Nothing says late summer like sunflowers. No matter where they are growing -- a commercial crop, flowers in a garden, or volunteers by the side of the road -- this iconic yellow flower reminds us that fall is around the corner.
Sunflowers are visited by a variety of bees; these visits are so consistent that sunflowers are used as the sentinel plant in The Great Sunflower Project, a San Francisco State University-based citizen science project to monitor bees.
Among the bees that visit sunflowers are honey bees and a complex of California native bees known collectively as sunflower bees. Surveys in Yolo and Solano counties found that 25 species of native bees visited sunflower crops, with an average of 37% of visits from native bees (Fremontia (2002) 30 (3-4): 41-49). Other research in Yolo County showed an interesting behavioral interaction between introduced honey bees and the native bees that, on average, doubled the pollination service of the honey bees that are typically placed in sunflower crops (PNAS (2006) 103:13890-13895).
These native bees include Diadasia spp., Melissodes spp., and a perennial visitor to my own bee garden, Svastra obliqua. Visit the Haven's YouTube channel to see video of this bee leaving its overnight sleeping aggregation as it warms up in the morning.
Sunflowers and other fall-blooming plants provide critical resources for honey bees as they put up stores of honey for the winter. Join us at the Haven for our fall open house, October 3 from 5:30 to 7pm, to see these and other fall-blooming bee plants.
