Emerald ash borer infestation spreads to Olmsted County

State officials say the emerald ash borer has now been found in Olmsted County, an indication that the destructive insect is moving west.

Officials with the Minnesota Department of Agriculture confirmed an emerald ash borer infestation near the interchange between Interstate 90 and U.S. Highway 63 in Olmsted County. That's about 45 miles west from the nearest infestation in Winona County.

Infested trees also have been found in St. Paul, Minneapolis and in rural southeastern Houston County.

State officials say the outbreak in Olmsted County likely was caused by humans moving infested ash products, like firewood. They've placed Olmsted County in a state and federal quarantine, to limit the movement of items that may be infested with emerald ash borer.

Minnesota is home to more than one billion ash trees — more than any other state in the country. Emerald ash borers have killed millions of trees in more than a dozen states.