Wasps are common, and their nesting habits vary significantly. While some species build visible nests, others prefer to remain hidden underground. Understanding these diverse nesting preferences is important for safely navigating areas they inhabit.
Wasps That Nest Underground
Many wasp species construct their nests beneath the ground. The most commonly encountered include yellow jackets, cicada killers, and various types of digger wasps. Each of these species exhibits distinct nesting behaviors and structures.
Yellow jackets are social wasps that frequently establish their colonies underground. Their nests, made of a paper-like material, are often built within existing cavities like abandoned rodent burrows, tree hollows, or wall voids. A single colony can expand significantly throughout the summer, potentially housing thousands of individual wasps by late autumn. These wasps can become highly defensive if their nest is disturbed.
Cicada killers are large, solitary wasps that are prominent ground nesters. Females excavate tunnels in the soil, which can extend about a foot deep and up to 70 inches in length. These burrows feature multiple chambers, each provisioned with paralyzed cicadas for their developing offspring. Their nest entrances are distinctive half-inch holes, often surrounded by a U-shaped mound of displaced soil. Unlike yellow jackets, cicada killers are generally not aggressive towards humans, reserving their sting primarily for their cicada prey.
Digger wasps, a broad group of solitary wasps, also create underground nests. Females dig individual burrows, sometimes reaching depths of 30 centimeters or more, with lateral branches leading to separate cells for their eggs. They often favor light or sandy soils in open areas or beneath vegetation for nesting. While some digger wasps nest in isolated locations, others may form aggregations of many individual burrows. These wasps are typically less aggressive than social wasps and will only sting if directly threatened.
Identifying Wasp Nests
Identifying a ground wasp nest requires careful observation of visual cues and wasp behavior. Unlike openly visible aerial nests, ground nests are hidden, often becoming noticeable only through activity around their entrance. Knowing what to look for helps distinguish these hidden nests from other types.
A primary indicator of a ground nest is a single, circular hole in the soil, usually one to two inches in diameter. This opening may be surrounded by a conical or U-shaped mound of excavated dirt, resembling a larger version of an anthill. Wasps will be seen consistently flying directly into and out of this specific hole.
Ground nests are commonly found in dry soil, as wasps tend to avoid excessive moisture. For social species like yellow jackets, activity around the entrance becomes more pronounced in late summer and early fall as colony populations peak. Yellow jackets may also utilize pre-existing burrows, such as old rodent holes, for nesting. In contrast, solitary digger wasps might create several individual holes spread across an area rather than a single communal entrance.
Distinguishing ground nests from aerial nests is straightforward. Aerial nests, constructed by wasps like paper wasps or bald-faced hornets, are visible structures made from a paper-like material of chewed wood fibers and saliva. These nests hang from eaves, tree branches, or other structures and have a distinct external appearance, such as an umbrella shape or an enclosed, egg-like form. Ground nests, conversely, lack this external papery structure, with only the entrance hole and surrounding soil providing clues to their location.