The "killer bees" found recently in California are not the first to reach the United States. About a year ago a swarm was found on a Brazilian freighter that docked in Oswego, a Lake Ontario port in upstate New York. The swarm was destroyed on board but not before a few escaped.

Researchers from Cornell University have been checking the surrounding area since then, but they say they are worried less about an invasion of the alien bees than the spread of a bee-killing parasite that the killer strain often carries.

The bees that escaped in Oswego are likely to have been sterile worker bees that, even if they joined a native honeybee colony, could not have mated. The queen of the shipboard swarm, the one most likely to establish a new colony, was among those killed.

If the escapees met native bees, they could have transmitted the parasite, called the Asian bee mite. The mites do not seem to hurt the Africanized bees but can devastate domestic bees by feeding on their pupae and sucking blood from the adults.

So far, no escaped "killer bees," more properly known as Africanized bees, have been found in New York, and native bees show no sign of mite infestation.

Roger Morse, who is leading the search, said that in any case, he is not greatly concerned about the threat from Africanized bees, which escaped in Brazil in 1956 and have been spreading northward. Morse said there is evidence that when the bees enter temperate climates, their usually nasty disposition improves.

Morse said that in Argentina, where the climate is similar to that in much of the United States, Africanized bees are hardly more aggressive than domestic bees and Argentinians do not see them as any great problem. In South Africa, where the strain came from, there are also few reported problems.

The real threat, Morse said, is the mite they carry. "These mites have already caused extensive honey bee colony deaths in more than 35 nations, including countries in Europe, Asia, South America and Africa. It is probably inevitable that they will make it to the U.S."

The rate at which Africanized bees are spreading northward naturally suggests they will reach the United States in force around 1988 to 1990, entering most likely at the southern tip of Texas on the gulf coast.

The Associated Press reported yesterday that a second batch of the African bees was found in California. The latest group was found in a commercial beehive only two miles from the underground burrow where an oil-field worker saw the first swarm kill a rabbit June 25, the state Department of Food and Agriculture said.

The leader of the state Africanized Bee Project, Len Foote, said he found what he believed to be a queen bee and three drones among worker bees in the colony destroyed Thursday.

Officials had said they believe two or three queens and swarms may have escaped the original burrow before it was destroyed in an oil field at Lost Hills, an isolated town about 120 miles northwest of Los Angeles. The bees are believed to have arrived on oil field equipment from South America.