What Exactly are Africanized Bees, and How Scary are They?

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With reports of Africanized bees moving into the San Francisco Bay Area and a recent attack (erroneously) ascribed to them, the time seems right to ask again: What the heck are these bees?

Last month, in the Bay Area town of Concord, a swarm of bees went, without seeming provocation, ballistic, stinging the beekeeper who was attempting to move them as well as anything in sight—including two neighborhood dogs, who died. The attack stayed in the San Francisco-area papers for weeks. Mitochondrial DNA testing later proved that the bees were not, in fact, Africanized, but the event pushed the concept of these bees, sometimes known as “killer bees,” into the news. Africanized bees as a threat haven’t really been newsmakers since the 1990s, but here they are, reminding us that, well, they’re not going anywhere.

Here’s some background: The honeybee is not native to the Americas; it was introduced in the early 1600s. There are a whole bunch of different species of honeybee, but the most common worldwide is the Western honeybee, which has a few subspecies, differing based on where they’re from: There are slightly different subspecies in different parts of Europe, Asia, and North Africa, which have variations in behavior and breeding and life cycle.

The African honeybee is one of these subspecies, native to most of the central and southern parts of Africa. Its sting is no more dangerous than other bees, but its behavior is unusual: It is much more aggressive than other bees, with a tendency to pursue and send many attackers after any perceived threat. It’s also much less desirable as a commercial honeybee, producing less honey and with a weird apathy about leaving the hive behind; during a threat, swarms will just fly away and abandon their hives in pursuit of any perceived aggression.

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But African honeybees also breed and build hives extremely quickly, much more quickly than other bees, and they place a greater emphasis on producing young. Because of that, they also tend to focus on gathering pollen, which can feed the young, rather than nectar, which is more easily converted into honey and thus can feed adult bees. Honey is produced in larger quantities by the European varieties of the Western honeybee because it, unlike the African varieties, has to store food for winter.

Seeking to combine the African honeybee’s prolific breeding and warm-weather adaptations with the European honeybee’s production of honey, Brazilian scientist Warwick Kerr cross-bred the African bee with an Italian variety of the European honeybee in the 1950s. Apparently he succeeded—these bees, in the right climate, do outperform non-hybrid bees in honey production—but one of Kerr’s assistants made history by accidentally releasing these hybridized bees into the wilderness.

The bees, which would later become known as Africanized bees, proved wildly invasive and aggressive, cross-breeding themselves with any bee colony they came across as they spread throughout the Americas. They first made their way into the United States in 1985, in Texas, and have now been reported as far afield as Tennessee, Utah, and northern California.

It’s not easy to tell Africanized bees from non-Africanized bees at first glance; theoretically, their wings might be a bit shorter, but the only foolproof way to tell is to perform a DNA test to look for African honeybee DNA. That means there is a spectrum of Africanization; bees can have a very small or a very large percentage of African honeybee DNA depending on their heritage.

Bees, including the Africanized hybrid bees, are not known for attacking without provocation; these bees do not fly around trying to find people to sting.

But their behavior is certainly different: They maintain the traits of quickness to attack, the legitimately scary tendency to chase potential threats, and a much greater willingness to sting. Even though the venom in an Africanized honeybee is no greater or more dangerous than in any other bee, an Africanized bee swarm is much more likely to attack in great numbers, meaning that deaths from Africanized bee swarms are much more common. That said! Bees, including the Africanized hybrid bees, are not known for attacking without provocation; these bees do not fly around trying to find people to sting. They simply react much more aggressively to threats than other bees.

The spread of the Africanized bee is showing no signs of abating, though it’s unclear that these bees, with their love of hot climates, can tolerate the winters of the Northeast, Midwest, and Pacific Northwest.

Some experts are even considering that Africanized bees, which may be more resistant to colony collapse disorder than other bees, could actually prove to be a boon to efforts to save bees. The research is young and limited, but if it ends up saving our bees, we may owe more to Kerr’s clumsy assistant than we ever thought possible.

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What Exactly are Africanized Bees, and How Scary are They?