Wasps, known for their aerial paper nests, also build homes beneath the earth’s surface. This subterranean nesting is common among several species, posing challenges for those who encounter them. Understanding which wasps nest underground, how to identify them, and how to manage these hidden nests is important for homeowners and outdoor enthusiasts.
Wasps That Nest Underground
Many wasp species nest in the ground, some solitary and others forming social colonies. Yellow jackets (Vespula and Dolichovespula genera) are common social ground-nesting wasps, often taking over abandoned rodent burrows or other cavities in the soil. These social insects create a papery nest structure within the underground void. Their colonies can grow to thousands of individuals, especially by late summer and early fall. Their aggressive nature, particularly when their nest is disturbed, makes them a concern.
Solitary ground-nesting wasps, such as cicada killers (Sphecius speciosus) and digger wasps, also burrow into the soil. Female solitary wasps excavate tunnels to lay their eggs and provision them with paralyzed prey for their offspring. Unlike yellow jackets, these solitary species typically do not defend a large colony, making them generally less aggressive towards humans unless directly provoked or handled. Digger wasps often prefer sandy or light soil for their burrows, sometimes creating numerous nesting holes in a concentrated area.
Identifying a Ground Nest
Identifying an active ground wasp nest involves observing specific behaviors and physical signs. The most telling indicator is a small, inconspicuous hole in the ground, often resembling a mouse hole or a divot, through which wasps consistently fly in and out. This entrance may be surrounded by a small mound of excavated soil, particularly with yellow jackets and solitary digger wasps. The hole itself is typically less than an inch in diameter for many species.
Observing the flight pattern of wasps entering and exiting the hole confirms a nest’s presence. Wasps fly directly into and out of the entrance in a steady stream, especially during warmer parts of the day. While the subterranean nest structure remains hidden, this constant activity around a single ground opening is a strong clue. Ground wasps often prefer dry soil for easier digging, so nests are often found in such locations.
Safe Conduct Around Ground Nests
Encountering a ground wasp nest requires caution, as these insects are highly defensive. Maintaining a safe distance, ideally at least 5 to 6 feet, is important to avoid provoking them. Sudden movements or vibrations near the nest, such as from lawn equipment, can trigger an aggressive response and multiple stings. Advise children and pets to stay away from suspected nesting sites.
If a ground nest is accidentally disturbed, move away slowly and calmly to avoid further agitation. Unlike honeybees, wasps can sting repeatedly and may release an alarm pheromone that attracts other wasps to attack. If stung, wash the area with soap and water, apply a cold compress to reduce swelling, and consider over-the-counter pain relievers or antihistamines. Individuals with known allergies should carry an epinephrine auto-injector and seek immediate medical attention if stung.
Addressing a Ground Nest
When addressing a ground wasp nest, safety is the primary concern. Professional pest control is often the safest option, especially for large or aggressive colonies, or if anyone in the household has a severe allergy. Professionals have the expertise and equipment to safely locate and remove nests. For smaller, less active nests, or if professional help is unavailable, some DIY approaches can be considered.
Applying insecticidal dust directly into the nest entrance during the evening, when wasps are less active, is a common method. Wasps carry the dust into the nest, affecting the colony. Alternatively, a mixture of dish soap and water poured into the nest can suffocate them. Avoid dangerous methods like pouring gasoline or blocking the entrance, as these can be ineffective, hazardous, or cause wasps to seek alternative exits, potentially into a home. Preventing future nests involves maintaining a clean yard, covering garbage cans, and filling abandoned rodent burrows in the spring.