In a troubling sign that the destructive emerald ash borer is widening its presence in the metro area, a new infestation of the metallic green beetles was discovered this week in trees in a Shoreview neighborhood.

That's 10 miles from the nearest known infestations, which have been reported in Minneapolis, St. Paul and Falcon Heights. The borer also has been spotted in Houston County, in southeastern Minnesota.

"We know that the emerald ash borer is going to spread," said Allen Sommerfeld, a spokesman for the Minnesota Department of Agriculture. "We do our best to slow it down. We'll take any means to isolate it."

Officials from the Agriculture Department were on the scene Friday trying to determine the extent of the infestation, which was found by a property owner in the vicinity of County Road I and Schutta Road. The property owner reported it to the city of Shoreview.

While new infestations have been found this year along West River Parkway in Minneapolis not far from where previous colonies were spotted, Shoreview is the first new location where the pest has turned up locally this year, Sommerfeld said.

It was not immediately clear how the borer arrived in Shoreview, but because the beetles are weak fliers, it probably caught a ride from somebody transporting ash trees, wood chips or firewood, he said.

Shoreview is in northern Ramsey County, which the Agriculture Department has under quarantine restrictions that prohibit moving items affected with emerald ash borer in or out of the county.

Also Friday, the department reminded people to buy firewood from approved vendors and burn it where they buy it.

Since the ash borer was accidentally introduced into the United States, it has killed millions of trees in 15 states.

The borer larvae kill by tunneling into ash trees, then feeding on and disrupting the flow of nutrients. They leave telltale 1/8-inch D-shaped exit wounds in the bark and serpentine tunnels underneath it. The borers are active from May to September.

The emerald ash borer was first detected in Minnesota two years ago.

More information about the ash borer and how to prevent its spread can be found at www.mda.state.mn.us.

Tim Harlow • 651-735-1824 Twitter: @timstrib