Swarm Information

Below is a good article on removing swarms written by Eric C. Mussen, Ph.D. (UC Davis Extension Apiculturist) followed by my views on the options of swarm and hive removal.

Removing Swarms and Established Colonies from Private Property

By Eric C Mussen, Extension Apiculturist, UC Davis

What is a swarm?

Swarming is the honey bee’s method of colony reproduction. The old queen and half of the worker bees leave their former nest and seek a new home mostly in the spring, but sometimes in late summer. A few worker honey bees, we call “scouts,” fly around areas in the vicinity of the old hive searching for a suitable, new habitat (the correct sized cavity with an easily protected entrance). Often, that job is not completed when the swarm “issues” from the hive. The outpouring of bees from the hive forms a large, buzzing cloud of insects that seems to be going every direction at once. That flying group of honey bees is the swarm. It is a phenomenal sight that frequently scares people. However, the bees eventually have to regroup, somewhere, while the search for a new home continues.

What do swarms do?

A few other worker bees, called “leader bees,” fly from the hive to a distant location, then land and secrete Nasanov pheromone. That lemon-like odor is attractive to the bees and queen in the swarm. The bees coalesce into a single group, on an object. The group properly is called a “cluster,” but most people still refer to it as a swarm. The bees in the cluster are carrying honey from the old hive and are much less defensive than they would be if they still were protecting combs containing brood (immature bees) and stored foods (pollens and honey). At this point in time homeowners attempt to reach someone to take the bees away. In the spring, this makes sense to a beekeeper, because the bees have all summer to build their population and collect enough honey to survive the winter. Fall swarms will not have a full season to collect stores and beekeepers often are not too interested in collecting them.

During the time that scout bees are seeking a new nesting site, foragers fly to and from the cluster collecting mostly nectar (dilute sugar syrup) to keep their cluster mates hydrated and energized. If the scouts do not find a new location for the swarms to live, the urge to build comb can become overwhelming and the bees will build an “exposed comb colony,” suspended from a tree limb, the overhang of a house, or so other unusual place.

How are swarms removed?

Experienced beekeepers often remove clusters simply by brushing the bees gently into a box and taking them away. This is best done after flight activity has ceased for the night, since the scouts and foragers will be back on the cluster. The beekeeper should be prepared for defensive behavior, in case it develops, but dealing with a cluster is usually quite easy. This changes, however, as the cluster becomes more difficult to reach, such as way up in a tall tree, intermeshed with the branches of a shrub, or wedged into the corner of a building. It is best to supply the beekeeper with as much information as possible about the swarm to prevent surprises.

Regulatory agencies and professional pest control operators probably will have no desire to “take them alive.” So, chemicals will be used to kill the bees in the cluster. Choice of chemicals varies from commercial formulations of “soapy” water that prevent flight and drown the bees, to quickly toxic materials that simply knock out the bees’ nervous system and kill them. Regardless of the material used, the dead bee bodies should be collected and disposed of properly to prevent poisoning of birds or mammals that might ingest the contaminated carcasses. A stomach full of soap or detergent is just as lethal as a stomach full of synthesized pesticide.

What if the swarm is moving into my house?

Sometimes it is difficult to determine whether a honey bee cluster on the side of a building is simply resting there or moving, one by one, through a hole into an inner portion of a building. If the cluster size is shrinking, but hasn’t flown away, chances are they are moving in. Obviously, when they first arrive, they are short on food and have to build combs from wax they produce from the honey they are carrying. If they are not allowed to continue foraging for nectar, they will not accomplish much building. At this point in time, they can be “locked in” their new home with screen, steel wool, or something else through which they cannot chew to escape. They will die in place over the next week or two. However, they will be roaming around the area trying to find a new entrance, and a number of them are likely to find their way into the living quarters, especially by following beams of nighttime room lighting. Bees do not fly in the dark, but they will fly to the windows the next morning and stay there most of the day while they die of dehydration. They can be sucked up safely with a vacuum cleaner hose. Remember there may be live bees in the bag for a couple days after they have been vacuumed up.

What if bees have been established in my house for a while?

Once the bees have become established, they will have built one or more combs in which they are rearing brood and storing food. Often they do no structural harm to the building, but they are noticeable by their incessant “humming.” That is the sound of the bees ventilating their hive with fresh air and blowing out carbon dioxide, if it accumulates. The sound picks up in intensity when ventilation also is being used to evaporate water from nectar to change it into honey.

