Causes of Swarming

In order to prevent swarms, you need to understand what causes them.

Bees naturally want to swarm. A swarm means success! But to a beekeeper it means no honey to harvest.

Here is a list of the general stages involved in spring buildup that contribute to Reproduction Swarms. This is what I believe happens as concisely as possible.

  • A couple of inches of capped honey around the outside of the brood nest is seen as the boundary of the colony.
  • Expansion of the brood nest by consumption of honey during winter, aiding in heating, and then during spring build up, generally moving upwards.
  • Due to lower temperatures, clustering continues, especially at night and so nectar is preferred to be stored in the brood nest.
  • Large amounts of pollen are available in early spring and this is stored in the brood nest to raise increasing amounts of brood. This is determined by cluster size.
  • Brood are often raised in batches during spring buildup due to limited space. Brood population can almost double with each batch. As the brood nest expands, gradually all stages of brood are present.
  • Wax making capabilities are very limited in late winter and early spring due to temperatures being too low and limited incoming nectar. So extension of comb is limited.
  • Expanding areas of brood, and storage of nectar and pollen in the brood nest by foragers puts pressure on the available space in the brood nest.
  • During a spring flow, empty cells are quickly filled by the foragers with nectar, before the Queen finds them.
  • Empty cells become less and less very quickly as they are filled with nectar. Quickly reducing the amount of open brood.
  • The Queen starts loosing weight due to laying less and less eggs.
  • With a large amount of young Nurse Bees, any very young brood start getting a lot of attention and large amounts of Royal Jelly is available to get deposited into these cells, making ideal conditions for Queen Cell building.
  • Once the brood nest is backfilled with nectar, and there is a large number of unemployed Nurse Bees, then queen cells are built.
  • Due to little space to store nectar, Nurse Bees are also full of nectar. This aids in preparing for wax production. (It is held on to as long as possible, in preparation for a swarm.)
  • The Nurse Bees are now ready to swarm as soon as weather permits.
  • Scouts start searching for a new hive location.
  • When ready to leave, a signal is sounded and bees (especially Nurse Bees) start flowing out of the hive, chasing the Queen out as they go to get her to leave with them.

Contributing factors to Swarming
So when looking at the stages in spring buildup it seems that the main issues in causing swarm conditions is Brood nest reduction by backfilling of the brood nest with nectar, which reduces the amount of open brood and then causes there to be large numbers of Nurse Bees. Once there is a large number of Nurse Bees, opening the brood nest may not be enough to prevent a swarm. Note, little wax is produced before swarming, as if it is saved up for the swarm.

Checkerboarding attempts to get the foragers to store nectar above the brood nest rather than in it, by providing empty comb above the brood nest, making it appear that the brood nest is very large. Ideally this is done before nectar sources becomes plentiful. It becomes clear that this leaves the brood nest free from congestion and allows for maximum population. All stages of brood continue throughout the spring buildup. Ensuring there is enough open brood to keep large numbers of Nurse Bees occupied. The issue with Checkerboarding for those new to beekeeping is lack of drawn comb.

Opening the Brood Nest does not stop backfilling of the brood nest with nectar. Rather it tries to maintain enough space in the brood nest to allow for backfilling, while maintaining enough space for the queen to lay and to ensure that there is always open brood to keep Nurse Bees occupied. Placing empty frames or foundation in the brood nest encourages wax builders earlier in the season, but wax making uses extra nectar.

There are basically two stages. Brood nest expansion into honey stores, then Brood nest reduction by backfilling of the brood nest until the queen has no room to lay. So based on that, it appears that deterring foragers from storing nectar in the brood nest in the first place seems the best way to prevent swarms, produce a higher population and to yield a larger honey crop.

Commit to Issue a Swarm

To summarize, in order for a hive to Commit to Issue a Swarm

  • A large number of Nurse Bees (Due to little or no open brood.)
  • A large amount of stores, of nectar, pollen and honey.
  • A queen to go with the swarm and a queen to stay with the hive (Queen cells.)
  • Good weather. (A warm to hot and humid day is preferred.)
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