SOUTH PORTLAND — Lisa Henderson first noticed something was affecting the health of her trees a couple years ago.
After learning she was dealing with a winter moth infestation, the Highland Avenue resident contacted the Maine Forest Service.
On Wednesday, Henderson’s property became home to a cage full of parasitic flies that will be released in May to counteract the winter moth population.
Henderson’s is the first private property to host a cage containing the flies, according to Charlene Donahue, a state forest entomologist. She said the South Portland release of the parasitic fly, known as Cyzenis albicans, would be the fifth in Maine.
Donahue said forest service originally planned to place the cage in Hinckley Park, but it gets so much use, particularly by people walking dogs, that it made more sense to bury the cage on Henderson’s property, which abuts the park.
Donahue said defoliation caused by winter moths is more than just unsightly, it’s also a tree killer. That’s because if a tree is defoliated enough, it will use precious energy reserves putting out a second canopy. If that cycle continues over the course of several years, the tree will die.
Funding for the fly cage was provided by the U.S. Forest Service. Donahue has also been working closely with Joseph Elkinton, a professor at the University of Massachusetts, on the best ways to control the winter moth population in Maine.
Donahue said multilateral cooperation on winter moth is vital to ensuring the health of trees in coastal Maine, as well as up and down the Eastern seaboard in both the U.S. and Canada.
Henderson said the winter moth problem is so bad at her home that the majority of her oak trees lost all their leaves. She said when she looks at her backyard on some days it looks like a covering of snow.
What Henderson likes about the bio-control approach the forest service is taking is “we’re not creating another problem to get rid of one.” Releasing the mature flies seems “like a fairly simple process that’s better than using pesticides,” she said.
Elkinton said the Cyzenis albicans species of parasitic fly was chosen because it specifically targets winter moths.
The flies have been released in both Cape Elizabeth and Kittery in past years and are beginning to become established and have a noticeable impact on the targeted moth population in those communities, Donahue said.
Elkinton said in Nova Scotia, which first began having problems with winter moth in the 1930s, use of the Cyzenis albicans fly has made the moths a non-issue. It seemed “like a no-brainer to try it here,” he said.
It takes several years for the fly to become established and start impacting the winter moth population, so getting the pest under control will take “tenacity and patience,” Elkinton added.
There are 3,000 fly cocoons in the cage buried in Henderson’s yard and not all of them will make it through the winter to emerge in the spring, Donahue said.
The public can also help the by reporting winter moth sightings, she said. An online survey is available on the forest service website, or residents can call 287-2431.
The information collected from the public will be used to better understand the locations and size of the winter moth population in Maine, according to Donahue.
The adult moths are active from late November to January whenever the temperature is above freezing. Males are small and light brown to tan in color, while the females are small, gray and flightless.
Winter moth was first recorded in Maine in 2012. In early spring the caterpillars feed on the leaves of deciduous trees and shrubs such as oaks and maples, as well as fruit trees like apple and blueberry.
In Cape Elizabeth, where thousands of trees have already been destroyed by winter moth, Tree Warden Todd Robbins and the Fort Williams Park Foundation have worked together to install BugBarrier Tree Bands.
Adhesive on the bands trap the female moths before they can climb the trees to lay their eggs. The banding stays in place for two to three weeks, which is long enough for the insects to end their egg-laying cycle.
Earlier this month Robbins said tree-trunk banding is considered to be one of the most effective ways to treat winter moth infestations.
Charlene Donahue, left, entomologist with the state of Maine, and Colleen Teerling bury a cage containing parastic fly cocoons Wednesday, Nov. 29, in a Highland Avenue backyard in South Portland. The hope is the flies will help contain the winter moth population in the city.
Charlene Donahue, a forest entomologist with the Maine Forest Service, shows off a male winter moth found in a South Portland backyard.