A third "killer bee" colony has been found in a tree stump in California seven miles from the first, which was in an old fox den in an oil field. The third colony and the second, found two miles away in a commercial beehive, appear to have been younger and smaller. All have been destroyed.

The new discoveries confirm suspicions that one or more queen bees escaped from the first colony -- which is thought to have been in California more than a year -- and took swarms of worker bees with them to establish new colonies.

Experts on the insects, which more properly are called Africanized bees, say that the finding of additional hives does not necessarily raise the chances of a more widespread invasion. They note that some 2,000 commercial beehives in the area have been checked and only one had been taken over by Africanized bees.

"If there were a significant spread, you'd expect to find more of them in commercial hives," said Thomas Rinderer, a bee expert at the federal government's Agricultural Research Service in Baton Rouge, La. "I think this is a hopeful sign."

More Africanized colonies may be found in 7,000 hives still to be checked , Rinderer said. But, he added, the low proportion of alien bees means that eventually they will be crossbred out of existence as a distinct race in that area. The spread of the bees from an introduced colony in Brazil almost 30 years ago has occurred mostly in regions devoid of competing European bees.

Thus, Rinderer said, there probably were millions of colonies of Africanized bees in existence before they encountered substantial numbers of European bees in Venezuela. The Africanized bees interbred and genetically overwhelmed those colonies, destroying in a year a honey industry that had just grown large enough to begin exporting.