THE WESTERN HONEY BEE
Size of worker bee: 15 mm / 1/2 - 3/5"
Western honey bees are non-native bees valued for their honey and their prowess as crop pollinators. They are medium-sized, with transparent colorless wings, heart-shaped, furry faces and abdomens commonly banded by amber and black stripes. Female honey bee workers transport pollen in baskets located on their hind legs. Honey bees vary somewhat in color and size, according to age, subspecies and function (drone, worker or queen).
There are various subspecies of western honey bee. Beekeepers often crossbreed subspecies to enhance particular traits -- such as honey productivity, resistance to disease, cold-hardiness, heat tolerance and level of aggressiveness. One notorious hybrid honey bee prevalent in the Lower Rio Grande Valley is known as the killer bee or Africanized bee. Killer bees are discussed further below on this guide page.
Honey Bee Society
Most wild, native bees of the United States are solitary. Honey bees, however, are social animals with highly complex societies.
Honey bee hives are organized around a caste system. At the top is a single queen bee, who is larger and longer-lived than other hive members and whose central purpose is to lay eggs: a queen honey bee may lay up to 2000 eggs per day.
The rest of the hive is made up of short-lived male drones, whose sole function is to mate; and female workers, who build, maintain and guard the hive, collect and store food for the colony and attend the queen.
Such social organization allows honey bees to cooperate with one another and to build honeycombs -- complex constructions of interlocking hexagons. The social organization of the hive also allows honey bees to propagate, to survive long periods when flowers are not blooming, and to live efficiently in large colonies. Typically, honey bee hives number between 30,000 and 60,000 members.
Honey bee societies are particularly adept at withstanding climate extremes. On hot days, honey bees collect outside of a hive, fanning their wings to keep the colony cool. During chilly days, workers cluster around the queen to insulate her from the cold.
Amazingly, during periods of extreme cold, worker bees are able to generate heat by engaging in an activity called shivering, shown in the photograph at right. When shivering, worker bees elevate their body temperatures by vibrating their flight muscles while keeping their wings still. On a day when temperatures are near freezing, a group of thousands of worker bees can raise the temperature of a hive to 95° Fahrenheit.
Such collective actions designed to regulate hive temperature have allowed honey bees to thrive in a wide range of climates. In the Western Hemisphere, honey bees are found from the Tropics to Alaska and northern Canada.
Distinguishing traits of honey bees
Feral honey bees huddled together and "shivering" outside a nest on a cold day
The Origin of the Honey Bee
Honey bees are not native to North America. Western honey bees were first brought to the Americas in the 1600’s by Spanish colonists, who domesticated them for honey and beeswax production.
The highly organized social life of honey bees allowed them to adapt to diverse environments in the New World. They spread throughout the Americas and are now naturalized in every part of the United States.
Honey bees probably arrived in Europe from sub-Saharan Africa. Recent genetic studies, however, indicate that all honey bees originated in Asia about one million years ago, and then traveled westward to Africa. Humans have kept domestic honey bees for only a fraction of that time, around 7000 years.
TAXONOMY OF HONEY BEES
Species shown here:
Apis mellifera (common or
western honey bee)
CROP POLLINATION AND THE RISE OF KILLER BEES
A third of all food we eat depends on pollination by bees. Although there are more than 20,000 species of bees in the world, only a handful have proven capable of domestication for use as pollinators or honey-producers. Of these, honey bees are the most important by far.
Honey bees are particularly well-suited for domestication, because their well-organized colonies concentrate large bee populations, as well as honey, in a single hive. Honey bees have other notable qualities that make them superior pollinators. They are able to range over wider areas than many native bees -- a worker honey bee can fly three or four miles in a single day when foraging for nectar and pollen. Honey bees, in addition, are unusually versatile foragers: they are generalist pollinators that thrive on a seemingly endless array of plants. They have proven capable of surviving on all continents except Antarctica.
For all of these reasons, honey bees are key pollinators of a diverse spectrum of crops, among them leafy vegetables, onions, berries and fruit and nut trees. Honey bees are, in addition, ubiquitous pollinators of garden flowers and cut flowers. Honey bees' value as pollinators of commercial produce is now estimated at more than 200 billion dollars annually worldwide.
