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California Department of Food and Agriculture

Media Contacts: Steve Lyle, CDFA Public Affairs, (916) 654-0462,

California Department of Food and Agriculture
Release #09-088
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Sterile Medfly releases planned; quarantine anticipated shortly

SACRAMENTO, November 3, 2009 – A Mediterranean fruit fly infestation has been discovered in Fallbrook, in San Diego County.  Two adult male flies were detected in one trap on October 29, and a mated female fly was detected in another trap on November 1.


CDFA crews are conducting eradication procedures in the area. Aerial release of sterile Medflies is set to begin next Tuesday, November 10, at a rate of 250,000 sterile flies per square mile per week. The release area is approximately 9.33 square miles. 


“The release of Sterile Medflies is a proven method of eradicating an infestation,” said CDFA Secretary A.G. Kawamura. “We are ramping up quickly so that we can eradicate this outbreak before it has time to spread throughout this important agricultural region.”


Later this week, agricultural officials plan to begin stripping fruit from trees within a minimum of 100 meters of the infested sites so that any larvae that may already be inside the fruit cannot survive.  Crews will also apply limited treatments to trees and plants in a 200-meter radius—about one-eighth of a mile—from the sites where the flies were found. The substance being applied is the organic compound Naturalyte (active ingredient: spinosad), a naturally occurring extract from bacteria.


Naturalyte was used in the 2002 Mexican fruit fly eradication program in the nearby community of Valley Center.  Residents of these “core” treatment areas will be notified in advance of the treatments.



The sterile male Medflies are brought in from the joint CDFA/U.S. Department of Agriculture rearing facility in Los Alamitos, which prepares hundreds of millions of sterile flies weekly for release over the Los Angeles Basin. The sterile release program has a proven track record in Southern California. Sterile male flies mate with fertile female flies in the environment but produce no offspring. The Medfly population decreases as the wild flies reach the end of their natural life span with no offspring to replace them, ultimately resulting in eradication of the pest.


An agricultural quarantine in the area is anticipated shortly. Residents are urged not to remove produce from the quarantine zone, and to consume homegrown fruits and vegetables onsite. The Medfly can infest over 260 types of fruits and vegetables, causing severe impacts on California agricultural exports and backyard gardens alike.  Residents who believe their fruit or vegetables are infested with fruit fly maggots are encouraged to call the state’s toll-free Pest Hotline at 1-800-491-1899.


The eradication approach in Fallbrook is the standard Medfly program used by CDFA and the safest, most effective program available. CDFA has successfully eradicated each and every detected Medfly infestation in California history, dating back more than 30 years.




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