The silver beetle stands out for its reflective capacity.
Imagine a walk through the tropical jungle of Central America, the warm breeze blowing across your face, and the anticipation of the creatures that might cross your path. Suddenly, a glowing object hangs from the leaves of the bushes, but it is not a hidden treasure, although it appears to be silver; it is the silver beetle, an insect that has attracted the attention of more than one for its metallic appearance.
We often think that most of life is divided between mammals and reptiles, but insects are actually the most abundant group of beings that inhabit the Earth. It is to be expected that among their ranks can be found a whole variety of surprises of diverse appearances. For example, we have the adorable poodle moth that looks like it’s made of a cloud or the Picasso bug that lives up to its name and is a work of art.
[Photo: David Pascual]
But among its more than 900 thousand species, there is an insect that has won the admiration of those who have had the fortune to come across it. It is the silver beetle that stands out for its reflective capacity, which gives it a metallic appearance and seems to be made of silver.
The species was first described in 1894 by zoologists Walter Rothschild and Karl Jordan. Although it was initially given the name Plusiotis limbata, its scientific name was later changed to Chrysina limbata. Today very little is known about the metallic insect, but its home has been identified in the tropical rainforests of Central America, from Costa Rica to southeastern Mexico.
The extraordinary beetle is of average size, measuring between 2.5 and 3.5 centimeters, and like all its congeneric beetles, it reproduces employing eggs that the female places in the roots of the plants. They then go through the process of metamorphosis, that is, they first become larvae and later transform into pupae and finally obtain their final form of reflecting beetle.
Not much is known about the mechanism that gives the silver beetle its metallic appearance, but entomologists believe that reflectance is achieved through the interference of a thin film within layers of a compound called chitin, a long-chain polymer derived from glucose.
These chitin coating layers are in turn chirped, which means that they act as a dielectric mirror with gaps of varying depth, which are capable of reflecting different wavelengths depending on the depth of the film.
The result is a beautiful mirror capable of reflecting almost all of the light that reaches it from the sun, which is why it acquires its characteristic metallic color. It is so amazing and literally works like a mirror, that in the photographs of silver beetles that have been taken, the photographer can be seen reflected in the insect’s shell.
Story originally published in Spanish in EcoosferaPodría interesarte