American pasqueflower provides an abundant amount of pollen to pollinators, an important, early-spring resource for female bees to provision their nests. The plant is protogynous, developing the female parts first (stigmas), with the male anthers shedding pollen after the stigmas are no longer receptive. This is one of many fascinating strategies to ensure cross-pollination. In order to attract pollinators during the male phase, small staminal nectaries located at the base of the stamens produce nectar. It is likely that a visiting insect seeking nectar only will come into contact with the anthers transferring pollen on their bodies to the next pasqueflower.
Frequent visitors, small sweat bees collect the white pollen which is abundant, circling around the outside of the numerous stamens on each flower.
Large mining bees belonging to the Melandrena subgenus are common in early spring and can be mistaken for bumble bees. They have shiny, black abdomens, unlike bumble bees who have hairy abdomens. Mining bees nest in the ground in sand or loose, loam soils.
Other pollinators to look for include large syrphid flies feeding on pollen. These flies are mimics of large mining bees and bumble bees. Bumble bees also visit the flowers.
Because American pasqueflower blooms in early spring during fluctuating temperatures, insect activity can be sporadic. If the sepals are closed on a cool day, look for bees forcing their way into the flower.
Bock, J. H., & Peterson, S. J. (1975). Reproductive biology of Pulsatilla patens (Ranunculaceae). American Midland Naturalist, 476-478. Retrieved from: http://www.jstor.org/stable/2424441