Occasionally, the bees use water to soften sheetrock and remove it in order to expand the nesting area. Residents then will notice an enlarging “damp” area on the wall. In a few cases, the bees actually open a hole through the sheetrock. Very few people will respond to that event as did the person who opened the hole wider and covered it with a sheet of glass to have his own “observation hive.”

How are established honey bee colonies removed?

Regardless of whether the bees are removed alive or dead, the combs have to be removed from the building. If they are not removed, the stored honey eventually will absorb enough water to allow yeast spores to germinate and ferment the honey. The resultant gas bursts the cappings and allows the honey to drain from the combs. Gravity starts moving the honey, then the first horizontal obstruction usually brings the honey into the home: a ceiling, a fire-break two by four, a window frame, a door frame, the floor, etc. The damage will be expensive to repair.

Bees killed by pesticides may drop into a pile, where their bodies do not dehydrate quickly enough. Microbes growing in the bodies of dead bees can produce very offensive odors. Since it is not a good idea to handle pesticide contaminated honeycomb, anyway, it probably is best to eliminate the bees without first killing them by opening a hole in an exterior or interior wall, ceiling, etc., that is large enough to reach in and get the combs out. It is wise to consult with a contractor before the hole is opened. Some holes close a lot easier than others. If the bees are to be saved, the bees and combs are taken out gently and placed in a box or some other suitable container. With less regard for the bees’ safety, they can be removed from the void with a vacuum device (shop vac). This process tends to stimulate the bees to release “alarm pheromone” (smells like bananas) that increases defensive behavior, so everyone nearby must be fully clothed in a “bee suit.” Many beekeepers have baffles and collection containers, in their vacuum lines, to try to protect and save the bees. If the homeowner has a lot of patience, the bees can be “trapped” out of the building using a one-way wire screen devise that forces bees that leave the building to relocate into a beehive placed adjacent to the original entrance. Consult with your county agent (Farm Advisor in California) to be directed to a bee specialist who can help describe this procedure.

What do I do after the bees are gone?

Once the bees and combs are removed from the building, there will be traces of beeswax left behind. Honey bees have an extremely acute sense of smell and the next swarm will be attracted to the site where the combs used to be. Therefore, it is mandatory that all holes or openings of one-quarter inch or larger be caulked, screened, or otherwise plugged to keep the bees out. Bees do not chew their way into buildings, but they are experts at finding a hole to get through. The area requiring examination and servicing includes the whole side of the building around the previous entrance or both sides of the building, if the entrance was on a corner. Some people fill the void where the previous nest was located with expanding foam insulation. But, if the bees can find access to a void adjacent to the previous nesting site, they will move right in.

During the extraction process some bees are likely to escape. Also, some honey bee foragers spend the night away from the hive in the summer. So, there is likely to be a cluster of bees forming around the entrance after the bees and combs have been removed. That small number of bees can be vacuumed up or eliminated with an aerosol spray labeled for use on wasps and bees outside the home. Be sure to read the label and follow the instructions strictly.

Where do I find beekeepers?

The best bet for finding beekeepers who are interested in picking up swarms or extracting bees from buildings is to look in the Yellow Pages under Beekeeper or Beekeeping. If someone is listed, be sure to ask how much it will cost to have the bees removed. You may wish to shop around to compare prices, especially in areas known to have Africanized honey bees. If no names are listed under the suggested headings, in California try contacting the office of the County Agricultural Commissioner listed in the County white pages at the beginning of the telephone directory. In some California urban counties, the title for that office will be the Sealer of Weights and Measures.

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A small hive in a wall exposed.

A small hive in a wall exposed.

Before I describe my views on options it is helpfull if you understand what makes up the beehive

An established beehive consists of:

  1. Between 8,000 and 50,000 adult worker bees, their population is at a minimum around December and at their maximum around June in central california. These are the bees we are familiar with that can sting if in a defensive mode.
  2. Between 0 and several thousand male drone bees, these can not sting you.
  3. One Queen Bee, all the bees in the hive are her children.
  4. Wax honeycomb, the structure of their home in which they raise new bees and store food.
  5. Between 0 and 40,000 bees to be, know as brood, in the egg, larval or pupa stage. The queen lays up to 2000 eggs per day, one per honeycomb cell, during the peak brood rearing season of April through June. The eggs become larva, which spin a cocoon and pupate into an adult bee in a sealed honeycomb cell.
  6. Between several pounds and several hundred pounds of honey. In the Monterey Bay area The quantity of honey will be at its minimum between December and March and at its maximum around August. Honey is the carbohydrate part of the bees diet which the bees must store for use when nectar is not available from flowering plants. If the bees do not store enough honey to last through the winter they will starve.
  7. Between a few and many pounds of stored pollen. Pollen is the protein part of the bee diet, which the bees must store for use when pollen is not available from flowering plants. If they bees do not store enough pollen as food to raise young bees in the fall and late winter months the hive may die due to under population and malnourished bees.

