Mediterranean Fruit Flies (Medfly)
In November 2017, two adult Mediterranean Fruit Flies were found in Half Moon Bay. This prompted an emergency quarantine response in and around Half Moon Bay to stop the fly from spreading. The female Medfly lays eggs in ripening fruit, which then hatch into larvae that feed on the fruit and render it inedible.
The Mediterranean Fruit Fly (Medfly) has been known to infest more than 300 varieties of fruits, nuts and vegetables and is considered the most important agricultural pest in the world. This fly is native to Africa but has spread to all the countries bordering the Mediterranean Sea, Australia, Europe, Central America, South America, Hawaii and other islands in the Pacific.
The main tool in California's fight against the Medfly is the aerial release of thousands of sterile male fruit flies, to disrupt the natural life cycle of the fly within the quarantined area. The California Department of Food and Agriculture (CDFA) is conducting releases of approximately 500,000 sterile flies by airplane over the quarantined area on a weekly basis.
In addition to sterile treatment, fruit has been stripped from all host plants in the immediate area, and the California Departmenf of Food and Agriculture is conducting limited localized bait applications in the area 200 meters from each find site.
Because the Medfly is such a severe agricultural pest, the quarantine of the area must continue for an extended period of time after the last fly was captured, to ensure that potential future generations of fruit fly are not detected. The Medfly is a cold-blooded animal- it goes through its life cycle faster or slower depending on the weather. Because of this, the duration of the quarantine is heavily dependent on temperature. Based on the current degree-day calculations as of April 18, 2018, the Medfly Quarantine is projected to end on October 3rd, 2018. The quarantine may be extended or reduced at any time, depending on changes in local temperature or additional wild fruit fly finds in the area.
Sellers of fruit within the quarantine area, including certified farmers' market vendors and retail stores that sell host fruit, are required to contact the California Department of Food and Agriculture immediately for issuance of a compliance agreement. In addition, all fruit on site must be kept and offered for sale in a way that safeguards the fruit from infestation from fruit flies. Please see the safeguarding document linked below for more information.
Residents with questions should contact the California Department of Food and Agriculture Pest Hotline at 1-800-491-1899.
You can also contact the San Mateo County Agricultural Commissioner’s Office at 650-363-4700 during weekday work hours for any general questions.
For the full list of Medfly hosts, the text of the current quarantine, a map of the quarantine area, and an informational brochure, please click on the links below.