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Dear forum,

aug, 2nd, 2015, garden, northern upper rhine rift, southwest germany, 6mm.
Visiting blossoms of Oxalis corniculata (creeping woodsorrel) and attacking small black 7mm-solitary bees with long antennas, which visited these blossoms as well and which I could not identify.
When resting, this fly often lifted legs 1, not together, but one after the other, which looked like greeting:-)

Does this fly belong to the Thecophora atra-species-group?

Thanks in advance for taking a look at this.
Best wishes, Thorsten