"Killer Bees" in North America

- An aggressive strain of honey bee -

Summary: So called "killer bees" are in reality a highly aggressive strain of the more familiar honey bee. The aggressive strain of honey bee was accidentally released into Brazil about 60 years ago. Colonies of these more aggressive bees have been moving north ever since and now occur throughout the southern US.

Jack DeAngelis, PhD
OSU Ext. Entomologist (ret.)

The term "killer bee" refers to a strain of highly aggressive honey bee originally collected in Africa in the 1950's and brought to Brazil for research purposes. Years later the African strain bee colonies were accidentally released from the research apiary and multiplied rapidly in the tropical climate of central Brazil around the facility.

Where do killer bees occur in the US?

Since their accidental release the African strain has breed with native strains producing an "Africanized" strain of aggressive and highly territorial bees. Africanized bee colonies have slowly displaced native honey bees wherever they occur together. Africanized bee colonies have moved steadily north eventually reaching the southwestern US in the 1990's. They now occur throughout the southwestern US from southern California, Nevada, Arizona, southern New Mexico, southwest Texas and as far east as southern Florida. New Africanized hives are found further north each year.

Identification of Africanized honey bees

In the US, our native honey bee is actually a strain that originated in Europe and hence is called the European honey bee (Apis mellifera). Africanized honey bees are the same species and are nearly identical to their European cousins. It takes an expert and a microscope to tell the two bees apart. What distinguishes European from African strains is their behavior. The African strain, and Africanized colonies, exhibit extreme aggression when the hive is disturbed. The European strain is much, much less aggressive in defense of the hive.

Africanized honey bees and queen

Africanized honey bees surrounding a European honey bee queen (marked with a red dot). Photo by USDA/ARS

Stings from Africanized bees are individually no more dangerous than those from European bees, since they are nearly identical. The difference is in the number of stings that one is likely to receive during any encounter.

How far will they spread?

Nobody is certain how far north "killer bee" colonies will eventually move. The two strains easily interbreed so colonies can be become more aggressive over time as more and more of the aggressive traits are bred into the European strain. Many researchers believe that the southern US will be dominated by the more aggressive bees while the northern states will remain the mostly non-aggressive, native strain. There will likely be a transition zone between the two regions where individual hives will be a mix of aggressive and non-aggressive bees.

Control of killer bees

Homeowners should never attempt to control any bee hive. If you live in an area where Africanized colonies have been confirmed you should consult with local experts about removal of threatening hives. If you live in areas outside the reported range of Africanized colonies you can contact a local beekeeper and they will likely be happy to safely remove the hive.

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