From La Selva Ecolodge, Ecuador.
Butterflies, like most animals (including humans) display bilateral symmetry, i.e. their left and right sides are mirror images.
This butterfly is one of the famous Blue Morphos of the Amazon rainforest. Morpho is actually the name of a genus of butterflies that includes up to 29 species. The blue color comes not from pigmentation, but from iridescence of the tiny scales that cover the dorsal side of their wings (the undersides are plain brown, decorated with eyespots).