To answer the questions, the image was shot as seen.

No backdrop nor significant post processing were used. Just camera settings combined with natural back lighting.
It had been rainy & overcast most of the day; however, in late afternoon the sun started to peek out a tiny bit in spots. Truthfully, I had waited 6 hours for the chance to hopefully get a shot like this. Then, Nature cooperated & I was rewarded.
Here is the same species of butterfly http://www.pbase.com/britestar/image/84386959 shot a year ago with a different lens (and camera settings) under different lighting.

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Copyright 2008 Elizabeth Bickel. All rights Reserved.