With spring in full swing in Southern Arizona, bees are busy gathering pollen, and, occasionally forming giant, somewhat alarming clusters which are often found on tree branches. This swarming behavior can be frightening, but is not necessarily dangerous to people.

Many community residents are asking about bee swarms.  Here’s what I found:

A swarm of bees in a tree, photo undated.
(Photo courtesy of Casey Lofthouse, St. George News)


There are two types of bee swarms, said Casey Lofthouse, a commercial beekeeper and Washington County bee inspector. The most common type is a reproductive swarm, which happens when a colony of bees outgrows its nest or hive. A new queen will be hatched, and the original queen and about two-thirds of the worker bees will fly off together. The bees will cluster together for a time, and this mass of bees is what is commonly found hanging on a tree limb or other structure in a large ball. “What they’re doing in a cluster is waiting for the scout bees to find a place for them to call home,” Lofthouse said, “like in a hollow tree, in a house ….” This usually last a few hours to a couple of days.

Reproductive swarms are usually quite docile, and will not attack. However, swarms consist of thousands of bees, and if the swarm is in a populated area, the flying insects can get tangled in people’s hair or clothing. If bees get trapped or stuck, they can become alarmed and may sting.  Do not disturb the bees. Do not spray water or chemicals.  Do not throw rocks or anything at the cluster.  Teach your children to stay calm and leave them alone.  Keep your distance!

“It’s kind of intimidating, because there are thousands of bees flying,” Lofthouse said. “It can be overwhelming to have 13,000 to 20,000 bees rolling through your neighborhood,” Lofthouse said. “In those situations, that’s just a reproductive swarm, and they’re generally nonaggressive.”

In an emergency, call 911.  For bee removal, consult your local directory for a qualified professional bee removal service.  Your local fire marshal will be happy to answer your questions and or direct you to an appropriate information source.

Fire Marshal Charlotte Herdliska Corona de Tucson Fire Department (520) 762-9370

Battalion Chief Jackie Bisnar Rincon Valley Fire Department (520) 647-3760

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