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Sorry, more than Thereva spec. is not possible for this couple. The lower picture shows the male, and Thereva males cannot be told apart from a photo. The upper female nicely shows the black spot between the eyes, but we need to see more characters, one picture is not enough. Compare the key https://home.hccn...ml#Thereva to understand which are the decisive characters to identify Thereva females (at least colour pattern of the tergites and haltere colour).
Regards, Sundew