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Honey Bee Swarms and Bees in Walls (C 824)

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Keith S. Delaplane, Extension Entomologist

This circular is for property owners who have unwanted honey bee swarms on their lands or colonies nesting inside walls. It explains these natural processes and gives options for dealing with them.

    The Value of Honey Bees

    Honey bees are one of the most beneficial of all insects. Honey is humanity's oldest sweet, and beeswax was the first plastic. Today, honey bees provide these and other valuable hive products. In addition, thousands of beekeepers in the United States keep bees for fun and profit.

    Honey bees are important pollinators of almonds, apples, blackberries, blueberries, cantaloupes, cranberries, cucumbers, forage crops, kiwifruit, squash, and watermelons. The annual contribution of honey bees to U.S. food production is more than $14 million. Declining bee numbers in recent years, sometimes referred to as Colony Collapse Disorder (CCD), have heightened our concern about conserving these important pollinators.

    What Is a Honey Bee Swarm?

    Honey bee colonies reproduce by a process called swarming. During mid-winter, the queen begins laying eggs and the colony population grows. By spring, the nest is congested with many new bees. The colony raises a new queen and the old queen flies away accompanied by more than half the bees.

    This flying swarm temporarily clusters on an object, such as a tree branch, while scout bees search for a permanent nest site. A hanging swarm may assume any shape, depending on the surface on which it is clustered. Most hanging swarms are round or oval, about the size of a basketball, and dark brown.

    Swarms in the clustered stage are relatively gentle, and the risk of stings is low. Nevertheless, treat swarms with caution. A swarm usually relocates to a permanent nest—a hollow tree, abandoned beekeeper's hive, or inside a hollow wall—within 24 hours.

    Options for Dealing with Swarms

    If a honey bee swarm lands on your property:

    • Do not disturb it. Keep pedestrians, children and pets away from the swarm.
    • If the swarm is safely located away from animals and people, you should wait for it to fly away on its own.
    • If the swarm poses a real risk to people or animals, consider finding a local beekeeper who will remove it. However, not all beekeepers collect swarms, and some may charge a fee for this service. Your county Extension agent can refer you to local beekeepers who collect swarms.
    • If Africanized bees are present in your area, do not ask a beekeeper to collect swarms. Instead, report honey bee swarms to your county Extension agent or state Department of Agriculture. Authorities may wish to collect the swarm for official testing. For more information, ask your county Extension agent about Bulletin 1290, Africanized Honey Bees.

    Bee Colonies Inside Walls

    The natural nest-site of honey bees is hollows inside old-growth trees. Today, the most available nest sites may be man-made features like voids in houses and other structures. Bees do not cause significant structural damage and may cohabit with humans indefinitely. But if the owner wants them removed, it requires the services of a specialist. Photo credit: Jim Quick.

    Wall voids are attractive to honey bee swarms seeking permanent nesting sites. This is especially true if the cavity has had bees in it before. To avoid this problem, caulk potential entry sites such as knot holes, gaps in siding, and openings around plumbing or electric wires. If ventilation is necessary around the openings, cover them with window screen.

    Honey bees in walls can be a problem for the following reasons:

    • They pose a sting hazard if their hive entrance is near human or pet traffic.
    • They may trouble people indoors with the sound of their buzzing.
    • If the colony dies, its beeswax combs are no longer ventilated by fanning bees. The combs may melt and stain interior walls with honey and wax.

    If you discover a bee colony nesting inside a wall, here are your options:

    • Save money and labor with quick action. If the swarm moved inside the wall very recently (within a day or two), a qualified person can kill the colony by injecting an insecticide into the void. If you wait longer than this, bees will build combs and store honey in the wall void.
    • If a more established colony must be eliminated, it is not enough to simply inject the void with an insecticide. The entire nest, including bees and combs, must be removed. If you leave behind the unventilated combs, they may melt and stain interior walls. Many pest control companies avoid these jobs because they involve unusual expertise and liability risks. It is usually best to hire a beekeeper and carpenter team specialized for this work. Typically, these specialists wait until evening, when all bees are inside the nest; they locate the nest cavity by listening and observing. Next, they expose the nest by removing the siding or necessary timbers, vacuuming the bees off each wax comb. They continue cutting away, vacuuming, and removing each comb in succession until all the bees and combs are removed. The carpenter then seals off the void. It is extremely important to close up all potential bee entry sites; otherwise, you run the risk of a new swarm quickly reoccupying the void. Depending on the nest's location, the beekeeper and carpenter may need to work either inside or outside. The following morning after the work is done, it is not unusual to find a few worker bees on the outside surface where the nest entrance used to be. These individuals are disoriented, pose a low sting risk, and will die or relocate within a day or so.
    • In some cases, bees and people cohabit with no problem for years. If the nest's entry point is far away from human and pet traffic, such as the peak of a roof, consider a leave-alone approach.

    Remember, honey bees are beneficial insects and are not aggressive. However, they will defend their nest if they perceive a threat. If you encounter flying honey bees, calmly walk away from them and never swat them. Swatting only threatens them and increases the chance of a sting. Your county Extension agent or local beekeeping association can help you with any questions about honey bees.

    Published with minor revisions on Jul 18, 2014