Africanized Bees Expanding Presence in California

Biologists at UC San Diego conducted a study that has found out that the Africanized honey bees are expanding their presence in California. The Africanized honey bees first started out in Southern California in 1994, but now, researchers say the bees are moving northward, and there is some concern with this new trend, although it is certainly not known whether this is going to be a continuing trend or it was just a one-off type of situation.

af honey bee

This study was published in PLOS ONE, and it found out that more than 60 percent of the aggressive hybrid of the European honey bee, are Africanized, and these types of bees are now as far north as the Delta region of California, which could spell trouble for residents. Joshua Kohn, a professor of biology at UC San Diego was the guy who headed the study. Kohn said that a majority of the bees that were found in San Diego county were indeed Africanized, and most of these bees people encounter are from the feral colonies and not managed hives. The pattern that is being documented in San Diego county and other places in California are similar to that of those in Texas, which is where the Africanized honey bees first showed up within the United States. There was an initial wave of hybridization, but then the remaining bees have been a mixture of both the African and European genes, although the majority of the genome were from Africa.

The Africanized honey bees were a subspecies from southern Africa and they were brought to Brazil in order to help improve the production of honey, but then escaped and were on the move from South America to Central America. The Africanized honey bees arrived in Mexico back in 1985, but by 1990 these bees were found in Texas, and these are bees you do not want to have around you. These bees are dubbed “killer bees” due to the fact they are very aggressive, and they have a tendency to swarm on its victims, which sometimes ends up being people. The bees have stabilized in Argentina, but the northward expansion of the bees is still going on, and the researchers wanted to know just how fast the northward expansion was happening in California. The researchers, including graduate student, Yoshiaki Kono, examined the genetic markets of 265 honey bees that they had collected throughout the state at 91 sites. The researchers found out that the Africanized genetic traits in the honey bees were as far north as 40 kilometers south of Sacramento, California, which is known as central valley. The researchers collected bees in San Diego and discovered that over 60 percent of the foraging honey bee workers had Africanized genetic traits, but the African traits were only in about 13 percent of the commercial or managed hives. When the researchers looked at the bees that beekeepers had, a majority of them were European. The researchers then found out that the feral honey bees found in San Diego county were smaller and the ones in the northern part of California. According to the biologists, the size of the honey bee is a great way to tell which type the bees are out of the two. The European honey bees were often larger than the Africanized bees. The San Diego county bees were smaller than the ones found north because the northern ones were mostly European.

The scientists are estimating that the Africanized honey bees are capable of expanding out 300 to 500 kilometers each year. An interesting part that the UC San Diego researchers found was that the Africanized bees had only moved 250 kilometers north since what it was in 2006, which means that the expansion rate of these bees in California has slowed down dramatically. The Africanized honey bees also have a hard time surviving in colder temperatures, which then slows down the expansion rates, and this means these bees are close or have research their northernmost temperature limits. The researchers have said that the sampling last spring had followed the warmest winter for California on record and that there is a continued warming trend, which could expand the reach of the Africanized honey bees even more. There are a lot of climate change models out there which show there is going to be a warming trend in the state for the next several years, and this concerning for the biologists. The issue with this is that the more Africanized honey bees are around in California, the more likely there is a chance these bees will have run ins with humans, and this could pose a danger to people who live in the state.

The good news though is that it gives researchers and biologists a chance to improve the genetic stock of the honey bees that are used in agriculture, and they can study why the Africanized bees are often more able to resist certain diseases than some other types of honey bee colonies. The biologists say that by studying these bees they can help find out what makes the managed honey bee populations work as far as genomes and traits go, and this could help stop the decline of the honey bee population. The researchers are very hopeful that they can find out more clues as to why these honey bees that help agriculture are dying off, which can then stop them from dying off, and this can also help the farming industry and many other industries that rely on these manged honey bee populations. For people, the best thing to do is stay away from the Africanized honey bees as much as possible, even though chance encounters can still happen. You do not want to mess with these Africanized honey bees and you should not try to poke at them if you see a hive, and because they are more aggressive, just a little bit of agitation can get them going, which could be very dangerous.

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Jeanne Rose
Jeanne Rose lives in Cincinnati, Ohio, and has been a freelance writer since 2010. She took Allied Health in vocational school where she earned her CNA/PCA, and worked in a hospital for 3 years. Jeanne enjoys writing about science, health, politics, business, and other topics as well.


  1. Africanized can be great after work pets! The lil’ reptiles cool right down about it when the temperature drops away.

    With aggressive bees e.g. feral or africanized, they tend to explode as a whirlwind, if you have met the outer perimeter patrol bee(s) you can have a good idea of how close you are.
    If they calm down and you move again and that becomes a bigger explosion then you will need to start from further away hanging around to get to know them.

    It’s least a month of sitting around near feral bees reading the newspaper after finding the patrol first and feeding it honey fingered treats on the outer edge territory 50 – 100 yards from the nest or leave a honey strip on your wall outside when the patrol spots you at your door(often takes a sting or too from secondary patrol when you get up close after the patrol lets you through – note: The patrol is the one comes over to you at the perimeter and flys side to side in front of you).

    Unfortunately, bees are like anything else surviving alone, unless you help them at something they don’t need you, again if you don’t offer them a better nest(40 Litres size is minimum for ferals to be tempted – 2x full depth Langstroth supers) they don’t find any reason to do anything more than eventually know as not an actual danger.

    If they swarm, dumping them in a Langstroth will result in them being upset so they require to be somewhere they can explode for an hour or two.

    The frames should be waxed and covered along the inner edges with strips of honey and some icing sugar-honey ball mixed for the queen in there too(about four tiny finger tip sized mixed balls of it in each corner on the floor).A small flat tray of pollen too in there.

    If they do stay in the hive with their queen, the most you can do for a month is open the lid to look in, don’t move anything or they get upset and form a swarm ball on the side of the hive.

    After a week you can at least open the lid to get them familiar with that intrusion(only for a minute or two), at the end of a month you can lift a frame or two out and inspect it/them, this takes a month to be familiar with for them so watch their wings do not all start to sit up at 45 degrees from lateral to their body or all start facing you suddenly also!

    It may be wise at this point to also point you should really use beekeeping protection on you though it costs!

    One more thing, pat them along their side with your finger tip whenever possible to be allowed that close by each bee helps them keep a register of human coexistence!

    Finally a fair word of warning about the feral queen, many of my experiences of getting to know feral bees enough for the queen to be nearby within a yard or two, is often that she will land in/on the grass outside the hive or on the way to the hive as much as 50 meters from the hive.This is often where you tread on the ground in your direct path, so “watch carefully as you approach because you could easily step on her”, whether lawn or paddock or trail (many beekeepers find their queen in the grass dead around the hive or on the trail leading to the hive) !!!

    Of stopping them, A carbon dioxide fire extinguisher is a good one and sometimes if you want to kill them in a confined space. For exterminators but more beekeepers a hand held extinguisher(just the same as a large fire extinguisher on a wall) should be developed with a mix of air and carbon dioxide to both cool and sleepy the bees for collection long enough to find the queen to pack her and some attendants into a queen cage(not for sale but control and re-homing), however it may require small compressed air tanks alike divers use in the ocean for a breathing system over the mouth only(carbon dioxide safety), but at least in the environment element of it all it is not seriously complex or dangerous. An air ice air conditioner that is not noisy that can get the attic below 10 degrees Celsius is among other tricks to slow them down to find the queen if she’s remained inside…