How did butterflies take on the look of dead leaves? Yes, it's a protective form camouflaging tactic to blend into its environs, but it's not like they can just slip on a jacket to avoid their predators. In actuality, it takes centuries of gradual evolution to acquire the look. In fact in the study titled "Stick Insects Have Mimicked Plants Since the Age of Dinosaurs," the dead leaf butterflies have worked on disguising themselves for over 126 million years . . . even before the advent of flowering plants.
As to "the how" closed wings of dead leaf (or oakleaf) butterflies from the Kallima genus came to perfectly resemble brown leaves—from their veins down to tiny fungus spots—has is a topic that's been hotly debated dating back to Darwin.
In fact, in the 19th Century, naturalist Alfred Russel Wallace studied Kallima butterflies in Southeast Asia and used them to advance Darwin's theory of natural selection, which would suggest the butterflies gradually evolved to look like leaves to escape hungry birds.
Countering that theory, other scientists proposed alternative explanations. For example, in the 1940s, U.S. geneticist Richard Goldschmidt argued that the butterflies' leaf mimicry originated suddenly, without intermediate forms—sometimes termed the "hopeful monster" theory. Unfortunately for Goldschmidt, many critics referred to him as the only one who was hopeful, since this theory attracted widespread ridicule.
Their research mapped small, incremental changes to markings on the undersides of Kallima butterflies' wings over time "to provide the first evidence for the gradual evolution of leaf mimicry," study co-author Takao Suzuki, of the National Institute of Agrobiological Sciences in Ibaraki, said in email.
Now, biologists who explain leaf mimicry with Darwin's theory have a way to validate their theory, said Suzuki, whose study was published recently in the journal BMC Evolutionary Biology.
Butterflies are not the only mimics. Flower mantises are a species of praying mantis that mimic flowers. Unlike other insects that use camouflaging as a method to hide from preys, flower mantises use camouflaging as aggressive mimicry. This type of mimicry is defined as a form of camouflage where a predator’s colors and patterns lure their prey to them. How's that for reverse psychology?
Primary Source: National Geographic