
I was heading out of the zoo when I noticed that a spider had built a web across the inside of a glass window into an animal enclosure, and this butterfly was caught in the web. The spider apparently hadn't come out to bite it yet, as it was struggling frantically. It was on the other side of the glass, so I couldn't have helped it even if I'd been so inclined. No reason for it, but I felt vaguely guilty as I took a variety of shots of its predicament.
I think this is a Hackberry Emporer (Asterocampa celtis) but my butterfly ID skills are weak, and I couldn't see the upper wing.
180mm macro
natural light
1/250th second @ f/9
ISO 1250