EL MONTE, Calif. (AP) _ Agriculture officials Thursday declared victory over the Mediterranean fruit fly, the crop-destroying insect that has taken California 15 months and $52 million to eradicate.

''We're here to celebrate that we have eradicated the Medfly in California. Unless there is another introduction, it will remain eradicated,'' said Jack Parnell, deputy secretary of the U.S. Department of Agriculture.

Parnell joined state agriculture chief Henry Voss at a news conference in pronouncing victory and lifting of a quarantine.

Traps will continue to be placed throughout the area to detect any new arrivals.

The arrival of illegal fruit and vegetables, usually carried in travelers' luggage, virtually ensures future infestations, one official said in an interview last weekend.

''There is some perverse streak in human nature. They seem to believe it's fun to outsmart authorities and bring in just one mango or just one pineapple from Hawaii,'' said Gera Curry, spokeswoman for the state Department of Food and Agriculture. ''All it takes is one person.''

Quarantines were imposed on movement of fruit from infested areas. The big worry was that the flies could spread to agricultural areas and wreck California's $18 billion-a-year farm industry.

Slightly smaller than a common housefly, the Medfly lays its eggs in fruit and vegetables.

Florida declared victory over the Medfly in August, four months after finding a single fly near Miami International Airport.

The fly has plagued California farmers since the early 1980s. From 1980 to 1982 state and federal officials spent $100 million to battle the pest.

The latest infestation caused a public outcry when the state repeatedly sent helicopters to spray the pesticide malathion in a 500-square-mile area encompassing dozens of communities. Citizens filed 300 damage claims and numerous lawsuits.

''There is no health hazard related to malathion in the amounts we use,'' Voss said, adding, ''It's cheaper and easier to keep agricultural pests out of California than to eradicate them once they're in.''

As for malathion spraying, he said, ''It's something we hope we won't have to do again. We hope science can come up with alternatives.''

Roy Cunningham, chairman of the state Medfly Science Advisory Panel, said last weekend that if the fly returns, enhanced detection measures should prevent infestations from reaching the same scale. In 1980 and 1989, the state waited too long to begin eradication, he said.