“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.”
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.