Spring: a word that conjures up thoughts of nesting birds, tulips, green grass, and sunny, warm weather. While some flora and fauna are just getting started, spring bees in the genus Andrena, commonly known as Mining Bees, have been busy for weeks. And it’s the only time of year that most Andrena species can be seen!
Andrena erigeniae, the spring beauty mining bee, has a special relationship with the woodland ephemeral spring beauty (Claytonia virginica). The pink pollen of this dainty flower is the only type of pollen that they collect.
Andrena erigeniae collects pollen from Claytonia virginica. Photo by Judy Gallagher CC-BY 2.0
Taxonomy Andrena erigeniae is in the family Andrenidae, subfamily Andreninae, and Tribe Andrenini. It is in the genus Andrena, and subgenus Ptilandrena. 91 species of Andrena have been recorded in Pennsylvania.
Where Can You Find It? In the United States, Andrena erigeniae can be found from Minnesota to New York and south to North Carolina and Georgia.
Claytonia virginica provides pink pollen for the specialist bee Andrena erigeniae. Photo by Judy Gallagher CC-BY 2.0
Life HIstory Andrena erigeniae is a solitary bee that nests in the ground and each female bee provides for her own young. They frequently nest in aggregations under dry leaf litter in the woods, a forest edge, or lawns near patches of spring beauty. Their life cycle is tied to the blooming of spring beauty, as they feed their larvae the pink pollen from this plant exclusively. Males and females emerge from the ground and mate before spring beauties begin to bloom, well before eastern deciduous trees begin to leaf out. Females then begin excavating a nest. They are “pretty in pink” as they return to the nest covered in Claytonia pollen that they form into balls and place into individual brood chambers. A single egg is laid in each chamber. The larvae eat the pollen and grow and develop underground into adults that overwinter. Researchers have observed that pollen collection usually takes place between the hours of 10 a.m. and 2:30 p.m. (pollen depletion later in the day may play a part in this) when the sun is shining. Spring beauty blossoms open late in the morning, and close their petals at night and on rainy or cloudy days. The delicate white flower with streaks varying from pink to magenta, begins to bloom by late March in Pennsylvania, and vanishes by the end of May along with this specialist bee, until the next year. Andrena erigeniae, is a univoltine bee, meaning they produce one generation per year.
Plant Use Andrena erigeniae is a specialist (also known as oligolectic), meaning that they collect pollen from a small number of closely related flowers.
Natural Enemies Cleptoparasitic bees in the genus Nomada lay their eggs in the nest of the host. Nomada eggs hatch and kill the host bee larva and eat the provisions of pollen. The nests are commonly located under layers of dry, fallen leaves, so that they are more difficult to find.
Relationships With Humans The Spring beauty mining bee is a common, black medium-sized bee that can be encouraged to live near you. Planting Claytonia virginica may help them colonize new areas. Bulbs and plants are available commercially. They prefer dappled shade and moist soil with abundant organic matter but are tolerant of a variety of soils. This wildflower will adapt to semi-shaded areas of lawn if mowing is delayed, as well as beneath trees. Both foliage and flowers fade away by late spring. Provide a well-drained, moderately bare area in your yard that is herbicide and pesticide free and you may tempt some of these specialist bees to live in your yard.
Contributed by
Peg Friese
Chester County Master Gardener
References
Carril, O. M., & Wilson, J. S. (2021). Common bees of eastern North America (Vol.123). Princeton University Press.
Holm, H.(2017). Bees:identification and native plant forage guide (No. 638.13 H747b). Pollination Press
Davis, Jr., L.R., & LeBerge, W.E.(1975). The nest biology of the bee Andrena (Ptilandrena) erigeniae Robertson (Hymenoptera: Andrenidae). Biological Notes, no. 95. Urbana, Illinois Natural History Survey
Wilson, J.S., & Carril, O.M.,(2016). The bees In your backyard. Princeton University Press
Van Dyke, M., Boys, K., Parker, R., Wesley, R., & Danforth, B. (2000). Creating a pollinator garden for native specialist bees of New York and the northeast. Cornell University, Cornell Botanic Gardens
Fowler, J. & Droege, S. Specialist bees of the eastern United States https://jarrodfowler.com/specialist_bees.html