Honey Bee Decline and Vulnerability
Once plentiful in the western world, honey bees in the past decade have experienced a swift drop in numbers in both Europe and the United States. In 2006, American beekeepers began reporting a 30% or greater yearly decline in honey bee populations.
Honey bee decline has been attributed to a variety of factors, including habitat loss, the use of pesticides and the spread of disease-carrying bacteria and pests such as hive beetles and Varroa and tracheal mites. Whatever the cause, honey bee decline threatens both large-scale agriculture and beekeeping industries in North America.
Within the United States, some efforts to fortify honey bee populations have focused on crossbreeding various strains that are hardy and disease-resistant. Tougher strains are frequently less docile. Bee breeding thus often requires a juggling of needs, in which hardiness may be balanced against aggressiveness.
In the 1950's, beekeepers and farmers in tropical and subtropical South America faced their own crisis: the European honey bees used as pollinators and honey-producers in most of the world were faring poorly in Latin America. Like North American beekeepers of today, Latin American apiaries looked to crossbreeding new honey bee strains as a solution.
The Making of the Africanized Bee or “Killer Bee”
All western honey bees belong to the species Apis mellifera. This species is subdivided into various subspecies, which include, among others, the African honey bee (Apis mellifera scutellata), and various European varieties such as the dark honey bee (Apis mellifera mellifera), the Italian honey bee (Apis mellifera ligustica) and the common European honey bee (Apis mellifera iberiensis).
The legendary entomologist Charles D. Michener once wrote: "Honey bees of European origin have never done particularly well in the tropics." European honey bees exhibit both physical and behavioral adaptions that allow them to survive cold winters, but they languish in humid, hot climates and lack the general hardiness of African honey bees.
In 1956, Brazilian geneticist Warwick Estevam Kerr traveled to southern Africa to find honey bee subspecies that showed high productivity and survival rates in tropical climates. At the time, Brazil's European honey output was low, and its lack of viable pollinators limited agricultural production.
In Tanzania, Kerr found the heat-resistant, productive and aggressive Apis mellifera scutella, which he brought back with him to Brazil. Kerr set up experimental hives for the African bees in Rio Claro, Sao Paulo.
Kerr commenced interbreeding the offspring of his imported African bees with the Italian honey bee, which flourished in warm areas of Europe bordering the Mediterranean. Kerr’s aim was to produce a bee with the gentleness of the European strain and the toughness and productivity of the Africanized bees.
As the story goes, in 1957, a visiting beekeeper overseeing Kerr’s hives accidentally released from quarantine and into the wild 26 swarms headed by Tanzanian queen bees. These bees commingled and crossbred with European honey bees then extant in Brazil, producing “Africanized” honey bees – a hybrid that became known for the belligerent and sometimes dangerous behavior that earned it the popular name “killer bee”.
The Spread of Killer Bees, and Their Arrival in the Lower Rio Grande Valley
Beginning in the late 1950’s, Africanized honey bees spread from Brazil fairly rapidly into neighboring South American countries and then northward through Central America, at a rate of about 200-300 miles per year.
Several factors enabled Africanized bees to dominate European honey bee populations. These included Africanized bees’ greater adaptability to hotter climates; their tendency to swarm and form new colonies with greater frequency than European honey bees; the ability of Africanized drones to outcompete European honey bee drones; and the faster development of Africanized honey bee offspring.
In October, 1990, killer bees established their first documented colony in the United States -- in Hidalgo, Texas, located in the Lower Rio Grande Valley, a mere twelve miles from the National Butterfly Center. (Hidalgo has embraced its notoriety: pronouncing itself “the Killer Bee Capital of the World,” Hidalgo erected a statue of a giant killer bee in the center of its town green, which outsiders flock to visit. A succession of hockey teams based in Hidalgo have called themselves the Killer Bees.)
To date, killer bees are well established in the United States along the Mexican border, from Texas to California. In the west, they have appeared as far north as Utah, and in the east, killer bee colonies have been discovered in Tennessee, Louisiana and Georgia.
Killer bees' more northward expansion has been thwarted by Africanized bees' lack of adaptability to long winters. Among other limitations, killer bees are unable to warm themselves during the winter through the process called shivering, described near the top of this page. Killer bees are also less able to withstand long periods of food shortage associated with winter climates.
