Tag Archive for: africanized hive

People want a simple field mark for Africanized “killer” bees: a color, a stripe, a size. There isn’t one. Mississippi State University Extension bee specialist Jeff Harris put it bluntly in 2025: European honey bees and Africanized bees “look exactly alike, and even experienced beekeepers can’t tell them apart just by looking.”

So how do scientists identify them? With measurements and DNA. And how should a homeowner or beekeeper decide whether a colony deserves extra caution? By watching how it behaves. This guide covers both. It builds on What Are Killer Bees? and is part of our Killer Bees 101 guide.

Why you can’t identify Africanized bees by eye

Africanized and European honey bees are the same species, Apis mellifera. UF/IFAS entomologists say Africanized workers are only about 10 percent smaller, a difference so subtle that it’s “nearly impossible to differentiate between the two without specific measurements and/or laboratory testing.”

Color doesn’t help either. Both European and Africanized colonies range from golden to dark, depending on their mixed ancestry. University of Arizona Extension captions its side-by-side photo of the two bees with a warning that, despite the color difference in that particular image, they normally can’t be identified by eye.

That’s why the safe rule in the southern U.S. is the one Arizona extension agents give: in areas where Africanized bees are established, treat any wild honey bee colony as potentially Africanized.

How labs identify Africanized bees

1. Morphometrics: measuring the bee

Morphometric analysis measures body parts and wing features and compares them to reference populations. UF/IFAS notes it has been used to separate honey bee races since the 1960s and remains the first round of identification when a suspect colony turns up.

The best-known screening method is FABIS (Fast Africanized Bee Identification System), developed by USDA scientists H. A. Sylvester and Thomas E. Rinderer in 1987. It starts with the length of the forewing. The FABIS critical value for forewing length is 9.001 mm. Samples averaging below that point toward Africanization and are sent on for more testing.

Ohio State University entomologists showed how this works in 2024. A Hamilton County beekeeper sent in bees from a hot-tempered colony he believed were “killer bees.” OSU measured the forewings of 10 workers. They averaged 9.27 mm, above the cutoff. The bees were ordinary western honey bees, just a defensive colony. (The beekeeper had already destroyed the colony, which is why OSU urges testing first.) OSU notes that any beekeeper with a good microscope, forceps, glass slides, and a millimeter ruler can run this first screen.

If FABIS results are inconclusive, Florida’s agriculture department uses a more detailed morphometric test called USDA-ID, according to UF/IFAS.

2. Genetics: reading the DNA

Morphology can be fooled by hybrids, so the strongest confirmation is genetic. UF/IFAS says genetic analysis is often needed when suspect bees are hybrids. Michigan State University Extension’s 2025 guide to diagnostic labs states that confirmation of Africanized honey bee genetics “is required through standardized testing using molecular analysis.”

One common approach looks at mitochondrial DNA, which passes from queen to daughters. Researchers at UC San Diego, writing in PLOS ONE in 2015, used a simple restriction test on the mitochondrial cytochrome b gene to tell bees with African maternal ancestry from those with European ancestry, and found a single DNA “barcode” marker that does the same job.

Where samples go

Testing options change, so check before you ship anything:

• The USDA ARS Carl Hayden Bee Research Center in Tucson says it can no longer analyze honey bee identification samples (morphometrics); that service has been discontinued.
• Michigan State’s diagnostic-lab table (adapted from the Apiary Inspectors of America) lists labs that test for Africanized genetics, including the Purdue University Honey Bee Lab and North Carolina State University.
• In many states, the state apiary inspector collects samples. MSU advises checking your state’s rules, since some states require you to report suspected Africanized colonies.

Signs of an Africanized hive

Behavior is what sets Africanized colonies apart. None of these signs is proof, and European colonies can show some of them too. But a colony that checks several boxes deserves distance and a professional.

Defensive response

UF/IFAS summarizes the difference:

	European colony	Africanized colony
Guard bees that respond	10 to 20	Several hundred
Distance of disturbance that triggers a response	Up to about 20 feet	Up to about 120 feet
Time to calm down	1 to 2 hours	May stay defensive for days
Stings from a disturbed colony	10 to 20	100 to 1,000

Source: UF/IFAS EDIS ENY-147.

UF/IFAS’s “Living with the African Honey Bee” adds that Africanized bees may pursue an intruder 400 yards or more.

Head-butting

A USDA Forest Service safety guide notes that Africanized guard bees patrol territories extending 30 meters or more from the nest and drive intruders away by head-butting: flying straight at the target with a high-pitched buzz. If bees start bumping your face or hat, the guide says to retreat quickly.

Unusual nest sites

According to UF/IFAS, European bees prefer dry, protected cavities of around 10 gallons, such as hollow trees. Africanized colonies will use cavities of 1 to 5 gallons, including:

• Water meter and utility boxes
• Cement blocks, old tires, and junk piles
• Cavities in the ground, even damp ones
• Exposed spots, such as combs hanging from a tree branch

Swarming, absconding, and other colony traits

UF/IFAS lists several more differences: Africanized colonies swarm and abscond far more often, are more “flighty” (more bees leave the comb when the hive is opened), use more propolis, raise proportionally more drones, and store proportionately less honey. Read more in Killer Bee Swarm Season.

