LAFAYETTE, Calif., Sept. 30 (UPI) -- Researchers at the University of California, San Diego, have for the first time confirmed the presence of killer bees in the Bay Area.
The bees were found and collected in Reliez Valley, a suburb of Lafayette, California. Previously, Africanized bees had only been found as far north as the Central Valley's Mariposa County.
Scientists say the discovery isn't reason to panic.
"They should be no more concerned than they are for rattlesnakes or mountain lions or things that can harm you if they attack but rarely do," Joshua Kohn, a biology professor at UC San Diego, told the San Jose Mercury News.
The bees' presence this far north is a sign of a changing climate, researchers say. Drier, hotter weather has allowed the bees' range to expand.
Africanized bees, or killer bees, were first introduced to Brazil from southern Africa in 1956. In the decades since they've slowly made their way north -- to Mexico in the mid 1980s and Texas in the early 1990s. They were first found in Southern California in 1994.
Most people wouldn't be able to tell the difference between a European bumble bee and an Africanized bee, and even scientists have to use to DNA analysis to confirm their presence. Most bee colonies are a mix of different wild bee species.
Killer bees -- whether pure or hybrids -- are distinguished by their aggressive tendencies and more persistent pursuit of an agitator.
Earlier this year, a farmer in Texas was killed after being stung more than 3,000 times.
