Praying mantises, with their distinctively folded forelimbs, are one of the most recognizable predatory insects in the world. As they sit motionless on a leaf or branch, many observers often wonder if their color is fixed or if they possess the ability to shift their hue to match their surroundings. The answer is that mantises do change color to enhance their camouflage, but the process is slow and deliberate, entirely unlike the rapid color shifts seen in animals like chameleons. This adaptation is a long-term survival strategy, allowing the mantis to remain cryptic as its environment changes over the course of a season or during development.
Color Change Is a Gradual Adaptation
The color alteration in a praying mantis is an example of chromatic adaptation, which is a fixed change to a new background, rather than the quick, physiological response seen in cephalopods or some reptiles. Mantises cannot instantaneously turn from green to brown when moving from a leaf to a tree trunk. Instead, the change is a gradual process that occurs over several days and is tied directly to the insect’s life cycle. This slow color shift is a long-term adjustment to the prevailing environmental conditions, not a reaction to an immediate threat. The resulting color—green, brown, or an intermediate shade—will then remain until the next developmental milestone is reached.
Biological Triggers for Pigment Shift
For the praying mantis, color change is intimately linked to ecdysis, or molting, where the insect sheds its rigid outer layer. The most significant color shift from one morph to another generally occurs during the short window immediately following a molt. As the new, soft exoskeleton hardens, new pigments are deposited into the layer, allowing the mantis to adopt a new color that is fixed until the next molt.
The triggers that signal the mantis to produce a different color are environmental factors like light, humidity, and the background substrate itself. Studies on species like the European mantis have shown that hot, dry conditions with intense light—which often cause vegetation to turn brown—promote the production of brown pigments. Conversely, moderate temperatures, higher humidity, and lower light intensity are associated with the production of green pigments. The color of the immediate surroundings influences the hormonal signals that determine the final pigmentation of the new exoskeleton.
The green coloration in mantises is attributed to the presence of a tetrapyrrole pigment, such as biliverdin IX alpha, sometimes combined with yellow carotenoids. Brown coloration, however, is the result of ommochrome and pteridine pigments. While the primary driver for color change is the environment dictating which pigments are produced during molting, the availability of certain pigment precursors in the mantis’s diet can play a secondary role. Carotenoids, which contribute to the vibrant green hue, must be ingested through the mantis’s prey.
The Role of Color in Survival
The color adaptation of the praying mantis serves the dual purpose of crypsis, or background matching, which is fundamental to its survival strategy. The ability to blend seamlessly into the environment is vital for evading visual predators like birds and bats, which hunt by sight. A brown mantis on a dry stalk or a green mantis hidden among foliage becomes virtually invisible.
Crucially, this camouflage is also a form of aggressive mimicry that benefits the mantis as an ambush predator. Mantises are sit-and-wait hunters, relying on their invisibility to lure unsuspecting prey within striking distance of their raptorial forelegs. By matching the surrounding vegetation, the mantis can remain motionless and undetected until an insect comes close enough to be captured at high speed.
Some species exhibit highly specialized color adaptations that go beyond simple green or brown matching. The Orchid Mantis, for example, displays a brilliant pink and white coloration that allows it to mimic a flower. This form of camouflage not only conceals the mantis from predators but also acts as a visual lure to attract pollinating insects, providing the mantis with a highly effective, specialized hunting advantage.