Dogbane beetles (Chrysochus auratus) appear suddenly, usually when the plant which they consume and for which they are named is flowering. Look on the leaves and blossoms of Dogbane, or Indian Hemp, (Apocynum cannabinum) for this blue-green beetle with a metallic copper and crimson shine to it.
The iridescence is a special type of color that shines and changes as the insect changes position or we change position looking at it. It is produced by special body structures and light. The surface of the body parts of this beetle is made up of stacks of tiny, slanting plates, under which is a pigment. Some light rays reflect from the surface of the plates, and other light rays reflect from the pigment underneath. At different angles, the light reflects at different speeds, causing interference and resulting in our seeing different colors that shine.
Although all parts of this plant are toxic to humans, Dogbane is tolerated by Dogbane Beetles, whose larvae reside underground where they eat the roots of Dogbane. When they mature into adult beetles, they climb up the plant to the leaves and flowers, which they then consume.
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.