arvind.venkataramani

Thanks for the ID. it was a very cooperative butterfly: it stayed put while I snuck up to it slowly and thrust my phone to within a few inches, and left when I was done :)

That looks like a good candidate. But the greenish tinge is actually that. I have a white object nearby in the same light, and that looks white (this is fluorescent lighting)

i didn't notice then, but I went back today and it was still there - yes, it's an exoskeleton.