Swarming often happens on fine, mild days, occasionally just after a period of rainy weather, in spring or early summer (April through May). Conditions inside the hive are very crowded — so crowded with young workers that many of them may have been hanging out outside the hive for a few days in advance. Here, we describe how to tell if bees are going to swarm, what a swarm looks like, and signs and phases of swarm-related behaviors.
Hours before a swarm, bees in the hive prepare to leave. On the morning of the swarm, workers begin filling their honey crops with honey from the cells. As late morning approaches, some bees begin rushing about through the crowded frames, making a vibrating, whirring sound that you can sometimes hear. The other bees become excited and restless.
At some unknown signal, the bees begin pouring out of the hive and forming a large, swirling mass in the air outside; this flight activity is clearly audible. The bees that leave the hive in the first, or “prime” swarm are mostly younger workers and the existing queen. A few drones may be influenced by the excitement to tag along.
One of the oddest things about the dramatic departure of a swarm is the contrast between the excited swarming bees, and the calm coming-and-going of returning foragers in the same hive, patiently working their way through the crowds of departing bees. The functional separation between the two groups has clearly already happened.
The first stop after bees swarm is to create a bivouac site near the original hive. Gradually, the flying bees begin to establish a clear flight path toward a temporary perch, or bivouac. As more bees arrive at the bivouac, the cluster becomes larger, with small groups of bees “dripping” off the mass as gravity momentarily overcomes the cohesion of the cluster.
The swarm settles here for a short time while scout bees search for a new home. Some of them may have already been checking out potential sites beforehand, but the activity takes on urgency once the swarm has irrevocably committed itself by leaving the parent hive. The scout bees return to the clustering swarm to share information through waggle dances about the location and attractiveness of each site’s characteristics. Other bees are recruited to visit the favored sites and report back. Eventually, a single site emerges as the preferred one and a small cohort of bees flies toward it.
And then, seemingly suddenly, the bees in the bivouacked cluster become aroused and warm up their wings and the entire swarm takes flight toward the chosen site. They fly directly in and begin settling down to arrange their new household.
A wonderful and detailed description of this extraordinary process is provided in the book Honey Bee Democracy by Thomas Seeley. Reading it forever changes your view of honey bees.
Swarms may stay in one place for a few hours to a day — or, occasionally longer — depending on the weather conditions and how quickly scouts find suitable options for habitation.
Yes, a swarm is a group of bees in transit from their original hive to a new home. Once an ideal location has been identified, the swarm will move on. Unless their temporary location poses a risk, it’s fine to leave them alone until their new home has been chosen.
For the best results, the best time to capture a swarm is “as quickly as possible.” From a practical standpoint, the massing of a swarm during the bivouac period, while the scouts are searching for a new location, makes it easier for beekeepers to capture and hive them. Timing-wise, newly-swarmed bees have the benefit of a crop full of honey, so they are mellow and calm. As time goes by, though, and food becomes scarcer, they can get cranky, like hungry children at the end of a long day. The more quickly a beekeeper can get to them, the better.
If you aren’t a beekeeper but have found a swarm near your property, refer to our swarm catcher list to find experienced beekeepers who may wish to hive your wild swarm.
The day of a swarm includes a flurry of activity followed by minutes to hours of waiting while the new colony searches for an appropriate home. You may have a small window of opportunity you wish to capture a swarm. Explore our Beekeeping Guide to find tips for beekeepers of all experience levels.