USA NPN National Phenology Network

Taking the Pulse of Our Planet

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Pheno Forecast maps estimate when insects and invasive plants will be in their vulnerable stages. For example, for emerald ash borer, the maps forecast when emerging adults will be present. 

Image credit:
David Cappaert, Bugwood.org

Pheno Forecasts

The USA-NPN Pheno Forecasts illustrate when insects and invasive plants will reach life stages critical for monitoring and management.

Emerald ash borer six day forecast

Emerald Ash Borer 6-Day Forecast.

Buffelgrass current day forecast

Buffelgrass Current Day Forecast.

Pheno forecasts for insects are based on USA-NPN Accumulated Growing Degree Day (AGDD) map products and published GDD thresholds. Detailed information on the underlying products to create these maps and the processing can be found in Crimmins et al. (2017, 2020). Pheno Forecast maps depict, on a given day, the status of a species’ life-cycle stage across the contiguous United States. 

The status of a location is determined by comparing the local GDD accumulation to a published heat accumulation threshold for the life-cycle stage. For insects, locations are categorized into one of the four conditions: not yet approaching the life stage of management interest, approaching the stage, experiencing the stage, and past the stage. References for the published thresholds used to generate the forecasts appear on the below table and on individual species pages.

The status of a location for invasive buffelgrass is based on rainfall accumulation thresholds that are known to trigger green-up in order to optimize treatment and control. These thresholds are based on research conducted in Southern Arizona and detailed in Wallace et al. (2016). Stages of interest represent the likelihood of green-up given the past 21 days of precipitation: “Green-up may occur in 1-2 weeks” or “Green-up likely to occur in 1-2 weeks”. 

These maps are intended to provide a broad-scale prediction regarding when management action may be necessary and are intended to supplement local knowledge. Forecast accuracy may vary locally based on microclimatic variation. In addition, thresholds may perform with variable accuracy across species ranges. For more information about these pests and invasive species specific to your state, contact your local Cooperative Extension program.

Insect and invasive plant species and phenological events for which USA-NPN offers Pheno Forecasts:

Species

Life stage predicted

GDD threshold, accumulation method (source)

GDD start date, base temperature

Apple maggot (Rhagoletis pomonella Walsh)

Adult emergence 

900 GDD, simple averaging (Wise et al. 2010

1 Jan., 10°C (50°F) 

Asian longhorned beetle (Anoplophora glabripennis Motschulsky)

Adult emergence 

689.75 GDD, double sine (Kappel et al. 2017; R. T. T., pers. comm.) 

1 Jan., 10°C (50°F) 

Bagworm (Thyridopteryx ephemeraeformis Haworth) 

Caterpillar emergence 

600 GDD, simple averaging (Cornell Cooperative Extension 2010

1 Mar., 0°C (32°F) 

Bronze birch borer (Agrilus anxius Gory)

Adult emergence 

450 GDD, double sine (Herms et al. 2004

1 Jan., 10°C (50°F) 

Buffelgrass (Pennisetum ciliare Linnaeus)

50% greenness may occur in 1-2 weeks

1-1.7 inches accumulated Precipitation over 24-day rolling timeframe
(Wallace et al. 2016)

NA

Buffelgrass (Pennisetum ciliare Linnaeus)

50% greenness will likely occur in 1-2 weeks

> 1.7 inches accumulated Precipitation over 24-day rolling timeframe
(Wallace et al. 2016)

NA

Eastern tent caterpillar (Malacosoma americanum Fabricius)

Caterpillar emergence 

90–190 GDD, simple averaging (Cornell Cooperative Extension 2010

1 Mar., 10°C (50°F) 

Emerald ash borer (Agrilus planipennis Fairmaire) 

Adult emergence 

450 GDD, double sine (Herms et al. 2019

1 Jan., 10°C (50°F) 

Gypsy moth (Lymantria dispar Linnaeus)

Caterpillar emergence 

571 GDD, double sine (Russo et al. 1993

1 Jan., 3°C (37.5°F) 

Hemlock woolly adelgid (Adelges tsugae Annand) 

Presence of eggs 

25 GDD, simple averaging (M. W. and S. L., pers. comm.) 

1 Jan., 0°C (32°F) 

Hemlock woolly adelgid (Adelges tsugae Annand) 

Presence of active nymphs 

1,000 GDD, simple averaging (M. W. and S. L., pers. comm.) 

