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Bug of the Week is written by "The Bug Guy," Michael J. Raupp, Professor of Entomology at the University of Maryland.

Red and green: Tailed jay, Graphium agamemnon, and cotton stainers, Dysdercus sp.

 

Plants like poinsettias and many insects derive their beautiful colors from light absorbing pigments.

 

Colors of the tailed jay butterfly are produced by thousands of scales on its wings.

For many of us red and green are colors of the holiday season. The deep green leaves and scarlet bracts of poinsettia have decorated churches and homes in Mexico for centuries, while in Europe the emerald leaves and bright red berries of holly symbolized the winter season from the times of ancient Romans and Celts. The green of leaves is created by the photosynthetic pigment chlorophyll and the reds of leaves and berries are produced by another family of pigments called anthocyanins. This is all fine for plants, but how do insects produce the magnificent colors found on their wings and bodies?  For many insects, such as the beautiful tailed jay butterfly, the striking colors on the wings are produced as light is reflected from thousands of shingle-like scales. Butterflies such as the magnificent morphos use a mechanism called interference to produce their iridescent colors. Within the scales are several tiny surfaces aligned to alter light and create specific colors. The spacing of these surfaces causes certain wavelengths of light such as blue to be reinforced and reflected, while other wavelengths such as reds are absorbed and not seen.

 

Thousands of tiny scales on its wing refract light and create the brilliant flash of the blue morpho butterfly.

Bright pigments obtained from plants give the cotton stainer its bright red color.

Other insects, such as the bright red cotton strainers, have a different way to generate striking colors. Like the beautiful poinsettia, many insects rely on pigments for their striking colors. Pigments are organic molecules. The chemical bonds of pigments absorb some wavelengths of light allowing others to be reflected. In the case of the scarlet cotton stainer, pigments in the exoskeleton of the bug absorb blues and yellows and reflect reds, hence the brilliant vermillion color. Some pigments found in insects contain nitrogen and are synthesized by the insect itself. However, many of the red and yellow pigments known as carotenoids and flavones cannot by synthesized directly by insects. Instead, these pigments originate in plants. As insects eat, they ingest the compounds necessary for the production of color. Their food serves as a source of protective coloration as well as sustenance for the hungry bug.

As Maryland and much of the nation receive their first taste of winter, somewhere in warmer climes bright red cotton stainers and green tailed jays bask in the tropical sun. Hmmm… must be nice.

Bug of the Week wishes everyone a wonderful Holiday Season filled with red and green!

References

“The Insects: Structure and Function” by R.F. Chapman was used a resource for this Bug of the Week.