Yellow jackets are highly social wasps that construct elaborate, concealed nests to house their rapidly growing colonies. They are known for aggressively defending their home, which often brings them into conflict with people as the warm months progress. Understanding their construction habits, life cycle, and physical characteristics is key to minimizing unwanted encounters with these stinging insects.
Identifying the Builders
Yellow jackets are easily identifiable by their bright yellow and black striping, which gives them a distinctly bold appearance. Unlike bees, which have hairy bodies and thick waists, yellow jackets possess a smooth, glossy body with a narrow constriction between the thorax and abdomen. The typical worker measures between 10 and 15 millimeters long, with the queen being slightly larger at about 19 millimeters.
They exhibit a fast, darting flight pattern, especially when approaching a food source. These wasps are predatory, hunting other insects to feed their larvae, but they also scavenge aggressively for sugary substances and proteins near human activity, such as at picnics or garbage bins. Female workers have a lance-like stinger with small barbs, allowing them to sting repeatedly, which contributes to their reputation for aggression.
Where Yellow Jackets Build Their Nests
Yellow jacket species are categorized based on their preferred nesting location, primarily falling into subterranean or aerial groups. The subterranean-nesting species, such as the Eastern yellow jacket, are the most common and often build their nests underground. They frequently select pre-existing cavities like abandoned rodent burrows, hollows near tree roots, or spaces beneath concrete steps and patios, making the nest entrance hard to detect.
The colony excavates the surrounding soil to enlarge the cavity as the population grows, sometimes creating a chamber that can reach the size of a basketball or larger. Aerial species, like the Aerial yellow jacket, build exposed paper nests in trees, shrubs, or on the sides of structures. Yellow jackets also readily establish nests in protected man-made structures, including wall voids, attics, and crawlspaces, using the insulation and enclosed space for protection.
Anatomy of a Yellow Jacket Nest
The nest is a complex structure built from a paper-like material created by chewing wood fibers and mixing them with saliva. This papier-mâché mixture dries into a brittle, layered envelope that provides insulation and protection for the colony. The color of the paper can vary, often appearing gray or beige, depending on the source of the cellulose the workers collected, such as weathered wood from fences or decks.
Inside this protective shell, the nest is organized into multiple tiers of horizontal combs suspended within the cavity. These combs are composed of thousands of hexagonal cells, similar to those of honeybees but made from paper instead of wax. The queen lays her eggs in these cells, where the larvae develop and are fed by the workers until they pupate under a small cap.
The Annual Life Cycle of a Colony
Yellow jacket colonies are annual, meaning they are active for only one season and do not survive the winter. The cycle begins in the spring when a single fertilized queen emerges from her overwintering location, having spent the cold months in a protected spot like a hollow log or under leaf litter. She starts a small nest and lays her first batch of eggs, initially foraging and caring for the larvae herself.
Once the first generation of sterile female workers emerges, they assume the duties of foraging, nest expansion, and caring for the young, allowing the queen to focus solely on laying eggs. The colony population expands rapidly throughout the summer, often peaking in late summer or early fall with thousands of workers and a nest containing up to 15,000 cells. As the season ends, the queen produces a final generation of males and new queens, which mate before the workers and the old queen die off with the onset of cold weather. The newly mated queens then find a secluded place to hibernate, ensuring the cycle begins anew the following spring.