I found this moth yesterday afternoon when I returned home from an Agricultural Show.
I'm pretty sure it is Chrysodeixis argentifera. The tell-tale silver "S" on the wing separates it from a similar Chrysodeixis species.
Now I might know one of the cuprits making holes in my Silver Beet!
Caterpillars of this moth also feed on canola, beens, sunflowers and tomatoes and has a bit of a reputation as being an agricultural pest.
The moth measured about 2.4cm in resting position.
It can be found all over Australia, including Tasmania.
(Click images to enlarge)
Duncan has a photo of this moth in his "October Moths" gallery.