Africanized Honey Bees in California
The result of attempts to hybridize European honey bees (EHBs) with an
African race, Africanized honey bees (AHBs) have been expanding their
territory since they escaped from Brazilian researchers and beekeepers in
the late 1950's. Arriving in southern Texas in 1990, AHBs have moved
north some, but west much more, during the past fourteen years. They
were discovered in southeastern California in 1994, just outside of Blythe,
in Riverside County.
Months later, AHBs were found along long stretches of the Colorado
River, but only on the Arizona side. Then they were detected in
Winterhaven, CA, across the river from Yuma, AZ, in the southeast corner
of Imperial County. For a few years new identifications of AHBs were
limited to Imperial and Riverside Counties.
Then, in 1997, AHBs were collected from eastern San Diego County in the
Anza Borrego Desert State Park. Shortly thereafter, they were located in
the Coachella Valley and around Palm Springs.
Individual worker bees, collected from blossoms and water sources in the
spring and summer of 1998, revealed that the population expansion
encompassed most of the southern portion of San Bernardino County and
was approaching the eastern borders of Los Angeles and Kern Counties.
Whether the hastened expansion of the colonized territory was related to
reduced pressure from the parasitic mite, Varroa destructor, or to
increased availability of food due to El Niño probably never will be
In the winter of 1998, AHBs were found in Torrance, a city in the southern
portion of Los Angeles County. A short time later, more colonies were
found in Lawndale, and it was suspected that AHBs had gotten a foothold
in the area. Subsequent finds in Redondo Beach, Carson, and West
Covina prompted regulatory personnel to designate the southern third of
Los Angeles County colonized by AHBs. It was theorized that the invading
colonies disembarked from ships in LA's southern ports and were not
connected to the population expansion occurring east of the LA Basin.
However, that idea probably was in error. During the spring and summer
of 1999, AHBs were found extensively throughout Los Angeles County
and all the way south to Mexico along coastal California. In the fall of
1999, AHBs were detected in Oxnard, in Ventura County. Currently
(8/6/04), AHBs can be found in an area that stretches from Las Vegas,
through Inyo County to Santa Barbara County, including Tulare and
Madera Counties (not detected in Fresno), then south to Mexico.
Why is it important to know where AHBs are in an area? Are they really
enough of a risk to generate concern? That depends upon your point of
view. Africanized honey bees are not predictable. At times a colony
population is no more apt to become disturbed and defensive than our
normally kept EHBs. At other times they respond quickly to minimal
disturbance and defend a very large territory around the hive location.
Such behavior is not restricted solely to AHBs, but colonies of EHBs
demonstrating such intensive defensive behavior usually are "requeened"
or killed by beekeepers.
Requeening is a process by which the original queen in the colony is
located and removed. Then, a young queen, mated outside the range of
AHB drones, is introduced into the colony. Over a period of four to six
weeks, the original worker bees die of old age and are replaced by
daughters of the new queen. Defensive behavior becomes less intense as
population replacement progresses.
Massive stinging events involving AHB colonies have not been very
numerous in the U.S. Some of the worst incidents have involved dogs that
have remained near the nesting site once the stinging started and
received in excess of 2,000 stings. In most human stinging incidents, sting
numbers have approached the hundreds at worst, but usually were less
than 100. At the time of this update, there have been eight human
fatalities attributed to AHB stinging incidents: two in Texas, three in
Arizona, and three in California. The first Californian was an 83-year-old
ex-beekeeper who had left some empty hives in his yard. Africanized
honey bees moved into the hives and when he began mowing the lawn
near them, they became very defensive. Reports of the number of stings
vary (25, 50, 200), but the man was in a coma for two weeks before
succumbing to the venom. The second individual was working around
brush and disturbed a nest. The third person was moving soil with heavy
equipment and caused a nearby colony to become defensive.
