Layers Produce Iridescence

a long yellow and black scoliid wasp rests on a white flower with a flurry green background

Biological Strategy

Scoliid wasps

AskNature Team

Image: Renee Grayson / Flickr / CC BY - Creative Commons Attribution alone

Modify Light/Color

Color in living systems comes from pigments and the interaction of light with surfaces. Color serves many purposes for living systems, such as attracting prey or mates, providing warnings, or protecting through camouflage. To create the effects needed for each purpose, living systems must control the expression or visibility of pigments and the interactions (such as reflectance and refraction) of light. To do so, they have strategies that modify color or light to increase or decrease the color’s position, intensity, opacity, and more. Male hummingbirds, for example, have brightly colored feather patches on their throats; the coloring comes from pigments, structures that refract light, or a combination of the two. When a male hummingbird hovers near a potential mate, it modifies the angle of these feathers to create a bright, colorful display. However, when it needs to mute the colors to reduce conspicuousness, such as to avoid a predator, it modifies the angle again.

Search this Function

Insects

Class Insecta (“an insect”): Flies, ants, beetles, cockroaches, fleas, dragonflies

Insects are the most abundant arthropods—they make up 90% of the animals in the phylum. They’re found everywhere on earth except the deep ocean, and scientists estimate there are millions of insects not yet described. Most live on land, but many live in freshwater or saltwater marshes for part of their life cycles. Insects have three distinct body sections: a head, which has specialized mouthparts, a thorax, which has jointed legs, and an abdomen. They have well-developed nervous and sensory systems, and are the only invertebrate that can fly, thanks to their lightweight exoskeletons and small size.

Search this Living System

The wing of the giant wasp produces iridescence due to a simple interference filter.

“We have shown that the iridescence of the wings of Megascolia procer javanensis can be reasonably well understood as resulting from the interference of light in a thin optical chitin layer covering a chitin-melanin absorbing structure…The black background defined by this chitin-melanin structure allows for a particularly highly visible structural blue-green coloration, generated by an extremely simple device, using a minimal number of interfering waves: a constant-thickness overlayer covering all four wings. This is among the most elementary interference filters and, in spite of its simplicity, it turns out to be very effective.” (Sarrazin et al. 2008:5)

“The wings of the giant wasp Megascolia procer javanensis are opaque and iridescent…the structure responsible for the iridescence is a single homogeneous
transparent chitin layer covering the whole surface of each wing. The
opacity is essentially due to the presence of melanin in the stratified
medium which forms the mechanical core of the wing.” (Sarrazin et al. 2008:1)

Last Updated August 18, 2016

References

Journal article

AskNature