“Killer Bees” Invade the United States

The arrival of Africanized honeybees threatened agriculture, tourism, and the honey industry in the United States.

Summary of Event

Honeybees originated in tropical regions of Asia and then migrated throughout Europe and into Africa, where they developed a more aggressive nature in response to the threats posed by army ants, honey badgers, anteaters, giant toads, and human beings. Early European settlers brought the first honeybees to the Western Hemisphere, carrying the relatively docile European variety into the interior, where the bees quickly became an important part of the agricultural economy. Africanized bees
Agriculture;Africanized bees
[kw]”Killer Bees” Invade the United States (Oct., 1990)
[kw]Bees” Invade the United States, “Killer (Oct., 1990)
[kw]Invade the United States, ”Killer Bees” (Oct., 1990)
[kw]United States, “Killer Bees” Invade the (Oct., 1990)
Africanized bees
Agriculture;Africanized bees
[g]North America;Oct., 1990: “Killer Bees” Invade the United States[07890]
[g]United States;Oct., 1990: “Killer Bees” Invade the United States[07890]
[c]Animals and endangered species;Oct., 1990: “Killer Bees” Invade the United States[07890]
[c]Health and medicine;Oct., 1990: “Killer Bees” Invade the United States[07890]
[c]Agriculture;Oct., 1990: “Killer Bees” Invade the United States[07890]
Kerr, Warwick Estevam
Winston, Mark L.
Rinderer, Thomas E.

From the early 1980’s, scientists, agriculturists, and a curious public followed the progress of migrating swarms of “killer bees” that had terrorized much of Latin America for almost thirty years and were then approaching the United States. In October, 1990, these Africanized bees crossed the Mexican border into southern Texas near Hidalgo. That event significantly affected the lives and jobs of many Americans. In 1993, the first death in the United States attributed to stings of Africanized bees was reported, raising fears among Americans about the potential danger posed by the bees.

In the mid-1950’s, the Brazilian government called on geneticist Warwick Estevam Kerr to develop a bee that would be well suited to Brazil’s Amazonian climate. Reports of outstanding honey production in Southern Africa convinced Kerr to go there for his breeding stock. He knew that African honeybees are aggressive, but he believed that crossbreeding them with indigenous South American stock would produce a gentler bee capable of greater honey production. In Africa, Kerr collected 173 African queen honeybees, less than one-third of which survived the trip back to Brazil. Of those that remained, he chose 35 to use in his breeding program. Headed by African queens, his colonies became some of the most productive ever seen. In 1957, a careless beekeeper allowed 26 of the 35 colonies to escape into the surrounding forest. There is some evidence to suggest that more Africanized queens were reared from the remaining colonies and distributed to Brazilian beekeepers, hastening the rapid spread of Africanized bees.

Africanized honey bee.


After 1957, swarms of Africanized honeybees spread at an alarming rate. By 2005, substantial numbers of counties in seven U.S. states (California, Nevada, Arizona, New Mexico, Texas, Oklahoma, and Florida) had reported the presence of Africanized bees, and a few counties in Arkansas and Louisiana had also observed their presence. The bees moved two hundred to three hundred miles each year, migrating through a process known as swarming. When swarming, worker bees first gorge on honey to fuel themselves while the new nest is being established. Next, they go into a frenzy, chasing, biting, and pulling their queen until she is forced out of the nest. Workers and queen then orient themselves to each other by secreting highly attractive chemicals. Finally, scout bees lead the cluster to a new nesting site.

Africanized bees swarm more often, and thus spread more rapidly, than European bees for two principal reasons. European honeybees normally construct large nests and store more honey; this provides them with greater resources but takes up much of the hive’s energy. Africanized honeybees build smaller nests and store less honey, reserving more energy to swarm. Africanized bees also tend to swarm at an earlier age. In Africa, this instinct compensates for colonies lost to predators. In Latin America, however, where the bees have fewer natural enemies, colonies proliferate. It was estimated in 1992 that there were one trillion Africanized honeybees in 50 million to 100 million nests throughout the Western Hemisphere.

These estimates, like others required for study, were necessarily difficult to arrive at because there is little physical difference between Africanized and European honeybees. The threat of further migration and its attendant dangers, however, made accurate identification imperative. As a result, Thomas E. Rinderer, an insect geneticist, and his colleagues at the Honey Bee Breeding, Genetics, and Physiology Laboratory Honey Bee Breeding, Genetics, and Physiology Laboratory in Baton Rouge, Louisiana, developed the Fast African Bee Identification System, Fast African Bee Identification System which involves measuring bees’ wings. The wings of the European honeybees are minutely larger than those of the Africanized bee. Another means of identification, developed around 1990 by entomologist Akey C. Hung, Hung, Akey C. involves the identification of two proteins that are distinct to Africanized honeybees.

