For the first time, the highly destructive emerald ash borer has been identified in Wright County, the Minnesota Department of Agriculture said last week.

The agency quickly placed the north metro county under an emergency quarantine on Thursday after the tree-killing insect was found in Clearwater, along the Interstate 94 corridor. The action is designed to limit the movement of firewood and ash material out of the county, reducing the risk of further spreading the blight.

Seventeen counties are now under a full or partial quarantine, the state Agriculture Department said.

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, now found in 30 states, was first found in Minnesota in 2009.

Minnesota has approximately 1 billion ash trees, the most of any state, according to the Agriculture Department.

"We are not surprised to find EAB in this area along I-94, since it's a high-traffic area for truckers and travelers alike," Kimberly Thielen Cremers, the agency's pest mitigation and regulatory response manager, said in a news release. "We can be certain that emerald ash borer was brought into Wright County by someone moving infested ash. The only way to protect Minnesota's ash trees is to stop moving firewood and other ash products around the state."

The agency said there are three key steps Minnesotans should take to prevent the spread of the ash borer:

• Don't transport firewood. Buy firewood locally from approved vendors, and burn it where you buy it.

• If you live in a quarantined county, be aware of the restrictions on movement of products such as ash trees, wood chips and firewood.

• Watch your ash trees for infestation. If you think your ash tree is infested, go to and use the "Do I Have Emerald Ash Borer?" guide. Suspected infestations can be reported to MDA's Arrest the Pest line at 1-888-545-6684 or e-mail