Yellow jackets (Vespula and Dolichovespula species) are highly social wasps known for their aggressive defense of their colony and their distinctive black and yellow markings. Their nests are often hidden from view, making understanding their structure key to identification and avoidance during warmer months. These insects build annual colonies that expand rapidly, creating a need for a functional, secure entrance for the thousands of workers that emerge throughout the season.
The Standard Yellow Jacket Nest Structure
Yellow jacket nests are typically characterized by having only one functional entrance or exit hole. This single opening serves as the main point of traffic for all foraging workers and is usually no larger than a nickel in diameter, especially in subterranean nests. The entire nest is encased in a brittle, paper envelope, which the wasps construct by chewing wood fibers and mixing them with their saliva to create a papier-mâché material.
Inside the protective outer shell, the nest contains multiple horizontal tiers of combs, which are rows of hexagonal cells used to raise the brood. The entire structure is completely enclosed, except for the small passage used by the colony. The perception that a nest might have two entrances often arises from misidentification or damage, where a secondary hole is created by an animal or human activity. While damage or tunnel collapse can create another opening, the wasps themselves deliberately construct only a single, heavily guarded access point.
Common Nest Locations
The location of a yellow jacket nest significantly influences how visible its single entrance becomes. Most species, like the Eastern Yellowjacket, primarily build their nests underground, often utilizing an existing cavity such as an abandoned rodent burrow or a deep tree root system. This practice allows the wasps to expand their paper structure within the protected confines of the soil cavity.
Other species, such as the German Yellowjacket, frequently establish their colonies in protected, structural voids. These aerial locations can include spaces within wall voids of buildings, attics, hollow logs, or even dense shrubbery. In these instances, the entrance might be a small crack in a foundation, a gap under a deck, or a hole in a tree, with the wasps lining the opening and tunnel with their gray, paper-like material.
Distinguishing Yellow Jacket Nests from Hornet Nests
The appearance of a yellow jacket nest differs considerably from those built by other common wasps, such as the Bald-faced Hornet, which is technically a type of aerial yellow jacket. Yellow jacket nests are usually hidden, either beneath the ground or concealed within a cavity, making them difficult to spot until activity increases. In contrast, Bald-faced Hornet nests are nearly always exposed, appearing as large, gray, teardrop or football-shaped structures hanging from tree branches or building eaves.
The paper material itself also offers a clue to the builder. Yellow jacket paper is often relatively brittle and can range in color from tan to red-orange, depending on the wood source used for construction. Hornet nests tend to be thicker and grayer in color, though both types are created from chewed wood pulp mixed with saliva. Yellow jackets are also generally smaller than hornets, typically measuring around a half-inch in length, and they exhibit a distinct, rapid, side-to-side flight pattern before landing.
Seasonal Nest Development and Size
Yellow jacket nests are annual, meaning they are started each spring by a single fertilized queen, and the entire colony typically dies off with the first hard frost. The queen initiates the nest by building a small paper structure and laying the first eggs, feeding the initial brood herself. Once the first generation of infertile female workers emerges, they take over the tasks of foraging, nest expansion, and brood care, allowing the queen to focus solely on laying eggs.
The colony rapidly expands throughout the summer, reaching its maximum size and population density in late summer or early fall. A mature, seasonal nest in temperate regions commonly contains between 4,000 and 5,000 workers and up to 15,000 brood cells. The physical size of the nest can reach that of a basketball by the end of the season. In certain warmer climates, however, some species can form perennial colonies that survive the winter, sometimes growing to harbor over 100,000 workers.