Updated on March 29th, 2021
Each year, a significant number of a colony’s bees may swarm, taking the reigning queen with them searching for a new home.
Swarming is a natural occurrence by which bees form a new colony and expand their population. The queen leaves a hive with about half the bees (including some drones). Before swarming, the colony begins the process of raising a replacement queen for the bees that remain.
A swarm trap (or “bait hive”) is a container designed and situated to attract bee swarms. Swarm traps should be water-tight with an opening of about 2 square inches and a cavity volume of about 40 liters. Traps can be “baited” with comb, foundation, or pheromone-like lures (such as lemongrass oil).
Some beekeepers use smaller boxes (as little as 15-liter cavities) for bait hives. Research indicates that 40 liters is the preferred size. As a frame of reference, a 10-frame, deep Langstroth hive box has a cavity volume of 42.75 liters, and a 5-frame deep nuc box is a bit over 22 liters.
A bee package can cost between $135 and $200 depending on shipping costs and other factors. Swarm traps are a great way to add (relatively) free bees to your apiary.
Trapped swarms are not really “free.” You will incur costs to build or buy a bait hive and mount it. You will also invest time and effort. However, compared to purchasing a bee package or a nuc, trapped swarms seem like “free” bees.
Swarming presents challenges and opportunities for beekeepers. Having half a colony leave one of your hives is obviously detrimental to that colony’s population growth and honey production. (How to prevent swarming is a topic for another article.)
On the other hand, while you may lose swarming bees from your apiary, swarm trapping is a very cost-efficient way to acquire more bees.
In this article, we’ll discuss everything you need to know to start trapping swarms.
Swarming is not the same as absconding. In swarming, about half the colony leaves the hive while others remain to carry on. Absconding is when the entire colony goes.
Why Do Honey Bees Swarm?
Honey bees swarm to expand their population and propagate the species. Swarming is triggered primarily by overcrowding in the hive or a decline in the queen’s health due to age or other factors.
Overcrowding In The Hive
Whether it is the hollow of a tree or a hive in your apiary, the amount of functional space available to a colony is limited. As the queen increases egg laying in the spring and the foragers expand the pollen and nectar stores, the hive may become crowded.
In a crowded hive, the queen may slow, or even cease, egg-laying due to lack of space. This lack of space is often called being “honey bound.” The queen’s pheromone production declines, signaling the colony that changes are in order.
An Aging Or Ailing Queen
The queen’s productive egg-laying capacity diminishes over time, as does her pheromone output. If the queen’s production drops off due to age or other reasons, it has the same impact as if she were reacting to overcrowding in the hive. The colony will prepare to swarm.
How Do Bees Swarm?
When the queen signals that change is coming, workers prepare to leave the hive with her.
Workers cease foraging and gorge on food stores to prepare for their trip. Queen cells begin to house potential successors to the soon-to-be gone queen.
After about a week of preparation, the queen exits with about half the workers and some drones. As the swarm settles somewhere nearby like a tree, scout bees go off searching for a new home.
Scouts look for desirable qualities: dry, adequate access, adequate size, and good orientation. Scouts report back to the swarm, which gradually forms a consensus on the best location. Once in agreement, the swarm heads off to their new home.
I have seen this process take from 2 hours to a whole day.
Thus, one colony becomes two, and the species spreads over a larger area.
If you are interested in learning the details of how bees select a new home, I highly recommend Honeybee Democracy by Dr. Thomas D. Seeley.
You can find other recommended books at 11 Best Beekeeping Books which we periodically update.
The first time one of our hives swarmed, we were working nearby in the garden. I heard a loud buzzing sound and looked up to see a cloud of bees forming in front of a hive. Bees poured out of the hive and joined the swarm. They settled in a ball on a nearby tree branch. After several hours, the swarm suddenly left and flew off into the neighboring woods.
Here is a video of one of our early hives swarming:
When Do Bees Swarm?
Honey bees usually swarm in late spring or early summer. Warmer weather and increasing supply of nectar and pollen create prime conditions for overcrowding the hive and moving. While they can swarm at any time of day, mid-morning to mid-afternoon on clear days seem most likely.
Swarming may begin earlier in the southern United States. According to one report, about 80% of swarms occur between May 15th and July 15th in New York. However, swarming may start in April in Maryland and as early as February in Florida.
Ask experienced beekeepers about the swarm season in your particular area.
When Should You Put Out Swarm Traps?
The best time to put out swarm traps is the early spring swarm season in your area. Trapped swarms are about the size of a new bee package and need time to build up stores for the following winter. Swarms caught later in the year may be short on time, particularly in colder climates.
How To Build A Swarm Trap
Swarm traps are relatively inexpensive easy to build with basic tools and materials. Your specific needs will vary depending on your plan, but generally, they include:
- Plywood or scrap wood to create a box with a cover and bottom. DO NOT USE TREATED WOOD.
