Tag Archive for: bee swarm what to do

A cluster of thousands of bees hanging from a branch looks alarming, and in parts of the southern United States people immediately wonder whether it’s a “killer bee swarm.” The surprising answer from extension entomologists is that a swarm, Africanized or not, is usually the calmest stage of a honey bee colony’s life. The real risk comes later, once the bees move in somewhere and start defending a nest.

This guide explains what swarming is, when swarm season happens, why Africanized honey bees swarm so much more often than European bees, and what to do if a swarm shows up on your property. It’s part of our Killer Bees 101 guide.

What is a honey bee swarm?

Swarming is how a honey bee colony reproduces. University of Florida (UF/IFAS) entomologists describe it this way: when a colony grows crowded, roughly 30 to 60 percent of the bees leave with the old queen to look for a new home. The bees left behind raise a new queen and carry on in the original nest.

The departing bees don’t fly straight to a new home. They usually settle into a temporary cluster on a branch, fence, eave, or even a parked vehicle while scout bees search for a cavity. According to the USDA Agricultural Research Service (ARS) Carl Hayden Bee Research Center in Tucson, exposed swarms like this are vulnerable and typically leave within 24 to 48 hours. If they can’t find a suitable site, they may fly several miles and cluster again.

Swarming vs. absconding

Africanized honey bees have a second way of moving that European bees rarely use. Absconding is when the entire colony abandons its nest, brood and all. UF/IFAS notes that African-derived bees abscond frequently during times of dearth (little nectar or pollen) or after repeated disturbance, while the behavior is unusual in European bees.

So a “swarm” in Africanized territory might be a reproductive swarm or an absconding colony on the move. To a homeowner, they look the same: a cluster of bees that isn’t attached to comb.

Why Africanized bees swarm so often

The behavioral gap is large:

	European honey bee	Africanized honey bee
Swarms per year	About 1 to 3 (UF/IFAS); USDA ARS says typically once every 12 months	10 or more (UF/IFAS); USDA ARS says as often as every six weeks during swarm season, sometimes with several swarms each time
Swarm size	Larger	Smaller
Nest cavity needed	About 10 gallons	About 1 to 5 gallons
Absconding	Rare	Common

Sources: UF/IFAS EDIS ENY-147 and EENY-429; USDA ARS Carl Hayden Bee Research Center.

UF/IFAS explains that Africanized colonies evolved in tropical regions where food is available much of the year, so they don’t build up big honey reserves. Instead, they grow fast, split often, and spread. Their smaller swarms fit into much smaller spaces, which is why they turn up in water meter boxes, cement blocks, old tires, overturned flower pots, and barbecue grills. You can read more about those behavioral differences in Africanized vs. European Honey Bees.

When is killer bee swarm season?

There isn’t one national date, because swarming follows the bloom. University of Arizona Extension explains that as spring days lengthen and plants produce new pollen and nectar, colonies raise more brood and become overcrowded, which triggers swarming. Swarming is common in spring and continues through the year while pollen and nectar can support growing colonies, so local rainfall and bloom drive the timing.

A few regional examples from public agencies:

• Florida: UF/IFAS Solutions for Your Life identifies March to July as swarming season and recommends inspecting your property weekly during that window.
• Arizona’s low desert: University of Arizona Extension notes two main nectar flows each year, one after the winter rains and one after the summer monsoons. Its homeowner guidance says to watch for swarms during spring and summer in particular.
• San Diego County, California: the county agriculture department, which considers the entire county colonized by Africanized bees, says bees are most active in spring and fall and advises extra caution then.

In northern states where Africanized bees aren’t established, ordinary honey bee swarming is concentrated in spring and early summer. Those swarms are European bees, and they’re just as gentle at the swarm stage. (See Are There Killer Bees in Ohio? for the Midwest picture.)

Are killer bee swarms dangerous?

Generally, no. USDA ARS states plainly that swarms are generally docile regardless of type, because a swarm has no brood, stored food, or nest to protect. ARS adds that Africanized honey bees do not fly out in angry swarms to attack random victims; stinging incidents happen when a nest, not a swarm, is disturbed.

That said, extension specialists give three important cautions:

1. You can’t always tell a swarm from a new nest. UF/IFAS advises never approaching a swarm, because you can’t be sure it’s only a swarm and not a colony that has already started building comb.
2. Swarms don’t stay swarms. If a swarm moves into your wall, shed, or meter box, it becomes an established colony. UF/IFAS warns that a small, calm colony left alone “can become larger and more aggressive as it gets established.”
3. Provocation changes everything. Throwing things at a swarm, spraying it, or hosing it down can trigger defense.

