Bangor could protect its more than 1,800 ash trees from an invasive insect by treating some with a chemical and removing hundreds of others altogether.
Sophia Cameron, a masters of forestry graduate from the University of Maine’s School of Forest Resources, worked for the city over this past academic year to develop a plan for how Bangor could proactively fight emerald ash borer.
The multi-year plan, which hasn’t yet been formally approved, would include removing and replacing more than 400 ash trees while treating 250 others with an insecticide that would kill the bugs.
Cameron presented the proposal to the city council’s Infrastructure Committee on Monday. The Bangor Tree Board will review the plan and issue an opinion on whether councilors should approve and enact it.
Emerald ash borer is an invasive species of bug that, as larvae, eat away the inner layer of bark of ash trees. That part of the tree carries water and nutrients up to the leaves, so when it’s damaged, the tree slowly dies from the top down.
An ash tree has only a 2 percent chance of surviving an emerald ash borer infestation if left untreated.
The bugs, which are metallic green and about the size of a penny, arrived in the U.S. in 2002, likely through wooden shipping pallets, and spread to nearly 40 states. In 2018, they were found in Maine, and an infestation was identified in Hermon in 2023, meaning it’s only a matter of time until the bugs reach Bangor, Cameron said.
Aside from being unsightly, trees killed by emerald ash borer become extremely brittle and can collapse under their own weight on a clear, windless day, according to Aaron Huotari, Bangor’s public works director. This is especially dangerous in an urban environment like Bangor with plenty of buildings, power lines and foot and vehicle traffic.
“We’re looking at a pretty disastrous scenario if we do nothing,” Cameron said.
Trees also provide several benefits to the city, as they filter air, raise property values, and cool urban areas. Ash trees in particular also absorb an especially large amount of water, Cameron said, which saves it from going into the city’s stormwater system.
Cameron’s plan to protect the city from an infestation involves removing 436 ash trees over the next four years that are already unhealthy or in dangerous locations, as they would be even more hazardous if they were to be infested. Those trees would be replaced with various types of trees, Cameron said.
Cameron also identified 250 ash trees on city property that are healthy and should be preserved. Under her plan, a chemical would be injected into the base of the tree that kills emerald ash borer larvae.
The insecticide is effective for up to three years, so each of the 250 healthy trees would be treated every three years for nine years in total, Cameron said. Trees on the west side of the city, closest to Hermon, would be treated first.
Huotari said the city aims to treat the first 80 trees this year.
In total, Cameron’s plan would cost the city an estimated $521,629.
Of that, treating 250 trees with insecticide over nine years would cost $26,864, Cameron estimated. Removing 436 trees over four years would cost the city an estimated $330,022, plus another $164,743 to replace those trees.
The proposal would also involve continuing to monitor the remaining ash trees and informing Bangor residents of how they can protect any on their private property.
The proposed plan was created after four University of Maine forestry students, including Cameron, spent last summer counting, categorizing and inspecting every single tree on public land in Bangor. In total, the students counted 8,574 trees, 20 percent of which are ash trees.
Ash trees are the second most common tree species found on public land in Bangor, just behind Norway maple, and most of the 1,854 ash trees are in the city’s residential areas.
Huotari and Cameron said they aren’t aware of any other communities in Maine that are proactively protecting its ash trees from the bugs in this way.
“Since we acted so early, we have this chance and we need to keep acting early,” Cameron said. “We can’t keep it from getting here, but we can plan for it to get here.”