Yellow jackets belong primarily to the genera Vespula and Dolichovespula, known for their distinctive yellow and black markings. These insects form annual colonies where thousands of workers cooperate to forage for food and protect the nest. Understanding where these colonies establish their homes is important for avoiding accidental disturbance. Yellow jacket nesting habits range from concealed subterranean chambers to prominent structures built high above the ground.
The Primary Nest Location: Subterranean Structures
Most yellow jacket species, particularly those in the genus Vespula, create their colonies in concealed, subterranean locations. The queen typically initiates the nest in the spring by utilizing an existing cavity rather than excavating a new one. These sites frequently include abandoned rodent burrows, voids created by decaying tree roots, or spaces beneath concrete steps.
The colony entrance is often just a small, single hole in the ground, sometimes only the size of a dime, making the nest difficult to detect until activity is high. Inside the cavity, the wasps construct their nest from a paper-like material called carton, produced by chewing wood fibers and mixing them with saliva. This material forms multiple horizontal combs encased within a protective, layered envelope.
Subterranean nesting offers significant advantages, providing temperature regulation and protection from predators. The surrounding soil acts as a natural insulator, which helps maintain the stable warmth necessary for the rapid development of the wasp larvae. The Eastern Yellowjacket (Vespula maculifrons) and the Western Yellowjacket (Vespula pensylvanica) are examples of species that commonly exhibit this ground-nesting behavior.
Aerial Nests and the Species That Build Them
Yellow jackets build nests above ground, which is the primary habit for a distinct group of species. Wasps in the genus Dolichovespula, including the Aerial Yellowjacket (D. arenaria) and the Bald-faced Hornet (D. maculata), are specialized aerial nesters. These species construct their nests in exposed locations, often suspending them from tree branches, dense shrubs, or under the eaves of buildings.
The construction of an aerial nest involves workers gathering wood fibers from weathered wood, which they chew and mix with saliva to create a light, durable paper pulp. This pulp hardens into a complex, multi-layered envelope that completely surrounds the internal tiered combs. The entire structure is typically round or pear-shaped and is securely attached to its anchor point.
In addition to exposed, hanging nests, other yellow jacket species, most notably the German Yellowjacket (Vespula germanica), frequently build aerial nests inside structural voids. These hidden locations include wall cavities, attics, soffits, and hollow trees, which provide a protected, above-ground environment. The size of these aerial structures can grow quite large by the end of the season, sometimes reaching the size of a basketball or larger.
Visual Differences Between Ground and Aerial Nests
The most obvious distinction between the two types of yellow jacket colonies lies in their location and visibility. Ground nests are inherently concealed, with the entire structure hidden within a soil cavity, meaning the observer only sees the entrance point. This entrance is characterized by a constant stream of wasps entering and exiting a small, often inconspicuous hole in the earth.
In contrast, an exposed aerial nest is a fully visible, distinct structure suspended from a tree or shrub. The paper envelope surrounding the nest is clearly identifiable, often having a smooth, clean gray appearance, particularly on the nests of species like the Bald-faced Hornet. Nests built inside structural voids, such as those made by the German Yellowjacket, are less visible, but the wasps will be seen entering and exiting a single opening on a building’s exterior.
The material and color of the exposed envelope can also provide clues, though both types are made of chewed wood fiber. Subterranean nests, which are constantly in contact with soil and moisture, may have a darker, dirtier, or less uniform texture. Aerial nests often feature a clearer, more defined papery texture, though the specific color can vary based on the type of wood the wasps utilized.
The entrance to the envelope is a structural difference. Exposed aerial nests typically have a clearly defined entrance hole located on the bottom surface of the outer paper shell. Conversely, the subterranean nest has no exposed envelope; the single entrance is the opening through the ground that leads into the hidden cavity below.