USA NPN National Phenology Network

Taking the Pulse of Our Planet

You are here

Apple maggot larvae cause damage to fruit and if left untreated, can affect the entire tree.

Image credit:
H.J. Larsen,

Apple Maggot Forecast

Apple maggot larvae cause damage to ripening fruit. If left untreated, these pest insects can spread across the entire tree. These insects primarily affect apple trees, but can also impact plum, apricot, pear, cherry and hawthorn trees. In southern states, the window for treating trees for this pest is now approaching. 

Apple Maggot Current Day Forecast.

Apple Maggot 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

Native to the eastern states, apple maggot (Rhagoletis pomonella) is widespread throughout the U.S. In late spring and summer, adults emerge from the soil and lay eggs in apples. The larvae tunnel into the fruit, causing decay and rot.

Treatment Summary

Apple maggot can be controlled by bagging the fruit, trapping, and spraying with pesticide. In all cases, treatments are most effective if initiated as adults are starting to emerge from the soil.

Female apple maggot, Photo: Joseph Berger,

 Ideally, treatments are undertaken prior to egg-laying, which occurs ~8-10 days after emergence. The Pheno Forecast map indicates when apples should be protected from maggots using mechanical or chemical methods. GDDs are accumulated from a base temperature of 50oF.

Model Source: Wise et al. (2010)

More information on map development and re-use policy.

Treatment guidance

University of Minnesota Extension

Michigan State University Extension

Washington State University Tree Fruit Research & Extension Center

Explore Forecast