Common morpho butterflies have brightly-colored, blue metallic upper wings. Their undersides, visible while the butterfly is at rest, are cryptic camouflage featuring 4 sets of "eyespots." The metallic colors are products of iridescence, not pigment; the scales covering the wings (almost all lepidoptera have scale-covered wings) reflect incident light repeatedly at successive layers, leading to interference  that most effectively yields wavelengths in the green-blue range (450-550 nm), depending on the angle at which they are viewed. Many creatures great and small exhibit iridescence, and it has been shown to have evolved independantly in several instances.

The morphos are largely confined to the tropical rainforest and other similar tropical habitats. The raising of butterflies like these for use in butterfly exhibits worldwide has become a viable economic engine for many indigenous peoples - giving them incentive to protect their irreplaceable rainforests.