Emerald Ash Borer Chews Trees in Three More Twin Cities Locations

Created: 02/02/2013 10:48 PM KSTP.com By: Mark Saxenmeyer

An invasive green beetle, the Emerald Ash Borer, is destroying even more Minnesota trees.

Just weeks after hundreds of ash trees infested with the beetle had to be cut down at Fort Snelling, it's been found at Lexington Parkway at Jessamine Avenue, and Pig's Eye Lake Road in St. Paul. And in Minneapolis, it was also discovered at Lakewood Cemetery.

As a result, some researchers fear an even larger outbreak is coming soon.

Arborist Joel Spies, president of Rainbow Treecare Scientific, said, "Ten percent of the trees here are ash in this specific area." He was gazing over the fence of the cemetery, near the intersection of King's Highway and 38th Street.

Spies was worried.

"It's starting to creep out and show up three to four miles away from any known infestations," he said. He was talking about the Emerald Ash Borer--or EAB, as it's known. "There could be thousands upon thousands of beetles feeding," he added.

Spies researches the EAB's destructive effect on ash trees. "It drys out the trees, and the bark cracks," he said. The beetle's larvae burrow into the wood and feed on the tree's nutrients. The Emerald Ash Borer is one of the nation's most destructive tree pests. It's killed tens of millions of ash trees in 18 states.

The new EAB discoveries were made by Minneapolis Parks and Recreation Board Forestry Department and the St. Paul City Forestry Unit, and then confirmed by the State Department of Agriculture. The trees have probably been infested with EAB for three or four years.

"It was probably somehow moved here by someone moving firewood," Spies said.

The question now: where else has the beetle migrated?

"I would say it's going to be throughout a lot of the South Minneapolis neighborhoods, near Lake Harriet and Lake Calhoun," Spies predicted. In fact, he spotted a woodpecker in an ash tree right on the water's edge of Lake Calhoun, hacking away at the tree's branches. The birds are known to feed on trees filled with the Emerald Ash Borer's larvae.

Other signs of EAB infestation: dying branches in the top canopy, vertical cracks in the bark, one-eighth inch "D"-shaped exit holes in ash tree bark, and winding "S"-shaped tunnels under the bark.

The beetle has been found in four Minnesota counties: Hennepin, Ramsey, Houston and Winona. The Department of Agriculture has put those counties under quarantine, making it illegal to take any ash trees or wood out of those counties.

Spies says homeowners throughout the Twin Cities need to start worrying about their own ash trees. "If they're not treated with an insecticide they will die," he warned. He said organic treatments cost about $40 at garden centers and can provide up to two years of protection.

"Every metro or community where it's established, EAB kills every ash tree," he said. "There is no 'some trees survive, some trees don't.' It kills them all."

Mark Saxenmeyer can be reached at msaxenmeyer@kstp.com