USA NPN National Phenology Network

Taking the Pulse of Our Planet

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Pine needle scale insect, showing waxy coating.

Scale insects are a diverse group of ‘true bugs’ that are hard to see! They feed on plant sap, and while many do no harm, some can form large infestations and kill trees or other plants.


Image credit:
Image Credit: Bugwood

Pine Needle Scale Forecast

Pine needle scale is a native pest that affects ornamental pines and Christmas tree plantations.

Pine needle scale current day forecast

Pine Needle Scale Current Day Forecast.

Pine needle scale six day forecast

Pine Needle Scale 6-Day 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. These maps are updated daily and available 6 days in the future.

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

Native to North America, pine needle scale (Chionaspis pinifoliae) specializes on pine trees. They pierce pine needles and consume sap. Females overwinter with their eggs, under a waxy covering. Crawlers emerge from the eggs in late spring the following year.

Close up of pine needle scale crawlers, photo credit Howard Russell, MSU Diagnostic Services

Crawler Forecast

We forecast crawler emergence based on growing degree days. Treatments are often applied when crawlers first emerge from their eggs and before they grow their protective waxy coating. For specific information on preferred treatment options in your region, we recommend contacting your local extension agent.  Additional treatment resources are available through Penn State Extension and Colorado State University Extension.


GDD threshold

Base temp

Start date

GDD method

Model origin


Crawler emergence



March 1

Simple average


Cornell 2010 

More information on map development and re-use policy.

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