How to tell a swarm from an established colony

University of Arizona Extension offers practical clues:

• A cluster that appears suddenly on a branch, wall, or other surface is most likely a resting swarm.
• Swarming bees won’t have yellow or orange pollen loads on their hind legs.
• Swarms won’t be streaming in and out of a cavity. If you see a steady line of bees flying into a gap in siding, a hole in the ground, or a valve box, there’s a colony inside.

What to do if a swarm lands on your property

1. Keep people and pets away. Give the cluster a wide berth and bring animals indoors. Extension guidance from UF/IFAS stresses that pets tethered or penned near bees can’t escape if the bees become defensive. Our guide to protecting pets and livestock from killer bees covers this in detail.
2. Don’t spray, swat, burn, or hose it. University of Arizona Extension specifically warns never to shoot, throw rocks at, pour gasoline on, burn, or treat bee colonies with pesticides yourself.
3. Hold off on noisy equipment. Texas A&M’s apiary inspection service lists mower, weed-eater, tractor, and chain saw vibration among the common triggers for Africanized bees.
4. Call for help, especially in Africanized areas. NC State Extension recommends contacting a local beekeeper about swarms. In states where Africanized bees are established, Florida’s agriculture department recommends that feral colonies near people be removed by a registered beekeeper or trained pest control operator, or eradicated by a licensed operator.
5. Watch where it goes. If the swarm leaves within a day or two, great. If bees start flying in and out of a spot on your house, treat it as an established colony and get professional help.

If bees do start stinging, don’t stand still. Read What to Do If Killer Bees Attack before swarm season so the steps are already familiar.

Bee-proof before swarm season starts

The best time to prevent a colony in your wall is before scout bees find the gap. UF/IFAS and NC State Extension both recommend:

• Seal gaps larger than 1/8 inch in walls and around chimneys, pipes, and plumbing.
• Screen openings such as vents, rain spouts, and water meter boxes with 1/8-inch hardware cloth.
• Clear junk piles, old tires, overturned flower pots, inverted buckets, and abandoned equipment.
• Fill rodent and animal burrows in the ground (University of Arizona Extension).
• Inspect regularly. UF/IFAS suggests weekly checks during swarming season; University of Arizona Extension suggests at least monthly checks around the house and yard.

Once a swarm moves into a cavity and starts building comb, it’s a nest, not a swarm. See Killer Bee Nest: Where Africanized Bees Build for the warning signs and How to Get Rid of Killer Bees for safe removal options.

Frequently asked questions

How long will a killer bee swarm stay in one place?

USDA ARS says exposed swarms typically leave within 24 to 48 hours once scouts find a new home. If a cluster is still there after several days, or bees are going in and out of a gap, they may have moved in.

Do Africanized bees swarm more than regular honey bees?

Yes, much more. UF/IFAS reports European colonies swarm about one to three times a year, while African-derived colonies can swarm 10 or more times. USDA ARS says Africanized colonies can swarm as often as every six weeks during swarm season.

Will a swarm attack me if I walk by?

It’s unlikely. Swarms are generally docile because they have no nest to defend. Still, keep your distance and don’t disturb the cluster, since you can’t be certain it hasn’t started a nest.

What time of year do killer bees swarm?

Mainly in spring, continuing into summer and sometimes fall wherever bloom continues. Florida’s swarming season runs roughly March to July, and Arizona’s low desert sees activity after both the winter rains and the summer monsoons.

Should I kill a swarm with insecticide?

Extension services advise against doing it yourself. Call a beekeeper or a trained pest control operator. A swarm will often move on by itself within a day or two.

Related reading

• Africanized vs. European Honey Bees
• What to Do If Killer Bees Attack
• How to Identify Africanized Bees
• Where Do Killer Bees Live?

Sources

• 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/
• 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
• UF/IFAS Solutions for Your Life, “Africanized Honey Bees”: https://sfyl.ifas.ufl.edu/natural-resources/africanized-honey-bees/
• University of Arizona Extension AZ1846, “Wild Honey Bees in Community Environments”: https://extension.arizona.edu/sites/default/files/2024-08/az1846-2020.pdf
• University of Arizona Extension AZ2046, “Monofloral Honeys”: https://extension.arizona.edu/sites/default/files/2024-08/az2046-2023.pdf
• University of Arizona Extension, “They are called Africanized Honey Bees”: https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/195020a.pdf
• NC State Extension, “Africanized Honey Bees: Prevention and Control”: https://content.ces.ncsu.edu/africanized-honey-bees-prevention-and-control
• Texas Apiary Inspection Service, “Africanized Bees”: https://txbeeinspection.tamu.edu/public/africanized-bees/
• County of San Diego Department of Agriculture, Weights and Measures, “Africanized Honey Bees: How to Avoid”: https://www.sandiegocounty.gov/content/dam/sdc/common_components/images/awm/Docs/ahb_avoid.pdf