Camouflage is a common defense mechanism within the animal kingdom but undeniably some are better at it than others. Perhaps one of the most impressive is the dead leaf butterfly, also known as the orange or Indian oakleaf (Kallima inachus). These impressive and sizable butterflies are found fluttering in Tropical Asia from India to Japan and lead something of a double life. On one side, they are vibrant shades of blue and burnt orange with black tips, and on the other side they look like a leaf that’s died.
The remarkable camouflage is undoubtedly impressive, but how does one go about starting off as a butterfly and ending up like dried up foliage? This leafy mimicry was studied by naturalist Alfred Russel Wallace who - in keeping with Charles Darwin’s theory of evolution - wrote in the Westminster Review in 1867, "But the most wonderful and undoubted case of protective resemblance in a butterfly which we have ever seen is that of the common Indian Kallima inachis..." Wallace suspected the butterflies evolved their leaf-life look as an adaptation to evade the attention of hungry birds, but exactly how was a mystery in his day.
More recently, scientists found evidence of four distinct intermediate forms of K. inachus before it evolved this mode of camouflage. By looking at tiny changes to these butterflies’ wings over time as well as those of 45 closely related species, they were able to piece together the most complete evidence of gradual evolution introducing a means of mimicry. They found that multiple related species shared a rough ground plan to their wings, suggesting that the patterns seen in leaf mimicry have been inherited across species.
“Leaf mimicry in butterfly wings provides a striking example of complex adaptive features and has led to speculation about how wing patterns evolve a close resemblance to leaves from an ancestral form that did not resemble leaves,” wrote the study authors. “Leaf mimicry patterns evolved in a gradual, rather than a sudden, manner from a non-mimetic [exhibiting no mimicry] ancestor. Through a lineage of Kallima butterflies, the leaf patterns evolutionarily originated through temporal accumulation of orchestrated changes in multiple pattern elements.”
The common baron caterpillar (Euthalia aconthea) is a similarly adept camouflaging critter native to India and Southeast Asia. Instead of dead leaves, E. aconthea blends in seamlessly with lush, green leaves. The little larvae lead a solitary life munching on mangoes and cashew nuts all the while hiding in plain sight from predators.
While the baron was showing off his great disappearing act, the monkey slug caterpillar (Phobetron pithecium) really said: “hold my beer” in opting for fear over evasion and dressing up like a tarantula. The larva itself is not dangerous, feeding mostly on trees and shrubs, and despite widespread misconceptions, its hairs don’t sting (unlike this walking-toupee for a caterpillar). The strangely shaped and weird-looking animal unfortunately missed out on the ugly duckling effect, as after pupation it emerges as a hag moth that resembles a fluffy turd.