Purdue Extension Service

Vanderburgh County, Indiana

Swarming Bees Shouldn't Cause Panic

By Larry Caplan, Extension Horticulture Educator, Vanderburgh Co, IN

For the Evansville Courier and Press, May 9, 2008

I've received several calls this week because a large swarm of bees has appeared from out of nowhere. This is the way wild honeybees reproduce to form new colonies. Swarming usually occurs in late spring and early summer and frequently occurs within a few weeks after nectar and pollen sources become abundant.

Within an established colony, swarming is preceded by a population explosion of young bees. The crowded condition inside the colony with all these new bees triggers the swarming behavior. Scout or searcher bees are sent out to look for new nesting sites while the rest of the swarmers engorge themselves with honey to prepare for the trip.

On a warm, calm, and sunny day the searchers will “perform” a special dance that incites 20-30,000 bees to swarm and leave the colony - a terrifying sight to behold the first time I witnessed a swarm. Within a few minutes after leaving the colony, the old queen and the swarm cluster on a nearby tree, shrub, or other object. Searcher bees return to the swarm and provide the direction and distance to potential nesting sites by means of another special dance.

The new colony often sets itself up in hollow trees and other enclosed areas. Unfortunately, they will sometimes set up a hive inside a building or attic or, worse yet, inside the walls of a structure. This not only sets up a dangerous situation for the (human) residents, but also can lead to serious damage and pest problems. I've heard of cases where the honey and beeswax actually oozed through the walls into the home. You can precisely locate a colony by placing a stethoscope against the wall and listening to the buzzing.

You shouldn't just kill the colony by injecting insecticides into the wall. The odor of 30,000 dead, rotting bees is not nice. Plus, mice, ants and other vermin will be attracted to the honey. The bees (dead or alive) and the honey and comb must be physically removed, preferably by a professional exterminator. That means tearing open the wall. After hive removal and cleaning, the wall void is usually filled with insulation materials, to prevent future problems.

If you discover a swarm resting in a tree, don't try to spray it or disturb it! It will only be there for a couple of days, before a permanent nesting site is found and the swarm moves on. Honeybee populations are very low due to disease and parasite problems, and every colony is important. Generally, swarmers are fairly docile without a home to defend so they are not likely to sting the casual observer. If you find a swarm and want it gone, local beekeepers will be more than happy to collect them, to increase their bee "herds".

For more information on wild honeybees, or to locate a beekeeper in the Evansville area, contact the Purdue Extension Service at (812) 435-5287.