As a University of Georgia Extension agent, each spring I receive several calls from people who encounter ground-nesting bees and wasps for the first time.
These are actually “good bugs” that are doing their job as pollinators or serving as useful predators by controlling other harmful insect pests. But when ground nests are located in areas such as yards, gardens, flowerbeds or playgrounds, most clients would rather not hear a discourse in entomology.
There are more than 3,500 species of solitary bees in North America. The most common ground-nesting bees and wasps we see include bumble bees (those “giant” ones), sweat bees, digger bees, leafcutting bees, digger wasps and cicada killer wasps.
Most bees aren't aggressive
All of these ground-nesting bees and wasps are curious and investigate people and pets near their burrows. This is probably what you would do if someone walked onto your front porch, right? Generally, these bees do not present a stinging hazard and do not defend their nest territory aggressively — unlike their yellow jacket and honeybee cousins who are more easily provoked.
With the exception of yellow jackets, most ground-nesting bees and wasps are solitary. This means only one female works and lives alone in each underground nest. However, multiple solitary nests can be found in an individual back yard or lawn. These neighborhood-like communities are what make them appear to be “swarming” around.
I’m often asked, “Why do certain back yards or lawns seem to have more ground-nesting bees than others?”
Sunny spots with well-drained soil
According to most entomologists, these yards are more attractive because they have an environment that these bees prefer. Ground-nesting bees generally nest in areas with morning sun exposure and well-drained soils containing little organic matter. Burrows are excavated in areas of bare ground or sparse vegetation.
The best control methods include heavy watering or irrigation with a lawn sprinkler during the nest-building period to discourage nest construction. Tilling the soil to destroy tunnels may help a little but establishment of a dense turfgrass is probably the best long-term discouragement to further nesting. Applications of heavy organic matter could be included as a soil amendment, if practical, when tilling the soil.
If the soil or location is not conducive to a healthy lawn, installing ground covers or heavy mulches may be an alternative solution. Mulches may be used on bare patches where grass will not grow.
Spraying pesticides is futile
Chemical pesticide applications are not generally practical because each individual nest cell or colony would require treatment in order to entirely remove the bees. If possible, try to identify which type of bee you have before reaching for the bug spray.
For aggressive bees and wasps - like yellow jackets - this may be your only option, but remember most ground-nesting bees and wasps are “good bugs.” They have a very important, valuable function in landscapes: pollinating and getting rid of bad bugs.
For some crops, bumblebees and other native bees are more efficient pollinators than managed honeybees. It’s estimated that one of every three bites of food you eat depends on pollination by bees. In fact, 90 percent of all commercially grown field crops depend on pollination for growth.
So, instead of destroying these valuable insects, take a moment to appreciate their importance and respect their place in nature.