A healthy hive is self-sustaining; the bees regulate the temperature of the brood area of the hive between 91 and 98 degrees Fahrenheit, drive out pests such as ants seeking honey, and rodents seeking pollen and old comb. The bees are constantly maintaining their hive by repairing the comb, cleaning up any leaking honey and removing dead bees. As long as the bee hive is healthy the main complaints are worries are the flying bees, the chance of being stung, and the spotting caused by their defecating.

If the hive becomes weak or dies then problems may develop. Without the bees to maintain the temperature and ventilation, honey absorbs moisture, ferments and ruptures the wax honeycomb causing any un-crystallized honey to flow into the surrounding area. Any remaining brood dies and rots, causing foul smells and generally becomes covered with mold. The pollen and old comb attract rodents, wax moth and small hive beetles that consume the pollen and old comb causing more honey leakage. The old comb may also attract moisture and become covered with mold.


Options for established hive removal

The most expensive and least risky option

Bees can be a nuisance coming and going from their hive and present a stinging hazard for your family. If the hive dies or becomes weak and is no longer able to keep the hive in good repair, it becomes a potential source of damage to your home from leaking honey and is an attractant for other pests. Bees’ wax melts at 147 degrees Fahrenheit and becomes weak and pliable at 120 degrees Fahrenheit. If the hive is in the sun and there are no bees to regulate the hive temperature, the wax comb may get hot enough to break and leak honey. Leaking honey attracts ants absorbs moisture and ferments causing foul odors, mold and stains.

Now that you understand what makes up a hive you can see that having them exterminated without completely removing the dead hive is not a good solution. There can be over a hundred pounds of honey, 50,000 bees and 40,000 immature bees as egg, larva and pupa (brood). Having them killed will leave thousands of dead bees and all the brood and honey to rot in your wall, creating a worse problem then the bees themselves. The safest course of action is to open the wall and remove all the bees, honeycomb, honey, wax and pollen, completely fill the space where the hive was with packed insulation and repair the wall. This can be very expensive as the only way to remove the hive material is to either open the wall from the inside by removing the sheetrock, or by opening the wall from the outside by removing siding. The opening of the wall and removal of bees can cost up to $1000 and the repair of the wall can be several thousand dollars more. If the presents of the bees causes you great anxiety and you want to be sure of no mold, leaking honey or potential problems that may affect the value of your home, this is the recommend course of action.

The least expensive most risky option

Bees can be very enjoyable to watch. They generally are not as aggressive as many people think. Just because you have a hive in your wall does not necessarily mean that it will cause enough damage as to warrant spending thousands of dollars to remove them. If the bee flight path does not intersect with a human walkway (generally means the hive is up high), you enjoy watching the bees, and you are comfortable living with the chance that the hive may die and create potential mold and pest attractant problems, then leave them alone.

With all the parasites and diseases that plague honeybees, each year there is a good chance that the hive will die (actually about 50/50). If the hive does die there is only a chance that the remaining honey will cause a problem. Generally when a hive dies it first goes through a weakened state where it may consume some of the honey. Most of the brood will have hatched during this time. The hive population will have gradually dwindled leaving only a fee dead bees and brood to rot. Also as flower blooms reduce in summer and fall, healthy hives will often rob any remaining honey from dead or weak hives for their own use. This means that if you do nothing, there is a chance that the hive will die on its’ own, the remaining honey will be robbed out and all that remains is old comb, pollen and a small quantity of bead bees and brood (this is not the guaranteed outcome but there is a good chance, say 50/50). There is no doubt that the old comb and pollen will attract moisture and become coated with mold in wet weather, but it may not be a big enough problem to worry about. Once the hive dies wait till late fall or winter in hopes that all the honey gets robbed out and then plug up all holes that would allow another swarm to take up residence in the same location the following spring.

