The term “sand bee” generally refers to various species of native, ground-nesting solitary bees, such as mining bees (Andrena species) or cellophane bees (Colletes species). Unlike honeybees or yellowjackets, these insects do not form large, aggressive colonies, but rather, individual females excavate their own nests in the soil. This article provides guidance for safely managing the presence of these beneficial insects when their nesting sites conflict with human activity. The goal is to address immediate concerns while outlining long-term, non-chemical strategies for encouraging them to relocate.
Identifying Sand Bees and Assessing Risk
Recognizing ground-nesting bees is the first step in determining the appropriate response, as they are often confused with more aggressive social wasps. These bees are typically small to medium in size, ranging from about a quarter-inch to a half-inch long. They often appear hairy with drab coloring like black and brown bands, though some species exhibit a metallic green or blue sheen.
Their nesting activity is characterized by small, volcano-shaped mounds of excavated soil, each featuring a single, pencil-sized hole that leads to an individual burrow. Because of their solitary nature, ground-nesting bees are non-aggressive and will rarely sting unless physically handled or accidentally crushed. The buzzing activity observed close to the ground usually involves the males, which lack stingers entirely. Their active season is also relatively short, lasting only a few weeks in the early spring or summer.
Environmental Factors Attracting Ground Nests
Ground-nesting bees are highly selective about their nesting environment, seeking specific soil and exposure conditions that optimize the survival of their young. They exhibit a strong preference for soil that is sandy, loose, and well-drained, which allows for easy excavation of their deep, individual tunnels. This type of substrate provides the necessary texture for creating stable brood cells.
The presence of bare patches of earth or areas with sparse vegetation significantly increases the likelihood of nesting. Dense turf or thick ground cover physically blocks access to the soil surface, making burrowing difficult. Furthermore, these bees prefer sites that receive full sun exposure, as the increased soil temperature helps regulate the development of the larvae within the underground brood cells.
Safe and Effective Control Strategies
Immediate management of an active nesting site should prioritize non-lethal methods, especially given the short nesting season. One effective, non-chemical deterrent is heavy and consistent irrigation of the affected area, as ground bees prefer dry soil. Soaking the soil thoroughly in the evening, when the bees are less active and inside their tunnels, can encourage the females to abandon their current nests and relocate elsewhere. Another passive technique is to temporarily cover the nesting area with a heavy layer of landscape fabric, straw, or a temporary barrier like a tarp until the nesting cycle is complete.
Non-Chemical Application
For a more direct, non-chemical approach, targeted application of natural products can be used at the burrow entrances. Diatomaceous Earth (DE), a fine powder made from fossilized algae, can be sprinkled around the holes. The microscopic, sharp edges of the particles abrade the bee’s exoskeleton upon contact, leading to dehydration.
Targeted Lethal Control
If immediate, lethal control is deemed necessary, only highly targeted methods should be employed to minimize harm. Applying an insecticidal dust or aerosol spray directly into the burrow entrance at dusk or dawn, when the bees are inside, is the most precise method. For large aggregations in high-traffic areas, or if you are unsure of the species, consulting a licensed pest control professional is advisable to ensure safe and effective treatment.
Modifying Habitat for Long-Term Prevention
The most sustainable way to prevent the return of ground-nesting bees is to structurally alter the environmental conditions that attracted them. These preventative measures focus on eliminating the bare, dry, and loose soil that they require for successful burrowing. Increasing the soil moisture through regular watering makes the ground harder to excavate and less hospitable for larval development.
A fundamental change involves covering any exposed soil surfaces across the property. Applying a thick layer of organic mulch, such as wood chips or compost, or installing landscape fabric acts as a physical barrier against burrowing. For thin or patchy lawn areas, overseeding with grass seed and maintaining a dense turf through proper fertilization and watering will discourage future nesting. By eliminating the patches of bare earth, the yard becomes undesirable for the next generation of bees.