Oriental fruit fly quarantine in portions of San Bernardino and Riverside counties

The California Department of Food and Agriculture (CDFA) announced on Thursday, Sept. 25, 2025, it has placed portions of San Bernardino and Riverside counties under quarantine for the Oriental fruit fly following the detection of multiple flies in the two counties.

Detections in and around the cities of Ontario and Jurupa Valley have resulted in a quarantine zone covering 131 square miles (57 sq. miles in Riverside County and 74 in San Bernardino County), bordered on the north by Highway 210; on the south by Norco; on the west by Ontario; and on the east by Rubidoux. A link to the quarantine map may be found on the CDFA website.

The Oriental fruit fly is known to target over 230 different fruits, vegetables and plant commodities. Important California crops at risk include pome and stone fruits, citrus, dates, avocados and many vegetables, particularly tomatoes and peppers. Damage occurs when the female fruit fly lays her eggs inside the fruit. The eggs hatch into maggots, which tunnel through the flesh of the fruit, making it unfit for consumption.

To prevent the spread of Oriental fruit flies through homegrown fruits and vegetables, residents living in the quarantine area are urged not to move those items from their property. However, homegrown produce may be consumed or processed (i.e., juiced, frozen, cooked, or ground in the garbage disposal) on the property where it was picked, or disposed of by double-bagging and placing it in the regular trash, not in green waste receptacles. Following the principles of Integrated Pest Management, agricultural officials use the “male attractant” technique as the mainstay of the eradication effort for this invasive species. This approach has successfully eliminated dozens of fruit fly infestations in California. Trained workers apply a small amount of fruit fly attractant mixed with a very small dose of an organic pesticide, Spinosad, approximately 8-10 feet off the ground on street trees and similar surfaces. Male fruit flies are attracted to the mixture and perish after consuming it. The male attractant technique is being carried out over an area that extends 1.5 miles from each site where Oriental fruit flies have been trapped.

While fruit flies and other invasive species that threaten California’s crops and natural environment are sometimes detected in agricultural areas, the vast majority are found in urban and suburban communities. The most common pathway for these pests to enter the state is by “hitchhiking” on fruits and vegetables brought back illegally by travelers as they return from infested regions of the world, or in packages of home grown produce from other countries sent to California.

Help protect California’s agricultural and natural resources — please Don’t Pack a Pest when traveling or mailing packages.

The Oriental fruit fly is widespread throughout much of the mainland of southern Asia and neighboring islands, including Sri Lanka and Taiwan, and it has invaded other areas, most notably Africa and Hawaii.

Federal, state and county agricultural officials work year-round to prevent, deter, detect and eliminate the threat of invasive species and diseases that can damage or destroy our agricultural products and natural environment. These efforts are aimed at keeping California’s natural environment and food supply plentiful, safe and pest-free.

Residents with questions about the project may call CDFA’s Pest Hotline at 1-800-491-1899. Additional information, including a fact sheet and treatment, may be found on the CDFA’s website.

Additional County Update News – October 2, 2025