- Fasteners (nails or screws) to assemble the box. SCREW, DO NOT NAIL TOP.
- Exterior wood glue for all joints EXCEPT where you plan to open the box (top or bottom).
- Frames (or bars if you have top bar hives) to easily relocate the swarm to a permanent hive.
- Method of hanging the trap: wood hanging board, ratchet straps, or even a tree stand.
- Exterior paint to protect the wood and prolong the life of the trap.
- An entrance closure for when you need to move the trap.
- Ratchet straps or bungee cords to help secure the trap and keep it level.
As I mentioned, about 40 liters is the preferred size for a bait hive. Scout bees measure cavities to determine if they make suitable homes.
Basic Plywood Swarm Trap
Hack n’ Build has an excellent guide on building a simple trap using plywood and basic tools. This video shows the process:
This trap holds only five frames, but since it is double the Langstroth height, it still provides a large cavity. Being thinner and taller can make it more manageable than a standard hive box.
Turn A Deep Box Into A Bait Hive
A 42-liter, 10-frame Langstroth deep hive box is ideal an ideal size for a swarm trap. An 8-frame deep box, at 35.5 liters, will work as well, will be easier to handle, and requires fewer frames.
A hive body will be more expensive than plywood; however, it requires less measuring and cutting. All you need to fabricate is the top and bottom.
Swarm traps are a great way to recycle old, slightly damaged hive boxes. The scents, wax, and propolis left in the box help attract swarms.
A few years ago, we switched from 10-frame boxes to 8-frame. Our old deeps became swarm traps and have worked well.
We added plywood tops and bottoms. The tops overhang on the sides, giving us a better handle on the box.
A 1-1/4” hole drilled near the bottom of one side serves as the entrance. A mason jar canning lid, held in place and able to turn on a small screw, serves as an entrance cover when it’s time to move the trap.
A nail across the opening keeps birds from nesting in the box. You can also use ½” hardware cloth.
We added a couple of screened openings near the top of the box for ventilation. Not sure this is necessary, but it didn’t keep the bees from moving in.
Buy A Swarm Trap Instead Of Building
If you have limited time, space, and tools, you can purchase a swarm trap that only needs assembly. However, buying a bait hive may be significantly more expensive than building one yourself. You can find some on Amazon and Etsy.
Wood pulp or cardboard bait hives shaped like flower pots are simple to install. They seem relatively cheap but are expensive because they will only last for a year or 2. A wooden bait hive can last quite a long time.
How Do You Bait A Swarm Trap?
You should “bait” your swarm trap before putting it up by adding:
- Frames (or bars for top bar hives);
- Foundation strips;
- Comb; and,
- Scented lure.
You do not need to use all the frames you might typically put in your box. For example, you could place six frames in an 8-frame box. You should transfer the swarm before they build out on all the frames.
However, without a full complement of frames, they will easily shift around and fall out of place. Also, without all the frames, bees may build from the top of the box, complicating removal.
A bait hive should seem as spacious as possible to the scout bees. Frames full of foundation make the space more crowded.
I would limit foundation to a top strip as a starting point for the colony. If using deep frames, wiring the frame will stabilize any comb they build.
In some areas, you may not want to add comb. Comb, especially unattended while awaiting a swarm, can become a home for wax moths.
Here in the northeast, we have not had wax moth issues in the early spring. However, it is a good idea to freeze the comb before putting it in the trap to kill any wax moth eggs or larvae, small hive beetles, or anything else that might be hiding in the comb.
Our excess comb sits in the barn and is frozen all winter.
Older, dark comb seems most attractive. As with foundation, do not fill the trap with comb. A partial frame or two should be sufficient.
You can purchase a packaged swarm lure for your bait hives. However, with one packet per bait hive they are relatively expensive. You may want to try these lures, but we opt for a cheaper, effective alternative.
Lemongrass oil is widely used to mimic Nasonov pheromones released by and attractive to worker bees. You can use plain lemongrass oil or a blended product containing lemongrass oil such as Swarm Commander.
Swarm Commander is more expensive than lemongrass oil. We used it with great success. Rusty Burlew, a master beekeeper, said, “For me, Swarm Commander was an overwhelming success, and I won’t go back to [prepackaged lures]” on her popular site, Honey Bee Suite.
To keep the oil scent from dissipating too quickly, put it on a cotton swab tip or similar item (we used makeup remover pads). Drop the swab in the trap before closing it up.
After a few weeks, if bees have not moved in, you may want to put a little oil on the entrance or push another swab into the opening.
How To Put Up A Swarm Trap
So far, we have used three different methods for hanging traps.
Hanging a trap from a nail is probably the most straightforward method.
