The Italian Honeybee, Apis mellifera, has been in North America so long that most people don’t even realize that it is not native. Since time immemorial, humans have been keeping hives of bees for their honey and for pollinating their fields. So when European colonists began moving to the New World in the 1500’s, they took their European honeybees along with them (the Native Americans in Virginia called the new insects “the white man’s fly”).
In 1956, a geneticist in Brazil named Warwick Kerr decided to try to improve the plain ole ordinary Italian Honeybee, by crossbreeding it with the African Honeybee of the subspecies Apis mellifera scutellata. The African bee lived in an environment that was much sparser than the Europeans, and consequently it had to work much harder to store sufficient food reserves for the winter. By crossing the African subspecies with the European, Kerr hoped he could develop a breed of honeybee that inherited the African genes for industriousness, resulting in a higher-producing honeybee. He imported 63 queen bees from South Africa and crossed them with Italian honeybee males from Brazil.
Unfortunately, things did not work out as planned. The African subspecies had another inborn trait: since they had to work so hard to store their winter reserves, they were also extremely aggressive in defending it, and were easily provoked into making massive stinging attacks on animals that tried to raid their supply. And, alas, the hybridized bees produced by Kerr also inherited this African trait. The hybrid Africanized bees were so aggressive in the defense of their hive that they were soon dubbed “Killer Bees”.
Then a disaster happened. Kerr had been breeding his hybrid bees in a special secure lab near Rio Claro. By October 1957, he had 26 active hives, and was using a “queen excluder”, a device that fit over the entrance and allowed the smaller worker bees to squeeze in and out but prevented the larger queen bees from entering or exiting, to keep the hybrids in the hive and prevent them from escaping the lab. But someone mistakenly removed all the excluders, and all 26 hybridized queens headed for the open jungle, taking their African genes with them. The Africans happily swam in the local gene pool, and soon most of the bees in the area were hybridized and had inherited the African propensity for aggressiveness. There were reports of farm animals being attacked and killed by angry swarms of Africanized bees, and soon human deaths also began to be reported.
The bees were helped by another African trait: like all bees, the Africans divided into two groups when the hive got too crowded, with a swarm flying off with a young queen to form a new colony. The Italian bees only traveled a few miles away for their new hive. African bees, however, routinely swarm as far as 60 miles to establish their new homes. By the early 1960’s, the Africanized hives had spread over much of Brazil. By 1986, they had moved up through Central America and reached Mexico. The United States made frantic efforts to try to prevent the “killer bees” from reaching the US: one plan was to place a large number of Italian honeybee hives in Panama to dilute the African genes as they passed through. But by 1990 the hybrid bees reached Texas, and were in California by 1993. They reached Florida in 2005.
There is no way to tell an Africanized bee from a regular Italian bee just by looking at it. The African bee is very slightly smaller, but not enough to notice. The venom in both species is the same: the African’s sting is not any stronger than any normal honeybee, and like all honeybees it can only sting once before dying. The African’s power comes from numbers. While European honeybees will defend their hives from threats, the Africans take this to an extreme, sending out thousands of defenders at the slightest disturbance, and actively pursuing intruders as far as 300 yards from the hive. While the “killer bee” image is exaggerated, Africanized honeybee hives have indeed caused a number of human deaths in the US.
The Africans have presented serious difficulties with Florida’s commercial beekeepers, who are crucial in providing pollination for the state’s agricultural businesses. In South America and Africa, beekeepers have been living with the aggressive bees for years now, and have developed methods of working with them safely. The problem in Florida is that most of the agricultural areas are also near residential areas where the bees can spread, and where people can inadvertently bother the hives and provoke an attack. The state has released a series of security guidelines for beekeepers, called “Best Management Practices”, that use security measures and inspections to try to prevent Africanized queens from setting up wild hives in residential areas. All beekeepers in Florida are required to register their hives with the state. But the African hybrids are already here, and there is really no way to eliminate them. It is estimated that about 90% of all the wild honeybee hives in the southern half of Florida are now Africanized.
Currently, the Africanized honeybees can be found in most of the American Southwest and all of Florida, and are moving north at an average rate of two miles a year. Scattered reports have occurred as far north as Tennessee, probably from imported bees. In hot semi-tropical areas like Florida, the Africans can outcompete the European bees and replace them. But in cooler temperate climates, the European bees seem to have the advantage. So it is not clear just how far north the Africanized hybrids can go.