The lethal emerald ash borer has been discovered in a tree on the University of Minnesota campus in Falcon Heights, about a mile from its initial outbreak.
Inspectors from the state agriculture department found the tree Tuesday, said Geir Friisoe, director of the department's plant protection division.
"The bad news is we found it a ways off from the core [of infestation] but the good news is that the emerald ash borer isn't a big traveler," Friisoe said. "I'm guessing it's only spread to a radius of a mile or two."
The insect's first appearance in Minnesota was confirmed in a nearby St. Paul neighborhood in May. It now threatens the state's 900 million ash trees.
In the days after the bug was confirmed in St. Paul, foresters removed 68 infested ash trees in and around the Hampden Park neighborhood. They also removed 46 other obviously declining ash in a ring outside "ground zero," and found only one infested.
Testing by the U.S. Department of Agriculture has determined that the borers entered St. Paul trees in 2006. By contrast, borers had been killing trees in Michigan for more than a decade before researchers even knew they were there.
The tree in Falcon Heights appeared to be healthy, "where you usually see obvious symptoms of decline," Friisoe said. "That indicates it was a recent attack."
Department spokesman Mike Schommer said inspectors were able to identify the tree because it had sustained woodpecker damage -- one sign an infestation because the birds like to eat ash borer larvae.
The discovery means city officials may now tap into a $1 million state fund that pays for immediate municipal response to the infestation, he said.
Staff writer Bill McAuliffe contributed to this report.