A praying mantis is known for its unique posture and mastery of camouflage. While most people recognize the bright green variety, observing a mantis turn a dull, earthy brown is common. This color shift is not random but a calculated adaptation, driven by the mantis’s need to survive in a changing world. The underlying mechanisms involve specific biological materials and are tied to the mantis’s environment and its life cycle.
The Role of Pigmentation and the Exoskeleton
The color of a praying mantis is determined by specialized pigments produced in its body and deposited beneath its hardened outer layer, the exoskeleton. The vivid green coloration is primarily due to the presence of carotenoids, which are organic pigments typically acquired from the mantis’s diet of plant-eating insects. Brown coloration, conversely, is the result of melanins, a group of dark pigments responsible for earth tones in many organisms.
Unlike chameleons, which can rapidly alter color, a mantis cannot change its hue instantaneously. The color change is a slower, structural process involving the regulation of pigment production within the epidermal layer. The mantis decides on its color based on environmental cues, and that color is “locked in” when the new exoskeleton hardens following a molt. The rigid exoskeleton is the final display case for the chosen color, making the change irreversible until the next shedding.
Seasonal and Habitat Adaptation
The shift to brown is a camouflage strategy that allows the insect to blend into its surroundings to hide from predators and ambush prey. This adaptive coloration is directly influenced by environmental factors such as ambient temperature, humidity, and the color of the vegetation. In environments dominated by lush, green leaves, green mantises have a higher chance of survival.
As the seasons change from summer to fall, the mantis’s environment transforms from vibrant green to dry browns and yellows. High temperatures, low humidity, and the browning of grasses trigger the mantis to produce melanin pigments instead of carotenoids. A mantis living in dry grass or on brown tree bark will molt into a brown morph to maintain its camouflage advantage against visual daytime predators like birds. This strategy ensures the mantis remains camouflaged as its preferred hunting and resting sites change color.
The Relationship to Molting and Age
The physical change from green to brown, or vice versa, is strictly timed with the mantis’s developmental stages, known as instars. A praying mantis is only capable of changing its established color immediately after it sheds its exoskeleton, a process called molting. This molting occurs several times throughout its life and is the only window of opportunity for the insect’s body to deposit new, environmentally appropriate pigments.
The decision to turn brown often reflects the mantis’s advancing age and the seasonal progression toward the end of its life cycle. Mantises typically hatch in the spring and reach their final molt into adulthood in late summer or early fall. The adult mantis adopts the brown coloration to match the late-season foliage and dead grasses. The final color morph is retained for the rest of its life, allowing the mantis to remain camouflaged as it mates and lays its egg case before winter.