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Fruit Fly Invasion Causes a Produce Quarantine in California

The invasive critters are originally from Asia, and local officials are trying to stop their spread out of L.A. county.

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A Tau fruit fly photo from the California Department of Food and Agriculture.
A Tau fruit fly photo from the California Department of Food and Agriculture.
Photo: California Department of Food and Agriculture (Fair Use)

Agricultural officials in California placed parts of Los Angeles County under a produce quarantine last week after several invasive Tau fruit flies were discovered.

According to a late July press release from the California Department of Food and Agriculture (CDFA), the quarantine area measures about 79 square miles. Officials have detected more than 20 of these invasive flies in the area of Stevenson Ranch, which is near the city of Santa Clarita. These fruit flies are about 7 mm (.2 inches) long. They lay eggs on all sorts of fresh produce, and the larvae that hatch from those eggs damage produce by tunneling through it, NBC News reported.


“Fruit that has been attacked may be unfit for consumption due to this damage and as a result of decay-producing organisms that enter, leaving the interior of the fruit a rotten mass,” a guide from the CDFA explained.

Officials believe that the fruit fly was introduced to the area after travelers brought uninspected produce that housed flies into the area. Now, produce cannot be removed from the quarantine zone in an effort to stop the destructive spread of the Tau fruit fly.


“This the first Tau fruit fly quarantine ever in the Western Hemisphere,” the CDFA’s press release said. “The fly is native to Asia and is a serious pest for agriculture and natural resources, with a very wide host range, including numerous fruits and vegetables as well as a select range of native plants in California.”

Produce grown in the quarantine area can be processed and consumed, but extra steps should be taken when discarding produce waste. The department advised double-bagging produce in the quarantine zone in plastic bags before throwing it away.

The CDFA is working with other agricultural departments including the U.S. Department of Agriculture to treat produce near fruit fly sightings with Spinosad. It’s a natural substance that can be toxic for insects, and it has low toxicity to people and other mammals, according to the National Pesticide Information Center.

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