UMass Extension Landscape Message December 3, 2010

"Winter Moth: Activity of the adult moths of this species began earlier than usual in MA this year as suspected would happen due to the very warm weather in mid-late March that accelerated the hatching of the eggs by 10-14 days. Adult male winter moths were first seen in Plymouth County on the last day of October. Last year at this time, record numbers of winter moths were counted and much defoliation was expected during the spring of 2010. However, the exceptionally warm weather in the latter part of March forced the over-wintering eggs to hatch when the host trees were not yet in prime condition for the caterpillars to obtain access into the buds. Many winter moth caterpillars starved or ballooned to areas or plants that could not sustain them. Record defoliation did not occur in MA in 2010 as expected but, overall, it is estimated by MDCR that 75,000 acres in eastern MA were defoliated by this pest in the spring of 2010. Research this summer in MA indicated that numbers of adult winter moths would be low this November. However, reports and sampling thus far indicates that the opposite may be true. Adult activity has been much heavier than expected, which suggests that problematic numbers of caterpillars may be present next spring. "

Claire