image - med fly
Shoppers at the Farmer's Market will no longer have to lift the white nets protecting fruit stands. The countywide quarantine to prevent the spread of Mediterranean fruit flies has been called off. Kyle Ludowitz/Review

Recently, Coastside farmers and agricultural officials alike were able to breathe a long-awaited sigh of relief. Nearly a year after San Mateo County agricultural workers discovered two Mediterranean fruit flies in Half Moon Bay, prompting a countywide emergency quarantine, officials called off extensive efforts to prevent the pint-sized pests from spreading. 

Since the flies were first found last November, growers, business owners and county officials have had to contend with exhaustive federal and state protocols within the 56-mile quarantine zone, said county Agricultural Commissioner Fred Crowder. The eradication measures included flooding the skies with millions of sterile male flies, treating residential properties with pesticides and covering produce sold at grocery stores or farmers markets — in addition to a smattering of restrictions and compliance agreements placed on growers and business owners. 

The quarantine was officially lifted in early October. 

Initially, said Crowder, trees within the quarantine area were stripped bare. The Mediterranean fruit fly, or Medfly, is one of the world’s most disruptive agricultural and economic pests, known to breed on more than 250 types of fruits and vegetables. After female Medflies lay eggs in ripening fruit, the newly hatched insect larvae feast on their host — rendering it inedible in the process.

“It’s been very distracting for everybody, and we really appreciate the community’s support,” he said. “So we’re really glad that it’s over. I just wish that we could have gotten this relief sooner.” 

Crowder said that officials weren’t able to declare that the Medflies had been completely eradicated until three generations, or life cycles, of the pest had passed and no additional flies were found. But because of the Coastside’s chilly climate, which slows the rate that the Medfly goes through its life cycle, that timeframe was significantly extended in Half Moon Bay. 

“It typically takes a relatively short period of time for it to go through three life cycles,” said Crowder. “With Half Moon Bay it’s so much cooler that the average temperatures made it take almost a year to go through all of them.” 

Many of the models for declaring Medfly eradication are based on warmer areas, where the insect is traditionally found. But, according to Crowder, the presence of Medflies in cooler-temperature areas has increased due to the ease of trade and travel. He said that the San Mateo County Department of Agriculture, Weights and Measures has been working with the California Department of Food and Agriculture and the United States Department of Agriculture to examine other ways of assessing whether an infestation has been eradicated. 

“It’s a question of whether we could have called the infestation off in Half Moon Bay earlier than we did,” said Crowder. “By law, right now, we can’t. But we need to take a look at the law if we’re going to start seeing the Medfly introduced in areas where there are cooler temperatures.” 

“There are some questions of whether or not an infestation (in Half Moon Bay) is even viable,” he added. 

Determining the Medfly’s survival prospects along the Coastside might have a major impact on growers and businesses if additional flies are found in the future. Crowder said that around 70 growers, businesses and vendors faced compliance agreements for their produce throughout the 11-month quarantine. 

“Talk about impact,” he added. “For some people, like our apple producers, they lost 100 percent of their crop. At the farmers market, generally, they saw a 30 percent reduction in sales, because (vendors) have to go through and safeguard the entire product, which discourages (consumers from) purchasing them.”

But while the farming community exhaled in relief after the lengthy quarantine process, Crowder still urged travelers to be vigilant when returning from tropical areas. 

“When you travel, make sure that you don’t bring pests back with you,” he said.


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