Scientists knew that European and Africanized honeybees would meet in a struggle for territory. Because Africanized bees are usually aggressive, they typically win the contest for territory. Sometimes Africanized drones—male bees that live only to mate with new queens—mate with European queens, which lay more Africanized eggs, eventually leading to the conversion of the colony. When swarming, Africanized bees sometimes simply fly in and colonize European hives. At times, when territories overlap, the species interbreed. In these transitional zones, scientists have found gentle Africanized bees and aggressive European bees, although usually the crossbred bees exhibit aggressive traits.

The contest for territory is directly related to the bees’ need for flowers from which pollen and nectar are gathered. Nectar, rich in sugars, is the energy source for the hive and is used to make honey. Pollen, which contains proteins, fats, minerals, and vitamins, is used for the growth of larvae and the maintenance of the adults. After pollen is collected, it is moistened with honey, then pressed into compact pellets and stored in special cells inside the nest. Africanized honeybees will fly miles out of their way to locate new sources of flowers for forage, thus challenging their European relatives, which remain in more confined areas.

Many tactics were developed to stop the Africanized honeybees’ invasion of the United States. A commission was established in Panama to intercept colonies being transported by ships passing through the Panama Canal. Reports of Africanized bees arriving in California by truck led to the establishment of a quarantine along roads leading out of Mexico. Areas reporting hostile bee activity were flooded with European bees. Traps baited with highly attractive substances (pheromones) were strategically placed in Mexico and the southern United States.

By late 1987, the United States and Mexico had jointly funded and implemented the Bee Regulated Zone, Bee Regulated Zone an effort to enforce a biological barrier at the Isthmus of Tehuantepec in southern Mexico. Although this comprehensive plan included quarantines, colony destruction, drone flooding, traps, and educational programs, it had virtually no effect on the advance of Africanized colonies toward the United States. The most effective means of protecting European colonies remained the localized marking of queen bees with acrylic paint, with monthly monitoring to ensure that colonies had not been contaminated. With the failure of international initiatives, American agriculturalists and researchers determined that the Africanized bee had become a permanent part of the natural environment and thus began to focus attention on how to cope with this new member of the insect community.


The United States faces many of the same problems caused by killer bees in Latin America since 1957. First, the threat to humans is significant. The sting of the Africanized honeybee is essentially the same as that of other bees, but the Africanized bees attack in greater numbers, giving off an alarm odor that immediately attracts hundreds of bees to the tagged victim. People who have disturbed Africanized hives have been attacked and followed for more than a mile, and dozens of people have been killed. One of the worst incidents occurred in 1986 in Costa Rica, when Inn Siang Ooi, a botany student from Miami University, died as the result of receiving more than eight thousand stings. Bees;Africanized

The first death caused by Africanized bees in the United States was reported in 1993, and attacks became more frequent thereafter. On one occasion, four Americans who were hunting near the Texas-Mexico border shot into a rattlesnake hole. Africanized bees immediately attacked David Reddick, who received more than six hundred stings. One of Reddick’s friends observed that “he’d pull a handful off his face and they’d be replaced immediately.” Such occurrences created a threat to tourism throughout the South, most notably in Texas, which relies heavily on tourism as a source of revenue.

In order to gauge the threat to humans more accurately, Mark L. Winston studied the behavior of Africanized bees in Surinam. Dressed in a veil, heavy gloves, and two layers of clothes under heavy bee overalls, Winston and an apiary owner approached the bees’ hives from a distance of five hundred yards. Simply walking toward the nests brought a massive response. Even before the two opened the first hive, bees were stinging through their protective clothing and ferociously slamming into the veils covering their faces. In those few minutes, Winston was stung more than fifty times. Events such as this drove many Latin American beekeepers away from the business, leading to the collapse of the region’s honey industry.

The presence of the Africanized bees has also posed a threat to agriculture in the United States. As much as one-third of American food crops rely on annual pollination by honeybees. Apples, berries, cantaloupes, cucumbers, almonds, and melons all require the deliberate transport of more than two million colonies each year. Fear of the Africanized honeybee has the potential to result in huge financial losses to both farmers and beekeepers, which would in turn burden consumers with higher prices.

