When Do Bees Swarm?
Bees swarm in late spring in search of a new home. During the winter the queen bee begins to lay her eggs and the colony sets about rearing its young. As the weather becomes warmer and the early flowers appear, the raising of young bees increases rapidly.
By the end of spring the colony has become so overcrowded that a large number of the bees, including the old queen, leave the hive and establish a new colony. In the old colony a new queen emerges who will experience the same swarming instincts the following year. And so the cycle of activity goes on.
Swarming is the natural means of reproduction of honey bee colonies. In the process of swarming the original single colony reproduces to two and sometimes more colonies.
Swarming creates a vulnerable time in the life of honey bees. Cast swarms are provisioned only with the nectar or honey they carry in their stomachs. A swarm will starve if it does not quickly find a home and more nectar stores. This happens most often with early swarms that are cast on a warm day that is followed by cold or rainy weather in spring.
The remnant colony after having cast one or more swarms is usually well provisioned with food, but the new queen can be lost or eaten by predators during her mating flight, or poor weather can prevent her mating flight. In this case the hive has no further young brood to raise additional queens, and it will not survive. An after swarm will usually contain a young virgin queen.
The propensity to swarm differs between the honey bee races. Africanized bees are notable for their propensity to swarm or abscond. Absconding is a process where the whole hive leaves rather than splits like in swarming. Being tropical bees, they tend to swarm or abscond any time food is scarce, thus making them vulnerable to colder locales.
Mainly for lack of sufficient winter stores, the Africanized bee colonies tend to perish in the winter in higher latitudes.
Generally, a weak bee colony will not swarm until the colony has produced a larger population of bees. Weak bee colonies can be the result of low food supply, disease such as Foulbrood Disease, or from a queen that produces low quantities of eggs.