ST. PAUL - The Minnesota Department of Agriculture has placed Stearns County under an emergency quarantine after emerald ash borer was found in the city of Sauk Centre.

According to a news release, city workers noticed several trees that showed signs of damage from the tree-killing insect and alerted the Department of Agriculture, whose staff examined the trees and collected samples of larvae for confirmation.

A total of 18 Minnesota counties, including Stearns County, are now under a full or partial quarantine to prevent the spread of this highly destructive tree pest. The quarantines place restrictions on movement of products such as ash trees, wood chips and firewood.

Emerald ash borer larvae kill ash trees by tunneling under the bark and feeding on the part of the tree that moves nutrients up and down the trunk. The invasive insect was first discovered in Minnesota in 2009 and is now found in 35 states.

Minnesota is highly susceptible as the state has approximately 1 billion ash trees.