The discovery of three Mediterranean fruit flies in a Tampa kumquat tree put Florida in a Medfly panic today, as state officials geared up for a possible eradication campaign.

Officials and citrus growers expressed fear that the insects had come from California and would cause severe problems for Florida's $2 billion citrus industry.

"Our first suspicion is that [the Medflies] have come from California," said Gov. Bob Graham, and he blamed a slow response by California to its infestation for the possible insect invasion of Florida.

Graham said he would order aerial spraying with the pesticide malathion, if it proved necessary. Such spraying was opposed by California Gov. Edmund G. (Jerry) Brown Jr., when the fruit flies invaded California in June, but later was forced by the federal government.

Graham said he might reimpose a rigid quarantine on California fruits and vegetables. The state imposed such a ban last month but a federal judge ruled it illegal.

"Our worst fears have been realized," said Frank Graham, counsel for the Florida Department of Agriculture.

California officials responded that Florida's attack was unfair. "There's no evidence the flies are from California," said Don Lesser, an aide to Brown.

Late today officials said no more Medflies had been found near the backyard in East Tampa where a state agriculture worker on a routine inspection yesterday found three flies, two males and a female, in a trap.

Officials said there was a chance that the three flies had "hitchhiked" into Florida on out-of-state produce, rather than being the first wave of an invasion.

There is also a chance the insects are sterile, officials said, and scientists were studying the flies tonight to try to make a determination.

After an agriculture inspector found the flies yesterday, they were flown to Washington, D.C., where Richard Foote, a research entymologist at the Smithsonian Institution, confirmed that they were Medflies.

"The whole state of Florida should be worried," Foote said. "The fly can survive in so many host plants that almost anything that grows fruit can harbor it. They could get several generations of these fruit flies developing before cool weather arrives. They spread quite rapidly.

"The problem in America is that the fruit grower cannot sell wormy fruit. Most places where there exist Medflies, people accept wormy fruit."

Foote said the flies were "fresh flies, mature adults." But he found no eggs in the female, an indication that she might not have begun to reproduce, or might be sterile.

Medflies, which have a 30-day life cycle, lay their eggs in fruit after piercing the outer layer. The eggs hatch and damage the fruit.

Florida officials said one Medfly was discovered in Miami 18 months ago, but it was determined to be a lone "hitchhiker" that had come in on a ship.

A five-man state Agriculture Department task force was dispatched to Tampa today to lay 100 traps in a one-square-mile area around where the flies were found.