UMass Extension Landscape Message April 29, 2011

"Winter Moth (WM) eggs hatched a couple of weeks ago and host plants with swelling buds were attacked by the tiny caterpillars wriggling into the expanding new foliage and flowers. Norway maples, blueberry and others are common hosts at this time for winter moth caterpillars. Oaks are another preferred host but generally break bud later than maples and thus preclude the tiny larvae from entering the buds. Cool weather and other factors that delay bud opening can result in much damage to leaf and flower buds, especially when many larvae exist per bud. Some areas of Rhode Island have reported as many as 12 caterpillars per bud in some plants within the past week. Overall, winter moth is expected to have scattered areas of outbreak numbers this year in eastern MA. Once buds have expanded sufficiently a spray with Bacillus thuringiensis (Kurstaki) or one that contains Spinosad as the active ingredient should provide the desired levels of control. "

Claire