A wooden board, bolted to one side, extends about 12 – 18 inches above the top of the box. A 1″ hole in the board provides a place to hang on a galvanized steel nail driven into the tree at a 45° angle. (The longer the nail, the better. The trap can get pretty heavy.)
On another tree, we placed sat a trap on a limb secured with bungee cords. We caught a swarm and will go back to that location. But the placement was a little too precarious and needed to be improved.
One tree on our property has a hunting stand that has been in place for at least 20 years. It was a great trap location, secured with a couple of bungee cords. I don’t think many people have random hunting seats available. If they weren’t so expensive, I would get some more.
There are many other ways to hang bait hives: French cleats, ratchet straps, tree stands, and hoist ropes are some of the options available.
Where Is The Best Place To Put A Swarm Trap?
The best place to put a swarm trap is:
- 15 feet high is often considered ideal. However, for safety reasons, consider placing it between and 6 and 8 feet high.
- Along lines that bees may use for navigation: tree lines, fence lines, canals, roadsides, etc.
- Not far from a water source.
- With the opening facing south.
- Shaded or at least partially shaded.
Placing a bait hive at 15 feet requires a hoist or, more likely, a ladder. Handling the box while on the ladder can be awkward. If you get stung while on a ladder with a box full of bees, your troubles have only just begun.
We have placed some traps high up, but in addition to the ladder, we used a tractor front loader to make the task easier and less hazardous.
Do not place traps on property that you do not own without the owner’s permission.
Put traps where you (and the bees) can see them. Unfortunately, traps may be a target for theft or vandalism in some locations. If so, you may need to camouflage them slightly or set them higher than you otherwise would.
How Often Should You Check Your Bait Hives?
Our traps have been close to home, so we try to check them weekly.
I would not go more than two weeks without checking your swarm traps. Keep this in mind when you place traps. Keeping bait hives far from home makes inspections more difficult and expensive (gas costs money!).
If a swarm has not moved in, re-bait the trap with lemongrass oil every couple of weeks. Make sure storms, vandals, or bears have not damaged the box.
Look for activity around the entrance. You may catch scout bees checking out the real estate. If you see bees carrying pollen, then you have caught a swarm.
Here is an example of why it pays to check swarm traps regularly.
These bees decided not to use the entrance and move INTO the trap. Instead, the bees built comb and brood OUTSIDE the box.
The colony remained calm while I cut the comb free, transferred it to a box and moved it to a hive in the apiary.
How Long Can Bees Stay In A Swarm Trap?
If a swarm moved in, you want to know how long they have been in residence. After a few weeks, the colony should have some brood, which keeps them from absconding and ready to move.
Leave them much longer, and the bees will become very oriented to the new location. The longer the stay, the heavier the box gets, making removal and transport more difficult.
How To Move A Swarm Trap
When it is time to remove the trap and get the bees to your apiary, you will be happy you included a simple entrance closure.
We hate to leave foraging bees behind. When moving our traps, we close the entrances when we expect most, if not all of, the bees are home (early evening or very early morning).
Protective gear is on in the event of a mishap, and we have angry bees.
When you get the bait hive to your apiary, the bees will be a little agitated from the trip. I would not transfer the bees to a hive right away.
If you want to open the hive immediately, place it very close to the permanent hive location so bees can begin to orient to that spot. Come back the next day and move frames from the trap to the permanent hive, just as you would with a nuc.
We left our traps closed up for a day. If you do that, make sure they are in a shaded location and not baking in direct sun. The next day we transferred them to the permanent hive.
Pros And Cons Of Swarm Trapping
- Relatively free bees can save you hundreds, possibly thousands, of dollars over the years.
- Swarms will be local bees that survived the winter. These are the genetics you want in your apiary.
- You may be able to sell swarms for additional income.
- Swarm trapping is not especially difficult.
- Catching a swarm is fun!
- Setting swarm traps can be a bit hazardous if you are not careful.
- Unwanted wildlife (wasps, birds, etc.) may settle in your bait hives.
- Traps are usually out of regular sight and subject to damage, potential vandalism, and theft.
- Periodic inspections can be time-consuming if you have many traps situated far from home.
We do not recommend swarm trapping to start beekeeping (despite “free” bees). However, catching swarms is an inexpensive way to expand your apiary and make up for the bees you will inevitably lose through swarming, disease, and harsh winters.
Get out there early and catch some bees!
 Bait Hives for Honey Bees – Information Bulletin No. 187, A Cornell Cooperative Extension Publication by Thomas D. Seeley, Roger A. Morse, and Richard Nowogrodzki
 Williams, I.H., Pickett, J.A. & Martin, A.P. The Nasonov pheromone of the honeybeeApis mellifera L. (Hymenoptera, Apidae). Part II. Bioassay of the components using foragers. J Chem Ecol 7, 225–237 (1981). https://doi.org/10.1007/BF00995745