Entomologist and insect photographer Alex Wild has captured a gorgeous image of this Greta oto, or glasswing butterfly, in Belize (click to enlarge). You can see the color of the flowers perfectly through its wings. Though it looks like an alien or mutant, the glasswing is perfectly natural. Most butterflies have tiny, colorful scales on their wings, but Greta oto does not. So what you're seeing here is a butterfly wing without adornment. See more of Alex Wild's work on his G+ page.
I saw some of this sort of butterfly (with the see-through wings) in the butterfly house at the Bristol Zoo in England. They were pretty amazing.
Also amazing is the Bristol Zoo, by the way. If anybody's ever in the southwest of England, go check it out. It's the best zoo I've ever visited.
Of course, that has *nothing* to do with the enclosed bat section at all, where you can wander around and watch the bats fly and land on trees and stuff right next to you. Nothing at all. I certainly didn't force my husband and in-laws to spend a half-hour in the enclosure while I wandered around, bat-enraptured. Nope.
(bats are my favourite animal of all time)