Parasitic Flies to the Rescue

May 7, 2013

For more information, contact: John Bott at 207-287-3156

Release of biocontrol agent designed to combat the winter moth

AUGUSTA – Starting Tuesday, state entomologists from the Maine Department of Agriculture, Conservation and Forestry’s (DACF) division of forestry will be releasing parasitic flies in an effort to try and control and minimize the damage to trees and shrubs done by the Winter Moth. The release is being conducted by Dr. Joseph Elkinton, University of Massachusetts Professor of Entomology. He is releasing parasitic flies, Cyzenis albicans, in conjunction with the DACF’s division of forestry.

“This is a long-term approach to limiting the damage caused by the winter moth,” Maine Governor Paul R. LePage said. “It is important that we protect our natural resource economy from invasive pests like the winter moth, which can also damage blueberry, apple and cranberry crops.”

Commissioner Walt Whitcomb highlighted the collaborative approach being taken between Maine and Massachusetts. “We thank Dr. Elkington and the University of Massachusetts for collaborating with us on the timely release of these flies,” said Whitcomb.

The winter moth is the latest invasive insect to attack Maine forests with defoliation in Harpswell in 2012. A citizen supported survey of winter moth in December indicated winter moth could be found from Kittery to Bar Harbor. Unlike some of the other invasive insects on our doorstep, this one has a potential biocontrol agent that can hopefully control the insects spread and limit future damage.

Beginning Tuesday, parasitic flies, Cyzenis albicans, will be released at two release sites in Harpswell and Cape Elizabeth. Flies will be released again later in the week on either Thursday or Friday. A total of 800 flies will be released at each site with 400 flies released on each day.

People frequently ask, “Will the flies bother anything else (like people)?” The answer is no. These flies were released in Nova Scotia in the 1960s, brought the winter moth population under control and there have been no adverse effects in the intervening 50 years. Flies were also released in British Columbia again with no impacts on other insects or people. The flies are very closely tied to the winter moth life cycle and need winter moth to survive. There will always be some winter moth around, now that they have become established in Maine, but hopefully the flies will do their job and bring the winter moth population under control in a few years.

It take years before Maine will see the results of the biocontrol effort, as it takes time for the flies to become acclimated to a new location and build up their population. Once their numbers reach a high enough level, it will have a noticeable impact on the winter moth population. In the meantime people will see defoliation on hardwood trees and shrubs in May. It is hoped trees will not be too adversely effected before the parasite fly population catches up to the winter moth population and brings them into balance in Maine.

For more information on the winter moth and other invasive pests, go to:

http://www.maine.gov/doc/mfs/InvasiveThreats.htm#wm