A male Red mason bee (Osmia bicornis syn. Osmia rufa) [1] forages for nectar on Lilac (Syringa vulgaris). Both the species’ males and females can be found on the plant.

Literature
1 Nederlands SoortenregisterOsmia bicornis (Red mason bee)♂︎
Syringa vulgaris (Lilac)A male Red mason bee (Osmia bicornis syn. Osmia rufa) [1] forages for nectar on Lilac (Syringa vulgaris). Both the species’ males and females can be found on the plant.
Literature
1 Nederlands Soortenregister