Yellow jackets are a familiar sight during late summer and early fall. These social wasps, easily identified by their distinct yellow and black markings, are encountered outdoors. Their seasonal presence can sometimes lead to interactions with humans, making an understanding of their annual patterns valuable for those who spend time outdoors.
Understanding the Yellow Jacket Life Cycle
A yellow jacket colony begins anew each spring with a single fertilized queen emerging from hibernation in a protected location, such as a hollow log or under tree bark. She constructs a small paper nest from chewed plant fibers and lays her initial batch of eggs. These first offspring develop into sterile female workers, which then take over the tasks of foraging, nest expansion, and caring for the queen and subsequent larvae.
Throughout the summer, the colony grows rapidly, with the queen laying eggs and workers expanding the nest and gathering food. By late summer, a single colony can reach its maximum size, sometimes containing thousands of workers and nest cells. This peak in population coincides with the production of new reproductive individuals: males and future queens.
Environmental Cues for Colony Collapse
The annual yellow jacket colony’s decline depends on colder temperatures. Most worker yellow jackets and the founding queen perish with the first hard frosts of autumn. This temperature drop, often around 50°F, slows their activity, ending the colony’s life cycle. In warmer climates, nests can occasionally persist longer, potentially growing to enormous sizes if temperatures remain above freezing.
A decline in available natural food sources, such as nectar and other insects, also contributes to the colony’s collapse. As the season progresses, the queen stops laying eggs, resulting in fewer larvae. Larvae typically produce a sugary substance that adult workers consume, and without this internal food source, the workers must forage more widely for external sugars. The newly fertilized queens, however, seek sheltered spots to overwinter to continue the species next spring. The old nest is then abandoned and decomposes, as it is not reused.
Late Season Yellow Jacket Behavior
Yellow jackets often appear more aggressive in late summer and early fall. This heightened activity stems from several changes within the colony and its environment. The social structure of the colony begins to break down as the season progresses, and the workers no longer have larvae to feed protein to.
With the queen ceasing egg production, the workers lose their primary source of carbohydrates. This shift causes them to seek out readily available sugar sources, leading them to human food and drinks, especially sweet items. Their desperation for food can make them more prone to stinging. They can also become more aggressive when disturbed.
Coexisting with Yellow Jackets as Their Season Ends
To minimize encounters with yellow jackets in late summer and early fall, take precautions. When eating outdoors, covering all food and drinks is effective, particularly sugary items and meats, which are strong attractants. Promptly clean spills and secure outdoor garbage bins with tight-fitting lids to deter scavenging.
Avoiding strong scents like perfumes and brightly colored clothing, which can resemble flowers, may reduce their attraction to individuals. Maintain distance from known nesting areas, as disturbing a nest can provoke a defensive swarm. If a yellow jacket lands on you, remaining still allows it to fly away; swatting can trigger a sting.