The presence of ground-nesting insects, often called “underground bees,” can appear in high-traffic areas of the lawn or garden. These insects can be either beneficial, non-aggressive solitary bees or highly defensive, social wasps. Safe and effective removal or management of the nest begins with accurately identifying the occupant and understanding the associated risk.
Identifying the Insect and Assessing Risk
The first step in determining the correct course of action is distinguishing between a benign solitary bee and an aggressive social wasp like a yellow jacket. Solitary ground-nesting bees, such as mining bees, are typically active for only a few weeks in early spring and pose no threat to people or pets. A solitary bee nest entrance is a small, pencil-sized hole, often surrounded by a mound of excavated soil. Activity is characterized by a single female bee flying in and out of her individual burrow.
Yellow jackets are highly social insects whose colonies can contain hundreds of individuals and will aggressively defend their territory. Their nest entrance is usually a single, larger hole, often the size of a silver dollar, with continuous, heavy air traffic. If you observe a steady stream of insects entering and exiting one large opening, assume it is a yellow jacket nest and maintain significant distance, as any disturbance can trigger an attack. Never attempt to seal the hole during the day, as this will force the insects to chew a new exit, potentially into a nearby structure.
Gentle Removal and Exclusion Methods
If identification confirms the presence of solitary ground-nesting bees, the least disruptive approach is best, as they are beneficial pollinators and temporary residents. Ground bees prefer to nest in areas with bare, well-drained soil, such as where the grass is sparse or the soil is sandy. Since the nesting period is usually only four to six weeks, avoiding the immediate area during this time is the simplest solution.
A simple environmental modification is to increase the soil’s moisture content, as ground nesters avoid damp conditions. Gently soaking the immediate area around the nest entrances with a hose in the evening, when the bees are less active, encourages them to relocate. Passive exclusion can also be employed by covering the area with a dark sheet of plastic or a layer of mulch, creating a physical barrier. If the bees are nesting in a bare patch of lawn, overseeding the area with grass seed will eliminate the exposed soil, discouraging future nesting.
When to Use Insecticidal Dust or Call a Professional
When the insect is identified as an aggressive social species, such as a yellow jacket, or if the nest is too large or located in a high-risk area, an escalated intervention may be necessary. The most effective method for yellow jacket ground nests is the targeted application of an insecticidal dust, not a liquid spray. The powder is easily carried deeper into the nest by returning wasps, contaminating the entire colony.
The application should be performed well after dark, ideally 10 p.m. or later, when all foraging wasps are inside the nest and dormant. Approach the nest entrance cautiously, wearing comprehensive protective gear, including a bee veil, long sleeves, gloves, and pants. Use a flashlight covered with red cellophane, as insects cannot see red light. Apply the dust directly into the hole and quickly retreat without sealing the entrance, allowing the wasps to pass through the treated dust.
A homeowner must call a licensed pest control professional if the risk of an accidental sting is too high. Professionals are necessary in several situations:
- If anyone in the household has a known allergy to stings.
- If the nest entrance is in a difficult-to-reach location, such as under a deck or porch foundation.
- If the nest is located immediately next to a doorway or high-traffic walkway.
- For very large or aggressive nests that have been active for an extended period, making a DIY attempt too dangerous.
Preventing Reinfestation
After the current infestation is managed, taking steps to make the area unappealing for future ground nesters is important. Eliminate evidence of the previous nest by filling in old holes with soil and tamping it down firmly. Ground-nesting insects are opportunistic and will often reuse existing burrows or choose areas with easily accessible soil.
Focusing on the health and density of the lawn will naturally deter these insects, as they prefer areas with sparse vegetation. Mow your grass at a proper height to encourage a thick, dense turf that physically blocks access to the soil surface. Ensuring the lawn receives adequate water, about one inch per week, will also make the area less desirable, as ground nesters avoid moist earth. Finally, eliminate debris such as leaf litter, fallen branches, or loose mulch, which can provide sheltered starting points for a new nest.