Hornets are large social wasps whose colonies are temporary, lasting only a single year. Unlike honeybees, hornets do not maintain a perennial colony that survives the winter. Their disappearance is a predictable biological event tied directly to the changing seasons and the completion of their reproductive cycle. This annual collapse means the vast majority of the hornet population seen during the summer will not survive the colder months.
The Annual Lifecycle
The foundation of a hornet colony begins when a single fertilized queen emerges from hibernation in the spring. She constructs a small paper nest and lays her first batch of eggs. These offspring develop into sterile female workers, who take over foraging, nest expansion, and caring for subsequent generations. The colony grows rapidly throughout the summer, fueled by workers hunting insects to provide protein for the developing larvae.
In late summer and early fall, the queen produces a final generation that includes males and new females, which are the future queens. These new queens and males fly out to mate. Once mating is complete, the original queen, the males, and all the worker hornets perish. Only the newly fertilized queens seek out a protected place to hibernate until the following spring.
Specific Timing of Colony Decline
The ultimate trigger for the colony’s disappearance is the onset of cold weather, as hornets are cold-blooded insects that cannot regulate their body temperature. The workers and males lack the necessary physiological mechanisms to survive sustained low temperatures. The first hard frost, or a period where nighttime temperatures consistently drop and remain below freezing for several hours, effectively ends the colony.
This natural collapse typically occurs from late September through November, depending significantly on the local climate and the timing of the first severe cold snap. Once the workers can no longer fly efficiently due to the cold, they cannot forage for food or maintain the nest, leading to the rapid death of the remaining members. The only individuals to survive are the newly mated queens, which have already dispersed to sheltered locations to overwinter.
Increased Aggression in Late Season
Just before the colony collapses, hornets often appear more visible and aggressive, particularly in late August and September. This behavioral change is linked to a shift in the colony’s priorities and diet. Throughout the summer, workers primarily gathered protein from prey to feed the developing larvae.
As the season ends, the queen stops laying eggs and the need for protein declines. Adult workers still require energy, so they switch their focus to finding carbohydrates and sugars. These are readily available from human food and drinks, like soda or picnic fare. This desperation, combined with a large population of aging workers who have nothing left to lose, makes them more persistent and likely to sting when interacting with humans.
What Happens to the Abandoned Nest
After the entire colony has died off with the cold weather, the paper nest structure is completely abandoned. Hornet colonies are annual, meaning the nest is never reused in subsequent years, even by a newly emerging queen. The nest, which is constructed from chewed wood fiber mixed with saliva, will naturally deteriorate and disintegrate over the winter due to weather and moisture.
It is safest to remove an abandoned nest only after a hard freeze has occurred, ensuring all occupants are dead. A distinction should be made between hornets and certain species of yellow jackets. Yellow jackets, in regions with very mild winters, can occasionally establish perennial, underground nests that may survive to the next season. However, the aerial paper nests constructed by hornets are safely cleared once the cold weather has passed.