Winter Moth Pheno Forecast, Contiguous United States, 2016 - Current Year

Pheno Forecast maps predict key life cycle stages in a range of species to improve conservation and management outcomes. For insect pest species, Pheno Forecasts are based on published growing degree day (GDD) thresholds for key points in species life cycles. These key points typically represent life cycle stages when management actions are most effective. These maps are updated daily and available 6 days in the future. We forecast caterpillar emergence in winter moth (Operophtera brumata) at 20-350F growing degree days (base 50F, start date: January 1, simple average GDD method). Forecasts are available for the current and prior year in the USA-NPN Visualization Tool (https://www.usanpn.org/data/visualizations) and 2016-present through USA-NPN Geo Web Services (available upon request). The caterpillars can defoliate certain species of deciduous trees. Some control measures are most effective when caterpillars emerge.