The California Department of Food and Agriculture said Wednesday the pests have been detected in parts of Anaheim, Artesia, Cerritos and other areas.
Trained workers will treat areas with pesticide, which attracts and kills male flies.
The fruit fly is known to target more than 230 types of fruit, vegetables and plants. The female fruit fly lays eggs inside fruits and vegetables, and maggots eat their way out, making them unfit for consumption.
Oriental fruit flies commonly infest urban and suburban areas by hitchhiking in fruits and vegetables illegally smuggled from infested regions, including much of Southern Asia.