Medfly quarantine remains necessary nuisance

Last November, San Mateo County agriculture officials discovered two adult Mediterranean fruit flies — or Medflies for short — in Half Moon Bay. Unearthing these notorious, pint-sized pests immediately prompted an emergency quarantine response around the area to stop them from spreading. Female Medflies lay their eggs in ripening fruit, which hatch into larvae that feast on the fruit, their host, rendering it inedible.

“It is hard to overstate how damaging a Medfly infestation can be,” said Erin Tormey, founder and manager of the Coastside Farmers Market. “It can ruin entire sectors of the agricultural economy.”

The Medfly is considered one of the world’s most disruptive pests. Although a rarity among cool coastal climates like Half Moon Bay, Medflies have been known to thrive in parts of California with a more mild, Mediterranean climate, hence the name. Agricultural authorities warn that, if left alone, they could result in billions of dollars in damages.

“It affects over 250 (types of fruits and vegetables),” said county Agricultural Commissioner Fred Crowder. “And that’s not just agriculture, that’s backyard produce, too. Anywhere that’s got peaches, plums, citrus or tomatoes — garden staples and backyard staples are Medfly host material. So, it’s (also) impacting the residential community.”

Immediately after finding the flies on two private properties, county agriculture officials went around the surrounding area and stripped all fruits from the trees. That produce was then taken to the dump and buried — 50 feet below the ground.

Other federal and state quarantine protocols followed, all to make sure that the pesky flies don’t spawn a new generation of a potentially devastating pest. Residents were prohibited from taking any “host material” outside of the quarantine zone, which covers 56 square miles in total. Initially, a sterile release program flooded the skies with thousands of irradiated male Mediterranean fruit flies that would breed with any females in the area to produce infertile eggs. Residential properties were treated with bacterial pesticides. And commercial growers faced a slew of restrictions about what they could do with their produce.

“It’s really an integrated effort,” said Crowder.

How long are all of these measures supposed to last?

“The idea is that if you’ve gone through three generations of Medflies without any new (ones), they consider them to be eradicated,” said Crowder. “How it works is that they’re monitoring the temperatures. And when the temperatures are cold, it’s going to take (the flies) longer to get to maturity.”

While the cold-blooded critters and our chilly climate make the duration of the quarantine difficult to pinpoint, Crowder said that county agriculture officials completed residential chemical treatments on July 29. The day before marked the last airborne release of the sterile males. The netting at the farmers market, however, will have to continue until the end of the quarantine.

“Every week, we have a representative from either the California Department of Food and Agriculture or the (U.S. Department of Agriculture), or both, ensuring that (the nets) are there,” said Tormey. “And if they’re not there, they will shut us down; they will take everybody’s fruit and destroy it. That is not going to happen on my watch.”

At the market this weekend, some vendors acknowledged that the netting has negatively impacted sales. “People don’t really see our product,” said Jennifer Simms, who owns an organic farm in Pescadero. “We know it’s necessary, but we’d really like them to wrap it up.”

Others, like Alexis Collazo of La Milpa Organic, hadn’t heard of the Medfly problem until he came to Half Moon Bay. “This is the only market that’s actually affected us,” said the Salinas resident. “We have another market in Pacifica, and we just hope it doesn’t affect (the area) over there, too.”

Coleen Brophy of Rainbow Orchards weighed the importance of the quarantine against her own frustrations. “Unfortunately, it’s not the most convenient thing,” she said. “But it is the safest. Without it, who’s going to buy (anything)? The whole point of the farmers market is quality. We’re not going to let the Medflies touch our stuff.”

Based on agriculture officials’ current temperature calculations, the Medfly quarantine is projected to end on Sept. 12.