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SACRAMENTO, July 21, 2026 - The California Department of Food and Agriculture (CDFA), U.S. Department of Agriculture (USDA), Santa Clara County Agricultural Commissioner's Office and Alameda County Agricultural Commissioner's Office have eradicated a Mediterranean fruit fly (Medfly) infestation centered in and around the City of San Jose, ending a 241-square-mile quarantine that began on August 19, 2025.
CDFA used the release of sterile male Medflies at a minimum rate of 250,000 flies per square mile per week as the mainstay of its eradication measures for this pest. The sterile fly release program has a proven track record of eradication in California. Sterile male flies mate with fertile female flies in the natural environment but produce no offspring, decreasing the overall fly population. The sterile male Medflies are brought to California by the joint CDFA/USDA sterile insect rearing facility in Los Alamitos, California, which prepares sterile flies for release everyday over California.
Additionally, properties within 200 meters of the detection sites were spot treated with an organic formulation of Spinosad, which originates from naturally occurring bacteria in soil, to eliminate any mated females and reduce the density of the population. To further reduce the population, properties within 100 meters of breeding populations (maggots or mated females) were subject to host fruit and vegetable removal to eliminate eggs and larvae.
USDA, CDFA, the Santa Clara County Agricultural Commissioner and the Alameda County Agricultural Commissioner acknowledge and thank local area residents for their cooperation in preventing the movement of backyard fruit and allowing property access to perform critical eradication activities. Working together, we rid California of this invasive species.
The Medfly is known to target more than 250 types of fruits and vegetables, potentially causing severe impacts on California agricultural exports and backyard gardens alike. Damage occurs when the female lays eggs inside the fruit, making it unfit for consumption.
While Santa Clara County's Medfly quarantine has ended, the ongoing threat of new infestations by non-native species remains. Invasive fruit flies and other invasive species can endanger the state's agriculture and natural resources, as well as homegrown fruits and vegetables. Agricultural officials are asking residents to help prevent future introductions of invasive species by following these guidelines:
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Assist agriculture crews working to protect your garden by allowing them access to your yard to place traps and inspect plants.
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When entering California from another state or country, avoid bringing agricultural products - including fruits and vegetables. Help us protect our agriculture, natural resources and California's unique biodiversity from invasive fruit flies - please Don't Pack a Pest (dontpackapest.com).
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Do not send or receive any homegrown fruit, vegetables or meat products, as they may contain invasive species that can "hitchhike" in these products.
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Inspect your garden regularly for signs of invasive fruit flies or maggots and report any findings to CDFA at 1-800-491-1899.
To learn more about invasive species and how to protect California's fruits and vegetables, please visit https://www.cdfa.ca.gov/plant/fruitfly.
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