Ash borer researchers probe felled Summit Ave. trees

Researchers are examining recently felled ash trees in St. Paul to learn more about the emerald ash borer infestation.

City workers cut down six boulevard ash trees near St. Paul's historic Summit Avenue earlier this week.

U.S. Forest Service biologist Rob Venette said larvae from the trees will help researchers understand if Minnesota winters inhibit the spread of the pest.

"The emerald ash borer larvae begin to freeze anywhere from -13 to -30 degrees Fahrenheit," he said. "When temperatures drop down to that we're starting to lose some of that population."

Venette said emerald ash borer infestation will be difficult to contain in the state's southeastern corner because of milder winter temperatures, but was curious about what will happen in the northern part of the state.

"That's a story that has yet to unfold," he said.

He said the larvae from the St. Paul ash trees will also be useful for learning more about the effectiveness of stingless wasps that are being released as a biological control agent.

The Minnesota Department of Agriculture plans to release stingless wasps near Summit Avenue on Friday, close to the recently-discovered infestation.