Wasps are ectothermic insects, meaning their body temperature and activity levels are regulated by external conditions. Weather, especially precipitation, significantly affects wasps, influencing their capacity for flight, foraging success, and overall colony survival. Understanding how wasps react to rain involves looking at the physics of flight, the engineering of their nests, and the ecology of their food sources.
Immediate Behavioral Response to Rain
Wasps generally stop routine activities when rain begins because water interferes with their ability to fly. A single falling raindrop can be many times heavier than a small flying insect, posing a major risk of collision and disrupting flight mechanics. The weight of water accumulating on their wings and bodies also compromises the delicate aerodynamics required for flight. Wasp wings generate lift through rapid oscillation, a process that becomes unstable when saturated with moisture.
Once precipitation starts, the immediate reaction of a forager is to abandon its task and seek the nearest dry cover. This swift transition to seeking shelter is a survival mechanism. It helps the wasp avoid becoming grounded and vulnerable to predators or the elements.
Nest Structure and Shelter Strategies
When rain threatens, wasps close to home quickly return, while those farther afield seek temporary refuge. The structural engineering of their nests allows colonies to survive downpours.
Aerial Nests
Aerial nests, built from chewed wood fibers mixed with saliva, use this papery material as a water-resistant binder. The outer layer, or envelope, is designed to shed water, protecting the inner cells where larvae reside. The entrance is often oriented downward, preventing water from pooling inside. Paper wasps, whose nests are more open, often build them under protected locations like eaves or dense foliage to avoid direct exposure.
Subterranean Nests and Individual Shelter
Subterranean nests, commonly built by yellow jackets, offer excellent protection from rain, as the surrounding soil acts as a natural barrier. However, these nests are susceptible to flooding during prolonged or extremely heavy rainfall. Individual wasps caught out in the open seek temporary shelter under large leaves, tree bark, or in protected crevices until the rain subsides.
Post-Rain Foraging and Survival
Once the rain stops and surfaces begin to dry, wasps resume foraging. The rain’s passage impacts their environment, creating both challenges and opportunities for the colony. One effect is the temporary disruption of chemical communication, as rain washes away the pheromone trails wasps use to navigate and communicate about food sources.
Heavy rain also affects the wasps’ food supply, both prey and carbohydrates. It may destroy or saturate soft-bodied prey insects, such as caterpillars, reducing the available protein for feeding larvae. Nectar and honeydew sources, which provide carbohydrate energy, can also be washed away or diluted. While adult wasps are generally not killed by rain directly, the interruption to foraging impacts the colony’s growth and health. The temporary scarcity of resources can lead to increased competition among foragers once the weather clears.