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Published April 07, 2009, 01:56 PM

Insect moves closer to Northland’s millions of ash trees

A small, tree-killing insect from China has jumped across the entire state of Wisconsin in a single bound.

By: John Myers, Duluth News Tribune

A small, tree-killing insect from China has jumped across the entire state of Wisconsin in a single bound.

Wisconsin officials announced today that emerald ash borer had been discovered in Victory, a small Mississippi River town 20 miles south of La Crosse.

It’s the first confirmed outbreak of the insect outside the greater Milwaukee area and the first anywhere near Minnesota.

“The presence of EAB in Vernon County was confirmed for us Monday morning. Our agency, in concert with other state and federal partners, is now working out the details of surveying the area and learning more about the age and extent of the infestation,” said Rod Nilsestuen, Secretary of the Wisconsin Department of Agriculture, Trade and Consumer Protection.

Vernon County becomes the third infestation in Wisconsin. The insects were confirmed in Ozaukee and Washington counties near Milwaukee last year. In March, state officials said the Ozaukee County infestation was too big to stop.

Minnesota and Iowa officials also were notified of the outbreak Monday; officials from those states will tour the Victory infestation later this week.

It’s believed that most emerald ash borer movement is caused by people transporting infested firewood. All firewood and nursery trees in the Victory area will be immediately quarantined.

Minnesota and Wisconsin officials have asked all residents and tourists not to move any firewood more than a few miles from where it was cut — and especially not to bring it north when they vacation.


Northern Minnesota and Wisconsin are considered vulnerable to emerald ash borer because of the millions of ash trees that grow in the wild and the large number of urban ash trees. There are 765 million ash trees in Wisconsin forests and 820 million in Minnesota. Experts say all are at risk because the bugs have no natural enemies here.

No species of ash has been able to withstand the bugs. Unlike some insects that kill only sick or drought-stricken trees, emerald ash borer has killed every ash tree it has infected. The beetles can fly and spread, but it is the larvae that bore into the trees and kill the ash.

Emerald ash borers first were discovered in the Detroit area in the 1990s after arriving in the U.S. in shipping crates from China. In less than a decade, the bugs have spread and killed millions of ash trees in Michigan, Indiana, Ohio, Pennsylvania, Maryland, Illinois, West Virginia, Virginia, Missouri and the Canadian Provinces of Quebec and Ontario.

The adult emerald ash borer is a metallic green insect about one-half inch long and one-eighth inch wide. The adult female deposits eggs on the bark of ash trees. The larvae hatching from the eggs chew their way through the bark, and into the soft layer of wood just beneath. There, they eat their way through the tree’s vascular system, cutting off the flow of water and nutrients in the tree, leading to decline and eventual death of the tree.

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