82 square mile quarantine area declared after Mexican fruit flies found in La Mesa: all 4 East County cities, some unincorporated areas and San Diego neighborhoods are included

Source: Donna Durckel, County of San Diego Communications Office

March 10, 2025 (San Diego) -- The California Department of Food and Agriculture (CDFA) has declared a new quarantine area affecting the cities of La Mesa, El Cajon, Lemon Grove, San Diego, and Santee as well as Spring Valley and Bonita in San Diego County after Mexican fruit flies were found during a routine inspection in La Mesa.

Residents should not move produce grown in these areas off of their properties, since this pest can infest more than 50 types of fruits and vegetables.

The quarantine zone covers approximately 82 square miles. It is bordered by:

• The San Diego River to the north
• Sweetwater Reservoir to the south
• Interstate 15 to the west
• The city of El Cajon to the east

View the quarantine map.at link, or scroll down to view map at bottom of this page.

The United States Department of Agriculture (USDA), the San Diego County Agricultural Commissioner, and the CDFA are working collaboratively to contain the infestation and provide guidance to fruit growers, wholesalers, retailers and home gardeners.

Eradication Efforts

• Sterile male Mexican fruit fly releases will be conducted in the area.
• Treatment of properties within 200 meters of detections will use an organic formulation of Spinosad, derived from naturally occurring bacteria.
• Fruit removal within 100 meters will occur at sites where larvae or flies are found.

This is CDFA’s standard, science‑based approach and is considered the safest and most effective method to reduce population density.

Impact of the Quarantine

The quarantine applies to growers, wholesalers, retailers, and nurseries handling any host fruits or plants. Home gardeners are urged to consume homegrown produce onsite and avoid moving it off their property to help prevent the spread of the pest.

Residents who suspect their fruits or vegetables may be infested should call the state’s toll‑free Pest Hotline: 1‑800‑491‑1899.

The Mexican fruit fly can infest more than 50 types of fruits and vegetables, posing a significant threat to California’s agricultural exports, local food supply, and backyard gardens. More information is available at: www.cdfa.ca.gov/plant/go/MexFly

While invasive fruit flies sometimes appear in agricultural regions, most detections occur in suburban and urban communities. These pests often enter the state by hitchhiking in fruits or vegetables brought back illegally by travelers from infested areas.

To help protect California’s agriculture and natural resources, CDFA urges travelers to follow the Don’t Pack a Pest guidelines (www.dontpackapest.com).