Is It Unsafe to Approach Honey Bees in the Lower Rio Grande Valley?
People usually encounter honey bees when they are collecting pollen or nectar from flowers. Individual worker bees engaged in such activities, away from their nests, are rarely aggressive and unlikely to sting, unless you accidentally grab or crush one. Most honey bee workers found on flowers are so absorbed in foraging for food that they will barely register your presence, even when you inspect them at close range.
Honey bees are most likely to become aggressive when their hives are threatened. As a rule, you should avoid approaching feral or "wild" bee nests without taking precautions. The best way to view honey bee colonies is to visit an apiary in the company of a beekeeper who can advise you of safety precautions. Local apiaries contain European honey bees of various subvarieties, and take pains to exclude Africanized bees from hives.
On the other hand, wild honey bee nests -- that is, those found outside of apiaries -- are potentially dangerous anywhere in the Lower Rio Grande Valley. According to Jack Neff, Director of the Central Texas Melittological Institute, killer bees are now endemic to much of southernmost Texas. Near the border, swarms of honey bees that you encounter outside of apiaries -- for example, in trees, rock crevices, ground holes or abandoned buildings -- are likely to be killer bees.
How Dangerous Are Killer Bees?
The 1978 movie The Swarm depicts killer bees that terrorize whole towns with an uncanny malice directed at humans. The bees massacre a group of schoolchildren, down helicopters, derail trains and precipitate the explosion of a nuclear power plant. Their sting venom has no antidote, causes victims to hallucinate giant bees and results in a fatal heart attack within days. Such sensational depictions of killer bees, popularized in comic books, pulp thrillers and B-movies, have been circulating since the 1950's.
Africanized bees' reputation for violence far outstrips reality. It is notable that Africanized bees are now the principal honey-producers and commercial pollinators used in most of South and Central America. Brazilian beekeepers routinely manage Africanized bee hives without mishaps. Some management techniques include using smoke to subdue bees; taping the openings of beekeeping suits; and keeping individual colonies apart from one another and at legally-mandated distances from town limits.
Nonetheless, several factors make killer bee colonies much more dangerous than those of European honey bees. Most notably, Africanized bees show a heightened defensiveness and willingness to attack when their nests are disturbed. Attacks by Africanized bees are also more prolonged, and killer bees chase their targets a longer distance.
Entomologist Charles Michener described an experiment in which a research team rapped on the outside of a killer bee hive and then dangled a piece of black leather at the nest opening. The killer bees, Michener wrote, "stung the leather 92 times in only about 52 seconds and followed our Committee member (protectively clothed!) carrying the leather for 1,044 meters, trying to sting the whole way."
Africanized bees are also more likely to form large swarms when attacking. European bees swarm at intruders as well, but tend to defend themselves in groups of ten to twenty bees, while Africanized honey bees might respond in groups of several hundred. In the last decade, there have been a handful of reports of Africanized bees killing livestock and people on U.S. soil.
If you encounter a feral honey bee nest on your property or in an area frequented by people or animals, call a local beekeeping service for advice. Texas A & M University Agrilife Extension has provided an advisory for dealing with wild honey bee nests.
Is it Possible to Tell Killer Bees from European Honey Bees by Sight?
It is not possible to differentiate European honey bees from killer bees with the naked eye, whatever you hear from local beekeepers or pest-management specialists.
Sometimes the behavior of a given bee colony may alert you that a nest contains killer bees. Africanized bees are more likely to fly in very early morning and late evening than the typical honey bee; they are more likely to brave inclement weather, including rain; and they take much longer (hours rather than 20 minutes) to calm down after their hive is disturbed.
A large wild honey bee nest in a tree: In the Lower Rio Grande Valley, such nests should be approached with caution.
Honey bees manufacture wax combs made up of hexagonal chambers that house food stores, eggs and offspring. The nest shown here has several layers of honeycombs.
European honey bees entering a hive at an apiary
The best time to observe honey bees is when they are pollinating flowers, away from the nest.
The giant killer bee statue of Hidalgo, Texas
Honey bees pollinating spider flowers
A small apiary that houses European honey bee hives in box frames
A European honey bee worker balancing on a flower stamen
Killer bees in Brazil entering a hive: Africanized honey bees cannot be distinguished by the naked eye from European honey bees.