Identifying California’s Numerous Fruit Flies

Daniel Cooper California Corner, Pests

Sandipa Gautam, University of California area citrus integrated pest management advisor, recently wrote that California is experiencing an unusually high number of invasive fruit flies in the 2023–24 season. She noted that several areas in California are now under fruit fly quarantines. Excerpts from her article follow:

Several species of invasive fruit flies that belong to the family Tephritidae are considered serious pests of citrus and hundreds of other agricultural crops. These flies lay eggs on or near the fruit surface, and when the maggots hatch, they bore into the fruit, making it unfit for human consumption and causing major losses to fruits and vegetable production.

For many invasive fruit fly species, quarantine is triggered when two or more adult flies are caught in a trap or by a single detection of larvae or pupae indicating a breeding population. A core area is a 0.5-mile radius around the detection site, and a quarantine area is a 4.5-mile radius around each detection.

IMPACTED AREAS

California counties currently impacted by invasive fruit fly quarantines include the following: 

  • 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
WHAT TO LOOK FOR

Four species of fruit flies are currently regulated in California. The adults may look similar to houseflies but are distinctly different in color and the markings on their bodies. They are about 5 to 8 millimeters in size, much bigger than spotted wing drosophila, another invasive species that has been established in California.

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Oriental fruit fly adult and areas in California under quarantine as of January 2024
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Mediterranean fruit fly adult and areas in California under quarantine as of January 2024
  • Oriental fruit fly: About 8 millimeters in size, bright yellow colored body with a dark T-shaped mark on the abdomen
  • Mediterranean fruit fly: Approximately 5 to 6 millimeters in size, yellow-light brown body, clear wings with brown bands
  • Tau fruit fly: About 7 millimeters in size, yellow body with black markings
  • Queensland fruit fly: Approximately 5 to 8 millimeters in size, wasp-like body, reddish brown in color with distinct yellow markings, clear wings with band along the top margin
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Tau fruit fly adult and areas in California under quarantine as of January 2024
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Queensland fruit fly adult and areas in California under quarantine as of January 2024

See Gautam’s full article to learn more about preventing fruit fly spread and what growers can do about the pest. Find more information on fruit fly quarantines in California here.

Source: University of California Agriculture and Natural Resources

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