Ground bees are a diverse group of native insects, representing nearly 70% of all bee species. They share the common trait of nesting in subterranean burrows rather than in trees or above-ground cavities. These solitary species, which include Mining Bees (Andrena), Digger Bees, and Sweat Bees (Halictidae), are a common sight in lawns and gardens during the spring and summer months. The sight of small soil mounds and buzzing insects often prompts concern about their potential for aggression and the threat they may pose to people and pets.
Identifying Ground Nesting Bees
Properly identifying the insect is the first step in determining the level of threat, as solitary ground-nesting bees are frequently mistaken for aggressive social wasps. Solitary ground bees are typically small, measuring between 1/4 and 3/4 inches long. They possess a fuzzy appearance with a robust, “puffed-out” silhouette. Many species are black or brown with fine hair, though some Sweat Bees exhibit a noticeable metallic sheen of green or copper.
The structure of the nest provides the clearest distinction from social insects like Yellow Jackets (Vespula), which also nest underground. Solitary ground bees create individual burrows, with each female constructing her own tunnel. This results in numerous small, volcano-like mounds, each with a single entrance hole. Conversely, a colony of aggressive, ground-nesting Yellow Jackets will utilize a single, large entrance hole to serve hundreds of individuals. Yellow Jackets are hairless and have a vivid yellow color and a narrow waist.
Threat Level and Stinging Behavior
The threat level posed by solitary ground bees is low because they do not have a hive or colony to defend. Unlike social bees and wasps, which mount a mass defense to protect their queen and stored resources, a solitary female focuses only on provisioning her individual nest. Her lack of defensive instinct means she is highly unlikely to sting unless she is directly handled or physically provoked.
Stings occur almost exclusively in defensive circumstances, such as when a person or pet accidentally steps directly on a bee or crushes it. Furthermore, the male bees, often seen flying rapidly and patrolling nesting sites in search of mates, are physiologically incapable of stinging because they do not possess a stinger. Although female ground bees are equipped with a stinger, they are generally docile and use it only as a last resort when their life is threatened.
Safe Coexistence and Nest Management
Given their non-aggressive nature, the preferred approach to managing ground bees is safe coexistence. This is encouraged by their status as beneficial pollinators. These native bees are important early-season pollinators for numerous plants and crops, including blueberries and apples. Their burrowing activity also helps aerate the soil. Since they are active for only a few weeks in the spring before the next generation develops underground, their presence is temporary.
If nesting occurs in a high-traffic area, non-lethal measures can encourage them to relocate. Ground bees prefer to excavate their nests in dry, well-drained, and sparsely vegetated soil. Changing these soil conditions is the most effective deterrent. This can be accomplished by regularly watering the area during their active season to keep the soil moist.
Covering the bare ground with a dense layer of mulch or establishing thick turf also makes the area unsuitable for nesting females. Attempting to kill the bees with broad-spectrum pesticides is discouraged, as this harms beneficial pollinators. Furthermore, pesticides are often ineffective since more bees will return the following season if the soil conditions remain favorable. If aggressive behavior and a single-entrance nest strongly suggest a social species like a Yellow Jacket, a pest control professional should be contacted for targeted removal.