Santa Clara County Urged to Spray for Medfly Infestation

Scientists recommended Tuesday a single aerial spraying of the pesticide malathion as part of a three-part plan to wipe out a menacing infestation of the Mediterranean fruit fly in Santa Clara County.

“The panel suggested we stick with the Los Angeles County integrated pest management program, a ground spray where the adults were found, one knockdown aerial application and release of sterile Medflies each week,” said Gera Curry, spokeswoman for the state Department of Food and Agriculture.

There have been three small Medfly infestations in Los Angeles in the last 12 months: in West Los Angeles, Northridge and a recent outbreak in the Elysian Park area that agriculture officials say they believe has been contained. Malathion was sprayed from helicopters in the Dodger Stadium neighborhood last month and millions of sterile flies have been released weekly in the area.

The department will decide today whether to follow the proposals by Medfly experts. Aerial spraying in the past has provoked controversy about possible health hazards.

An international group of scientists discussed the infestation in a telephone conference call Tuesday connecting Guatemala, Hawaii, Florida and other locations, Curry said. Other options available to the state could involve a fruit quarantine or treatment of the affected plants.

Agriculture workers on Tuesday also expanded their search for the destructive pest after an infestation was found in a residential Mountain View neighborhood.

“We are checking the traps in 81 square miles to make sure they are not farther out, but all the checking so far has found them just in that area,” said Bob Clement, a Santa Clara County coordinator for pest control.

Thirteen of the Medflies and a larvae infestation were found within a square mile in Mountain View within the last six days, officials said.

Devastating Threat

Medflies lay eggs in 250 varieties of fruits and vegetables--including all citrus, apples, cherries, avocados and tomatoes--and are capable of devastating California’s $14-billion annual agricultural industry, authorities say.

Under state law, aerial spraying of the pesticide malathion requires at least 24-hour notice to each home in the area. A state study issued in 1987 found no damage to people’s health as a result of large-scale spraying in the early 1980s, said Isi Siddiqui, assistant director of the Department of Food and Agriculture.

Two male Mediterranean fruit flies were found Sunday about a third of a mile from Thursday’s discovery of the first male fly. A fruit infested with Medfly larvae was found Sunday.

After discovery of the first fly, authorities placed more than 1,000 traps in an 81-square-mile area around the location.

Another 10 specimens, seven males and three females suspected of being Medflies, were found early Monday on a nearby ranch. The 10 are being analyzed at a state laboratory in Sacramento, but Clement said authorities are sure that they are part of an infestation.

Coming From Peach Tree

“We know they are emerging from a peach tree here,” Clement said. “The first was found in a pear tree, then in a lemon tree, then an orange tree. The fourth tree in this diamond was a peach tree where they appear to be coming from.”

The “second best thing” to finding no trace of the insect is finding them clustered, Clement said.

“They’re not a fast-moving insect. As long as they got some food, they’re going to stay put,” he added.

Crews stripped some of the remaining fruit from the ranch Monday, and homeowners were warned not to move home-grown fruits and vegetables.

In 1980-81, Santa Clara County suffered a large-scale Medfly infestation. The pests spread during a bitter public debate over the use of chemical sprays. Helicopter spraying of malathion over eight San Francisco area counties eventually wiped out the insects.

Small infestations are more typically treated with a single aerial spraying combined with fruit stripping and the release of sterile flies.

Flies Hatch in Fruit

When Medfly eggs hatch, the larvae feed on the fruit, which spoils and falls to the ground. The larvae develop within the soil and emerge in about one week as adult flies.

“It’s a crime,” Curry said. “People keep smuggling (Medflies) into California in infected fruit. These insects are not native to California. One piece of infected fruit starts an infestation. We need cooperation from the public.”

California forbids bringing fruit in from outside the state.