Bees depend on flowers for pollen and nectar. The resulting is an important ecosystem service. The decrease of this ecosystem service can be a result from increased agriculture and large monocultures which decrease both flowering recourses over time and habitat for bees. Flowering fallows is a way to work against this.

The aim of this study was to examine if three bee species changed their flower visiting behavior in fava bean fields with and without flowering fallow nearby. Twelve fava bean fields, six near flowering fallow and six without, were observed. The fields were paired in similar surroundings.

Bombus terrestris and Apis mellifera have short tongues, while Bombus hortorum has a long tongue and can more easily collect nectar (legitime visit). Bombus terrestris often collects nectar by biting a hole (robbery) in the flower base, which A. mellifera also uses (second robbery). The fava bean plant has extrafloral nectaries.

There were no significant differences in behavior for B. terrestris or B. hortorum between the fields. Apis mellifera showed significant difference in visiting the extrafloral nectaries, but no significant difference in other visitation options. 

Bombus terrestris was the only species to bite holes in the fava bean flower, the holes were used by A. mellifera and B. hortorum. Previous studies show that B. hortorum is better making legitime visits, which my observations also pointed at. My observations showed that B. terrestris often performed second robbery, with A. mellifera also using these holes but preferring to visit the extrafloral nectaries.