In 2013, a Waco, Texas man bumped his tractor into a chicken coop and disturbed a hive of so-called “killer bees.” He died at the scene after being stung repeatedly by the attacking swarm of 40,000 bees he was unable to outrun.

Scary stuff indeed. But deaths from “killer bees” — Africanized honey bees — are rare. Since 1990, when these bees first appeared in the United Sates, only a handful of fatalities have been recorded. The bees are now established in states ranging from Florida to California. A study from the University of California, San Diego indicates they have recently arrived in the San Francisco Bay Area.

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The bees aren’t more dangerous than regular bees unless their hive is disturbed. But if disturbed, Africanized honey bees are more aggressive than European honey bees, which have traditionally populated the United States. Although their venom is the same, they will pursue victims up to a quarter of a mile from their hive, compared to just a 50 yard-chase from European honey bees. They also have an impulse to sting that is ten times greater than that of European honey bees. Once agitated, the bee will remain aggressive for up to 24 hours, according to Texas A&M AgriLife Research and Extension Center at Lubbock.

The best advice on what to do if you encounter a hive of Africanized honey bees can be summarized in one word: Run.

“They are potentially hazardous, particularly to people of limited mobility — either young children, elderly, or handicapped folks,” says William H. Kern, Jr., PhD, associate professor at the University of Florida’s entomology and nematology department in Fort Lauderdale's Research & Education Center. “Usually the response of healthy adults or older children is to run away, and that’s the right thing to do. Run away and get into a vehicle or shelter or building.”

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The Department of Agriculture offers advice on what to do if attacked by Africanized honey bees.

  • Run and do not stop until you reach shelter in a car or building. A few bees may follow you inside, but well-lit areas will leave them disoriented and they will fly to windows.
  • Pull your shirt over your head to protect you face while your run. This will protect sensitive areas like your eyes, but be sure not to let this slow you down.
  • Use blankets, sleeping bags, clothing or anything else available to cover yourself if you are trapped and unable to seek shelter.
  • Do not jump into water. The bees will hover and wait for you to come up for air and attack.
  • Do not wave your arms or swing at the bees. The movement will attract bees and if you crush one, the smell will attract more bees.
  • Scrape the stinger(s) out asap. If you pull the stingers with your fingers or tweezers, this will force more venom into the wound. Instead, scrape the stinger out with a fingernail, butter knife or credit card.
  • Don't try to rescue someone if you see them being attacked by bees. Call 911 and yell to them to run and seek shelter.
  • Seek medical attention immediately if you have been stung more than 15 times or are feeling ill, or if you have any reason to believe you may be allergic to bee stings.

Finally, don’t panic. The average person can tolerate 10 stings per pound of body weight. This means that although 500 stings can kill a child, the average adult can withstand more than 1,100 stings, according to the USDA.

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Daniel S. Levine is an award-winning journalist who heads the Levine Media Group and hosts The Bio Report and RARECast podcasts. He was an editor of The Burrill Report and worked for the Oakland Tribune, Adweek, the San Francisco Business Times and other publications.