He harvested only 0.25 seed per flower where bees were infrequent, but 0.70 per flower where bees were plentiful. Peterson et al. In this case, bee activity is essential for seed production. He also found that self-pollinated plants were less vigorous. He considered strawberry clover a cross-pollinated species and found a high correlation between set of seeds from hand and bee pollination.
Honey bees seem to be the primary pollinators.
Iowa State College Press, Ames. Welsh Plant Breed. Col. of Wales Aberystwyth, ser.