An emerald ash borer infestation has been discovered in a second area in St. Paul, this one just north of historic Summit Avenue and three miles southeast of the first site.

“It’s kind of disappointing for it to be showing up someplace else, but you have to expect that would happen with this bug,” said Mark Abrahamson, a Minnesota Agriculture Department entomologist and emerald ash borer project coordinator.

City workers cut down six boulevard ash trees along Dale and Kent streets between Summit and Portland avenues Monday and hauled away the wood for burning.

State crews, meanwhile, will monitor other nearby ash trees to see if they are infected, too, Abrahamson said.

“We fully expect there to be additional findings because of the proximity of other ash trees,” said Brad Meyer, a spokesman for the city’s Parks and Recreation Department.

About 20 percent of the public trees in that part of the city are ash trees.

Since the invasive, metallic-green beetles were discovered in St. Paul’s St. Anthony neighborhood in 2009, they have been found in Minneapolis, Falcon Heights and Shoreview. They also have infested portions of Houston and Winona counties in far southeastern Minnesota.

The ash borers have killed millions of ash trees in more than a dozen states since being accidentally introduced into North America more than a decade ago. They tunnel through the bark and disrupt the flow of nutrients, leaving D-shaped exit marks in the bark.

The trees cut down Monday, estimated to be 15 to 20 years old, were not recent victims, Abrahamson said.

“This tells you they’ve been in here for a couple of years,” he said, pointing to wood growth around an exit hole on one of the trees.

In the past two years, St. Paul has embarked on an ambitious effort to contain the spread of the beetles, removing about 1,000 of its 30,000 ash trees on public land each year, inoculating other trees with a chemical treatment that’s effective for three years and launching education efforts with residents.

People worried or interested in protecting their private ash trees should contact certified arborists and have them inspect their trees, Meyer said. Treatments are available but can be costly.

The state also has been releasing stingless Chinese wasps onto infested ash trees in the Twin Cities and in southeastern Minnesota. The wasps, also natives of Asia, are natural predators.

The most recent discovery is three miles from the state’s first infestation, an area north of University Avenue and east of Minnesota 280. Thirty-four infested trees were removed there in 2009, 87 in 2010 and 101 this year.

In addition, 61 infested ash have been removed from private properties over that period.

Minneapolis, meanwhile, has identified 255 infested trees between its border with St. Paul and the Minneapolis campus of the University of Minnesota and on both sides of the Mississippi River southeast of the campus.

Those and 1,250 other ash trees on public property have been removed.

The Shoreview infestation, 10 miles north of the initial discovery, was identified in July.

Liz Erickson, a communication coordinator for the agriculture department, said a state emerald ash borer trapper discovered the most recent infestation Sept. 16 when he noticed a couple of the ash trees showing signs of decline.

The city plans to replace the six ashes with other trees, perhaps as early as this fall, Meyer said.

Dennis Lien can be reached at 651-228-5588.