California Is Releasing Millions of Fruit Flies

State is fighting Medfly infestation by dropping sterile males over LA County
By Rob Quinn,  Newser Staff
Posted Nov 3, 2023 10:43 AM CDT
Updated Nov 5, 2023 7:02 AM CST
California Is Fighting Fruit Flies With Fruit Flies
California doesn't want this bug to spread.   (Scott Bauer, USDA Agricultural Research Service,

California is dealing with an invasion of Mediterranean fruit flies—aka Medflies—by saturating the affected area with millions of fruit flies. The California Department of Food and Agriculture says it plans to drop 250,000 sterile male fruit flies per square mile over a 9-square-mile area of Los Angeles County every week in an operation that could take six months or more, SFGate reports. Officials say the plan is to eradicate the Medfly infestation through a form of birth control. When the sterile males mate with females, they produce eggs that never hatch. CDFA entomologist Jason Leathers, who is overseeing the program, tells the New York Times that residents are "unlikely to notice" the influx of the tiny flies.

Los Angeles County Agriculture Department spokesperson Ken Dell tells SFGate that the flies, incubated at a military base and marked with purple dye, are loaded onto small planes and then "just released out of the bottom of the cabin." The operation was launched after three wild Medflies were found in traps in South Los Angeles neighborhood of Leimert Park early last month. The USDA describes the fly as "the most important agricultural pest in the world," capable of devastating agriculture in California by infesting hundreds of kinds of fruits, nuts, and vegetables.

Authorities believe the Mediterranean flies were brought in on uninspected produce. A produce quarantine is in effect for a 69-square-mile area of LA County, with residents urged to keep homegrown produce on their property and to double-bag fruit before throwing it away. Smithsonian magazine reports that California has battled Medfly infestations for decades and has been using sterile flies since 1990. Before that, the state sprayed the pesticide malathion over neighborhoods. During an unusual infestation in 1989, a group calling itself the "Breeders" claimed to have released the flies to protest aerial spraying of pesticides. (Another kind of fly caused a first-of-its-kind quarantine in LA County this year.)

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