Citrus Industry Guide to Fruit Fly Quarantines


Over the last several months, a variety of invasive fruit fly detections have triggered quarantines across numerous counties in California. These fruit fly species – including Mediterranean fruit fly, Mexican fruit fly, Oriental fruit fly, Tau fruit fly and Queensland fruit fly – are considered not established in California. Quarantines and their associated regulatory actions are implemented to stop the artificial spread of these pests and thus avoid additional negative impacts to growers and the state’s agriculture and natural resources.

The Citrus Pest and Disease Prevention Division is working to provide boots-on-the-ground assistance to the California Department of Food and Agriculture’s Plant Health and Pest Prevention Services Division as they lead efforts in eradicating the fruit flies by conducting larval surveys, host fruit removal, delimitation trapping, treatment activities and regulatory actions across the state.

Fruit fly quarantines are established after a certain number of adult flies are captured within three miles of one another and within one life cycle. Fruit fly quarantines are also established when detections of reproductive populations such as larva, pupae or mated flies are found in an area. These thresholds have already been met in certain areas of the state, including the following areas:

Counties Currently Impacted by Fruit Fly Quarantines:

  • Oriental fruit fly: Contra Costa, Riverside, Sacramento, San Bernardino and Santa Clara Counties
  • Mediterranean fruit fly: Los Angeles County
  • Tau fruit fly: Los Angeles County
  • Queensland fruit fly: Los Angeles and Ventura Counties

To review the quarantine maps, regulatory information, pest profile information for various fruit flies and additional resources, please visit

FAQ: Bulk Citrus Movement Requirements in Fruit Fly Quarantine Zones

Treatment information & maps can be found here:

Quarantine information on fruit fly species and other invasive pests can be found here:

Frequently Asked Questions:

How is a fruit fly quarantine triggered?
A quarantine is triggered by the number of adult flies captured within three miles of each other and in one life cycle:

  • Mediterranean, Melon, Caribbean Fruit Fly – 2
  • Mexican Fruit Fly – 5
  • Oriental, Guava, Peach Fruit Fly – 6 Rural or 8 Urban
  • All other adult invasive fruit flies (e.g., Queensland Fruit Fly) – 2


  • SINGLE detection of larva, mated female, or pupae indicating a breeding population.

How large is the fruit fly quarantine zone(s)?

There are three main areas to consider within the fruit fly quarantine zone, and each has different requirements for harvest/bulk citrus movement:

  1. The property where the detection occurred
  2. Core Area: A one-half mile radius around the detection
  3. Quarantine Area: A 4.5-mile radius around the detection.

What steps must growers in these three areas of the quarantine zone follow in order to harvest/move their bulk citrus?
For properties where the detection occurred and properties within the core area (0.5-mile radius around the detection site), this citrus is not eligible for packing, but may be stored, processed and consumed on the growing site. If properties within the core areas have no fruit fly or life stages detected on the growing grounds, fruit can only be moved for juicing, processing, freezing, etc. under compliance and safeguarding with approval of the receiving county ag commissioner.

Growers in the quarantine zone, but outside of the core area, may receive regular pre-harvest treatments with approved insecticides, applied at recommended intervals, starting a sufficient time before harvest (but not less than 30 days before harvest and a minimum of 4 treatments) to allow for development of fruit fly egg and larvae. Determination of the pre-harvest treatment window is based on the degree day model for the specific fruit fly. Once treatment has begun, it must continue through the harvest period.

Have additional questions? Please reach out to your local County Agricultural Commissioner.

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