Fruit Fly Forces LA County Under Produce Quarantine

Fruit Fly Forces LA County Under Produce Quarantine

Summer offers a wide variety of brightly colored fruits and vegetables to create beautiful, nutritious meals. / Photo by Krasula via Shutterstock

Dylan Morgan

Dylan Morgan


Updated: 8/9/2023

The California Department of Food and Agriculture (CDFA) announced on July 25 that a portion of Los Angeles County was being placed under a produce quarantine following the detection of over 20 tau fruit flies in the unincorporated area of Stevenson Ranch.

The quarantine area measures 79 square miles and is bordered on the north by Castaic Junction, the south by Oat Mountain, the west by Del Valle, and the east by Honby Avenue.

Residents within this area have been told by the CDFA to not move any fruits or vegetables from their property. However, on the property where they were picked, they may be consumed or processed. If they are to be disposed of, it must be done by double-bagging in plastic and throwing the bags in a bin specifically for garbage.

A tau fly is a yellow and black fly measuring approximately 7 mm in length and of similar size to a housefly. Its eggs are nearly a millimeter long, white, and cylindrical. Originating in Southeast Asia, the fly is a huge pest for agriculture and natural resources, with a wide host range, especially in California.

A 2016 host list by the CDFA lists over 100 plants that can host the fruit fly.

It’s suspected the pest was introduced by travelers who brought uninspected produce from outside California.

The CDFA stated that these fruit flies were discovered in San Bernardino County in 2016 but have since been “successfully eradicated” three separate times.

Jason Leathers, environmental program manager at the CDFA, gave a clearer timeline of the fly’s history in California, telling The Epoch Times: “It was first found in California in 2016 not far from the Ontario airport. It was later found in 2019 in San Pedro near the port of Long Beach/Los Angeles. Last year it was found outside the air cargo facility at LAX. However, this is the first time an infestation has been found in the environment of California.”

“This is the first time this particular fly has had a large enough documented infestation in the Western Hemisphere to prompt a quarantine,” Ken Pellman, spokesperson for Los Angeles County’s Agriculture Commission, told The Epoch Times.

California has become quite familiar with quarantines brought about by exotic fruit flies. There have previously been quarantines in California for the Mediterranean, Malaysian, Mexican, melon, guava, and Oriental fruit flies, with some of these quarantines being ongoing.

However, according to Mr. Pellman, the lack of experience with this fly is what has allowed it to be so noteworthy.

“There are fruit flies, such as what we call the ‘Oriental Fruit Fly,’ that attack a wider variety of fruits and vegetables. However, we have much more experience eradicating ‘OFF’ and can usually eradicate it quickly. We don’t have nearly as much experience with [the] Tau Fruit Fly,” said Mr. Pellman.

“It has not been studied by entomologists as much as the other fruit flies that have been well-known pests for a long time. There is some uncertainty about the crops that it will affect,” Mr. Leathers stated.

These “exotic pests” have not become established in California due to “(1) strict federal exterior and state interior quarantines, (2) a pest detection program, and (3) aggressive eradication programs when an infestation is discovered,” the CDFA stated, according to the AP article.

Mr. Pellman stressed the need to wipe out these flies due to the importance of the area for produce.

“We’re a big conduit in terms of shipping and trade,” he said. “We want to keep an eye out and prevent stuff from coming here in the first place, and if it comes here, to eradicate it quickly before it spreads.”

Brian Brown, who has researched flies throughout his career, said that if fruit flies get out of control, they can hurt California’s produce exports in the national and world market.

“Once these things get going in a large area, they’re almost impossible to eradicate,” he said in the AP article.

While the fly is quite unknown at the moment, Jason Leathers, environmental program manager at the CDFA, believes increased infestations will result in information on the fly increasing. He added that the tau fly’s quick reproduction and ability to evade human detection are its largest threats.

“What’s really insidious about it is they use an egg-laying organ to insert the eggs under the skin of fruit, so people don’t realize that their fruit is infested and it looks just fine,” Mr. Leathers said in the article.

Los Angeles County has a fruit fly trapping program, and traps have been placed throughout the quarantined area in an effort to eradicate the fly’s population before it has a chance to spread. The state has nearly 95,000 traps to catch flies.

Additionally, any produce or plants within 200 meters of another detected tau fly will be inspected for larvae, according to county officials.

Mr. Pellman described it as “an ounce of prevention versus a pound of cure.”

“The more cooperation we get from residents in the area, the sooner the quarantine can be lifted,” he said.

“This infestation is an example of why it is important that any fruits or vegetables being brought into California from travels outside of the state or country, or being shipped from friends and family outside of the state or country, be officially and properly inspected for pests.”

Mr. Leathers stated the quarantine will last for three fruit fly life cycles after the last detected fly.
“The life cycle calculation is based on a degree day model that is affected by temperature. So if it is warmer, it can run faster or if it is cooler it can run slower,” he said.
As for a likely timetable for the quarantine, Mr. Leathers said: “We are still finding flies right now, so we do not know for sure when this will be. However, it might be as early as November.”
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