Through-out the year, the activity changes within the beehive and the number of bees fluctuates according to these changes. Heading into winter a hive contains about 30,000 to 40,000 bees. By February/March that number has dropped down to around 20,000 provided the hive has survived winters icy grip. As April approaches and the days are getting warmer the Queen is in full laying mode and over the next few months the hive expands rapidly. Birthrates exceed death rates, and by June/July there are roughly 60,000+ bees in the hive. With this rapid growth, the hive becomes overcrowded, space is limited, and the queen may start to run out of brood space to lay her eggs. With more bees in the hive, the queen’s pheromones may not “get around” to all the workers. All of these factors can contribute to the hive deciding to swarm. In nature, swarming is instinctual, and results in creating a new hive from an existing (strong) colony. In other words, it’s a method of reproduction. Most swarms take place in the spring and early summer, however, bees can swarm at any time. The later in the season a hive swarms after July, the less chance it has for survival through the winter months.
Once a hive has decided to swarm they put their game plan into motion. First, they select several eggs that will be developed into the hives new queen(s). These peanut-shaped swarm cells are usually found along the bottom of the frames. As these queens are developing, the old queen slows down her egg laying and “slims down” in preparation of flying off with the swarm. The hive does not wait around for the new queen(s) to emerge. Shortly before swarming, the worker bees gorge themselves on a 3-day supply of honey and nectar. Once they are ready the hives original queen along with 50%-60% of worker bees take flight (truly a sight to be seen). As the virgin daughter queens hatch out, they fight each other to the death until there is just one. This new queen will go on her mating flight and then resume the role left to her by her mother.
Bees swarm without having a new location in mind to move into. At first they will stop and cluster not far from their original hive, keeping the queen in the center of the swarm. The queen is not great at flying and needs to stop and rest. While resting, scout bees go out in search of a new home. They return to share their findings with the others. Collectively, the hive must agree before moving into their new location. When swarming the bees are focused on finding a new home. They are not protecting brood so they tend not to be aggressive. (Bees attack when they are protecting their hive or feel threatened). If you see a swarm of bees, keep your distance. Typically, they will not remain at that location for very long. You can also contact a beekeeper, who would be happy to come and “rescue” a swarm. Catching a swarm is the equivalent to free bees. (A package of bees cost roughly $95)
Swarming reduces the original hives numbers by disrupting the brood cycle, slowing down the hives growth and honey production. Sometimes, once a hive has swarmed, it is followed by after swarms. After swarm are smaller swarms that fallow the original or first swarm but usually with a virgin queen. This can result in the depletion of the hive. Since a hive swarms before new queen emerges there is always the risk of losing the new queen resulting in a queen less hive. This happened to us last year while inspecting a hive that had swarmed. Lifting off one of the brood boxes, we damaged the swarm cell killing the larva inside. There were no other swarm cells, nor were there any eggs to create an emergency queen. This left us scrambling to locate a queen for sale and to re queen the hive.
Beekeepers hate swarming and employ various methods to prevent it. They may clip one of the queen’s wings to keep her from flying or try to trick the bees into thinking they have already swarmed by doing what are called “splits”. They will continue to add supers, manipulate the brood boxes or even destroy swarm cells. All of these methods may post pone swarming, but it may not stop the inevitable.
This past summer we caught our first swarm of bees! Yea, free bees! It was easy since they were wrapped around one of the legs of our hive stand. Could it had been a swarm from one of our hives? Who knows? Either way we were able to scoop them up along with the queen and place them into a nuc box. (When catching swarms, you must catch the queen or the hive will not stay.)
As we enter into fall foraging/ nectar sources are becoming more scarce and swarming should be behind us, hopefully. Of course there is always absconding, when ALL bees in a hive leave in search of a new home.