Understanding the relationship between solitary bee fl ight and fl owering phenology is globally relevant for environmental management and habitat restoration. Using Swedish citizen science data over an 11-year period, the fl ight behaviours of two oligolectic solitary bees (Andrena hattorfi ana and Andrena marginata) were compared to the fl owering phenology of their hosts (Knautia arvensis and Succisa pratensis) in southern Sweden. There were 2,327 and 4,566 records of fl ight and fl owering, respectively. While associative studies cannot resolve the degree of oligolecty, a strong temporal association of Andrena hattorfi ana with Knautia arvensis and Andrena marginata with Succisa pratensis was indicated. Three conclusions emerged when comparing annual data: fi rst, the fl ight period of both bee species studied overlapped with the fl owering period of their corresponding host plants. Second, earlier fl owering of Knautia arvensis corresponded with the earlier fl ight of Andrena hattorfi ana. Third, the fl ight period duration was unaff ected by the fl owering period duration. For Andrena hattorfi ana/Knautia arvensis, climate change may shift the start of fl ight and fl owering periods to earlier dates in the year. A similar response would be expected for Andrena marginata/Knautia arvensis, but not for Andrena marginata/Succisa pratensis where there instead might be an increasing mismatch between the fl ight and fl owering periods.