Hornets are large, social insects belonging to the wasp family, typically known for building papery nests. While many people associate hornet nests with trees or building eaves, certain species and their close relatives can establish their colonies underground. Understanding which of these insects nest in the ground and how to identify their presence is helpful for safely navigating outdoor spaces.
Common Ground-Nesting Species
The European hornet (Vespa crabro) is the only true hornet species found in North America and can occasionally nest in the ground, though they more commonly prefer hollow trees or wall cavities. These large insects typically measure between 17 and 25 millimeters for workers, with queens reaching up to 35 millimeters. They have a reddish-brown body with yellow or orange markings, and their wings are often reddish-orange. European hornets aggressively defend their nest if threatened.
More commonly found nesting underground are yellowjackets, which belong to the genera Vespula and Dolichovespula. These wasps are frequently mistaken for hornets due to their similar yellow and black striped bodies. Yellowjacket workers are generally smaller than European hornets, typically measuring between 10 and 16 millimeters. While Dolichovespula species often build aerial nests, Vespula species show a stronger tendency to nest underground. Yellowjackets are known for their aggressive defense of their underground colonies, especially as the season progresses.
Another large insect often referred to as a “ground hornet” is the cicada killer wasp. These solitary wasps can be quite large, up to 5 centimeters in length, with black bodies and yellow markings, resembling yellowjackets. Unlike true hornets or yellowjackets, cicada killers are solitary and generally not aggressive unless directly provoked, such as by being stepped on. Female cicada killers dig tunnels in sandy soil to provision their young with paralyzed cicadas.
Identifying Ground Nests
Ground nests can be challenging to locate until activity around them increases. A common sign of a ground nest is a small, circular entrance hole in the soil, measuring about 2.5 to 3.8 centimeters in diameter. This hole may be surrounded by a conical or horseshoe-shaped mound of excavated dirt. Yellowjackets and some other ground-nesting wasps prefer sandy or loose soil for easier digging.
These nests are typically found in concealed locations, such as old rodent burrows, beneath tree roots, within dense vegetation, or even in cracks in foundations or sidewalks. Increased activity around the entrance can indicate an active nest. A buzzing sound might also be heard near the nest entrance, especially during periods of high activity. The presence of multiple such holes in a small area can also suggest a ground-nesting colony.
Safety Around Ground Nests
Encountering a ground nest requires caution, as these insects are aggressive when their colony is threatened. Unlike honey bees, hornets and yellowjackets can sting multiple times without dying. Their stings are painful and can cause severe reactions in allergic individuals. Disturbing the nest, approaching too closely, or blocking the entrance can trigger a defensive response and multiple stings.
If a ground nest is discovered, maintain a safe distance and mark the area to prevent accidental disturbance. Avoid shining direct light into the nest entrance, as this can attract the insects towards the light source. For large or inaccessible nests, or if anyone in the household has a known allergy to stings, contacting a professional pest control service is the safest option. Attempt removal during cooler hours, such as early morning or late evening, when insects are less active and most are inside the nest. Wearing thick, protective clothing is also recommended. If a nest is in an isolated area and poses no direct threat, leaving it undisturbed may be the best course of action.