The big caveat

A 1996 USDA ARS forum on the bees’ spread made the point that the defensive behavior of the two types “can completely overlap; that is, some aggressive European bees are more prone to stinging attacks than some milder Africanized bees.” That’s exactly what OSU found in Ohio. A mean colony is not proof of Africanization, especially outside the known range.

What to do if you suspect Africanized bees

If you’re a homeowner:

1. Keep away from the nest and keep children and pets inside. USDA ARS recommends at least 100 feet of distance from any Africanized colony.
2. Don’t try to kill or remove the bees yourself. University of Arizona Extension warns against spraying, burning, or otherwise disturbing colonies.
3. Call a trained beekeeper or pest control operator. In Florida, state guidance is to use a registered beekeeper or trained pest control operator.
4. If anyone is being stung, run for shelter and call 911. See What to Do If Killer Bees Attack.

If you’re a beekeeper:

1. Test before you destroy. OSU’s Ohio case shows why.
2. Contact your state apiary inspector. NC State Extension recommends calling the inspector so a sample can be taken.
3. Requeen defensive colonies with a queen of known gentle stock, as NC State Extension and UF/IFAS recommend.
4. Mark your queens. NC State Extension advises marking every queen so you’ll notice if one is replaced, for example by an Africanized swarm taking over the colony.

Frequently asked questions

Can you tell an Africanized bee by its color?

No. Color varies in both European and Africanized bees. Mississippi State and UF/IFAS specialists agree that the two can’t be told apart by looking.

What is the FABIS test?

The Fast Africanized Bee Identification System is a USDA-developed morphometric screen. It starts with forewing length; a sample averaging under the 9.001 mm critical value is flagged as possibly Africanized and needs further testing.

Can I test my own bees for Africanization?

You can run the first FABIS wing-length screen with a microscope and ruler, as OSU describes. Confirmation requires lab analysis, usually DNA testing through a diagnostic lab or your state apiary program.

Does an aggressive colony mean I have killer bees?

Not necessarily. European colonies can be very defensive because of genetics, a missing queen, hunger, or pests. In 2024 OSU tested a suspected “killer bee” colony from Ohio and found ordinary western honey bees.

Does the USDA still identify Africanized bees?

The USDA ARS bee lab in Tucson says it has discontinued its morphometric identification service. Other university and state labs still test for Africanized genetics.

Related reading

• What Are Killer Bees?
• Africanized vs. European Honey Bees
• Are There Killer Bees in Ohio?
• Killer Bee Myths vs. Facts

Sources

• Mississippi State University Extension, “Africanized honey bees not established in Mississippi” (2025): https://extension.msstate.edu/news/feature-story/2025/africanized-honey-bees-not-established-mississippi
• UF/IFAS EDIS ENY-147, “Differences Between European and African Honey Bees”: https://ask.ifas.ufl.edu/publication/IN784
• UF/IFAS EDIS EENY-429, “African Honey Bee, Africanized Honey Bee, Killer Bee”: https://edis.ifas.ufl.edu/publication/IN790
• UF/IFAS EDIS ENY-170, “Living with the African Honey Bee”: https://ask.ifas.ufl.edu/publication/IN1205/pdf
• Ohio State University BYGL, “Myths and facts – Africanized honey bees” (2024): https://bygl.osu.edu/node/2431
• Sylvester & Rinderer, “Fast Africanized Bee Identification System (FABIS) Manual,” USDA ARS: https://www.ars.usda.gov/ARSUserFiles/60500500/PDFFiles/101-200/185-Sylvester–Fast%20Africanized%20Bee%20Identification.pdf
• USDA ARS Carl Hayden Bee Research Center, “Africanized Bee Identification”: https://www.ars.usda.gov/pacific-west-area/tucson-az/carl-hayden-bee-research-center/docs/africanized-honey-bees/africanized-bee-identification/
• USDA ARS Carl Hayden Bee Research Center, “Africanized Honey Bees Overview”: https://www.ars.usda.gov/pacific-west-area/tucson-az/carl-hayden-bee-research-center/docs/africanized-honey-bees/africanized-honey-bees-overview/
• Michigan State University Extension, “Diagnostic labs and services for beekeepers” (2025): https://www.canr.msu.edu/news/diagnostic-labs-and-services-for-beekeepers
• Kono & Kohn, “Range and Frequency of Africanized Honey Bees in California (USA),” PLOS ONE (2015): https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0137407
• USDA ARS, “Africanized Honey Bees: The March North Has Slowed,” Agricultural Research (1996): https://agresearchmag.ars.usda.gov/1996/mar/forum/
• USDA Forest Service MTDC, “Working Safely in Areas With Africanized Honey Bees”: https://www.fs.usda.gov/t-d/pubs/htmlpubs/htm00672313/index.htm
• University of Arizona Extension, “Feral Honeybees” (Backyard Gardener #119): https://extension.arizona.edu/sites/extension.arizona.edu/files/attachment/FeralHoneybees.pdf
• NC State Extension, “Africanized Honey Bees: Prevention and Control”: https://content.ces.ncsu.edu/africanized-honey-bees-prevention-and-control