Unwanted immigrants: Africanized bees are steadily spreading closer to Colorado

Swarms of “killer” bees, an aggressive hybrid true to their name, have long inhabited Texas, Nevada and southern Arizona. More recently they have been spreading through New Mexico, arriving in Santa Fe neighborhoods last November.

Will they migrate further north into Colorado? Experts say the possibility is remote but can’t be ruled out.

“Colorado’s colder year-round climate appears to be the approximate boundary for their range,” said Whitney Cranshaw, a professor of entomology at Colorado State University. “Aside from reports of some testy bees, there have been none (of the Africanized strain) confirmed by lab in the state.”

The hot-tempered insects, known as Africanized bees, are the result of a hybrid experiment gone wrong in Brazil in 1957.


Breeders there successfully combined the European honeybee with the genetically more defensive African honeybee, thinking the resulting strain would be better adapted to warmer climates.

African honeybees’ very aggressive, territorial nature is a result of that continent’s temperate climate, which allows for a persistent threat of competition from hordes of predatory insects and animals.

But the genetically altered bees escaped, forming feral colonies in Brazilian forests. They have been breeding and migrating north ever since, occasionally injuring or gruesomely killing pets and people who wander too close to active hives.

The Smithsonian Institute estimates that 1,000 people in the western hemisphere have been killed by Africanized bees, mostly in rural areas where there is limited shelter. Some 100,000 cattle are estimated to have been killed by the insects as well.

In 1990 they hit the United States at Hildago, Texas. Since then that state has had 11 deaths linked to Africanized bees. Their presence has also been verified in Florida, Georgia, California, Utah, Arkansas, Louisiana and Oklahoma.

According to entomologists, Africanized bees view an otherwise casual threat, such as a hiker on a trail, a dog in a yard or homeowner cleaning a woodshed, to be worth attacking. And they do so with chilling effectiveness, chasing and then swarming over victims, stinging them repeatedly in the face and neck, forcing them to fall to the ground so they are more vulnerable. It takes 2,000 stings to kill the average person. But swarms can include 10,000 or more bees. One hive found last June in Kenna, N.M., estimated by agriculture extension agents to have 80,000 bees. Each bee can only sting once before it dies.

Allergic reaction is the typical danger for victims, but death can easily occur in the elderly and the young as well, usually from asphyxiation due to swelling from thousands of poisonous stingers released into the bloodstream. The stinging itself releases airborne hormones that alert the rest of the hive to join in the attack on the perceived threat.

Entomologists dislike the term “killer” bees, but the insects have lived up to their reputation on occasion, as these news clips tracked by stingshield. com since 1996 confirm.

  • In Santa Fe, Joel Simko, a pestcontrol worker, fell off a roof as he was attacked by bees later confirmed to be from an Africanized colony. He survived after escaping into his truck, where he said the bees kept on swarming, trying to find a way inside. Experts believe the September incident is the furthest north that killer bees have ever been found in the western United States.
  • In November, 2005, killer bees were confirmed near several homes southeast of Albuquerque in Torrance County. Samples from a hive in a homeowners woodpile tested postive. So far 16 counties have detected the vicious strain of honey bee, and speculation by state entomologist Carol Sutherland is that they are likely in every county.
  • In 2000, Lucille Kincaid, 74, of Carlsbad, died of cardiac arrest when attacked by a swarm while in her backyard. She is the only reported death from the bees in New Mexico.
  • During a picnic in El Campo, Texas, Francis Hernandez was attacked by killer bees and died. She was 36. Her mother told reporters that Francis, who was blind, was covered from head to toe with the bees.
  • In Mesa, Ariz., a man cleaning a shed foolishly knocked a hive from a wall. When the bees swarmed he fled and the bees gave chase. He ran past an 88-year-old man and the bees turned to attack him instead, killing the elderly man. A firefighter described the horrifying scene, explaining that the man’s head looked like a hive of bees.
  • Two farmers from Texas, one from Houston, the other from Richmond, were attacked by Africanized bees while operating tractors. They both died after jumping off and being crushed by their still-running equipment.
  • In Bisbee, Ariz., Africanized bees swarmed over pedestrians and motorists, prompting panic and fear, reported the Bisbee Police Department. A four-block area was cordoned off, and witnesses reported that everywhere you looked bees were attacking. Pigeons dropped from the sky covered in the bees.
  • Carol Davies of Tucson watched in horror as her Labrador was stung to death by a colony living in a adjacent vacant house. “Her whole body was just brown with bees. It was a living nightmare,” she said.
  • In Scottsdale, Ariz., a man attacked by bees ran into traffic and was hit by a car, but survived. A 13-year-old boy from Ahwatukee, Ariz., was not as lucky. He ran into traffic fleeing the bees and was killed by a van.
  • Hurrican Katrina is thought to have blown killer bees into Miami, Fla., officials report. The bees took refuge in a log at Miami Gardens. When a pestcontrol worker tried to remove them, they swarmed over a neighborhood, killing two dogs and stinging residents, officials said. Firefighters on the scene reported that the colony was so large, it covered their truck. They had to put on full bunker gear.

Africanized bees appear to be able to handle colder temperatures by clustering around the queen and quivering their thoraxes.

They adapt well to the Southwest, experts say, because there are frequent sunny winter days. It is then that they can become active if disturbed. Spring and summer, they are feeding and breeding, so extra caution is needed.

A shorter growing season in Colorado and higher altitudes may contribute to keeping them out of the state, Cranshaw said, “because there is just less food here for them.”

But global climate change that is warming the earth makes it “possible they could arrive if (global warming) were persistent,” Cranshaw said.

“We’ve seen insects migrate from southern, warmer climates in the state to the north where they have not been seen before.”

But a bigger concern for apiaries are mite infestations, he said, that kill off honeybee colonies.

A pheromone was discovered by researchers in Africanized bees that smells like bananas and is emitted from direct attacks.

The hormone has been re-created synthetically and has been used successfully for traps in Florida, Louisiana and Texas. Cranshaw advises people to not use fruit-scented perfumes found in shampoos, skin creams and sunscreen. If attacked, Cranshaw said, the best

thing to do is run in a straight line, don’t fall down, cover your face and seek a shelter that seals off completely. If hiking, carry an emergency shelter blanket for use in case of attack.

Beekeepers are familiar with the Africanized strain’s peculiar habits. If captive bees seem unusually aggressive, the hive is destroyed or the queen is replaced with a more docile strain.

In Montezuma County, honey producers have not reported any problem with bee populations within their operations, reported Jan Sennhenn, CSU ag extension agent.

Killer bees look exactly like the calmer European bees, but do not produce as much honey. A DNA test is required to identify the Africanized strain.

Extension offices should be contacted if a killer-bee hive is suspected so they can be professionally exterminated and sent to a lab for identification.

From January 2006.