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Emerald Ash Borer beetles returning to SE Wisconsin

Posted at 6:50 AM, Mar 14, 2019
and last updated 2019-03-15 10:21:50-04

BROOKFIELD — During 2019's polar vortex, there was a small hope the extreme cold would wipe out the invasive Emerald Ash Borer.

Even with temperatures dipping close to minus-30 degrees, that still was not the case.

Along with the Wisconsin Department of Natural Resources, we found countless living and healthy larva in the Brookfield area. Bill McNee, DNR forest health specialist, said "even if 80 percent of larva die, that is still the potential for a very rapid population increase."

In fact, each adult female beetle will produce up to 200 eggs by late summer.

The City of Brookfield has seen a recent infestation. According to Gary Majeskie, the superintendent of Brookfield Parks and Forestry, the removal of trees has quadrupled during the last two years.

Brookfield has now taken advantage of a unique study with the U.S. Department of Agriculture. They will pick up the tab of removing infested trees and send them to a lab in Brighton, Michigan.

The growing beetles in these trees are used to feed a particular wasp, which is also bred at the facility. The newly formed wasp army will then be released into an environment infected by Emerald Ash Borer, including here in southeast Wisconsin.

According to McNee, "the wasps come from a cold climate in northeast China and adjacent Russia, and when people hear wasp, they think of a large, yellow stinging insect. Instead, these are tiny blackish insects the size of a grain of rice. They don't sting, and they don't bite."

"Even if 80 percent of larva die, that is still the potential for a very rapid population increase." — Bill McNee, DNR forest health specialist

The DNR says it's too early to tell if the wasps will work here in Wisconsin, but the Emerald Ash Borer isn't going anywhere.

"Even though the bigger trees are expected to have more than 99 percent mortality, the young trees we hope or expect to have some long-term persistence," McNee said.

The DNR says it's also important for you to do your part by treating any healthy Ash trees on your property. For more information on professional and D.I.Y. treatment options,click here.