Winter Moth Article
Winter moths, swarming in area, are in assault mode
Offspring of pests threaten leafy trees when spring comes
By Dorian Block, Globe Correspondent | December 8, 2005

Michael Welch was on his way home to Appleton Street in Arlington last week with his two children when he came across something he had never seen before.

''I noticed the moths in the headlights on the way home, and when we got home, the front step light was on, and all around the door and the side of the house and near the steps there were 40 or 50 at least,'' recalled Welch, who said he had never seen so many moths at this time of year. ''We were just amazed at them."

The next day when Welch, a middle school special education teacher, went to work 15 miles away in Billerica, the moths were there, too.

Winged pests called winter moths were first spotted in New England three years ago in Plymouth County, and have been spreading since. Last year, the moths had a modest presence in the suburbs north and west of Boston. But last week was the first time that swarms were seen in communities as far west as Acton and Concord, as far north as Gloucester, and as far south as Rhode Island and Connecticut.

Robert A. Childs, an entomologist at the University of Massachusetts Extension Landscape, Nursery and Urban Forestry Program, is one of a few scientists trying to control these foreign insects. He compared the arrival of winter moths in Massachusetts in the last few years to the arrival of gypsy moths in this country in 1869.

''It is the classic story of a pest coming to a new land," Childs said. ''It has plenty of food. It can tolerate our climate. The trees are not resistant to attack. There's nothing here that bothers it."

The problem with winter moths is that they lay eggs in the winter, and when the larvae hatch in the early spring, they eat the buds on trees. This results in leaves filled with holes and fruitless crops, Childs said. Farmers on the South Shore have complained about damage to their blueberry crops before the buds have had time to flower.

If the infestation lasts several years, complete defoliation can result, causing the death of trees, according to a paper written by Childs. In parts of Nova Scotia, the moths are responsible for the death of nearly 40 percent of red oaks at forested stands.

The male moths are tan and have four wings that are fringed at the end, while females are gray and wingless. The larvae are pale green caterpillars with white stripes running down each side of the body.

Large populations of moths moved from Europe into Nova Scotia and British Columbia, 60 years ago, but Childs said it's not clear whether they are related to the Massachusetts moths. He speculates the moths in Plymouth County were imported along with nursery plants.

Unlike the Massachusetts moths, Canadian moths are controlled by natural parasites that feed on them. Another entomologist at UMass-Amherst, Joseph Elkinton, went to Canada to collect larvae that were infected with the parasites, a type of small fly. He brought them back to his lab to separate the parasites and introduce them into the community.

Last year, Elkinton released 400 flies into Plymouth County and has another 5,000 moths he works on in his lab to generate more flies.

Childs called Elkinton ''the only person in North America doing that on a large scale."

''It will continue for a while until this fly catches up with it," Childs said. He added that the presence of the flies has not caused subsequent environmental problems and he doesn't expect any problems here. ''This fly that they got from Canada has been tested for a long time," Childs said.

Mark Bezreh, owner of ArborCare Tree Service Inc. in Woburn, said he has received many calls from people complaining of the moths attacking their trees since last year. But he said the problem is noticeably worse this year.

While most of the damage is done in the spring, when the larvae eat the buds, people notice them more in the winter, when they mature and flock to porch lights and doorways.

''The moths themselves are surprising people this time of year because normally there aren't moths around in December," Bezreh said. ''We watch the temperatures and weather conditions very closely in general when spring is coming."

His company uses nontoxic sprays to attack the larvae in the spring.

Julie Corliss, one of Bezreh's clients on Davis Avenue in Arlington, first noticed the effect of the moths on her trees in the summer. She described the leaves in her backyard as ''chewed" and ''destroyed."

''We have a big yard with big Norway maples and beech trees, and they all have really damaged leaves,'' Corliss said. ''Trees are a really important part of what makes this neighborhood nice. I would hate to see them infected."

Residents in many communities around Boston are similarly concerned, including in Lexington and Arlington, where messages about the moths have been flying on the towns' websites.

Childs said the moths should disappear by the beginning of January. But while the moths will die, the eggs they are laying will live on.

''They are not going away,'' Childs said. ''It is going to take a long time. And now that the world has grown so much smaller and we are moving so much stuff all around the world at a phenomenal pace, we will continue to see more and more of this."