While many wasp species are known for aerial nests, a considerable number establish their homes beneath the ground. These subterranean dwellers often spark interest due to their concealed nature, contrasting sharply with visible paper structures. Understanding these hidden populations reveals a diverse group of insects with unique behaviors.
Identifying Ground-Nesting Wasps
Yellowjackets
Yellowjackets, including the Eastern Yellowjacket and German Yellowjacket, are well-known ground nesters. Eastern Yellowjackets (Vespula maculifrons) are about 0.5 to 0.7 inches long, with black and yellow bands on their abdomen, and often take over abandoned rodent burrows for their nests. German Yellowjackets (Vespula germanica) are similar in appearance and size, and can also nest in wall voids. Both types of yellowjackets are social insects, living in large colonies that can contain thousands of individuals. They are recognizable by their rapid, side-to-side flight pattern before landing.
Solitary Ground Wasps
Another notable ground-nesting wasp is the Cicada Killer. These are large, solitary wasps, with females measuring approximately 1.5 to 2 inches in length. They have a reddish-brown thorax, a black abdomen with bright yellow bands, and reddish-amber wings. Cicada Killers are often seen in late summer, particularly in areas with well-drained, sandy soil and abundant cicada populations, which they hunt to provision their young.
Digger Wasps, a broader category, also frequently create underground nests. These solitary wasps vary in appearance but are often black with yellow or red markings and can be up to 1.5 inches long. Many species of digger wasps are named for their female’s behavior of burrowing into dry dirt to create nests.
Recognizing Their Nests
Identifying a ground wasp nest typically involves observing specific signs of activity rather than seeing a visible structure. The most common indicator is a small hole in the ground, usually less than an inch and a half in diameter, which serves as the main entrance and exit point for the wasps. This opening can often be found in abandoned rodent burrows, under rocks or logs, or in areas with loose soil, particularly in sunny spots. Around the entrance, there may be a small mound of excavated dirt, sometimes described as horseshoe-shaped or conical, indicating the wasps’ digging activity.
Activity levels around the nest entrance are also a strong clue. Wasps are most active during the day, so observing them repeatedly flying in and out of a specific spot signals a nest. While many ground-nesting wasps are solitary, social species like yellowjackets may have multiple entrances or burrows in a single area, creating a busy hub of activity. The actual nest structure, composed of interconnected tunnels and chambers, remains hidden beneath the surface.
The Advantage of Underground Homes
Nesting underground offers several benefits for wasp survival and the success of their colonies. The subterranean environment provides natural protection from many predators that might otherwise target exposed nests. The earth acts as an insulating barrier, helping to maintain stable temperatures within the nest, shielding the developing young from extreme heat in summer and cold in winter. This thermal stability is important for larval development.
Underground nests also benefit from consistent humidity levels, which are less prone to fluctuations than above-ground environments. This stable moisture helps prevent the desiccation of eggs and larvae. The surrounding soil provides structural stability, protecting the nest from wind, rain, and other environmental disturbances that could damage exposed structures. These factors collectively create a secure and favorable microclimate, allowing the wasp colony to thrive.