Town Releases Winter Moth Advisory

This was submitted by the Town of Andover. 

The Town has received reports of tree leaf defoliation in various parts of Andover. The Parks & Tree Division has investigated the situation and has identified the cause to be Winter Moth caterpillars. This species has become more pervasive in the New England area over the past few years due to weather patterns. The Winter Moth caterpillar over-winters on bark and larger tree branches. In early May, the Winter Moth eggs become green caterpillars that feed on the emerging leaves of Maple, Oak, Apple and Crabapple trees. Flowering trees are not generally affected.

These small caterpillars spin a silk strand and become air buoyant and are carried upward on air currents to spread throughout the tree canopy. The Winter Moth will stay in the caterpillar stage, feeding on new leaves, until late May or early June. They will then drop to the soil and pupate into a moth. These moths then emerge from the soil around Thanksgiving and lay their eggs in the bark of trees. The eggs will start the cycle again in early May of the following year. In most cases the affected trees will re-foliate during July and early August. 

Additional information on Winter Moth life cycles and control can be found on the this Fact Sheet from the UMass Extension Landscape, Nursery, and Urban Forestry Program.