloem and cambium (vascular tissue) layers just under the bark, interrupting the flow of nutrients and water, creating S-shaped tunnels as they feed.

“The larvae lie dormant, spending the winter in the tree, and then emerge as adults in the spring,” Smith said, “leaving D-shaped exit holes 1/8 of an inch in diameter. The next year, the process begins again. The disconnection of nutrients produces stress on the ash tree, causing thinning and yellowing leaves, dieback in the tree’s canopy and bark loss.”

In Ohio alone, there are roughly 3.8 billion ash trees. The loss of the species has created a void in the existing fragile ecosystem. Counties in Ohio remain under federal regulation for EAB.

“EAB are not always easy to detect when they first hit an area,” said Lake Metroparks (Ohio) biologist John Pagacnik. “They are usually pretty well entrenched by the time it gets noticeable. Typically 5 percent or less white ash will be left when they get done infesting. Green, black and pumpkin ash would be lower.

“Once infested, the ash trees have a 99 percent mortality rate. How long it takes a tree to die is a variable depending on size. There are five different species of ash native to Ohio, but all are susceptible to EAB.”

Pagacnik said the EAB transportation has been exacerbated by human-driven movement, like infested firewood and nursery stock, and movement from quarantine to non-quarantine areas.

For more information on EAB or for the latest quarantine map, read www.ohioagriculture.gov/eab or call 888-OHIO-EAB (644-6322).