VINALHAVEN — The island was just blessed with the arrival of 2,000 parasitic flies (Cyenis albicans). It doesn’t sound like much of a blessing, but islanders hope the flies will help control the winter moth population, which has been defoliating deciduous trees noticeably for the last two years.
The release was the result of hard work by residents, who noticed the problem and contacted the state, wrote letters of concern to representatives in Augusta and Washington, and helped monitor the infestation.
It also ended up being the culmination of two years worth of work for the Vinalhaven middle school’s Vital Signs club.
In the fall of 2012, five seventh-grade students volunteered to join the new program sponsored by the Vinalhaven Land Trust. The idea was to work on a project in which data would be collected that would help the community. The original objective was to document invasive species on the island using the Gulf of Maine Research Institute’s program Vital Signs (thus the name of the club). However, a small, nondescript moth hijacked those plans.
That fall, the town learned why all the maple leaves began to resemble Swiss cheese—an infestation of winter moths, a species that feeds on hardwood tree buds.
The Vital Signs kids decided to do something about it. They banded trees all over town to prevent the winter moth females from crawling up the trees (females can’t fly) and laying their eggs. They then documented where the winter moth was found and not found. The kids started to become the local experts on this pest, making recommendations to townspeople about whether or not to worry about their trees based on the data.
In the fall of 2013, students learned from state entomologist, Charlene Donahue, that banding trees was a good idea for documenting where winter moth was located, but not particularly helpful in reducing the population of the moth. So a few trees were banded to monitor and map the range of winter moth on the island.
Work also began on bringing the parasitic flies to Vinalhaven. The club helped Dr. Joseph Elkinton, a professor of entomology at the University of Massachusetts, get an estimate of the winter moth population on the island to assess whether a parasitic fly release would be feasible.
A pheromone trap was set up to capture male moths, and all those captured were sent them to the lab. Two special tree bands to assess the number of females in the area. The Vital Signs crew visited these bands every few days in December and sent the numbers to Elkinton.
This spring, students watched the eggs turn from pink to blue, indicating hatching, and reported the dates to scientists. After months of anticipation, Elkinton visited the island on May 21 to release the parasitic flies.
It will be years before the winter moth population decreases, since it takes time for the flies to build up their population to a high enough level to have a noticeable impact. The Maine Forest Service will monitor the winter moth and fly populations over the next several years to see how the release is working. The next generation of Vital Signs students may help them in this endeavor.
For more information: http://www.state.me.us/doc/mfs/InvasiveThreats.htm#wm
Amy Palmer is a science and social studies teacher at Vinalhaven’s middle school.