**Ground-Nesting Bees** is a general term referring to a diverse and very large group of native bee species that dig burrows in the soil to create their nests. This group includes numerous genera, such as **Digger Bees** (*Anthophora* spp.), **Mining Bees** (*Andrena* spp.), and **Sweat Bees** (*Halictidae* family). They are critically important, highly effective **pollinators** and are overwhelmingly non-aggressive and harmless, but their presence often causes concern when they emerge in large numbers in lawns or gardens.
Taxonomy and Classification
Ground-Nesting Bees belong to the order Hymenoptera. Most species are **solitary**—meaning each female digs and provisions her own individual nest burrow—though they may nest in dense aggregations or colonies in favorable soil. They undergo complete metamorphosis. Unlike honeybees and wasps, they are not social and therefore do not defend a collective hive or storage of food, making them reluctant to sting.
Physical Description
Ground-Nesting Bees vary greatly in size and appearance, from tiny metallic green Sweat Bees to large, hairy Digger Bees.
- **Appearance:** Often hairy, with varying colors from black to metallic green/blue to striped.
- **Nests:** Identified by small, distinct, volcano-shaped **mounds** of excavated soil, often with a clear, single entry hole in the center. These mounds appear suddenly in lawns, flower beds, or bare soil, usually in spring or early summer.
- **Behavior:** Females are busy collecting pollen and digging, while males fly erratically above the nesting area to find mates.
Distribution and Habitat
Ground-Nesting Bees are globally distributed and make up the vast majority of native bee species. Their preferred habitat is well-drained, sandy, or loamy soil, especially in areas with sparse vegetation, such as edges of gardens, sunny slopes, and thinly grassed lawns. They require specific flowering plants in the vicinity for pollen and nectar collection.
Behavior and Conflict
These bees are vital pollinators, often emerging for only a few weeks in the spring to complete their life cycle.
- **Pollination:** They are essential for the reproduction of native wildflowers and many fruit and vegetable crops.
- **Solitary Nature:** Since the female is only responsible for provisioning her own brood cell, she has no defensive impulse to protect the nest site or food source. The males lack stingers entirely.
- **Conflict (Nuisance):** The conflict is generally due to misidentification and fear. The appearance of dozens or hundreds of bees emerging simultaneously from the lawn is alarming, and the small mounds may be aesthetically undesirable in pristine lawns.
Management and Prevention
Control is strongly discouraged due to their beneficial role. The bees are usually present for only 3–6 weeks a year.
- **Tolerance (Recommended):** The safest and best approach is simply to tolerate their short presence. Mark off the nesting area and avoid walking through it barefoot during the few weeks of peak activity.
- **Habitat Modification:** If the bee activity is truly intolerable in a specific area, increasing ground cover density, watering the soil more heavily (they prefer dry, exposed ground), or applying a thick layer of mulch will discourage future nesting.
- **Chemical Control:** Applying insecticides to kill these beneficial pollinators is strongly opposed by ecologists and should be avoided at all costs.
Conservation and Research
Ground-Nesting Bees are high-priority species for pollinator conservation. Research focuses on habitat restoration, understanding the dietary needs of various species, and educating the public on their essential, non-threatening role in ecosystems.