Mexican Fruit Fly Quarantine Declared in Portion of San Diego County

SACRAMENTO – A portion of San Diego County has been placed under quarantine for the Mexican fruit fly following the detection of five flies including a mated female within the City of La Mesa. The United States Department of Agriculture or USDA, the San Diego County Agricultural Commissioner, and the California Department of Food and Agriculture or CDFA are working collaboratively on this project.

The quarantine area in San Diego County measures 77 square miles, bordered on the north by the San Diego River; on the south by Sweetwater Reservoir; on the west by Interstate 15; and on the east by El Cajon.  Find a link to the quarantine map here: www.cdfa.ca.gov/plant/mexfly/regulation.html.

Sterile male Mexican fruit flies will be released in the area as part of the eradication effort. The release rate will be approximately 250,000 males per square mile per week in an area up to 50 square miles around the infestation. Sterile male flies mate with fertile female flies in the natural environment but produce no offspring. The Mexican fruit fly population decreases as the wild flies reach the end of their natural life span with no offspring to replace them, ultimately resulting in the eradication of the pest. Properties within 200 meters of detections are being treated with an organic formulation of Spinosad, which originates from naturally-occurring bacteria, in order to remove any mated female fruit flies and reduce the density of the population. Finally, fruit removal will occur within 100 meters of properties with larval detections and/or mated female detections.

The quarantine will affect growers, wholesalers, and retailers of susceptible fruit in the area as well as nurseries that grow and sell Mexican fruit fly host plants. The quarantine will also affect local residents – home gardeners are urged to consume homegrown produce on site and not move it from their property. These actions protect against the spread of the infestation to nearby regions where it could affect California’s food supply and our backyard gardens and landscapes.

The Mexican fruit fly can lay its eggs in and infest more than 50 types of fruits and vegetables, severely impacting California agricultural exports and backyard gardens alike.  

Details: www.cdfa.ca.gov/plant/go/MexFly.