Local residents learned about methods of detecting the emerald ash borer, an invasive insect that kills ash trees, at a demonstration hosted by Blue Hill Heritage Trust on April 30. The demonstration was led by Colleen Teerling, an entomologist with the Maine Forest Service, and Tony Aman, a local arborist. A program organized by the trust and Downeast Audubon earlier in April highlighted the potential impact of the emerald ash borer on all ash trees throughout Maine, including black ash used for centuries by Native Americans for basketmaking.
The insect, native to Asia, was first detected in Michigan, arriving on wooden shipping pallets. With no natural biological controls on this continent, it has devastated the ash tree population there and has since spread east. In 2013 it was detected in Massachusetts and New Hampshire. Its migration eastward has been hastened by people transporting wood infested with the insect’s larvae
The Maine Forest Service, expecting the insect’s arrival in Maine, is working to create public awareness of detection methods.
“The appearance of the insect in Maine is inevitable,” said Teerling, “but it is not inevitable that all ash trees will die. We can slow down the rate it spreads and with time, biological controls may develop.”
The insect larvae do the damage, tunneling beneath the bark for as much as two years, disrupting the flow of nutrients to the tree that weakens and then kills the tree. Once infested, a tree dies in three to five years. The adults, emerald green as their name suggests, emerge in June, lay eggs and die with the frost in the fall.
The detection method demonstrated by Teerling involved removing the bark from a large section of a healthy ash tree to make it serve as a “trap tree.” The exposed sap wood emits smells that will attract the adult ash borer if any are in the area. In the fall, the tree will be cut and examined by the Forest Service. The tree is located on trust property along Pleasant Street near the junction of the Mountain Road. It has a sign identifying its purpose.
At the demonstration, Teerling and Aman reminded attendees of the large number of ash trees in the area and the effect their loss will have. To help demonstrate that, they flagged some of the other ash trees on the trust’s property near the trap tree with purple ribbons. They also placed a sign on a very large ash tree in front of the trust’s office that estimates the annual value of the ecosystem services that one tree provides.
More information about the emerald ash borer is available on the Maine Forest Service website at maine.gov/dacf/mcf/forest_health/invasive_threats.