Agriculture officials expect to declare victory this week in the 16-month, $52 million campaign to eradicate the crop-destroying Mediterranean fruit fly from Southern California.

But the continued arrival of illegal fruit and vegetables, usually carried in travelers' luggage, virtually ensures future infestations, officials said Sunday."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 pineappple from Hawaii," said Gera Curry, spokeswoman for the state Department of Food and Agriculture. "All it takes is one person."

Quarantines could be lifted by Thursday or Friday in areas of Southern California, Curry said. No flies were found in traps last month, but officials want to be certain the flies really are gone before declaring victory, she said.

The 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, causing them to rot.

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, and farmers lost $100 million in damaged crops.

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.

Emotions continue to run high, and opponents of aerial spraying disputed the state's claim of victory.