Swarming

Why do bees swarm? Most of us are familiar with the term ´a swarm of bees´, but what the fascinating phenomena of swarming actually entails is a mystery to many.

Reasons for Swarming

There are two reasons why bees swarm. First, swarming is a natural process that happens when a beehive gets too crowded. When a colony of bees reaches a certain size and there is no room to expand, the hive becomes overcrowded. This can prompt the bees to swarm. The bees will split into two colonies, whereby the old colony stays put and the new colony leaves to find a new home.

Researchers in Orit Peleg’s lab at CU Boulder use a honeybee queen to coax thousands of bees to form a dynamic, undulating swarm. (Credit: Peleg Lab at CU Boulder)

The second reason for swarming could be a parasite or disease infestation of the hive, a lack of resources, frequent disturbances, poor ventilation, or problems with the queen. For instance, if the queen is older, she often fails to lay enough eggs when the honey production is at its peak. In these cases the bees will swarm to find a new home and abandon the hive.

Cues and Timing

The workers can detect when the queen is unable to lay enough eggs by producing insufficient pheromones. Equally, they know when the hive begins to become overcrowded. They start to prepare for the swarming by preventing the queen from laying too many eggs by agitating her. The workers allow her to lay eggs in the bigger queen cells so that a new queen can take over once she emerges. In addition they deprive the queen of food to slim her down so she can fly.

Bees swarm when the weather is warm and sufficient food is available. This usually happens late morning to early afternoon from May to the end of July when it is warm and sunny. If the hive is particularly large, swarming can also occur in the fall.

Some horror movies feature swarms of insects to scare the viewers, and witnessing a swarm of thousands of bees in a large, noisy cloud can be a frightening experience by all means. Having said that, it is also a fantastic and dramatic experience. Usually, a swarm of honeybees settles into a cluster within a short period of time. A group of bees acts as scouts to find a new location, while the others stay behind. When the scouts have found a new location they return and  communicate the location and quality of the site by performing a dance. The other bees then choose the best location based on the dances of the scouts.

Prevention and Control

If you want to prevent bees from swarming, give them plenty of room to rear brood, store honey, nectar, and pollen, and produce beeswax. It is always better having too much room than not enough.

Bees that are in the process of building up the colony and growing need sufficient sunlight and warmth. When they start to produce honey, it may be necessary to provide them with some shade as it takes a lot of energy to cool the hive. Shade and good ventilation to allow more air flow is essential, particularly in hot climates or when it is hot. Placing a hive on a stand can help the hive to stay ventilated and maintain good drainage.

Replacing older queens with younger ones can also help to prevent them from swarming as older queens often fail to produce enough eggs during times of high growth.