Idaea sylvestraria and I. obsoletaria are similar, but I think it is neither of those.
They have too many lines crossing the wings.
To me, it looks most like I. straminata / deversaria / aversata.
And of those, I think I. straminata is the best fit, based on pattern (which of course is somewhat variable in all these species).
In coming to that decision, I have considered the images on these pages, and the 'Similar Species' sections:
You will note that genital examination of the specimen ('Genitals' sections) would be helpful in making a firmer ID, but I presume that is not available to you.
All three species occur in Italy (http://en.wikipedia.org/wiki/List_of_moths_of_Italy_(F-M)).