The Swarming Mechanism
The Swarming Impulse
The mechanism by which a swam of bees, perhaps consisting of 10 000 individuals, is able to transfer itself from the parent hive to another home over a mile away has aways been a puzzle which confronts every beekeeper in the swarming season. But now by the use of modern technology the mechanism of the swarm's time frame can be established.
Methods used are :
within the hive : micro thermometer, thermo- and infra-red cameras, sensitive microphones for high and low pitch,
outside the hive : microchip carried by the bee, radar - the bee carries a transponder on its back.
Preparation for swarming within the hive
As the queen cells are near to being sealed the queen goes on a slimming course. Her egg laying capacity is reduced and she is fed less. She loses about 25% of her body weight and is now capable of flying.
Workers on the other hand fill themselves with honey; their weight increases by 50%. The workers thus carry their stores with them to their new home where wax is secreted to build new comb.
30 minutes before the swarm emerges the temperature of the cluster rises significantly from the normal brood temperature of 35 ºC to close to 39 ºC. Some bees can be seen running across the comb in a high state of excitement. A thermocamera shows the bees become over heated. Foraging almost ceases and the swarm emerges 5 minutes later.

Emergence of the swarm
The queen flies to and settles on a nearby branch and is immediately covered by the bees forming a tight cluster. Mature bees i.e. those that were previously foragers and know the area depart as scout bees to look for a new home.

Discovery of the new site
The scout bees leave the swarm and set out on a voyage of discovery. Those that are successful return to the cluster and dance on the surface to indicate the direction and distance of the proposed new home. At the new site scout bees fly around releasing pheromones from the Nasanov gland so indicating the position of the home. On the cluster more bees are encouraged to investigate the new sites and return with the information. Eventually the bees form a consensus and only one site is chosen.

Preparation for takeoff
The dancing bees not only indicate the position of the new chosen home but induce the swarm to take off. These bees emits low frequency piping sounds. On receiving these vibrations the bees even those deep in the cluster raise their body temperature ready for departure. This takes place very suddenly.

Take off
Once the decision has bee made to take off there is no holding them. The swarm circles around for a few seconds and then is off in the chosen direction slowly at first and then at an increasing pace. Guide bees fly backward and forwards within the swarm indicating the direction. The new home is indicated by the pheromones released earlier by the explorers and is quickly occupied.
Summary: what is observed
The first indication that the bees are preparing to swarm is the appearance of queen cups holding a growing grub. The queen cup is enlarged to contain the growing grub and finally sealed as a fully formed queen cell. Only then when the bees have ensured that a new queen is safely enclosed will they swarm.
Just prior to the swarm leaving there seems to be a moment of calm when some bees are seen to cover the hive front.

When the swarming starts the bees are seen with great urgency leaving the hive with the queen.

The swarm settles quite close to the hive sometimes on a neighbouring tree branch. The bees appear to be quite calm with only a few flying around.

After a while the bees take off, circle around, and then head off in a specific direction slowly at first and then with increasing speed in a direct line to their new home.

What on first sight seems to be a simple operation on closer inspection reveals a highly complex procedure is taking place.
The various steps are described below.
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