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UMass Extension Landscape Message December 2, 2011

UMass Extension Landscape Message December 2, 2011

"Winter Moth adults are active. The drab grey males do fly while the females are virtually wingless and cannot fly. They are most active at night, especially after a rain and especially if the weather is warm. Females emerge from the soil, visually seek a vertical silhouette (such as a tree trunk), run to it and upwards all-the-while emitting a pheromone that attracts hundreds of male moths. During years of high emergence numbers, the scene is often referred to as 'a blizzard of moths'. The males are also easily attracted to outside lightning and often congregate on porches or lighted holiday decorations. Thus far this November, winter moth emergence has been quite substantial and more are expected within the next couple of weeks, especially if the nights remain as warm as they have been in recent weeks. This portends a large population of winter moth caterpillars early next spring, excluding any unforeseen events that may diminish the population numbers over the winter. This insect hatches from the egg in the very early spring, just prior to budbreak, and wriggles into the swelling buds to feed. Dormant oil sprays can be applied to blueberries and apples, in particular, at that time as long as the correct weather conditions prevail. The tiny caterpillars also balloon onto new plants once the buds open and can infest or re-infest new plants at that time. Spinosad products are very effective once the buds are open and the caterpillars are free-feeders. Maples, crabapples, apple, blueberry, birches, oaks, and many other deciduous species are susceptible host plants.

Reported by Robert Childs, Extension Entomologist, Plant, Soil and Insect Sciences Department, UMass, Amherst.

Claire

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