1 Site Yields 15 Medflies : Pest: The number is a record. Ground spraying of malathion begins Thursday but aerial application isn’t likely.

State workers found 15 more Mediterranean fruit flies in a residential neighborhood here Tuesday--the most ever found in Orange County at a single site--as the effort to gauge the threat to the region’s agriculture intensified.

State officials announced they would begin a day of ground spraying of the pesticide malathion Thursday in a 200-meter radius around the intersection of Newland Street and McFadden Avenue, near where three Medflies were found Friday.

But they said aerial spraying--the controversial method of fighting the pest used in 1989 and 1990 after four flies were discovered in Orange County--is not likely to be conducted this time, in part because officials do not believe the infestation is as widespread as it was three years ago.

The state has dramatically improved its early warning system for the destructive Medfly, so the capture of 15 Medflies Tuesday does not indicate the presence of a large-scale infestation like the previous one, which cost $52 million to eradicate in Southern California, said Larry Hawkins a spokesman for the state Department of Food and Agriculture.

“We expect to find more Medflies now,” Hawkins said. “Now, when we find 30 or 40 or 50 flies, it doesn’t mean that the infestation is that serious.”

But that claim was disputed by a member of a panel that advises the department on efforts to wipe out the Medfly.

“It takes multiple years for them to build back from being knocked down. Now, they’re coming back,” said James Carey, a UC Davis entomologist and member of the Medfly Scientific Advisory Panel. “This is a potentially developing problem.”

State workers went door-to-door in the neighborhood of single-family homes Tuesday, picking fruit from trees and slicing it up to check for larvae hatched from eggs deposited by female Medflies. No larvae, also called maggots, were found.

State officials said they hoped to gather enough information on the findings to set up quarantine boundaries in the area sometime within the next two weeks.

After formal quarantine boundaries are set up and the spraying is done, Hawkins said, the state will begin a program to release sterile Medflies in the area to eradicate the insect by disrupting its reproductive cycle. More than 650 million sterile flies are available each week to help wipe out the Medfly, lessening dependence on malathion spraying.

In the meantime, they asked residents in a one-square-mile area around the intersection to keep all home-grown fruits or vegetables on their property.

“The real issue for us right now is for homeowners to comply” with that request, Hawkins said. “We really need their cooperation in order to keep this thing contained.”

Residents in the area where the pests were found said they would do all they could to help contain the infestation, but many couldn’t help but recall the aerial spraying in 1990.

“I’m allergic to (malathion),” said Dean Greenhalgh, as he and his daughter stood outside his home watching state workers examine some of the 1,000 yellow insect traps that were hung in a one-square-mile area around his neighborhood over the weekend.

“When I walked barefoot across the lawn” after a 1990 aerial spraying, “my feet got numb,” he said. “I picked up the paper and my fingers tightened up and I couldn’t make a fist.

“Luckily, I’m going on vacation next week,” Greenhalgh said.

Most residents said that as long as the state kept them informed, they would cooperate.

“Whatever they need me to do, I’ll do,” said Mark Challender, 30, who usually gives friends and relatives the overflow from the hundreds of avocados his two back-yard trees produce. “I’ll invite everybody over and we’ll have an avocado party here.”

The infestation marks the first find of Medflies in Orange County since 1992, when one fly was discovered in Los Alamitos. The discovery of 52 fruit flies last month in Granada Hills in Los Angeles County resulted in the creation of a 67-square-mile quarantine area and the weekly release of 42 million sterile Medflies, a campaign that is scheduled to continue through next spring.

State officials said that the detection system in place promises to do a better job at heading off a major infestation than earlier systems.

During the last infestation, the state relied on a system that included 10 early warning traps per square mile. Today, there are 35 per square mile. The traps themselves are seven times better at attracting the insect, said Carl DeWing, a spokesman for the Food and Agriculture Department’s Sacramento office.

Still, the prospect of a new infestation worried local agriculture officials and fruit growers.

“We’re real concerned,” said Alan Reynolds, general manager of Treasure Farms, which grows 6,000 acres of fruit trees and vegetables in Irvine. “If the find expands and they find it close to us, they put a quarantine on us that makes it difficult to ship out of this area.”

James Harnett, commissioner of agriculture for Orange County, said he is also worried about environmental damage from pesticide use by homeowners trying to wipe out the fly. “There’s going to be a lot more spraying done by individual homeowners,” Harnett said.