State and federal officials have declared Alameda County free of the Mediterranean fruit fly (Medfly), ending an 11-month quarantine that covered 213 square miles in and around Fremont.
The California Department of Food and Agriculture (CDFA), the U.S. Department of Agriculture (USDA), and the Alameda County Agricultural Commissioner’s office announced this month that the pest has been eradicated using a sterile insect technique combined with targeted organic treatments.
The strategy involved releasing sterile male Medflies—up to 250,000 per square mile each week—into the affected area. These sterile males mated with wild females, preventing reproduction and driving down the population. Properties near detection sites were also treated with Spinosad, an organic pesticide derived from naturally occurring bacteria in soil.
“Fruit flies are very destructive pests for crops as well as backyard gardens,” said CDFA secretary Karen Ross in a press release. “I would like to thank the farmers and residents of Alameda County who helped us eradicate this infestation by cooperating with the quarantine.”
Agricultural commissioner Cathy Roache noted that while the quarantine has ended, the threat of new infestations remains. She urged residents not to bring fruits and vegetables from out of state or overseas, a common way invasive pests enter California.
The Medfly is considered one of the world’s most destructive agricultural pests, capable of attacking more than 250 types of fruits and vegetables. Residents are encouraged to remain vigilant and report any suspicious infestations to CDFA at 1.800.491.1899.
