USA NPN National Phenology Network

Taking the Pulse of Our Planet

You are here

Winter moth caterpillars can defoliate large deciduous trees. The species is present across New England. 

Image credit:
Milan Zubrik, Forest Research Institute, Slovakia,

Winter Moth Forecast

Winter moth is a non-native insect pest that causes damage to deciduous trees, particularly maples and oaks. The treatment window for this pest is not yet approaching.

Winter Moth Current Day Forecast.

Winter Moth 6-Day Forecast.

Pheno Forecast maps show when management actions should be taken for key pest species. These maps are updated daily and are available 6 days in the future.

Pheno Forecasts are based on published growing degree day (GDD) thresholds for points in pest life cycles when management actions are most effective. Forecasts are currently available for five insect pest species. 

Help us improve these maps! Our Pheno Forecast map products are still in development, and we seek input on their performance in your area. Give your feedback on the sidebar on the right side of this page. 

Species Background

Winter moth (Operophtera brumata) is a non-native insect that was first identified in the eastern United States in 2003. The caterpillars can defoliate certain species of deciduous trees. The species is present across New England, though damaging populations are only found in eastern Massachusetts, Rhode Island and Maine. This pest does not appear to be spreading rapidly. 

Treatment Summary

Winter moth, Photo: Louis-Michel Nageleisen, Département de la Santédes Forêts,

A biological control (a tachinid fly) appears to be successfully controlling this pest. Treating the caterpillars, particularly when they first emerge, with an insecticide spray can also be an effective control. The Pheno Forecast map indicates when treating caterpillers with insecticide spray is most effective. GDDs are accumulated from a base temperature of 50oF.

Source: UMass Extension

More information on map development and re-use policy.

Treatment Guidance

 For additional resources, see the: UMass Landscape Extension Information Sheet

Winter Moth Forecast