A butterfly’s coloring is impressive, similar to that of many paintings. The pattern of a butterfly’s coloring is created by two distinct processes of color combined with the art form of mosaics. Mosaic painting and patterns are made up of multiple small, colored stones or other objects carefully organized by an artist to create the resultant image piece of individual piece. A butterfly’s wing is made up of chitin, a very thin hard protein that is basically clear. Mounted on the wings are a series of scales, either colored or clear and sometimes bent to create the final result. They may also be overlapping to provide enhanced effects.

Butterflies belong to the order Lepidoptera. “Ptera” is Greek for wings and indeed, many orders of insects end with “ptera” as most insects have wings. “Lepid” refers to scales, and butterflies are insects whose wings are covered in scales.

If you remember catching a butterfly when you were a child, or if you were with your children or grandchildren when they caught a butterfly, you know it is not uncommon to have the “powder” come off on their fingers. This powder is made up of very tiny colored scales.

Figure 1 is a close-up view of a section of the wing of a monarch butterfly, and one can get an impression of the individual scales.

Figure 1: The tan and black scales can be seen at the base of the wing of a Monarch butterfly. The larger and longer scales (individually black or white) are on the body and appear to be hairs but they are actually pigmented scales.

When we look at an object that is colored, two phenomena are occurring. For the color of the object, the wavelengths in the visual spectrum that comprise the color are reflected back to our eyes while the other wavelengths corresponding to the other colors in the spectrum are absorbed. If all of the wavelengths are absorbed and none is reflected, then the object appears to be black. If all of the wavelengths are reflected back to us, the appearance is white.

Hence, in Fig. 1, the black coloration represents absorption, while the white colors represent reflection of all portions of the visual spectrum.

When there are colors within the visual spectrum, these scales reflect the specific colors of the visual spectrum as shown in Fig. 2.

Figure 2: The browns, orange, blues and subtle shading in between represent the colors of individual scales reflecting those colors of the visual spectrum while absorbing the other wavelengths. The butterfly is the California Sister photographed while hiking Wiley Canyon. The white color as noted above represents reflection of all the wavelengths of the visual spectrum while the black represents the absorption of all the wavelengths.

On some butterflies, we can see silver markings much like looking in a mirror, or when there is an air bubble in clear water. This is a combination of reflection and refraction. This is shown in the silvery, reflective patches on the undersurface of the Gulf fritillary, another local butterfly whose basic coloration is orange, brown and black, but with distinctive silver ovals on the undersurface of the wings.

Most people who have seen the large blue iridescent butterflies from Central and South America – these are the Morpho’s butterflies – are impressed by the spectacular shining appearance. There are also green, yellow and orange iridescent colors in other butterflies.

If one looks at the scales of these butterflies under a microscope, the scales are clear but bent in the middle like a prism. The light entering the prism is bent with only a portion of the visual spectrum passing through and exiting the other side, giving the iridescent colors that also change slightly given the angle by which they are viewed. While we have some butterflies with iridescent colors in the greater Los Angeles area, the area of iridescence is small and made up of a part of the eye-spots on the hind wings of the small blue’s butterflies.

Figure 3: The undersurface of the wing of a Gulf Fritillary. The photo does not reproduce the silvery reflectance of these large spots on the undersurface of the wings.

The butterflies found in Central and South America commonly have larger areas of iridescent scales as shown in Fig. 5.

The pattern of the coloring and indeed the colors used are various means the butterflies use to identify other butterflies of their species from a distance, for identifying members of the opposite gender, for protection – either by helping to hide the butterfly from predators as with camouflage, or helping it look like a distasteful or poisonous other butterfly (mimicry), or serving as a warning flag – don’t eat me as I am poisonous – or for distracting the predator from following the butterfly while it is flying such as with multiple spots or iridescent coloring. Thus while all of the colors serve a purpose, they also enhance our ability to enjoy and appreciate what in the past has been called “flying flowers.”

Paul A. Levine is a docent-naturalist at Placerita Canyon Nature Center and an avid butterflier.

Figure 4A is a photo of the Marine Blue. The small eyespots on the hindwing have a circle of iridescent blue but one needs a perfect specimen to see this combined with the ability to get close requiring either a mounted specimen, good binoculars or a camera.

Figure 5 showing the large areas of iridescent blue coloring on the undersurface of the wings of a small butterfly in the genus Ancyluris (sorry – I do not have a common name for this butterfly). It was photographed in Rio Claro, Colombia.