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There are two genera of Hippoboscidae in Europe with very narrow wings.
Below is a key to separate it:

Wings narrow, slightly sickle-shaped, about 6 times longer than wide (Slika 3). Ocelli poorly developed.
Stenepteryx

Wings broad, leafy, 3 to 4 times as long as wide (Slika 4). Ocelli absent.
Crataerina

Your species is Stenepteryx hirundinis

Best wishes, Tomi (i.e. local guy according to BubikolRamios)