Walking through a meadow, a glint of metallic green catches your eye. After zipping about for a bit, you notice that a stunning bee has landed on a nearby aster. Your patience has rewarded you, and you have observed one of our most striking native bees: Agapostemon virescens, the bicolored striped sweat bee.
Agapostemon virescens is fairly easy to recognize. This medium-sized bee has a brilliant, metallic green head and thorax, and its abdomen is striped. Females have black and white stripes, while males have black and yellow stripes.
Agapostemon virescens, male, side. Photo Credit: USGS Bee Inventory and Monitoring Lab / CC PDM 1.0
Taxonomy. Agapostemon virescens is a sweat bee in the family Halictidae, the subfamily Halictinae and Tribe Halictini.
Distribution. This bee is widespread across the United States but rare in the Gulf States.
Life History. This species is a solitary bee that nests in the ground (solitary meaning that each female lives alone and provides for her own young). It has also been known to nest in aggregations, sometimes with multiple females using the same enterance. This behavior is commonly referred as communal. Their nests can be found in lawns, near gardens or in disturbed areas. Quite often, the entrance of the nest is surrounded by a tumulus, a mound of dirt that is similar to an anthill. Tunnels extend downward and branch off to the sides, each containing a single cell at the end.
Females that have mated the previous fall and have overwintered, emerge in the spring and begin excavating and provisioning their nest. In the spring, females provision each cell with pollen and nectar, then lay an egg on top of the provision, and male and female individuals emerge in summer from these nests. After emergence, summer males patrol flowers and mate with females, who begin the process again, starting a second generation. The females that emerge from this second generation will mate and overwinter, laying eggs the following spring while the males will die. Agapostemon virescens is active from April into November in Pennsylvania.
Agapostemon virescens nest aggregation. This species is solitary but several females share the same nest entrance. Photo credit: Katy Evans.
Plant Use. Agapostemon virescens is a polylectic species, meaning that they collect pollen from a high number of unrelated plants. However, they prefer plants in the sunflower family (Asteraceae). Look for them on coneflowers, asters, and goldenrod.
Agapostemon virescens collecting pollen. Photo credit: Heather Holm
Natural Enemies. Cleptoparasitic bees in the genera Nomada and Sphecodes lay their eggs in the nest of Agapostemon. Sphecodes species destroy the host bee egg in the nest, leaving their own egg to enjoy the provisions that are provided by the host. Nomada species also lay their eggs in the nest of the host, but their larvae hatch and kill the host bee larvae, and eat the provisions of the host bee.
Relationship with Humans. The bicolored striped sweat bee is a common, medium-sized bee that can be seen in your garden. You can encourage this bee to thrive near you by providing a sunny, moderately bare, well drained area in your yard that is free of pesticides and herbicides.
References
Carril, O. M., & Wilson, J. S. (2021). Common Bees of Eastern North America (Vol. 123). Princeton University Press.
Holm, H. (2017). Bees: an identification and native plant forage guide (No. 638.13 H747b). Pollination Press.
Wilson, J. S., & Carril, O. M. (2015). The bees in your backyard. Princeton University Press.
Contributed post by
Peg Friese
Master Gardener Chester Count