Medfly Find in Riverside County Spurs Grower Fears

State agriculture officials announced Friday that a single Mediterranean fruit fly has been discovered in Riverside County, marking a leap by the pest into a new corner of Southern California and raising the possibility of aerial spraying and quarantines on its orchard-rich lands.

The immature female Medfly was trapped in a commercial orange grove Wednesday in the community of Woodcrest, about 45 miles east of Los Angeles.

Jim Wallace, Riverside County agricultural commissioner, said intense trapping has begun over 81 square miles to determine if the fly is an isolated find or the first sign of a full-blown infestation in Southern California’s richest agricultural county. Infestations already are being battled in Los Angeles and Orange counties.

Aerial spraying or a quarantine on crops is not yet required because only one fly was found, Wallace said. But with the weather warming and plenty of food available for the pest around Woodcrest, he said the situation is precarious.

“I’ve been worrying all my life about this day,” Wallace said. “It’s horrible.”

Word of the find spread quickly through Riverside’s agricultural community, and the reaction among growers and political leaders was one of alarm.

Unlike Los Angeles and Orange counties, Riverside County remains heavily reliant on agriculture. An infestation could wreak havoc on the county’s leading crops, among them oranges, grapefruit, wine and table grapes, and dates. The citrus industry alone accounts for $175 million a year.

County Supervisor Norton Younglove, whose district includes the orange grove in which the Medfly was found, said he was “disappointed and extremely worried” when he learned of the discovery.

“We, like anybody else, hate to see this rascal running loose in our county,” Younglove said. “I only hope it’s just one isolated incident. . . . If we let that fly get established, it could have a very serious impact on Riverside County’s economy.”

The Woodcrest discovery is the second in Southern California in the last week.

A single immature female was found in Diamond Bar on Tuesday, prompting some scientists advising the state in the eradication program to question the current strategy against the Medfly.

On Monday, Henry J. Voss, the director of the state Department of Food and Agriculture, announced that he was rejecting the panel’s advice and set a May 9 deadline to end aerial spraying over the current infestation zones. In a switch of tactics, helicopter-borne pesticides will be replaced by sterile flies, released by the millions, in an effort to breed fertile Medflies out of existence.

The panel unsuccessfully argued that the sterile flies should be held in reserve so there would be enough to combat any new outbreaks.

James R. Carey, a UC Davis entomologist and a member of the science advisory panel, said the discovery in Woodcrest shows that any optimism about beating the Medfly may be premature.

“It’s clear we have to rethink strategy now,” Carey said. “I think we still need to find another fly or two, but it’s becoming clear that it is throughout the Los Angeles Basin and that it is widespread and not contained.”

Riverside County Supervisor Walt Abraham said the state’s recent declaration that the Medfly problem was under control was “not too wise.”

“This isn’t the kind of situation you can ever totally beat,” Abraham said. “We’re treating it as a dire emergency. The stakes are very high.”

“We are absolutely, absolutely shocked,” said Tom Mazzetti, who farms 2,000 acres of citrus and is president of Blue Banner Packing Co. in Riverside. “They hadn’t found a fly in months and the state was planning to stop spraying a month early, so we were all optimistic. Now this. We just hope to goodness they don’t find anymore and this is the end of it.”

An infestation, Mazzetti said, “would be devastating. If we get quarantined, there go our foreign markets.

“Think about the lost jobs,” he added. “There’s the trucking industry. The workers at the harbor. I don’t think anyone realizes the impact this pest could have on our state.”

Mazzetti said he spent much of Friday fretting about the Medfly find with colleagues in the industry, worrying about the what-ifs that inevitably accompany such a discovery.

The veteran grower said that if aerial spraying of malathion became necessary, he hoped his more urbanized neighbors would be more understanding than other Southern Californians.

But Supervisor Younglove was less hopeful: “I think the old-timers would be less upset, because they’re accustomed to living with agriculture. But we have many citizens who have moved here from Orange County and L.A., and they won’t feel any different than the people who are still there.”

The fly was found in a tree on the John Gless Ranch, a commercial citrus operation located just outside the southern boundary of the city of Riverside. The unincorporated area once was carpeted with verdant orange groves, but today it is dominated by new housing tracts.

Some farmers held out hope that the discovery was an isolated find or that the fly was actually a misidentified sterile fly.

“Right now I think there is an awful lot of overreaction,” said John S. Gless, ranch manager. “I believe the chances are it’s a sterile fly.”

Eric Fisher, a state entomologist who worked on the identification, said there is a slight possibility that the fly is one of millions of harmless sterile flies that have been released in Southern California over the last few months to eradicate the Medfly.

Sterile flies are dyed and are easily identifiable by a colored mark on their heads, although occasionally there are undyed sterile flies that must be dissected to confirm that they are sterile.

In this case, Fisher said there was no dye visible on its head, but the fly’s organs were too badly decomposed to verify its identification. “It’s a 90% to 95% probability that it’s wild,” he said.