California working to eliminate invasive fruit fly in Alameda County

CBS News

30-04-2025

California agricultural officials said they are releasing millions of sterile Mediterranean fruit flies in Alameda County to try to eradicate the pest, first discovered summer 2024.
For decades the Medfly has posed a threat to farmers, and politicians, but one expert thinks it may be here to stay.
This latest release of sterile Medflies is not the beginning of an infestation, in fact, it may be the end of one. When they were discovered last August in Fremont, it was the first time the bug had been found in Alameda County since 1981.
And that was the year that things got pretty crazy.
The Medfly, nicknamed "old blue-eyes" for its iridescent color, poses a huge threat to agriculture, laying its eggs inside fruit, making it inedible. But more importantly, it can leave an entire region subject to bans from other states and even foreign countries. So, when more than 100 flies were found in Fremont within six months, it sounded a lot of alarms.
"So, in response to that, our protocol is to release sterile male Mediterranean fruit flies at a rate of 250,000 sterile flies per square mile per week," said Dr. Jason Leathers, with the CA Department of Food and Agriculture. "And the idea is that any female Medflies that are in the area will hopefully choose one of the sterile males as her mate. And when she does, it renders her infertile and none of her eggs will hatch. And so, over time, that leads the population to extinction."
Dr. Jason Leathers said the Sterile Insect Technique has been pretty successful and is currently used on a year-round basis in Southern California. But before they figured out how to do that, back in 1981 they used a different technique — one that most will never forget.
At the time, many compared it to the helicopter attack scene from the movie Apocalypse Now. A squadron of crop-dusting choppers flew in formation, spraying the city of San Jose with a sticky solution of the pesticide, Malathion. Then-governor Jerry Brown initially resisted the spraying, which upset local farmers.
"I've got to weigh the health effects, the impact on people," said Brown.
But then, under pressure from the federal government, he approved it, which frightened, and angered, everyone else.
"We feel like we're just trapped here, and we're going to be sprayed and be living in a sea of Malathion," said one woman.
"I could have a 2-pound baby instead of a healthy 7-pound baby," said another.
Brown ran for the US Senate the following year and lost; some believe the Medfly controversy was a factor. But despite the uproar, the flights continued, night after night.
"And it was even unbelievable to me, actually," said Dr. James Carey, who was studying the Medfly at the time for UC Davis. "I mean, in retrospect, the thought of spraying Malathion, even one time, over millions of people is really something that certainly wouldn't be accepted today."
He said, though the spraying was generally successful at knocking down the Medfly infestation, the public outcry convinced the state to give up the practice and focus instead on other strategies like the Sterile Insect Technique. But Dr. Carey said he has his doubts that it can really eradicate a species.
"It's very, very difficult. In fact, it's impossible to declare whether flies have been totally eliminated," he said. "It is kind of a whack-a-mole problem right now. You get Medflies here and there and you have to go after them. But pretty soon, there's so many outbreaks every year that the whack-a-mole approach is not going to work."
The professor said climate change may also be playing a part in the increase in invasive pest outbreaks. Many of the more damaging insects come from tropical climates and are better able to adapt to California as the average temperatures rise.
Dr. Carey believes the Medfly is here to stay, but he said the state can't acknowledge that without its agriculture being quarantined by the rest of the world. So, in August, if no more Medflies are found in Alameda County, the state will consider it officially "eradicated."
Until the next time they show up.