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“Killer Bees” found in San Francisco Bay Area for the first time!

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Africanized honeybees, sometimes called “Killer Bees” because of their swarming, aggressive, and deadly nature when a colony is threatened, have been found in the San Francisco Bay Area for the first time! According to

The bees were found in a Lafayette subdivision called Reliez Valley, near the southeast side of Briones Regional Park, by UC San Diego researchers who have been tracking the bees’ movement throughout the state. Until now, the bees had been detected only as far north as Mariposa County in California’s more inland Central Valley, but they were probably attracted by the Bay Area’s warming temperatures.

Joshua Kohn, who is a Professor of Biology at UC San Diego, said that it is hard to tell how many of the bees are in the area, other than there is likely to be more than one colony.

“Normally honeybees forage within about a mile of their hive, though they can go up to about 5 miles,” Kohn said. “There is no way we found a member of the only Africanized bee colony in that region.”

Kohn said that, although the bees can pose a threat to humans, there is no reason to be too concerned.

“An Africanized honeybee out foraging on flowers is no more aggressive than your average European honeybee. Nor is the sting of an individual any different,” he said. “It’s only when a hive is disturbed that the level of aggression from Africanized bees is elevated.”

Brian Johnson, a honeybee researcher at UC Davis reminds us that the bees do pose danger whenever they are present.

“Africanized bees are a public health threat,” he said. “People should be educated on what to do if they encounter them.” gives examples of the dangers:

Experts say bees overall kill about 40 people a year in the U.S. No statistics are kept for Africanized bees, but people and animals are the most at risk if they don’t have a way to escape an attack, Kohn said. The Africanized bees have killed animals on chains and in fenced enclosures in Southern California and Texas.

Last month, a swarm of Africanized bees killed a construction worker and injured two others in Riverside as the workers graded land for a parking lot unaware that an underground vault housed a hive.

So, what exactly ARE these bees?

The Africanized honeybee is a hybrid of the European bee and the African bee, originally brought west to Brazil to improve honey production. The breed eventually escaped and spread through South America, Central America and ultimately the U.S. It entered California in 1994 and has gradually spread north since, primarily circulating in the state’s warmer, southern regions.

The hybrids are much more defensive than the European breed and more likely to attack a perceived threat to their hive, and do so much more relentlessly and in larger numbers. Their venom is the same as the European breed, but it is delivered in higher amounts since the Africanized bees are more likely to sting than their European counterparts. Africanized bees have been known to pursue a perceived threat for distances well over 500 yards.

The bees have been known to build their hives in trees, under rocks, within caves and under edges of man-made objects such as sheds or chimneys.

What should we do if we encounter Africanized bees?

Although Africanized bees are slightly smaller than European bees, there is no accurate way for the casual observer to distinguish between them.

Africanized bees out foraging will usually not attack.

If you get close to a hive, you should move away quickly.

If you sense that bees are approaching, run away as quickly as possible, at least 100 yards. Africanized bees have been known to swarm perceived threats relentlessly and in high numbers.

Do not swat away or crush Africanized bees. That will only further antagonize other members of the hive.

If you can get away from enough of them to run inside, do it. You can deal with the ones who made it in with you. Brush them off your clothes. Then remove the stingers by scraping them with a credit card or similar object. Don’t use tweezers (that will inject more venom).

Don’t jump in a swimming pool or bodies of water to get away. They have been known to wait for people to surface.

When in a safe location, call a local bee professional and emergency personnel.

Be careful out there!

-Bill at

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