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Medfly infestation in Escondido, Calif.

A Mediterranean fruit fly infestation has been discovered in Escondido in San Diego County, Calif. A mated female fly was detected in a trap.

California Department of Food and Agriculture (CDFA) crews are conducting eradication procedures in the area. Aerial release of sterile Medflies began on Sept. 11 at the rate of 250,000 sterile flies per square mile. The release area is nine square miles.

“By utilizing sterile Medflies, we rely on biology to help us achieve eradication,” said CDFA Secretary A.G. Kawamura. “It’s a great example of the progress that is possible through agricultural research.”

Crews will also apply limited treatments to trees and plants in a 200-meter radius - about one-eighth of a mile - from the site where the mated fly was found. The applied substance 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 this “core” treatment area will be notified in advance of the treatments.

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 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 Escondido 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.

A map of the sterile fly release zone is available online at:

TAGS: Management
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