Hornets are common insects whose presence is a seasonal phenomenon, directly tied to their annual life cycle and environmental conditions. Understanding these patterns clarifies why hornets disappear from our surroundings each year.
The Hornet Annual Cycle
The annual cycle of a hornet colony begins in spring when a single, fertilized queen emerges from her winter hibernation. She selects a sheltered location, such as a hollow tree or wall void, and starts constructing a small nest using chewed wood fibers mixed with saliva to create a paper-like material. The queen then lays her first batch of eggs, which hatch into larvae and develop into sterile female worker hornets.
Once these first workers mature, they take over the responsibilities of foraging for food, expanding the nest, and caring for subsequent generations of larvae, allowing the queen to focus solely on egg-laying. Throughout the summer, the colony rapidly grows, reaching its peak population in late summer or early autumn. At this time, a hornet nest can contain hundreds of individuals, with European hornet colonies sometimes reaching up to 700 workers.
Environmental Triggers for Disappearance
The gradual disappearance of hornets in the fall is primarily driven by changing environmental conditions, particularly dropping temperatures and reduced food availability. Hornets are cold-blooded insects, meaning their body temperature is influenced by their surroundings. As temperatures fall below approximately 50 degrees Fahrenheit (10 degrees Celsius), their metabolism slows significantly, making them sluggish and less active.
Freezing conditions are detrimental, as most hornets cannot withstand extreme cold. Their paper nests offer limited insulation, insufficient to protect the colony from winter. Concurrently, their primary food sources, such as insects and sugary plant sap, diminish as the season progresses. This food scarcity, combined with the physiological effects of cold, contributes to the colony’s natural decline.
The Fate of the Hornet Colony
With colder weather, most of the hornet colony perishes. Worker hornets, whose lifespan is typically a few weeks to a couple of months, and male drones, who die shortly after mating, cannot survive winter. The old queen, workers, and males from the current year’s colony die off as part of the natural seasonal cycle.
However, the species continues through newly produced queens. In late summer or early fall, the colony shifts its focus to producing these new, fertile queens and males. After mating, these new queens leave the nest and seek sheltered locations to overwinter, entering dormancy.
These sites can include under tree bark, in leaf litter, hollow logs, or inside building crevices. The old nest is abandoned and not reused. When spring arrives, these new queens emerge to establish new colonies, restarting the annual cycle.