When colder temperatures arrive, many wonder about the fate of ground bees, insects often seen in lawns and gardens. Do they perish with the onset of winter, or do they possess a unique survival strategy? Understanding their annual cycle reveals how they endure the harshest months and prepare for spring.
Understanding Ground Bees
“Ground bee” is a general term encompassing various bee species that construct their nests in the soil. This group includes common types like mining bees (genus Andrena) and sweat bees (family Halictidae). About 70% of all bee species are ground-nesting.
Unlike honeybees, most ground bees are solitary, meaning each female builds and provisions her own nest independently. They are generally non-aggressive and rarely sting unless directly provoked. They play an important role as pollinators, contributing to the health of gardens and ecosystems. Ground bees vary in appearance, with some being fuzzy and honeybee-sized, while others may have metallic green or blue coloration.
How Ground Bees Survive Winter
As autumn transitions to winter and the first hard frosts arrive, adult ground bees typically complete their life cycle and die. However, the species persists through the winter by overwintering in immature stages deep within their underground burrows. Ground bees commonly spend the winter as larvae or pupae, which are the developing stages after an egg hatches.
These immature bees enter a state of dormancy known as diapause, a physiological arrest in development that allows them to conserve energy and endure cold temperatures and lack of food. The underground burrows provide crucial insulation, shielding the developing bees from extreme temperature fluctuations. Chemical changes within their bodies also help prevent freezing during this extended dormant period.
Spring Emergence and Annual Cycle
With the arrival of spring and the warming of soil temperatures, the overwintering larvae or pupae complete their development. They transform into adult bees and emerge from their underground cells, typically in early spring. The adult ground bees then begin their brief active season, which usually lasts only a few weeks.
Males and females mate, and the mated females dig new burrows. Each female provisions her individual nest cells with pollen and nectar from early blooming flowers, before laying a single egg in each cell. This cycle ensures the continuation of the species, with the next generation prepared to overwinter as immature stages.
Coexisting with Ground Bees
Ground bees are beneficial insects that contribute to pollination, often emerging earlier than other pollinators and supporting early-blooming plants. They are generally docile and pose little threat; females are unlikely to sting unless physically handled or stepped on, and male ground bees cannot sting at all.
If ground bees nest in an undesirable area, non-harmful strategies can encourage relocation. Watering the area heavily deters them, as they prefer dry soil. Planting dense ground cover or turf also makes an area less appealing for nesting, as they seek out bare or sparsely vegetated soil. Allowing them to complete their short active season naturally is often the best approach, avoiding pesticides that harm these pollinators.