Medflies Discovered in Westminster Trap : Agriculture: The finding is the largest in the county since a widespread 1990 infestation. Officials will battle the fruit pest with a quarantine and malathion pesticide sprayed from the ground.

State agricultural workers discovered three Mediterranean fruit flies in a back-yard peach tree over the weekend and set out Monday to establish a quarantine area and begin ground spraying of the pesticide malathion.

The finding was the largest in the county since the voracious and destructive insects caused millions of dollars in fruit tree damage during a widespread infestation in 1990, authorities said.

At that time, state officials conducted an aerial spraying program that was highly controversial despite the assurance of experts who said that malathion poses no danger to humans.

Three male Medflies were pulled from a trap in the back yard of a Lido Avenue home on Friday and were positively identified Saturday, said Larry Hawkins, a spokesman for the state Department of Food and Agriculture.

State officials on Monday were determining boundaries around the Newland Street-McFadden Avenue neighborhood for a fruit quarantine and were preparing to have workers spray nearby trees with malathion tanks mounted on their backs.

Authorities say they do not know if they are dealing with the first signs of a large infestation or an isolated discovery of the yellow, black and white fly, which is slightly smaller than the common house fly but can devastate crops by laying eggs inside fruit, which is then eaten by the larvae.

County agriculture officials took a wait-and-see stance about the finding.

“This is just an indicator that there were three males there and nothing more at the moment,” said James D. Harnett, the county agricultural commissioner. “These may be all of them. We don’t know. It could be all of them, but it’s anybody’s guess.”

In the wake of the discovery in Westminster, state agriculture officials, who maintain hundreds of small yellow traps around Orange County, put up about 1,000 traps in a square-mile area around the peach tree where the flies were found. The traps, to be checked daily, will help inspectors determine if there are any more Medflies in the area, authorities said.

To combat the spread of any other Medflies, state agriculture officials plan to go door-to-door today in a 200-meter radius of the Lido Avenue neighborhood, asking residents for permission to spray malathion on fruit trees, officials said.

State officials have not decided whether to use sterile Medflies as well, Hawkins said. When they mate with fertile Medflies, no offspring are produced.

Hawkins said residents of the Westminster neighborhood are urged to keep home-grown fruit at home for now.

The Medfly discovery over the weekend was a scary reminder of a widespread infestation in 1989 and 1990, which prompted extensive aerial spraying of malathion and protests in Orange and Los Angeles counties. The Medfly can destroy more than 200 crops, including Orange County crops of oranges, lemons, grape fruits, avocados, tomatoes and cucumbers.

State officials believe that Medflies are arriving in Southern California through illegally mailed shipments of fruit from Hawaii or Asian countries.

In January, 1992, a Mediterranean fruit fly was found in an orange tree in Los Alamitos, triggering an intensive trapping effort but no immediate need for a quarantine.

The Medfly “is one of the most destructive pests to fruit,” said Leon Spaugy, the agricultural commissioner in Los Angeles County, where officials have dealt with Medfly discoveries each year since 1987. Since December, county officials have discovered Medflies in Pico Rivera and in the Granada Hills area, Spaugy said.

“If the Mediterranean fruit fly were to become established, there is a number of things that would happen--all negative,” Spaugy said.

Flies found: Three medflies trapped in peach trees.