We hear a lot about honey bees and other species of social bees (that live in colonies) pollinating crops and other flowering plants, but there is another, larger, group of bees, called solitary (nesting) bees, which plays a significant role in pollinating plants. These bees live alone, forage for pollen for their larvae and in the process pollinate vast numbers of flowers.
Mining bees make up one group of solitary bees. They are small and nest individually in the ground. One species of mining bee you often see on Spring Beauty is Andrena erigeniae. Females are hairy and often loaded with Spring Beauty’s pink pollen. Males are smaller, slimmer and less hairy. The thing that sets this species of mining bee apart is the fact that it is a “pollen-specialist” — it collects pollen from only two plant species, Virginia (or Narrow-leaved) Spring Beauty (Claytonia virginica) and Carolina Spring Beauty (C. caroliniana).
Pollen from these blossoms is formed into balls and placed into underground brood chambers the female bee has dug with her jaws and legs. She deposits a single egg on each ball of pollen for the larva to eat when the egg hatches. During the summer the larva pupates and by late autumn development of the adult is complete. Winter is spent in the adult stage within the brood chamber and the bee emerges in the spring just as Spring Beauty flowers. Male and female bees emerge at roughly the same time and their mating, as well as their food collection, is said to take place on the flowers of Spring Beauty. (Photo: male Andrena erigeniae on Carolina Spring Beauty)
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Spring Beauty (Claytonia virginica) is one of our earliest woodland wildflowers to blossom, and thus an important source of nectar and pollen for the earliest foraging insects. Pink lines (“bee guides”) on each of its five petals lead pollinators to the center of the flower, where the nectar is located. The pollinator in this image, Andrena erigeniae, is one of the more common species of bees that visits Spring Beauty in the early spring. Notice the slightly pink pollen she has gathered into the pollen basket on her hind leg. If you’re interested in spending time observing the series of different insect pollinators that visit Spring Beauty as the season progresses, there’s a golden opportunity for you. If you go to http://springbeauties.wordpress.com/ you can participate as a citizen scientist volunteer and participate in their survey.