I only collect the dead butterflies I come across. This was a "roadkill" from last summer. Since then it had become quite dry and fragile. When I was handling it yesterday, it started to fall apart. Luckily, what was left behind was enough to identify it (if I am not mistaken) as a Common Buckeye.
The "eye" above is the one marked with an arrow in the first picture. It was about 4 mm across. Once I flattened under a glass plate, it became a good target to test my set-up for "extreme" close-up photography. The picture below is an enlargement of the purplish scales near the center of the eye. Each of those scales was about 53 micrometers wide.
Technical info: The wing was photographed with an Olympus E-500 with a Zuiko 35 mm macro lens plus an EX-25 extension tube. The camera was mounted vertically as shown here. I used two 1-watt L.E.D. lights positioned across from each other, saved the pictures in RAW format and corrected the slight shift in color towards blue by specifying a gray point as explained here. Focus was adjusted manually (auto focus doesn't work with the extension tube). At ISO 200 exposure was 1/25 s at f5.6 with a 3-second mirror lock.