An experiment conducted by scientists at the Smithsonian Institution using three heat systems revealed that heat increases the mortality of pupae and makes the colors of surviving butterflies pale.
The bright blue Morpho butterfly, considered one of the most beautiful and admired butterflies, has even been added to emojis. However, researchers have discovered for the first time that climate change may be robbing it of this beauty. It turns out that rising temperatures during the caterpillar-to-butterfly transformation cause its color to fade.
The experiment involved exposing butterfly pupae to three temperature regimes—normal tropical, temperate, and very high—as predicted in a warmer future climate. The butterflies remained in the chrysal beds longer, died at a higher rate, and the surviving butterflies lost their bright sheen in the hotter conditions. Importantly, this change is not only noticeable to humans but also to birds of prey and other butterflies.
According to researchers, the blue color of morpha butterflies is not a pigment, but rather a result of light interacting with tiny structures on their wings called nanostructures. These structures, similar to roof tiles, are arranged in a specific pattern and reflect light, giving them an iridescent sheen. As the butterfly's temperature rises during its development, these structures shrink, the spaces between them decrease, the scales become narrower, and light is reflected differently, resulting in a loss of color saturation. This can make the butterflies more visible to birds or less attractive.
It should be noted that the study was conducted in the butterflies' natural habitat, which allowed for an accurate modeling of the climate's impact.
