Mexican Fruit Fly Quarantine in Portion of San Diego County

Southern California

A portion of San Diego County has been placed under a quarantine for the Mexican fruit fly following the detection of six flies and one larva in and around the unincorporated area of Valley Center. The quarantine will affect any growers, wholesalers, nurseries and retailers of host fruit or host plants in the area. The United States Department of Agriculture (USDA), the San Diego County Agricultural Commissioner and the California Department of Food and Agriculture (CDFA) are working collaboratively on this project.

The quarantine area in San Diego County measures 77 square miles, bordered on the north by Wilderness Gardens Preserve; on the south by the Lake Wohlford Park; on the west by Moosa Canyon; and on the east by Hellhole Canyon Preserve. A link to the quarantine map may be found here.

The Mexican fruit fly can lay its eggs in and infest more than 50 types of fruits and vegetables, including citrus, avocados and tropical fruits, severely impacting California agricultural exports and backyard gardens alike. Growers, nurseries or other industry operations located in or near the quarantine zone are encouraged to follow regulatory practices set in place by CDFA. While fruit flies and other invasive species that threaten California’s crops and natural environment are sometimes detected in agricultural areas, the vast majority are found in urban and suburban communities. The most common pathway for these pests to enter the state is by travelers inadvertently bringing them back on fruits and vegetables as they return from infested regions of the world, or from packages of home grown produce from other countries sent to California, allowing pests to “hitchhike”.

As part of the eradication effort, approximately 250,000 sterile Mexican fruit fly males will be released per square mile, per week, in an area of 43 square miles around the infestation. Sterile male flies will mate with fertile, wild female flies but produce no offspring. This reduces the Mexican fruit fly population as wild flies reach the end of their natural life span with no offspring to replace them, ultimately resulting in the eradication of the pest. This eradication approach is the standard program used by CDFA and is the safest, most effective and efficient response program available.

In addition, properties within 200 meters of the detections are being treated with an organic formulation of Spinosad, which originates from naturally occurring bacteria, to remove any live fruit flies and reduce the density of the population. Fruit will also be removed from host plants within 100 meters of properties with larval detections and/or female fly detections.

Local residents and home gardeners affected by the quarantine should consume homegrown produce on-site and should not move host fruit or plant material from their property. These actions protect against the spread of the infestation to nearby regions which may affect California’s food supply and our backyard gardens and landscapes.

If you have questions, please call CDFA’s Pest Hotline at 1-800-491-1899. Additional information about the Mexican fruit fly can be found here.

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