This may be a good approach for you if you are not worried by much and don’t mind a little mold in your wall. It all depends on you comfort level knowing that you have some moldy old wax and pollen in your wall. You can always decide to have it removed after the hive dies. The wall repair contractor can do that and you have at least saved the cost of a beekeeper removing the bees. This option does have some risk of damage and stings from the bees, but any repairs are not likely to cost more then the cost of having the bees removed in a effort to prevent the same damage in the first place. Another problem with this option is that the hive may never die or if it does, a new swarm of bees may take up residence replacing the hive that died while you were waiting for winter. I also think that when you sell your home you are required by law to divulge that you have an old dead beehive in your wall that was never removed.

Bee Extraction without opening the wall (The bee friendly removal)

This is a version of the least expensive option with forced bee removal. This is my favorite option.

A variation of the do nothing option is to cause the hive to slowly weaken and finally die by depriving the hive of its field force (the worker bees leaving the hive to gather nectar and pollen). This is often referred to as a bee friendly hive removal because the individual bees are not killed but the hive is.

A bee friendly hive removal is accomplished by plugging or screening all access holes into the wall hive leaving only one. The remaining access hole is fashioned with a one-way door allowing the bees to leave the hive but not return. I use a cone of screen with the base secured over the access hole. The bees crawl out a small hole at the end of the cone, when they return they fly to the base of the cone and are unable to get back in. A weak beehive in a box (a hive with a queen and only a few thousand bees) is placed on a small scaffolding outside the wall with its opening very near the one way door. Bees leaving the hive in the wall are unable to return to it and join the hive placed outside the wall.

It takes 21 days for an egg to hatch and develop into a bee from the date the egg is laid. Since the queen is laying eggs every day, new bees are hatching out every day replacing some of the bees that are being trapped out of the hive. The bee population in the wall hive will gradually decline as bees leave the hive to forage for food but not quite as fast as you might think. Since no food is coming into the hive the remaining bees must eat food that is stored in the honey comb. Bee brood must be covered with nurse bees (young bees caring for the brood). As the hive gets less populace the queen is forced to lay fewer and fewer eggs, as she will only lay as many eggs as can be cared for. This decline continues until finally the hive is so weak that it dies, usually taking about six weeks. By the time the hive finally dies most of the brood has hatched so there are few bees and little brood remaining to rot and cause a problem. The amount of honey and pollen is reduced because the bees were forced to consume it.

When the wall hive is dead, the outside hive that collected all the bees is removed. You now have the option to either open the wall and remove the old honey comb along with any remaining honey and pollen or to leave the one way door in place until late fall, hope that any remaining honey will be robbed out and then seal the holes to prevent a swarm from establishing a new hive the following spring.

The obvious problem with this method is that it takes so long and will require numerous trips by the beekeeper checking on the progress. If your main concern is with the bees themselves, and you want to be rid of them as soon as possible then this option is not for you. If the bees themselves do not bother you too much and you are more concerned with the potential problems and cost, then this option may be for you.


What if the bees just arrived and went into my wall?

If the bees just arrived or have only been in your wall a short time

Right now all you have are thousands of bees, there is no wax comb to mold, no brood to rot, no honey to ferment and no pollen to attract other pests. Immediate action is required, each day you wait will allow for more honey comb to be built, more eggs to be laid, more honey to be stored. A large swarm can make several square feet of comb and several pounds of honey in just a few days.

Some people may choose to have the bees exterminated by an exterminator at this time. It is certainly an option as it will prevent some of the potential problems a fully established hive poses. If you are concerned about mold then simple extermination is not a good option. The result will be thousands of dead bees gorged with honey that will creat a large mass of moist dead organic matter to rot and mold inside the wall, you should also open the wall and remove the dead bees. If you are not concerned about the mold then simple extermination may bee a good option for you.

Some people will be tempted to seal the bees into the wall by closing off all openings right after the bees move in. This will work causing them to starve to death if you can completely seal them in. I don’t recommend this method however as you may have the same rot and mold issue as if they are exterminated, also the bees will frantically look for ways out, often resulting in many bees getting into your living space.

To stop the hive from developing you must stop the flow of food into the young hive. Hire a beekeeper to do a bee friendly removal as described above as soon as possible. It will take two to four weeks for a bee friendly bee removal to cause the young hive to die. You will not need to worry about any honey in the wall if you do this immediately after the swarm just arrives, and there will only be a small quantity of clean wax with little brood and dead bees remaining. If you wait more than a few days to take action then treat it as an established hive containing all hive parts, it may take the full six weeks to complete the removal and there may be some residual of honey and pollen. My minimum charge for a bee friendly removal of a very young hive is $350.