Another Medfly in Much-Sprayed Rosemead : Infestation: Discovery triggers fears of a summer population explosion. A new round of malathion applications is likely.

Agriculture officials reported Wednesday that another Mediterranean fruit fly has been trapped in Rosemead, virtually assuring a new round of aerial malathion applications in what was one of the most heavily sprayed sectors in a yearlong eradication effort across Southern California.

The discovery reinforced fears among scientists and community activists that the state’s strategy in fighting the pest has failed.

It was the second fly trapped in Rosemead in a week. Moreover, officials announced late Wednesday that what was tentatively identified as a Medfly had been discovered in Central Los Angeles. Entomologists hypothesize that every Medfly trapped signals the presence of hundreds more of the insects.

Some of the state’s scientific advisers said that the latest Rosemead discovery is a distressing sign that the pest may be on the verge of a summer population boom. A similar explosion last summer eventually led to widespread spraying across the region.

James R. Carey, one of five members of the state’s Medfly Science Advisory Panel, has said that over the last 15 years the vast majority of Medflies found in California were trapped in August, September and October, when warm temperatures and an abundance of ripe fruit offer ideal breeding conditions.

“We’re only in the foothills,” Carey said Wednesday. “The peak is in September and October. It’s very possible this could grow as large as before.”

Carey and the four other members of the state’s advisory panel, which oversees the eradication effort, participated Wednesday in a telephone conference to discuss a new battle plan to combat the pest. They were unavailable for comment afterward.

But state Department of Food and Agriculture Director Henry J. Voss said the panel recommended that the Rosemead neighborhood be sprayed twice and then treated with the release of sterile flies intended to breed the pest out of existence.

Voss said plans already were being laid to spray malathion in the area on Monday, although he said his final decision will come today after a related court hearing in Los Angeles.

“Our concern is that with the hot weather and with these flies popping up now, we need to be right on them,” Voss said. “It’s not a very satisfying situation, that’s for sure.”

Carey said: “This is the beginning of Round 2.”

Just hours after announcement of the Rosemead discovery, state officials said they had found yet another Medfly about three miles north of where a single fly was in Echo Park two weeks ago. Officials said identification of the fly was not completely certain, so no decision has yet been made on what action to take.

In Rosemead, the single mated female Medfly was trapped in a nectarine tree just north of Interstate 10, three blocks from where a fly was trapped last week. The first Medfly normally would have prompted an order for spraying, but a decision was delayed because scientists were unable to make a complete identification of the specimen.

Complicating the Rosemead situation is an ongoing attempt by the city of Los Angeles to obtain a court order to block spraying over a 14-square-mile sector of downtown, including Echo Park, Silver Lake, Chinatown, Bunker Hill and Skid Row. That spraying is scheduled to begin tonight and continue every Thursday night for at least three weeks.

The city has asked a Los Angeles County Superior Court judge to block the spraying. It contends that recent laboratory tests have shown excessive quantities of lead, nickel and chromium in the sticky mixture of malathion and fly bait sprayed by state-chartered helicopters.

State health officials say the amounts are minor and pose no significant health risks.

Voss said that a ruling by Superior Court Judge John Zebrowski could influence his decision on what to do in the Rosemead outbreak.

The new discoveries came just as it appeared Southern California was on verge of victory over the stubborn infestation. At the height of the yearlong siege, helicopters rumbled over 536 square miles of Los Angeles, Orange, San Bernardino and Riverside counties. The malathion treatment zone had shrunk to nothing over the last two weeks, after spraying was completed in San Bernardino and Riverside counties on June 26.

For residents of Los Angeles and Rosemead living near the latest discoveries, the possibility of more spraying brought frustration.

The neighborhood near Dodger Stadium where a Medfly was found June 27 was the first one sprayed when the infestation began last year.

Rosemead--along with parts of Pasadena, El Monte and Arcadia--was sprayed 10 times from November through May--still a record in the current infestation.

“There’s no question now that this program doesn’t work,” said Patty Prickett, who chairs a community group called Residents Against Spraying Pesticides. “All it’s done is taken millions of dollars of taxpayers’ money and exposed people to a toxic chemical. It’s a disaster.”

Carrol Calkins, a federal entomologist who serves on the advisory panel, said scientists had expected to find more flies this summer, but the hope was that they would be limited to new areas.

They’re Back Two Mediterranean fruit flies have been discovered in the past two weeks in Rosemead. The Medflies were trapped within the old Rosemead spray zone, which was sprayed 10 times from November, 1989, to May. Spraying was halted in the zone on May 9 after the pest was supposedly eradicated from the area. Medfly Spraying Map, B2