The presence of Africanized bees also threatens the American beekeeping industry, particularly those beekeepers who rent colonies for the pollination of crops. Almost every acre of crops requires one or two colonies, with up to six in the case of alfalfa seeds; some farmers require four thousand colonies at a time for pollination. Beekeepers, who are paid a set amount for each colony they provide, were badly hurt financially by a quarantine against bee transport that was imposed in parts of Texas to prevent the further spread of Africanized bees.

This quarantine also affected Canadian agriculture. Instead of transporting queens from the south, Canadian beekeepers changed their requeening season to late spring or early summer in order to produce their own. They also started insulating hives and keeping colonies indoors in order to avoid transport to the south for winter. To keep Africanized bees out, Canada closed its borders to bee importation from the United States, buying instead from New Zealand and Australia.

In addition, the quarantine made beekeeping itself more expensive. Beekeepers in the northern part of the United States traditionally moved their colonies south during the winter, and southern beekeepers moved their colonies north when pollen and nectar were in short supply. Quarantine and fear of Africanization, however, made these practices impossible, costing beekeepers thousands of dollars in lost bees and feeding costs. Beekeepers also faced additional costs in requeening their hives. With 90 percent of queening areas in the southern United States under quarantine, beekeepers found it necessary to purchase queens from other countries at higher prices.

In addition to farmers, beekeepers, and consumers, American taxpayers in general have paid for the entry of the Africanized honeybee into the United States, as the federal government has spent large sums of money on projects to stop or modify the killer bee. In Mexico, at Puerto Escondido on the Pacific coast and at Huatuxco on the Caribbean coast, traps were set to funnel bees flying under three thousand feet into passes, where they are killed. These two projects alone cost the United States and Mexico an estimated $6.3 million. The cost of enforcing quarantines in southern Texas alone during the early 1990’s was estimated at more than $1 million.

Although the impact of the Africanized honeybee’s arrival has been substantial, the worst fears of early commentators have not been realized. Having learned that the bees cannot be stopped, or the feral population altered, American agriculturalists have instead focused resources on management of the new arrival. With greater resources, decades of experience, better facilities for education, and a widespread agricultural extension program, the United States should be better able to cope with the problem than were Latin American neighbors. Most scientists agree that Africanized bees will not naturally spread north of the thirty-second parallel because of cold temperatures, and this natural barrier serves to assist human efforts. Nevertheless, as much as one-third of the United States may eventually be inhabited by these bees, affecting farmers, beekeepers, and consumers throughout the country. Bees;Africanized
Africanized bees
Agriculture;Africanized bees

Further Reading

  • Borrell, John. “Rising Unease About Killer Bees: But a Surprise Awaits the United States-Bound Invaders in Mexico.” Time, May 30, 1988, 58. Discusses attempts by the United States and Mexico to destroy Africanized bees before they could cross the Rio Grande. Focuses on funnel traps being built along the Pacific coast, trapping bees in scented bags, and quarantine posts in Mexico. Discusses potential American losses.
  • Buchmann, Stephen, with Banning Repplier. Letters from the Hive: An Intimate History of Bees, Honey, and Humankind. New York: Bantam Books, 2005. Entertaining volume examines the relationship between humans and honeybees throughout human history. Includes index.
  • Hubbell, Sue. “Maybe the ’Killer’ Bee Should be Called the ’Bravo’ Instead.” Smithsonian 22 (September, 1991): 116-126. Downplays the danger posed by Africanized bees and discusses aggressive behavior in American subspecies.
  • Ocone, Lynn. “Here Come the Dreaded Killer Bees.” Sunset 192 (February, 1994): 75. Provides a brief history and description of the Africanized honeybees, with helpful advice on how to prevent them from moving into an area and what to do in case of attack.
  • Seuft, Dennis. “The Africanized Honey Bees.” Agricultural Research 38 (December, 1990): 4-11. Reviews research findings from the Honey Bee Breeding, Genetics, and Physiology Laboratory in Baton Rouge, Louisiana, involving new means of controlling, repelling, and destroying Africanized colonies moving northward. Includes maps of migration patterns and information on defenses against the bees.
  • Winston, Mark L. “Honey, They’re Here! Learning to Cope with Africanized Bees.” The Sciences, March/April, 1992, 22-28. Discusses the biology and behavior of the Africanized bee along with the short- and long-term effects of their invasion. Includes pictures of honeycombs constructed by the bees.
  • _______. Killer Bees: The Africanized Honey Bee in the Americas. Cambridge, Mass.: Harvard University Press, 1992. Explains the biology and behavior of the Africanized honeybee for general readers and details the impacts of Africanized honeybees on the United States and Latin America. An excellent starting point for information on the bees.

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