The Maine Forest Service wants the public to report any winter moth sightings across the state. The winter moth’s larvae is destructive to the state’s deciduous trees and shrubs, according to a MFS memo sent out to municipalities last month.

The Edgecomb Board of Selectmen discussed the memo Dec. 7. The MFS has provided municipalities with a 2015 winter moth status report, an at-risk map for 2014 and 2015, a table of moth catches in pheromone traps for the past two years, and a list of trap locations.

The MFS reports receiving several winter moths sightings in Boothbay and Boothbay Harbor during the past three years.

The MFS sent out its winter moth report the day before Thanksgiving. The service has since received over 1,800 reports online and over 100 phone calls of reported sightings, according Forest Entomologist Charlene Donahue.

The Maine Forest Service wanta municipalities, especially in coastal Maine, to report any sightings. The winter moth has spread along Maine’s coast with sightings recorded from Kittery to Bar Harbor.

The winter moth is foreign to North America. It was introduced into North America from Europe in the 1930s. According to the MFS, the first North American sighting was in Nova Scotia. The first U.S. sighting occurred in the Pacific Northwest during the 1970s.

The winter moth was first sighted in New England in the early 2000s, in eastern Massachusetts. The species later expanded into western Massachusetts and into Rhode Island.

The MFS report indicates deciduous trees and shrubs serve as hosts to winter moth’s larvae. This destructive relationship defoliates deciduous trees and shrubs in the early spring. Trees heavily defoliated for three or more years may exhibit branch die-back and mortality.

Winter moths feed on leaves of deciduous trees and shrubs. Preferred hosts include oak, maple, apple, elm, crabapple, cherry and blueberry. The species’ larvae may also feed on many other plants, according to the MFS.

The larvae hatches in early spring from eggs on the host’s tree trunks. It crawls up the trees and burrows into leaf and flower buds feeding on the expanding foliage. The moth’s larvae is light green to brownish-green inchworms with longitudinal white strips on each side of the body. The moth is a half inch-long at full-growth.

The MFS believe the some of the winter moths were transported into Maine by landscapers.

“At least some were likely introduced into Maine as cocoons in the soil of landscape trees and plants from infested areas in southern New England,” according to a Maine Department of Agriculture, Conservation and Forestry website.

The winter moth is closely related to the native Bruce spanworm. State officials report the two species are difficult to tell apart, but have one major difference.

“Bruce spanworm is an occasional pest of trees in Maine and rarely remains a problem for long. This is in contrast to the winter moth which has no natural enemies in North America,” according to the Maine Department of Agriculture, Conservation and Forestry website.

The only way to differentiate between the winter moth and Bruce spanworm is to dissect them. Despite the similarity, arborists and pest control applicators have reported seeing winter moths along Maine coastal communities.

The MFS is also using research provided by the University of Maine to mitigate the winter moth’s damage to Maine forests. 

“Once here, they’re here,” Donahue said. “You cannot eradicate the population.”

The Maine Forest Service and the United State Department of Agriculture’s Forest Service have introduced a parasitic fly to combat the winter moth. Donahue expects it will take almost a decade before the flies are a factor in combating the winter moth.

“We’ve released the parasitic flies for three years in high population areas of winter moths. The problem is it takes 7-10 years for the parasitic flies’ population to grew large enough to impact the winter moths’ numbers,” Donahue said.

Anyone who sees a winter moth is advised to contact the MFS at 800-367-0223 or on its website maine.gov/dacf/contact_us.html.