Social wasps, such as yellow jackets and hornets, live in annual colonies where the vast majority of individuals do not survive the winter. The cold season ends the entire colony structure, including all workers and males. Only the new, fertilized queens survive the winter months by entering a period of metabolic dormancy. This annual life cycle means every new colony is founded by a single queen emerging in the spring, restarting the social structure.
The Autumnal Decline of the Colony
As late summer transitions into autumn, the established wasp colony begins its decline, driven by dropping temperatures and the cessation of the old queen’s egg-laying. The original queen, having laid thousands of eggs, reaches the end of her natural lifespan and dies. Her death removes the central command structure and the source of pheromones that maintain the colony’s social order.
The colony’s focus shifts to producing the next generation of reproductive individuals: new queens and males. Once these reproductive wasps emerge, the remaining sterile worker wasps have no further brood to feed, and the colony structure rapidly disintegrates. With colder weather reducing insect prey and sugary food sources dwindling, the workers and males perish from cold and starvation. The old nest is never reused and is left to decay.
Preparation of the New Queen for Survival
The few female wasps that will become queens emerge late in the season, destined for a different fate than their worker sisters. These new queens leave the natal nest to mate with males, often aggregating in specific areas. Mating is a prerequisite for survival, as the fertilized queen carries the sperm necessary to found the new colony in the spring.
After mating, the future queens immediately begin intense feeding to build up energy reserves for the long winter. This involves the consumption of carbohydrates and proteins to create a substantial fat body within their abdomen. The stored fat, or lipids, will be the queen’s sole source of fuel for the next six to eight months while she is inactive.
Queens that do not reach a sufficient weight threshold are unlikely to survive the winter. Once provisioned, the queen seeks a sheltered location, known as a hibernaculum, where she will spend the entire cold season. She must find this shelter before freezing temperatures arrive to ensure stable, non-freezing conditions.
Overwintering and the State of Diapause
To conserve the fat reserves built during the autumn, the newly mated queen enters a physiological state called diapause. Diapause is a deep, hormonally-controlled metabolic dormancy that is distinct from simple hibernation. During this state, the queen dramatically lowers her metabolic rate and oxygen consumption, sometimes reducing her energy expenditure by over 90%.
This metabolic suppression allows the queen to survive months of cold and food scarcity by slowly depleting her stored lipids. The queen seeks a hibernaculum that offers stable temperatures and protection from predators and extreme weather fluctuations. Common overwintering sites include protected spaces, such as under loose tree bark, deep within rotting logs, or buried beneath the soil and leaf litter.
She may also utilize human structures, like wall cavities, attics, or sheds, provided the location remains dry and insulated. The success of diapause relies on the queen’s ability to remain still and cold, allowing her reduced metabolism to stretch her limited fat body reserves until conditions are favorable for her emergence.
Spring Emergence and Colony Restart
The queen’s diapause ends when rising spring temperatures trigger a hormonal shift that restarts her metabolism. When ambient temperatures consistently reach about 10 degrees Celsius, the queen emerges from her hibernaculum. Her immediate priority is to locate a suitable, sheltered nesting site, often in a loft, eave, or hollow tree.
Using her mandibles, the queen scrapes wood fibers from dead wood, chews them, and mixes them with saliva to create a small, papery pulp structure. This initial nest, often no larger than a golf ball, contains a few hexagonal cells where she lays her first batch of eggs. She must forage for food, defend the nest, and feed the growing larvae herself, performing all the duties that worker wasps will later take over.
This first brood of eggs hatches and develops into sterile female workers. Once these first workers emerge, the queen is freed from her solitary duties and remains in the nest solely as an egg-laying machine. The workers then take on the tasks of nest enlargement, foraging for food, and caring for subsequent broods, allowing the colony to rapidly grow throughout the summer.