Darkest butterflies

The world's darkest butterflies currently investigated are three species belonging to the subfamily Biblidinae – namely, Catonephele antinoe, the male of C. numilia and Eunica chlorochroa. In a study of several different species of ultra-black butterflies published in March 2020 in Nature Communications, patches of black scales on the wings of these species recorded the lowest light reflectances – as low as 0.06% when light was shone on them perpendicularly, which approaches the level of reflectance produced by certain human-made low-reflectance materials such as Vantablack coating. In contrast, patches of black scales on the wings of species that in colour were normal black, not ultra-black, exhibited a light reflectance of between 1 and 3%.

The study also examined whether differences in the size and shape of holes between the scales on these butterflies' wings had any influence upon the extent of light reflectance, because there was considerable difference in these factors between the species, but such differences were shown not to influence light reflectance. However, what did influence it were the depth and thickness of parallel ridges and trabeculae (microscopic support rods) on the scales' upper surface, these being much deeper and thicker in the ultra-black butterfly species than in the normal black species examined.

All three species are native to forests in the Neotropic region including Mexico, Central America and South America.