During the last 50 years the number of bumblebees in Europe has declined, most likely because of agricultural intensification leading to destruction and fragmentation of flower-rich habitats that are important for bumblebees (Stoate et al. 2001). This decline may have serious consequences for plant species pollinated by bumblebees, and so in turn also negatively affect other species in the pollination systems (Kearns et al. 1998). However, because bumblebees are not only important pollinators of wild flowers but also of crops, the decline in bumblebee abundance could have long-term economic as well as ecological effects (Allen-Wardell et al. 1998). For these reasons it is important to monitor bumblebees in terms of species occurrence, diversity and changes in abundance. To do this, the bumblebees’ preferred landscape elements must be known, as well as how many inventory-sites to use and when and how often inventories should be performed. The aim of this study was to improve monitoring methods and to study the phenology (seasonal change in abundance), the importance of various landscape elements and the impact of weather and daily variation in bumblebee abundance.