The population in a beehive fluctuates depending on the season. These changes—due to changes in temperature and food availability—vary somewhat depending on local conditions and the subspecies of bee. But a keen understanding of this cycle helps a beekeeper make good management decisions. The example below is based on the climate in temperate North America, but the pattern is similar no matter where you live—only the dates will change.
When making management decisions, it is often easiest to divide the population into four segments: adult workers, brood, drones, and queens. Here’s a simplified look at each segment.
Adult workers: The number of adult workers declines throughout fall and winter and reaches a low point somewhere around February. A healthy colony at this time may have fewer than 20,000 bees. As soon as the day length increases and food becomes available, the number of workers increases until it hits a maximum in June of approximately 60,000.
Management tip: This maximum population corresponds to swarm season. Look for swarms to occur during a six- to eight-week period during May and June.
The number of adult workers drops slightly in the hot months of July and August, but may increase again in September if the colony is in an area with a fall nectar flow.
Brood: The production of brood is also variable. Little brood is produced from mid-autumn until early spring, and almost none is produced in December and January. Once the temperature warms and food is available, brood production increases and may require up to 40,000 cells at one time. During the summer brood production gradually decreases, although it may spike with a fall nectar flow.
Management tip: The autumn decrease in brood is an excellent time to treat for Varroa mites. Since there are few brood cells in which the mites can take refuge, a greater proportion of them are phoretic, meaning they are riding around on adult bees.
Drones: Drones are only reared during spring and summer when food sources permit. The number of drones is greatest just before and during swarm season and tapers off during the summer.
Management tip: The appearance of large numbers of drones coincides with swarm season. Before you see drones, there is no reason to worry about swarms.
Management tip: Large numbers of drone larvae yield large numbers of Varroa mites. Now is a good time to use drone traps to reduce mite loads.
Management tip: When you see workers ousting drones from the hive, you know fall is just around the corner. It’s time to get your hives ready for winter.
Queens: Most queens are raised in the spring during swarm season. Supersedure queens—to replace an ailing or defective queen—may also be raised in the summer. However, a queen is seldom raised during other times of the year. Even in the unlikely event that a queen is raised off-season, there is no chance of her mating since there are no drones.
Management tip: Swarm cells are a sign of an impending swarm. Depending on your beekeeping philosophy, you can let it go or take steps to prevent it.
Management tip: If you see repeated attempts to supersede late in the year, you may want to remove the queen (if she is still there) and combine the colony with another before she fails completely. (Some subspecies build more just-in-case supersedure cells than others. Observe carefully before taking drastic measures!)