CAPE ELIZABETH — The northern red oaks and other stately trees in Fort Williams Park are a pleasure to behold.

Lining the parade ground, circling the brick-paved Council Ring and dotting the Cliff Walk that overlooks Casco Bay, they provide color and shade in warmer months and marshal the park through leafless winters.

And they’re under attack by winter moths, like an increasing number of oak, maple, ash, elm and fruit trees across southern Maine. Cape Elizabeth is ground zero for the devastation, and the town is stepping up efforts to combat the insect that has already destroyed more than 300 acres of oak trees here.

About 50 volunteers braved freezing winds Saturday morning to arm the park’s trees against the anticipated onslaught. Like clockwork, between Thanksgiving and the start of the new year, the insects will emerge from the ground when the temperature rises above freezing and begin their assault.

While the male moths are most noticeable, swarming in eerie clouds around porch lights and street lamps, the near-wingless and flightless female moths are the real culprits. They crawl up tree trunks and lay eggs that will hatch into larvae in the spring and gorge on new buds and leaves.

With long strips of polyester batting and wide, sticky arborist tape, the volunteers banded more than 100 trees in the park Saturday. Volunteers were to band another 50 trees in Robinson Woods on Sunday. Placed about 4 feet off the ground, the bands will trap the female moths during their climb and be removed in January.


“It’s not 100 percent effective,” Todd Robbins admitted Saturday while instructing volunteers. “We’re going to catch as many as we can.”

Banding is part of an integrated pest management plan that Robbins, the town’s tree warden, has developed to combat the winter moth problem. The town has tripled the budget to care for trees in parks and along roads – from $20,000 two years ago to $60,000 this year – recognizing that winter moths have exponentially increased demand for pest control, pruning, dead-tree removals and replacement plantings.

First identified here in 2011, winter moths are damaging and killing trees in coastal Maine communities from Kittery to Bar Harbor, according to the Maine Forest Service. An aerial survey last year found 300 acres of oak mortality in Cape Elizabeth – an area encompassing 2,000 to 3,000 dead trees – and the infestation has spread into South Portland and Scarborough.

Todd Robbins, at right, the Cape Elizabeth tree warden, explains to volunteers how to band the trees, before the helpers break off into groups at Fort Williams Park on Saturday.


Tell-tale signs of the moth’s impact were apparent throughout the three communities last spring and summer, when hungry caterpillars left otherwise hardy-looking trees with lacy canopies. In some cases, damage done in the spring was so drastic that trees immediately put out a second flush of leaves, diverting much-needed energy from the usual growth process.

Most trees can survive moderate winter moth infestations that destroy less than 50 percent of their foliage, Robbins said. Three or four years in a row with a second flush of leaves will kill a tree, especially under recent drought conditions.


Scott Akerman has seen winter moth damage in the trees around his house, so his purpose in volunteering Saturday was twofold.

“I figured I’d help out and learn what to do, then I’ll do my trees,” Akerman said. “All my neighbors want to do their trees, too.”

The small, light brown moths came to North America from Europe in the early 1900s. Infestations were seen first in Nova Scotia in the 1930s and then in the Pacific Northwest in the 1970s, according to the forest service. The moths arrived in Massachusetts in the early 2000s, spreading south into Rhode Island and north into Maine.

Entomologists believe the moths were brought to Maine when people transplanted perennial flowers and shrubs from infested gardens to the south. The spread continues in much the same way, hastened by climate change and opportunities built into the moth’s life cycle.

After the eggs hatch on warm spring days and the larvae feed on tree buds and young leaves, the small green caterpillars spin down to the ground and burrow into the soil, where they form cocoons and remain from June to November, waiting for the next mating season.

Consequently, the moths can be spread by gardeners who swap plants with friends or sell them at fundraisers, and through mulch made from contaminated leaves, lawn clippings and other garden debris. They also can be transported by cars, boats and other vehicles that happen to be where the caterpillars fall.



The forest service has taken steps to control and reduce winter moth infestations. Parasitoid flies have been released in recent years in Cape Elizabeth, Harpswell, Kittery Point, Vinalhaven and Peaks Island, in the hope of repeating successful moth population reductions achieved in Nova Scotia.

The flies, Cyzenis albicans, lay eggs on leaves that are eaten by winter moth caterpillars. The fly eggs hatch into maggots and lay dormant inside the caterpillars until late summer, when they eat the moth larvae as they pupate underground. It’s unclear how long it will take for the flies to have an effect on the local winter moth population, but it’s expected to take years.

In the meantime, Robbins recommends that residents band trees in the fall and apply horticultural oils in the spring to smother any larvae that might slip through the barriers. Further guidance is linked on the homepage of the town’s website,

A licensed arborist who is assistant property manager at Ram Island Farm, Robbins also suggests planting a variety of attractive, indigenous trees that aren’t susceptible to winter moths. They include hickory, black gum, northern catalpa, tulip poplar, black walnut, and American linden, beech, sycamore and sweetgum trees.

Robbins and other town officials hope that steps taken now will stave off further damage to the town’s trees, especially in Fort Williams Park, a 90-acre property that attracts about 1 million people annually to see Portland Head Light, the Children’s Garden and other features.

While trees in the park have been infested for a few years, there hasn’t been a second flush of leaves, Robbins said. Spending some time and money to protect the trees now could prevent costly tree loss in the future.

“The goal is to significantly reduce the effects of winter moth,” Robbins said.

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