Some sort of mass death event over night. I found a number of mainly white moths (probably less than 15) floating in the dam next morning Some face down and some face up.
Were they all the same species? The second photo matches Thalaina clara (after a bath) quite well. But he top photo looks quite different, another Geometridae, possibly an Idiodes species.
Hi Glen, Now that you've shown me what to look at, (and for), I can see the distinctive faint brown N marking in the under fore wing. We'll have to wait for the sites administrative back end to revive before creating the species. I've removed the other image which did indeed seem to be another species. I'll post that separately.