Minnesota on alert to keep pine beetles out, state wants quarantine on western pine logs

Minnesota agriculture officials are sounding the alarm for yet another invading insect. This time it's the mountain pine beetle that's already devastating forests of the Rocky Mountains and has moved as close as the Black Hills of South Dakota. T...

Minnesota agriculture officials are sounding the alarm for yet another invading insect.

This time it’s the mountain pine beetle that’s already devastating forests of the Rocky Mountains and has moved as close as the Black Hills of South Dakota.

The Minnesota Department of Agriculture on Wednesday proposed a quarantine to keep the beetle out of the state and protect native red, white, and jack pines.

The proposed quarantine would restrict pine logs or wood with bark on it from entering Minnesota if it came from the 13 western states known to have a mountain pine beetle infestation.

It’s hoped the quarantine might stop the beetle from hitchhiking on bark-covered pine logs trucked into Minnesota.


“If it’s not stopped at our border, the mountain pine beetle has the potential to have a major impact on Minnesota’s forests,” said Mark Abrahamson, entomologist for the Minnesota Department of Agriculture.

Abrahamson said all of Minnesota’s major pine species “are potential targets for the insect.”

Just last month, Abrahamson found mountain pine beetles in firewood imported to Minnesota from Wyoming.

“The wood was a little seasoned, so the larvae had died. But it was clear they had been alive as recently as this summer,” he said.

Abrahamson also found dead mountain pine beetles in wood trucked to Minnesota in 2012.

“That was a pretty close call,” he said.

So far, traps laid for the insect in the state haven’t caught any live beetles here.

The quarantine mostly will affect logs brought to Minnesota for firewood and log home construction, Abrahamson said. So far, there’s been little opposition from the state’s wood products industry. Nursery trees, cured lumber and already debarked trees would not be affected by the quarantine.


Researchers say that even if the beetles could be stopped from moving on transported wood, the bugs may march on their own across northern Canada’s boreal forest and then south into Minnesota.

The insects are native to the far western U.S. and Canada and are known for their periodic outbreaks. But until the past 20 years, they had never been able to cross the Rocky Mountains.

Now, with a trend toward warmer winters, the bugs have crossed the mountains and spread north and east for the first time in recorded history. They have moved into eastern Alberta and the Black Hills and have destroyed trees across 120 million acres.

Research by University of Minnesota scientist Brian Aukema - part of a $250,000, three-year study - showed that mountain pine beetles will colonize and kill Minnesota pine species. Aukema’s team placed Minnesota white, red, jack and Scotch pine logs in the Black Hills, and the bugs colonized them quickly.

The beetles, each about the size of a grain of rice, lay eggs that burrow under the bark of pines larger than 5 inches in diameter. The larvae tunnel through the outer layer of the tree that transfers water and nutrients, and the tree quickly dies.

“All the action happens right under the bark, so de-barked logs aren’t an issue,’’ Abrahamson said. “They kill the tree pretty much the same way as emerald ash borers do.”

The mountain pine beetle is just the latest in a barrage of invading threats for Northland forests, after the encroachment of the gypsy moth in Northeastern Minnesota and the influx of the emerald ash borer that is killing trees as close as Superior.

The state wants to impose the quarantine starting Jan. 1. The Department of Agriculture is accepting comments and will hold an open house from 5-6 p.m. Monday at the Floodwood City Hall, 111 W. Eighth St. Comments are due by Dec. 15 to Mark Abrahamson, Minnesota Department of Agriculture, 625 Robert St. N., St Paul, MN 55155, to or by fax to (651) 201-6108. For more information, go to .


The Minnesota quarantine can’t stop Canadian wood from entering the state - that would take federal action. Abrahamson said Minnesota has asked the U.S. Department of Agriculture to intervene to keep wood from infested provinces out.

John Myers reports on the outdoors, natural resources and the environment for the Duluth News Tribune. You can reach him at
What To Read Next
Get Local