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What can I do to get rid of winter moths? They get in my house, climb on my siding and even seem to survive through the winter. Help! Gerald N, Groton
Winter Moth, Operophtera brumata, is an invasive insect pest prevalent
throughout Europe that first showed up in Nova Scotia after World War II. Since
then, they have emerged in western Canada, Oregon and the state of Washington.
Over the last ten to fifteen years, parts of eastern New England have become infested
with them. The hardest hit areas are Massachusetts east of Route 495, especially
Cape Cod and Martha's Vineyard. They have also been observed in Rhode Island,
southeastern New Hampshire, Maine and Southeastern Connecticut.
The moth, which is the adult stage of the Winter Moth, first shows up around Thanksgiving
and will be seen into January if the temperatures remain above freezing. The
male Winter Moth has wings and will be often seen in large numbers flying around
outside lights. The female Winter Moth has stubby wings and cannot fly. Once the
eggs are laid, both male and female moths die but the eggs survive the winter. Each female lays 150 eggs, often in the bark
of trees. In April when the temperature averages around 55 degrees, the eggs hatch into caterpillars that eventually grow
to about an inch long. The caterpillars can show up in incredible numbers.
The caterpillars feed on buds of leaves and flowers as well as on developed
leaves of apple trees, crabapples, beech, cherries, blueberries, oaks, maples
and a wide range of other trees and plants. After several years of complete
defoliation, trees are seriously stressed to the point they can eventually die.
The caterpillars feed until June and then drop to the ground and pupate below
ground level only to emerge as moths around Thanksgiving to start the cycle
Help is already on the way in the form of a small fly called Cyzenis albicans,
which has shown to be an effective biological control of Winter Moths in Nova
Scotia and British Columbia. This fly is a parasite that infests the Winter
Moth by laying its eggs on leaves eaten by the Winter Moth caterpillars. The
fly eggs hatch inside the caterpillar. This fly is a specific control for the Winter
Moth; when the Winter Moth disappears, so does the Cyzenis albicans fly. This control method has been demonstrated in
Nova Scotia and in the Pacific Northwest and is being led locally by UMASS Amherst. It is expected within a decade that
the Winter Moth will be no more of a nuisance than the Gypsy Moth.
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About Linda Lillie
Linda K. Lillie is the President of Sprigs & Twigs, Inc, the premier
landscape design and maintenance, tree care, lawn care, stonework, and carpentry
service provider in southeastern Connecticut since 1997. She is a graduate of
Connecticut College in Botany, a Connecticut Master Gardener and a national
award winning landscape designer for her landscape design and landscape installation work.