1 Jan., 0°C (32°F) 

Lilac borer (Podosesia syringae Harris)

Adult emergence 

330 GDD, double sine (Herms 2004

1 Jan., 10°C (50°F) 

Magnolia scale (Neolecanium cornuparvum Thro)

Crawler emergence 

1938 GDD, double sine (Herms 2004

1 Jan., 10°C (50°F) 

Pine needle scale (Chionaspis pinifoliae Fitch)

Crawler emergence 

298–448 GDD, simple averaging (Cornell Cooperative Extension 2010

1 Mar., 10°C (50°F) 

Winter moth (Operophtera brumata Linnaeus)

Caterpillar emergence 

20 GDD, simple averaging (UMass Extension 2017

1 Jan., 10°C (50°F) 

Purpose

Pheno Forecast maps predict key life cycle stages in insects and invasive plant species to improve management efficacy. For insect species, Pheno Forecasts are based on published growing degree day (GDD) thresholds for key points in species life cycles. For invasive plant species, Forecasts are based on published precipitation thresholds for green-up. 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 for insects and up to 1-2 weeks for invasive plants.

Recommended Citation

Format: USA National Phenology Network. [Year Published]. [Species Name] Pheno Forecast for [date as of [Date]. USA-NPN, Tucson, Arizona, USA. Dataset Accessed [Date of Access] at www.usanpn.org/data/forecasts.

Example: USA National Phenology Network. 2020. Emerald Ash Borer Pheno Forecast Current Day as of June 1, 2020. USA-NPN, Tucson, Arizona, USA. Dataset Accessed 1 June 2020 at www.usanpn.org/data/forecasts.

Data

The USA-NPN is currently generating Pheno Forecast maps for 12 species of insects and one invasive plant species. Pheno Forecast Maps for each species can be explored in the USA-NPN Visualization Tool and on individual species Pheno Forecast pages, linked in the table above. The data behind the insect pest maps are the USA-NPN AGDD layers (link), and maps can be readily created by binning AGDD accumulation. 

Content, maps, and data accessible via usanpn.org are openly and universally available to all users. USA-NPN is not responsible for the content or the use of the data. Content may be re-used and modified with appropriate attribution (e.g., "source: USA National Phenology Network, www.usanpn.org"; see our complete Content Policy). See our Data Use Policy for suggested citation and attribution of the underlying data products.

Additional Documentation

Crimmins, T.M., R.L. Marsh, J. Switzer, M.A. Crimmins, K.L. Gerst, A.H. Rosemartin, and J.F. Weltzin. 2017. USA National Phenology Network gridded products documentation. U.S. Geological Survey Open-File Report 2017–1003. doi.org10.3133/ofr20171003.

Crimmins, T.M., K.L. Gerst, D. Huerta, R. Marsh, E.E. Posthumus, A. Rosemartin, J. Switzer, J. Weltzin, L. Coop, N. Dietscher, D. Herms, S. Limbu, R.T. Trotter, & M. Whitmore. 2020. Short-term Forecasts of Pest Insect Activity Inform Management Activities. Annals of the Entomological Society of America, Volume 113, Issue 2, March 2020, Pages 139–148, https://doi.org/10.1093/aesa/saz026.

Wallace, C. S., J. J. Walker, S. M. Skirvin, C. Patrick‐Birdwell, J. F. Weltzin, and H. Raichle. 2016. Mapping presence and predicting phenological status of invasive buffelgrass in southern Arizona using MODIS, climate and citizen science observation data. Remote Sens. 8, 524.

Pheno Forecast Information Sheet