The scarring left by an emerald ash borer, an invasive forest insect that has killed hundreds of millions of ash trees in the United States, was found on a tree in Madawaska, along with a pre-pupa stage of the insect, on May 22, 2018 Credit: Courtesy of the U.S. Forest Service

PORTLAND — Portland’s forestry team is working to remove ash trees infected with emerald ash borers.

Emerald ash borers are an exotic wood-boring beetle that has killed hundreds of millions of ash trees in 35 states and five Canadian provinces.

Emerald ash borers will greatly impact ash trees in Portland and Southern Maine next year and over the years to come, a City of Portland press release warned.

“One can assume that all ash trees are infected. Unfortunately, ash trees decline quickly and become brittle adding to the risk created,” according to the news release.

Forestry staff has been working with the Maine Forest Service for the past five years on survey and planning for this outbreak, city staff said.

The first removal of many infected ash trees happened on Portland’s District Road, where the infestation is regionally affecting Portland, South Portland, and Westbrook.

So far, the infestation has been sporadic, but city officials say it is expected to ramp up in the following years to nearby communities, placing ash trees at risk.

Seven infected ash trees in the Lincoln Middle School parking lot are slated to be removed and replaced.

Forestry staff are working with the Maine Forest Service and U.S. Forest Service on a biological control project for ash tree woodlands along the Presumpscot River, Portland officials said.

A few Greater Portland communities, including Portland, have been actively treating ash trees to prevent infection. Treatment for ash trees is ideally done in May and June.