For the first time, Africanized bees have been found in the Bay Area.
The so-called killer bees have moved up from Southern California to parts of the Bay Area in Vacaville, Martinez and Lafayette.
The biologist who found them is advising precautions, not panic, now that the bees have arrived in the region.
"The problem arises when you disturb a hive or nest," Professor Kohn said. "They are more aggressive and persistent when disturbed."
Last month, a man was killed by swarming killer bees in Southern California. There are also periodic reports of pets or livestock being killed by killer bees.
If swarmed, Kohn advises to run and keep running as the killer bees will pursue you longer than other honey bees.
Africanized Killer Bees like warm temperatures. Experts said the warmer than usual winters are contributing to the killer bees move up north.