Eudonia mercurella is quite common in Holland but is easily confused with Eudonia lacustrata, Eudonia truncicolella, Scoparia ambigualis, Scoparia basistrigalis (rare in The Netherlands) and Scoparia ancipitella (not in the Benelux).
Eudonia mercurella usually has a rather dark appearance; usually darker than the other Eudonia species.
This moth species flies from June up to the end of August.

Caught in my self made moth trap.

1st & 2nd photo: In my yard, Hilversum, The Netherlands, 27 July 2019
3rd & 4th photo: In my yard, Hilversum, The Netherlands, 25 July 2019