Hornets are a type of social wasp, and while many people associate their nests with trees or building eaves, some species do establish their homes underground. This subterranean nesting behavior offers specific advantages, providing insulation and protection from external threats. Understanding which hornets nest underground and how to identify their nests is key to safely coexisting with these insects.
Hornets That Nest Underground
While many hornets build aerial nests, the European hornet (Vespa crabro) is a species that occasionally nests in the ground. These hornets often seek out existing cavities for their nests, such as old rodent burrows, tree hollows, or even voids within walls that extend underground.
European hornet nests are constructed from a paper-like material, which they create by chewing wood fibers and mixing them with saliva. Inside these hidden cavities, the hornets build multi-tiered combs where the queen lays eggs and the colony develops. Though European hornets prefer nests six feet or more above ground, their presence in subterranean spaces is a notable exception. Yellowjacket species, often mistaken for hornets due to their similar appearance and aggressive nature, are much more notorious for building extensive nests underground.
Identifying Ground Nests
Recognizing a hornet ground nest requires observing visual cues and patterns of activity. A clear sign is a single, distinct entrance hole in the ground, often one to one and a half inches wide. This hole may be surrounded by a small, conical pile of loose soil. Hornets will have a defined flight path to and from this entrance.
Observing activity around the hole provides further confirmation. A steady stream of hornets flying in and out, especially during mid-day, suggests a thriving colony below. While hornets are generally not aggressive unless provoked, an increased number foraging in an area can signal a nearby nest. Ground nests are commonly found in lawns, flower beds, under shrubs, near tree roots, or in abandoned rodent burrows.
Safety Precautions Around Ground Nests
If a ground nest is discovered, remain calm and avoid disturbing it. Moving away slowly and deliberately, without sudden movements, prevents alarming the hornets. Disturbing a nest can trigger a coordinated defensive attack, as hornets release alarm pheromones that lead to multiple stings. Unlike bees, hornets can sting repeatedly, and their venom can cause significant pain, swelling, or even severe allergic reactions.
Attempting to remove a ground nest without professional assistance is not recommended due to the aggressive nature of hornets when threatened. Pest control professionals have the necessary equipment, protective gear, and expertise to safely manage hornets. They can apply targeted treatments, often at night when hornets are less active and inside the nest, to eliminate the colony. Prevention measures include wearing closed-toe shoes when gardening and being aware of surroundings, especially in areas with dense vegetation or potential burrow sites.