Yellow jackets (Vespula species) are common social wasps often found near human activity, building nests underground or within structural voids. Since these insects are cold-blooded (ectothermic), their body temperature depends directly on the surrounding environment. This means both extreme cold and extreme heat can stop their activity and cause colony collapse.
Lethal Temperature Thresholds
Yellow jacket workers become sluggish and foraging activity slows significantly below approximately 50°F (10°C). Acute exposure to freezing temperatures, 32°F (0°C), rapidly kills exposed adults and larvae due to ice crystal formation. For widespread colony eradication, temperatures must remain below roughly 45°F (7°C) for five to seven continuous days.
The high temperature threshold also leads to physiological collapse under heat stress. Temperatures sustained above 114°F (45.5°C) for an extended duration can be lethal to workers and developing brood. This heat overwhelms the wasps’ ability to regulate their internal temperature, causing them to become lethargic and die.
Natural Temperature Tolerance and Survival
Yellow jackets use natural strategies to mitigate environmental temperature fluctuations. The paper nest structure, made from chewed wood fibers, provides insulation, especially for exposed colonies. Inside the nest, worker wasps cluster together to generate metabolic heat. This collective thermoregulation helps maintain a stable core temperature for developing larvae and pupae, buffering against mild cold snaps.
At the end of the season, the majority of the colony, including workers and the old queen, succumbs to cold weather. Only newly fertilized queens survive winter by entering diapause (dormancy). These queens seek sheltered locations, such as under tree bark or in wall voids. They possess adaptations like “antifreeze” proteins to prevent internal freezing during this period.
Limitations of Temperature-Based Control
While the lethal temperature thresholds are known, achieving these conditions throughout an entire nest for eradication is difficult for a homeowner. Applying heat, such as boiling water or steam, is often ineffective because the heat dissipates rapidly upon contact with the ground or the nest’s outer layers. This method typically only kills surface-level workers and fails to raise the temperature of the core brood comb to the necessary 115°F threshold for a sufficient amount of time.
Using cold is similarly challenging, as yellow jacket nests are frequently located in insulated cavities like underground burrows or wall voids. A ground nest, for example, is naturally insulated by the surrounding soil. This insulation makes it nearly impossible to maintain a sustained freezing temperature deep within the colony. The lethal temperature must be achieved and maintained uniformly throughout the entire nest volume, a feat that is impractical without specialized equipment.