A large swath of Alameda County is now under a quarantine for the invasive Mediterranean fruit fly after agriculture officials recently discovered one mated female in Fremont.

The quarantine area is 71 square miles and defined by state Highway 84 in the north, the Alameda-Santa Clara county border in the south, the Don Edwards San Francisco Bay National Wildlife Refuge in the west and on the east by Calaveras Creek.

During the quarantine, produce grown in the area should stay in the area — this applies to farmers, wholesalers, retailers and home gardeners, according to officials from the California Department of Food and Agriculture.

Produce can be consumed on the property where it was grown or, if infected, can be placed in a double bag and thrown into a trash bin, not green waste.

In order to eradicate the pest, sterile male medflies will be released in the area at the rate of 250,000 males per square mile per week in a 39-square-mile area around the infestation.

Also, properties within about 650 feet of infested areas are being treated with an organic pesticide and fruit will be removed from areas with about 330 feet of properties with mated females, larval detections or multiple adult detections, according to CDFA officials.

The Mediterranean fruit flies feed off jello molds in 2019 at the U.S. Department of Agriculture Animal and Plant Health Inspection Service’s Sarasota Sterile Insect Rearing Facility in Sarasota, Florida, where they process 100,000,000 flies a week. (Preston Keres/USDA via Bay City News)

The mated female medfly was found in a trap on Aug. 28 and it is unclear how long the quarantine will last.

The last medfly quarantine in Alameda County was in 1981.

Medflies will infest more than 250 types of fruits and vegetables and people who think they might have an infestation can call the state’s Pest Hotline at 800-491-1899 or via email.

State officials say most invasive pests arrive in this country by people illegally bringing back produce from travels abroad.

For more information about how to avoid causing an infestation, people can review the USDA’s “Don’t Pack a Pest” program online.

Kiley Russell writes primarily for Local News Matters on issues related to equity and the environment. A Bay Area native, he has lived most of his life in Oakland. He studied journalism at San Francisco State University, worked for the Associated Press and the former Contra Costa Times, among other outlets. He has covered everything from state legislatures, local governments, federal and state courts, crime, growth and development, political campaigns of various stripes, wildfires and the aftermath of Hurricane Katrina.