Africanized honey bees, sometimes called “killer bees,” are a recognized part of the American landscape. Their specific journey to the Americas, and eventually the United States, is often not fully understood. This narrative traces their origins back to a controlled experiment in Brazil and follows their natural expansion across two continents.
The Brazilian Experiment: Origin of the Africanized Honey Bee
The Africanized honey bee originated in Brazil from a scientific breeding program. In 1956, Dr. Warwick Kerr, a Brazilian geneticist, initiated this project to develop a honey bee better suited to Brazil’s tropical climate. European honey bees, common in the Americas, did not thrive in these warmer conditions.
Dr. Kerr imported queens of the East African lowland honey bee, Apis mellifera scutellata, from South Africa and Tanzania. His intention was to cross-breed these African bees, known for high honey production in tropical environments, with the more docile European honey bees already present in Brazil. The goal was to create a hybrid strain combining the productivity of African bees with a manageable temperament for beekeeping. These imported African queens were kept in an apiary near Rio Claro, São Paulo, under controlled conditions to prevent their escape.
The Accidental Escape and South American Migration
In 1957, despite careful measures, these African bees were accidentally released into the Brazilian environment. A beekeeper removed queen excluders from 26 hives, allowing 26 swarms to escape into the nearby forest.
These escaped African bees interbred with local European honey bee populations, creating the Africanized honey bee hybrid. This new hybrid rapidly colonized and spread. Their swift movement across Brazil and into neighboring South American countries was facilitated by frequent swarming and absconding behaviors. Africanized honey bees swarm more often than European bees, establishing new colonies quickly and expanding their territory at an estimated rate of 100 to 300 miles (160 to 480 km) per year. By the late 1960s and early 1970s, they had spread into countries like Paraguay, Bolivia, Argentina, and Uruguay, colonizing most of South America.
Arrival and Spread Through North America
The northward expansion of the Africanized honey bee continued through Central America, reaching the region by 1982 and Mexico by 1985 or 1986. Their natural migratory patterns, driven by swarming and absconding, allowed them to traverse vast distances. The bees adapted well to the tropical and subtropical climates encountered on their journey, outcompeting other honey bee populations.
The first confirmed sighting of naturally spreading Africanized honey bees in the United States occurred in October 1990, near Hidalgo, Texas. This marked their official arrival into North America’s southernmost contiguous states. Following this initial detection, the bees continued to spread naturally across the southern and southwestern United States. Their presence has since been confirmed in states including Arizona, New Mexico, California, Florida, Nevada, Arkansas, and Louisiana.