'Killer bees' keep spreading (and killing) across the US

USA Today

22-06-2025

Scientists say the bees' temperament is to ward off predators. But unsuspecting humans will find them to be aggressive, spiteful and terrifying.
Africanized honey bees, often called "killer bees," are now found in 13 states and are slowly spreading northward, attacking people, livestock and pets along the way.
In the last three months alone, a man mowing his property died after a bee attack, three people were taken to the hospital after tree trimmers disturbed a colony, hikers ran a mile to get away from an agitated hive and a woman and three horses were swarmed by bees spooked by a lawn mower. The horses later died from "thousands" of stings, their owner said.
Scientists say the bees' temperament is a defense mechanism to ward off predators – and note that because honey bees die after stinging, they are sacrificing themselves to protect their colony. But to unsuspecting humans, killer bees sure seem aggressive, spiteful and terrifying.
They've been known to follow their victims for up to a mile – even following cars and trucks – and can sting through regular beekeeping gear. In the attack on the Texas horses, owner Baillie Hillman said, "they didn't give up."
As parts of the west become warmer and drier, it's only going to get worse as the bees' preferred climate moves northward.
There's no national database of deaths related to bee stings, but a 2023 study by the Centers for Disease Control and Prevention found that on average 72 people died a year from hornet, wasp and bee stings.
"In Texas, every year there's at least four big (Africanized bee) attacks that make the news," said Juliana Rangel, a professor of apiculture (beekeeping) at Texas A&M University, where they're widespread in the wild.
"Killer bees" first made headlines in the 1990s when they began to appear in the United States, spawning alarming news stories and a surge of horror movies such as Deadly Invasion, The Swarm, The Savage Bees.
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 honey bees don't survive in areas with cold winters and don't like high levels of rain, making for natural cutoffs in areas where temperatures fall, Rangel said.
However in the coming decades, climate change means the bees could potentially move into southeastern Oregon, the western Great Plains and the southern Appalachian mountains, according to research published in 2014.
"By 2050 or so, with increasing temperatures, we're going to see northward movement, mostly in the Western half of the country," said Rangel.
How dangerous are Africanized honey bees?
Africanized honey bees don't have more, or more potent, venom than Western honey bees. "The stings feel the same," said Rangel.
What differentiates them is the numbers a colony sends out to attack. While each bee can only sting once before it dies, a colony of Africanized honey bees will send out proportionally more bees in a defensive response, leading to more stings.
"If I'm working around one of my European honey bee colonies and I knock on it with a hammer, it might send out five to ten individuals to see what's going on. They would follow me perhaps as far as my house and I might get stung once," said Ellis.
"If I did the same thing with an Africanized colony, I might get 50 to 100 individuals who would follow me much farther and I'd get more stings. It's really an issue of scale," he said.
Africanized honey bees are also much more sensitive to potential threats. "You could be mowing a lawn a few houses away and just the vibrations will set them off," Rangel said.
There are multiple reports of people cutting into colonies when trimming trees, clearing brush or doing landscaping. In some cases tree trimmers set off an attack merely by throwing a rope over a branch.
In toxicology, researchers speak of the LD50, the lethal dose required to kill 50% of those exposed to it, said Rangel. For honeybee stings, it's calculated at about 9 stings per pound of weight. So half of people who weigh 150 pounds might die if they got 1,350 stings. That's unlikely with Western honey bees, but can happen with Africanized bees.
In 2022, an Ohio man suffered 20,000 bee stings when cutting tree branches. He survived but only after being put in a medically-induced coma.
What states have Africanized honeybees?
At least 13 state have reported Africanized honeybees. In the south, southern Florida has the highest numbers.
"From Tampa to Orlando to Daytona, south of that a large percentage of the feral bee population are of African decent. North of that we don't have much," said Ellis.
Africanized bees have also been reported in Alabama, Georgia, Louisiana and Mississippi, though they don't seem to thrive in those wetter environments as much.
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 they're originally 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 Szalanski.
Where did killer bees get their killer instincts?
There are around 20,000 species of bees on the planet and only 12 of them are honey bees. Of those, 11 are found in Asia and only one in Europe, the Middle East and Africa. It is called Apis mellifera, the Western honey bee, said Jamie Ellis, a professor of honey bee research at the University of Florida.
There are multiple subspecies of Apis mellifera. It was one of these, the East African lowland honey bee (Apis mellifera scutellata), that was imported to Brazil in the 1950s.
In the areas where East African lowland honey bees live, they have many predators so they've evolved to be more defensive, said Ellis.
"They're not really aggressive, they're not just looking for a fight," he said. "They're just trying to communicate that, 'You are too close to us. We don't want you here – go away.'"
That can feel pretty scary when they're coming after you, said Rangel.
She's done research on bees in Belize, where people keep hives far from their homes and livestock and put on their protective beekeeping clothing in their trucks before getting out near a hive.
"They can pursue you in your vehicle for a mile," she said "The only thing preventing them from killing you is the veil. It's like a cloud of bees that all want to sting you. It's scary."
How did Africanized honey bees get to the United States?
Africanized honeybees are a cross between Western honey bees, from Europe and the East African lowland honey bee. They first occurred in 1956, when a prominent Brazilian geneticist, Warwick Kerr, brought African bees to Brazil to hybridize them with Western honey bees from Europe, which didn't do well there.
His plan was to breed bees that were better adapted to Brazil's climate while retaining the gentleness and high honey-producing traits of the Western honey bees.
He didn't get the chance. A year later, 26 Africanized queen bees were accidentally released into a nearby forest, where they thrived, said Kirk Visscher, an emeritus professor of entomology at the University of California, Riverside.
"The beekeeping industry in those areas is now far more vital than it was – they just have mean bees," he said.
That hybrid between the two subspecies, called Africanized honey bees, began to make its way north, arriving in south Texas in 1990.
"They spread a lot quicker than what people thought was possible. They never thought they could get from Brazil to Texas in a span of less than 40 years," said Allen Szalanski, a professor of entomology at the University of Arkansas. "But they did."
The two bee subspecies are impossible to differentiate without either DNA analysis or careful observation of their wing vein patterns. It is their behavior that sets them apart.
Most of the danger is from feral hives in the wild. Beekeepers carefully manage their hives to keep Africanized queens out. Because bees are so critical to agriculture, the movement of bees is regulated in many states. Most have a bee inspector to oversee the process.
Currently a total of 38 states regulate the movement of honey bees within the United States and require a permit or health certificate to do so. Four states, Arizona, Kansas, North Dakota and Oregon, have no regulations on the movement of bees, according to research published in 2022. Another eight states have no regulations requiring permits or health certificates for the interstate movement of bees.
Africanized honey bees aren't all bad
Scientists who study bees emphasize that while Africanized honey bees are more defensive, they hold a lot of promise for overall honey bee health because they're more pest and disease resistant and are very genetically diverse.
That's important because honey bees play a critical role in agriculture and the environment and have been subject to large die-offs in the past two decades. In 2017, one-third of the nation's hives perished.
Breeding and even gene manipulation could result in better – and gentler – bees, said Ellis.
"Although they have heightened defensive behaviors, science may be able to maximize their positive traits and minimize their negative traits," he said.
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 Ellis. "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, the biggest threats are to tethered or penned livestock and pets that can't get away as well as humans using heavy equipment who accidentally get too close to a hive without being able to hear the angry buzzing of the bees.
Once you've evacuated the area, call for professional help. "If you're in a rural area, it's very likely these bees have been Africanized," said Rangel.
Nobody should try to deal with a colony on their own "just to save a few bucks," she said. "You don't want to mess with them."