06-07-2025
Are Africanized 'killer bees' closing in on your state? See how they've spread
Africanized honeybees, or "killer bees," are a cross between Western honeybees from Europe and East African lowland honeybees. Though they look like European honeybees, they are known for their aggressive defensive behavior, including swarming, pursuing intruders over longer distances and attacking in larger groups.
Africanized honeybees are slightly smaller than Western honeybees (European honeybees). The size difference is subtle, typically around 10%, and not easily noticeable.
What U.S. states have Africanized honeybees?
Africanized honeybees are now found in 13 states and are slowly spreading north, attacking people, livestock and pets along the way.
Today, people in the South and the Southwest are learning to live with them, but the danger remains, especially when the highly defensive bees first appear in an area or when people accidentally run into a colony.
Africanized honeybees don't survive in areas with cold winters and don't like high levels of rain, which makes for natural cutoffs in areas where temperatures fall, said Juliana Rangel, a professor of apiculture (beekeeping) at Texas A&M University.
The bees have found a natural home in the Southwest, in part because the landscape is much like the arid and semi-arid parts of Africa where they're from. Feral colonies are common in Southern California, Nevada, Arizona, New Mexico and especially Texas.
They've also been seen in southwest Arkansas, southern Utah and about two-thirds of Oklahoma, said Allen Szalanski, a professor of entomology at the University of Arkansas.
How did Africanized honeybees come to the United States?
Africanized honeybees first arrived in South America in 1956. A prominent Brazilian geneticist, Warwick Kerr, brought East African lowland honeybees to Brazil to hybridize them with Western honeybees from Europe, which struggled there.
A year later, 26 Africanized queen bees were accidentally released into a nearby forest, where they thrived. That hybrid between the two subspecies, called Africanized honeybees, began to make its way north, arriving in South Texas in 1990.
How dangerous are Africanized honeybees?
Africanized bees are extremely defensive; they're capable of launching swarm attacks and delivering thousands of stings quickly. They can chase victims for nearly a mile and sting through standard beekeeping suits.
What differentiates Africanized bees from Western honeybees is the number of bees a colony sends out to attack. Each bee can sting only once before it dies, but a colony of Africanized honeybees will send out many more bees, leading to more stings.
In toxicology, researchers speak of the LD50, the lethal dose required to kill 50% of those exposed to it, Rangel said. For honeybee stings, that's calculated at about nine stings per pound of weight. So someone weighing 150 pounds might die if they were stung 1,350 times. That's unlikely with Western honeybees, but it's possible with Africanized bees.
What should you do if you encounter an Africanized honeybee hive?
Because of their highly defensive nature, if you encounter aggressive bees, the best response is to leave – fast.
"Get away as quickly as possible. Don't jump in water, don't swat with your arms. Just run away as as fast as you can," said Jamie Ellis, a professor of honeybee research at the University of Florida. "You might want to pull your shirt up around your nose and mouth to protect against stings that could cause swelling of your airway."
In general, tethered or penned livestock and pets that can't get away face the biggest threats. Humans using heavy equipment can also be endangered if they accidentally get too close to a hive because they might not be able to hear the bees' buzzing.
SOURCE USA TODAY Network reporting and research; University of Florida/IFAS Extension; Texas A&M University
