The Maine Department of Agriculture, Conservation and Forestry announced on April 17 a formal quarantine on emerald ash borer and material that may harbor the pest. The quarantine area includes all of York County and the northeastern corner of Aroostook County. Credit: Courtesy of the University of Maine

AUGUSTA, Maine — Officials in Maine have announced a formal quarantine to slow the spread of a destructive, invasive forest insect found within trees in two areas of the state.

The Maine Department of Agriculture, Conservation and Forestry on Wednesday said the quarantine on emerald ash borer includes all of York County and the northeastern corner of Aroostook County.

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The quarantine rules prohibit movement of ash nursery stock from the quarantine area, and regulate the movement of products such as untreated ash lumber.

Since 2018, the borer has been found in western York County in far northern Maine.

The borer has killed hundreds of millions of ash trees. It was found in Michigan in 2002 and has been found in 35 states and four Canadian provinces.