Why Is Western Cherry Fruit Fly a Problem?

Western cherry fruit fly (Rhagoletis indifferens) is a native pest of North America that can cause significant damage to cherries and other soft fruit crops. Adults attack ripening fruit and deposit larvae into the fruit flesh. The presence of larvae inside the fruit can compromise a grower’s ability to pack fruit for export markets, leading to significant financial losses. Fruit from affected orchards may instead be directed to domestic markets, which typically return lower value.

Where Do Western Cherry Fruit Flies Come From?

Western cherry fruit flies overwinter in orchard soil and have one generation per year. Adults emerge prior to harvest as fruit begins to ripen and can cause damage throughout their lifespan, which typically lasts 15–30 days. Peak populations are usually observed around harvest timing. Growers should monitor orchards regularly to detect activity and protect fruit quality.

How the BC DAS System Helps

The BC DAS system helps growers assess the current risk of Western cherry fruit fly populations based on their orchard location. By using temperature data, degree‑day accumulation, and regional trap catches, the system provides up‑to‑date information on when risk is increasing. For the most accurate assessment, growers should use the model alongside trap monitoring within their own orchard throughout the growing season.

The DAS Spray Guide provides spray options, rates, and timing information to support control of Western cherry fruit fly. The guide allows growers to select products registered for conventional or organic use and to plan spray coverage effectively. By following the BC DAS model and Spray Guide together, growers can better protect fruit quality and reduce the risk of economic loss.

For more information, please check out the BC Tree Fruit Production Guide. 

Learn More (Video)

Interested in finding out more? Check out the BC DAS Western cherry fruit fly model video to connect field observations with the online DAS system.