@donhe they were both very satin-y. There wasn't any direct light so if they were forester moths the iridescence may not have shown up. Definitely less than 1cm.
I'm not sure they are Zyganids - neither of the pair has the male's feathery antennae. These insects seem to be smaller and leaner than Myrtartona coronias. Could they be flies or caddisflies?