"Killer Bees" Were Created By Scientists In An Experiment That Went Wrong


Tom Hale


Tom Hale

Senior Journalist

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

Senior Journalist

The Africanized honey bee is feared across the Americas, however, it's not quite as deadly as you might think. Felipe Duran/Shutterstock

The origin story of the “killer bee” is like something straight out of a low-budget disaster movie. It started as a humble attempt to increase honey production during the 1950s and ended in thousands of newly-created killer bees accidentally escaping, amounting in a trail of bee-stung bodies across the Americas.

It all began in a lab near Rio Claro in Brazil around 1957. Biologist Warwick E Kerr was commissioned by the Brazilian government to create a species of bee that produced more honey. European species of honey bees had been introduced to South America but unfortunately, they proved to be fairly unproductive in the sleepy heat of Brazil.


“The European honey bees just sat in the hammock all day drinking lemonade,” Eric Mussen, Emeritus Extension Apiculturist at UC Davis, told IFLScience. “Not having much experience with animal breeding, he [Dr Kerr] thought that if he could introduce into European honey bees some African genes, the result would be a hybrid that would work better at collecting honey in a tropical setting than the temperate-climate European honey bees.”

Kerr and his team eventually created Africanized honey bees, now colloquially known as "killer bees”, through selective breeding of the African honey bee with various European honey bees. Initially, it was a success as the new hybrids seemed to do a much better job of producing honey. There was one big downside, though – they also adopted some extreme colony defense instincts.

Then came the decisive moment. Somehow, under hazy circumstances, thousands of these bees managed to escape.

“The best known and most sensationalized "stock release" story was about a visiting person who did not like seeing the queens confined behind "queen excluder" screens on the entrances of hive, so the screens were removed," explains Dr Mussen. "Somewhere near 20 colonies escaped into the wild. Theoretically, that escape led to the complete overwhelming of many places in South and Central America by Africanized honey bees.”

Closeup of a European honey bee species (Apis mellifera). SanderMeertinsPhotography/Shutterstock


Kerr prayed they would quickly die off in their new surroundings or have their aggressive characteristics diluted by breeding with their European relatives. However, that was not the case. The bees swarmed through South American and headed north through Central America over the coming decades. By the mid-1980s, the killer bees made it as far as the US. They can be now be found in many southern US states, including California, Texas, Arizona, Nevada, New Mexico, and Florida.

Killer bees have since caused the death of at least 400 people across the world, including many in the US. A 60-year-old woman was even stung to death by Africanized honey bees in Belize earlier this month. But despite their fearsome reputation and intimidating name, their venom is not actually any more potent than their European relatives.

“The sting of an African honey bee is no worse than for a European honey bee, about 1,000 stings is a fatal dose,” Professor Francis Ratnieks, a bee and animal behavior expert at the University of Sussex, told IFLScience. “They are more dangerous as they are more likely to defend their colony in numbers. As there can be 10,000 bees or more in a colony, a fatal dose can occur.”


These hybrids did not actually get the name “killer bees” because they are capable of killing humans. In Portuguese, the new bees were referred to as "assassin bees" because tiny swarms attach themselves to a European hive, eventually kill the queen, and replace her with their own kind. The word for “assassin” simply became slightly lost in translation and they became known as "killer bees".  

There’s also some evidence to suggest that some killer bees are becoming less aggressive. A scientific study looking into the levels of aggression among Africanized honey bees in Puerto Rico discovered they are actually about as aggressive as the European honey bee. The killer bees only arrived on the island in the mid-1990s, so that means this change in behavior has occurred in only around 20 years.

While killers bees will undoubtedly continue to grab more headlines and capture the public's imagination, just be sure you never forget their truly unusual origin story. Like all the best tragic "monsters", it's never of their own making.


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