Mining bees are a large group of native bees found across the world, also known as digger bees for their behavior of excavating tunnels for nests. Unlike social honeybees or bumblebees, mining bees are solitary. Each female builds her own nest and provides for her offspring without help from a queen or worker bees. They are a common sight in gardens and yards during the spring.
Identifying Mining Bees
Mining bees can be difficult to identify because they belong to a large group with many different species, such as those in the genus Andrena. They are about the size of a honeybee, though their length can range from 5 to 17mm. Their colors are often dark or metallic, and some may have faint, light-colored stripes on their abdomens. Compared to the fuzzy appearance of bumblebees, mining bees are less hairy.
One common species, the tawny mining bee (Andrena fulva), is notable for the female’s dense, fox-red coat, while males are smaller and less vibrant. Another example, the ashy mining bee (Andrena cineraria), is recognizable by its black body and two distinct grey hair bands. A distinguishing feature for some mining bees is the presence of grooves, called foveae, running down the inside of their eyes. Males can sometimes be identified by a patch of light, fuzzy hair on their face.
The Solitary Life and Nests of Mining Bees
Although each female mining bee builds and provisions her own nest, it is common to find many nests built close together. This behavior is more about tolerating neighbors than social cooperation, as each female tends only to her own burrow. These bees often return to the same nesting locations for many years.
The life cycle begins in the spring when a female bee emerges and mates. She then excavates a tunnel in the ground, often in areas with sparse vegetation or sandy soils. The entrance to this tunnel is marked by a small, volcano-like mound of soil with a single, pencil-sized hole in the center.
Inside the main tunnel, she digs several small chambers, or cells. Within each chamber, the female places a ball of pollen mixed with nectar. She then lays a single egg on top of this food provision and seals the chamber. This process is repeated until all her eggs are laid. The female bee dies after her work is complete, and the next generation develops entirely underground.
Mining Bees in Your Yard
Discovering dozens of small dirt mounds on a lawn can be alarming, but mining bees are gentle and beneficial insects. They are docile and rarely sting, as males do not have a stinger. Females possess a stinger but are not defensive of their nests and will only sting if physically handled or trapped against the skin.
The small mounds of excavated soil are a temporary sign of nesting activity. These piles do not harm the grass roots and provide a mild soil aeration benefit. The mounds and bee activity are present for only a few weeks in the spring and will disappear on their own. Given their gentle nature, the best course of action is to leave them undisturbed.
These bees prefer to nest in areas with thin turf and bare patches of soil. A healthy, thick lawn is a natural deterrent if their presence is unwanted. However, tolerating these temporary visitors supports a healthy local ecosystem.
The Role of Mining Bees as Pollinators
Mining bees are effective pollinators, playing an important part in their local ecosystems. They are among the first bees to emerge in the spring, making them important for the pollination of early-blooming plants. Their activity is timed with the flowering of many fruit trees, such as apple, cherry, and pear, as well as blueberries and other shrubs.
Beyond fruit crops, they pollinate a wide variety of spring wildflowers. Some mining bee species are specialists, meaning they have evolved to pollinate only a single type of flowering plant. Their presence in a garden is an indicator of a healthy environment. It also contributes directly to the success of nearby flowers and food plants.