I think this may be Culex territans (found in my garden, in the East of France) : the siphon is long and thin, and lacks dorsal hairs. Is it correct ? Thank you very much.
This looks more like Culex (Maillotia) hortensis - the siphonal tufts are long and arise quite close to the base of the siphon (within the pecten area).
I totally forgot about this species. Found a drawing of the siphon in Mohrig (1969) and it differs from territans in the longer hairs. So I agree with Tony (of course).