Reported California AHB stinging incidents include:
# 1 Blythe, Riverside Co. Feral nest in tree 2 people: stung 15 & 25 X
# 2 Brawley, Imperial Co. Feral nest in tree 1 person: stung 8 X
# 3 El Centro, Imperial Co. Feral nest in hay bales 1 person: stung 50 X
# 4 Ogilby Road, Imperial Co. Feral nest in sign post 2 people: stung 1 & several X
2 people: stung2 & 15 X; dog many
# 5 Calipatria, Imperial Co. Feral nest in wall
# 6 El Centro. Imperial Co. Feral nest in tree 1 person: stung 3 X; 1 dog killed
# 7 Blythe, Riverside Co. Feral nest in rubbish 2 people: stung > 300 & > 90 X
#8 Feral nest (?) 1 dog killed
# 9 Calipatria, Imperial Co. Feral nest in wall 1 person: stung 8 X; 1 dog killed
# 10 Holtville, Imperial Co. Feral nest in hay bales 2 people: stung 15 & 1 X
# 11 Blythe, Riverside Co. Feral nest under mobile home 1 person: stung 20 X
# 12 Brawley, Imperial Co. Feral nest in bee boxes 1 person: stung > 100 X
# 13 Palo Verde, Imperial Co. Feral nest in vehicle tire 1 person: stung 40 X
The first three incidents occurred in 1995, 1996, and 1997, respectively.
The rest of the incidents have occurred in 1998. Updated information is
not being compiled, but stinging incidents are occurring regularly and often
involve people and dogs.
How many stings does it take to kill someone? We don't know for sure,
because the experiment can not be conducted. However, data from
mammalian laboratory toxicity studies suggest that about half the
individuals would die and half would live (LD50) if they were stung 8.6
times per pound of body weight.
There are four complicating factors relating to that estimate. Individuals
who are highly sensitive to honey bee venom proteins may succumb to
anaphylactic shock (allergic response) with only one sting. Elderly
individuals with compromised cardio-pulmonary systems seem to be at
increased risk of bee sting-induced heart attacks. Beekeepers, who have
been stung many times, develop very high titers of protective antibodies
against venom proteins and can tolerate many more stings than non-
The final complication for anyone stung numerous times by honey bees,
bumble bees or wasps, is the potential, delayed problem of "organ failure."
Bee and wasp venoms contain proteins that destroy cells and tissues in
mammalian bodies. Normal disposal of such debris is through the kidneys.
If too much debris arrives in a short time, the kidneys can become
clogged, resulting in kidney failure. Increasing the intake of fluids
(including IV) can help with the flushing process, but sometimes dialysis is
required. Patients who recover quickly from multiple sting incidents should
be monitored over the next week or two to be certain that a dangerous,
secondary condition is not developing.
If the consequences of being stung can be so dire, should everyone just
stay in the house and only venture outside in a "bee suit?" Fortunately,
things are not nearly that bad. By paying attention to what is going on
around you, you can avoid getting into a stinging situation. It is not hard to
determine where honey bees live. On sunny or cloudy days, when the
temperature is above 55oF, some bees usually fly to and from their nests.
This "directed" flight is pretty easy to see, if you look for it. The bees may
have moved into a shed, garage, abandoned car, cardboard box, water
meter box, utility box, discarded tire, wall or roof of a house. To prevent
that from happening near your home, remove or seal off potential nesting
sites. If you see bees coming and going from a specific place, stay away
from there until a knowledgeable person has checked for and mitigated
the problem, if one exists.
If you are going to be working or relaxing in areas where quickly getting
into a building or vehicle will not be possible, and if bees or wasps start to
sting, take an Army surplus gnat/mosquito veil with you. At the first sign of
being "buzzed," put on the veil. As long as you are not being stung in the
face, you will not become disoriented. You will be able to see well enough
to run from the area until you are no longer being chased. Jumping into
water will not help - AHBs fly around and sting when you come up to
breathe. The tactic of losing yourself in the brush, that works fairly well
with EHBs, doesn't work nearly so well with AHBs. They come right into
the brush following the scent (alarm pheromone) emanating from previous
stings that are still in your skin.
Africanized honey bees are not something to be feared, but they are to be
respected. By understanding how they behave, you can avoid close
encounters with AHBs or respond appropriately if a problem develops.
Dr. Eric C. Mussen