Season of the Swarm – Part 2: Why, oh why???

By William Rowe1 & Geoff Williams2

1The Alabama Cooperative Extension System, Fairhope
2Department of Entomology & Plant Pathology, Auburn University, Auburn

All colonies are prone to swarming at some point or another. In Part 1 we briefed you about the consequences of swarming. Here in Part 2 of our Season of the Swarm series, we introduce you to some swarm biology basics.

Swarming is typically a good sign. It means that your colony is strong and able to make an investment in reproduction. It also likely means that food resources are locally plentiful. This is why swarming typically happens in the Spring, when loads of nectar and pollen are around.

Changes in a colony preparing for a Spring swarm are very interesting. In brief, the situation generally unfolds like this:

First, the colony grows in size (both bees and brood) concurrently with Spring nectar flow and pollen availability. An uptick in population is your first clue that swarming might happen.

Next, the large population begins to result in crowding, which causes a dilution of the queen’s mandibular pheromone. This pheromone is the scent that the workers rely on to be ‘Queenright’, or cohesive. When not enough of it is dispersed within the colony, new queens will be produced as part of swarm preparations.

Queen cells are very different from worker and drone cells. They are large, elongated, resemble a peanut shell (Fig. 1), and for Spring swarms, are usually on the edges of your brood frames (Fig. 2).

Figure 1. Queen cell
Figure 1. Honey bee queen cells hang vertically, and resemble the shell of a peanut. The large cell in the center is capped, and contains a developing queen pupa. Photo by G. Williams.
Figure 2. Honey bee swarm cells on frameFigure 2. Honey bee swarm cells are typically found at the peripheral edges of the broodnest. The blue arrow denotes a queen cell likely built in preparation for colony swarming. Photo by G. Williams.

Queen cells located in central positions on a frame are usually suggestive of queen replacement, rather than swarming (Fig. 3). Perhaps the current queen is old, or weak, or damaged, or even missing!

That said, one can never be 100 % confident the cell they are observing marks replacement or swarming.

Figure 3. An emergency queen cell
Figure 3. A queen cell centrally placed on a frame containing few brood. Based on colony conditions (e.g. poor brood pattern, low worker population, and late summer timing), this is likely an emergency queen cell, rather than a swarm cell. Cell denoted by a green arrow. Photo by G. Williams.

Once new queen swarm cells are capped, and there can be as many as 10-20 at any given time, the queen and workers of the colony begin making preparations to depart the hive. It’s very difficult to prevent swarming at this point (more on this in Part 3).

Workers begin by starving the queen a bit, which trims down her weight so that she can take flight. Simultaneously, they begin gorging on the colony’s honey stores to fuel their tanks and to carry as much with them to their new nest site as possible. Some also begin running through the colony to initiate a swarming event.

The tell-tale sign that swarming has begun is when the front of your hive and landing board looks exceptionally busy. At this time, your colony will sound noticeably louder, with sounds higher in pitch. Soon a steady stream of bees will emerge and take flight. This stream, and really we should say ‘flood’, pushes and drags the queen out of the hive with them. It looks haphazard at first (Fig. 4), but with the help of a pheromone, the flying bees will soon assemble together nearby (Fig. 5).

The first swarms of spring will likely take anywhere from 40 to 80 percent of the workers in the colony, along with the original queen! This is a big loss, leaving your hive with a new, unproven queen and substantially less population. This definitely can affect honey harvest.

Figure 4. An early honey bee swarm
Figure 4. Early stages of a swarm, prior to workers and the queen assembling near to the original colony. Photo by G. Williams.

Once in flight with the swarm, the old queen will pick a landing site not too far from hive. If you are lucky it’ll be within reach, but often it will be 20 or more feet up (Fig. 6). Remember the queen’s been a non-flyer since her mating flights, so she usually doesn’t get far. Any number of spots are acceptable, not just tree branches.

Once the queen has landed, the workers in the swarm immediately begin to cluster around her, to protect and maintain her. Scouts leave the swarm cluster to begin searching the neighborhood for an acceptable space to found a new colony. This may take minutes, or even days, depending on the availability of suitable sites.

Figure 5. A swarm cluster
Figure 5. A swarm clustered on a fig tree in Mobile County, Alabama. Thankfully it was only 6 feet off the ground! Photo by W. Rowe.
Figure 6. Swarm high in tree
Figure 6. Honey bee swarms can cluster in a variety of locations. This swarm chose a spot 30 feet above the beekeeper’s home. Swarm denoted by a blue arrow. Photo by W. Rowe.

Once scouts find a suitable colony site, the whole flight procedure happens again. The sound of the cluster ramps up and then bees take flight urging the queen along to the new home. Generally, once the swarm has lifted off a second time, they travel the full distance needed to get to the new site instead of taking pit-stops along the away. Once this happens the swarm is usually lost to the beekeeper.

Next time we’ll discuss swarm management and how to take advantage of your bees’ reproduction habits to increase your success!

Stay tuned for Part 3 next week!

Further resources

  • Seeley, T.D. 2010. Honeybee Democracy. Princeton University Press, 280 pp. Public lecture available @ https://www.youtube.com/watch?v=JnnjY823e-w (Accessed 9 April 2017)

  • Graham, J.M. (Ed.) The hive & the honey bee. Dadant & Sons, Inc., Hamilton IL. 1057 pp.

p.s. There are exceptions to every situation, particularly involving honey bees!


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