Very nice photo, as usual!
I think the closest Paranthrene is P. tabaniformis ssp. synagriformis
But the wings are always much more plain than on your specimen.
More likely is Bembecia scopigera
But (as the text states there, translated from the German):
It "is distributed from the Iberian Peninsula to Asia Minor. The males are often only able to be distinguished from similar species of the same genus by genital examination. The females, however, are reasonably well identified by the alternating wide and narrow rings of the abdominal segments."
Similar species include:
(the last page includes a guide to differentiate B. albanensis and ichneumoniformis)
They are all listed as occurring in N. Italy
(apart from Chamaesphecia proximata, which is not listed there.)
So it may be difficult for you to get an accurate ID on this one.
Looking at the other similar genus, seems that the Bembecia sp. look like the one more near to it.
I don't know if they are valid key or they are variable, the black ants, the pattern of the abdomen, the final part of the abdomen (it's yellow in the center and black external), the wings.
I put here a dorsal view too, maybe it could help, but I see it's hard to ID ...
When I saw it, the first thing I thought was "a wasp, better to stay away..." only while I was shoting I saw the difference, there was a lot of wind and I was unable to focus it!
Thanks for your help!
Sorry Marcello - I reall don't know of a useful way to differentiate these species by macro characters, apart from the guide to the venation at the end of this page - http://www.lepiforum.de/lepiwiki.pl?Bembecia_Ichneumoniformis. I hope you can see the veins well enough in your original photos; to me (without that detail) it seems more like Bembecia ichneumoniformis than Bembecia albanensis.
But I still can't choose between Bembecia ichneumoniformis and B. scopigera.
If you collected lots of these moths, you'd see how confusing it gets - you'd see how the variation within each species is about the same as the variation within the group of similar species.
Don't worry Mike, I know without to collect the specimen it's not always easy.
So, the wing seems the same of the B. ichneumoniformis:
Yes, I agree Marcello; thanks for the detail.
So I think we could call it B. aff. ichneumoniformis ('aff.' meaning it 'has an affinity with' that species).
In some circles, 'aff.' is used with newly described species (as explained here - http://en.wikipedia.org/wiki/Open_nomenclature). I choose to use it more widely, as in this case.