UNDATED (KDAL) - The extreme cold this week in Minnesota and Wisconsin could help to reduce the population of Emerald Ash Borers, the invasive bug that threatens to destroy thousand of ash trees. The Director of the UM Center for Forest Ecology, Lee Frelich says prolonged 20 below temperatures could kill around 80 percent of the bugs while nearly 90 percent would not survive sustained 30 below temperatures. We won't know until surveys are done in the spring what affect the cold winter weather will have on the numbers and spread of the Emerald Ash Borer. The bugs found closer to the base of the trunk in ash trees would have a better chance of surviving because of the deep snow that provides some insulation. In recent years, the borers have been found in several areas of Minnesota and Wisconsin including Superior last summer.