USA NPN National Phenology Network

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Emerald ash borer adult

An invasive pest, emerald ash borer has killed millions of ash trees in the United States.

Image credit:
David Cappaert,

Emerald Ash Borer Forecast

Emerald ash borer is a beetle that causes significant harm to ash trees throughout the eastern United States. 

Emerald ash borer adult emergence forecast

Emerald Ash Borer Adult Emergence Forecast.

Emerald ash borer egg hatch forecast

Emerald Ash Borer Egg Hatch Forecast.

Pheno Forecast maps predict key life cycle stages in invasive and pest species, to improve management efficacy.  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. For Emerald Ash Borer, we forecast the first emergence of adults and the earliest egg hatch in the spring, for the full calendar year.

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

Emerald Ash Borer (Agrilus planipennis) is non-native beetle from Asia which has spread across the eastern United States since 2002. In their larval stage, the beetles destroy the heartwood of ash trees, killing them within a few years. The pest is responsible for the death of hundreds of millions of ash trees.


EAB larvae, Photo:Pennsylvania Department of Conservation and Natural Resources - Forestry,

We forecast adult emergence and egg hatch based on growing degree days. The forecast is available for the contiguous United States, except for those areas where the temperatures for the current year are expected to exclude the organism in each life stage. Treatments are applied to control for adult beetles on infested trees, to reduce the spread of the pest. Adults lay eggs approximately 14 days after emergence, so treatment is critical in this window. Knowing when these eggs hatch helps managers know when larvae are active in the tree. For specific information on preferred treatment options in your region, we recommend contacting your local extension agent.  For more information on treatment guidance, visit Insecticide Options for Protecting Ash Trees from Emerald Ash Borer or Emerald Ash Borer Information Network.


GDD threshold

Base temp

Upper Threshold

Start date

GDD method

Model origin


Adult Emergence (earliest date that overwintering individuals are expected to emerge as adults)




January 1

Single triangle


DDRP, Duarte 2014 and Barker et al 2023

Egg Hatch (earliest date that overwintering eggs are predicted to hatch)




January 1

Single triangle


DDRP, Duarte 2014 and Barker et al 2023

The development of this forecast was funded primarily by USDA NIFA AFRI TSAB Award #2022-68013-37138 to support agricultural biosecurity.

Learn more about the forecast in a presentation hosted by Emerald Ash Borer University.

More information on map development and re-use policy.

Explore EAB Forecasts