You Brought Home a Green Mantis—So Why Is It Now Sporting a Tan?
You've been watching your pet mantis grow, fascinated by its alien-like grace and predatory prowess. It started as a tiny nymph, pale and delicate. As it grew, it stayed a vibrant green—until one day, after a molt, it emerged a completely different shade. Brown. Or maybe you spotted a mantis in your garden that was green last week, and now it's tan, blending perfectly with the autumn leaves. The question that naturally arises is simple: why do praying mantis turn brown?
This color shift is one of the most intriguing mysteries of these already fascinating insects. It's not magic, and it's not a sign of illness (usually). It's a complex survival strategy shaped by evolution, environment, and even the mantis's own life stage. Whether you're a mantis keeper, a curious gardener, or just someone who appreciates nature's wonders, understanding this transformation reveals a remarkable story of adaptation. Let's dive into the science behind the shift.
The Short Answer: It's All About Camouflage
If you're looking for a quick answer to why do praying mantis turn brown, here it is: praying mantises turn brown primarily for camouflage—to blend in with their surroundings and avoid detection by both predators and prey [citation:2][citation:5]. This color change is not instantaneous like a chameleon's; it happens gradually, typically during the molting process, and is influenced by environmental factors like humidity, temperature, and the colors in their habitat [citation:2][citation:3][citation:8].
Think of it as nature's wardrobe change. A mantis living among green leaves in spring might benefit from being green. But as summer turns to fall and vegetation browns and dries, a brown mantis becomes nearly invisible against the dead foliage and bare branches [citation:5][citation:8]. This adaptation significantly increases their chances of survival [citation:5].
The Molting Connection: When the Magic Happens
Understanding why do praying mantis turn brown requires understanding molting. Mantises have an exoskeleton—a hard outer shell that doesn't grow with them. To get bigger, they must periodically shed this old skin and form a new one [citation:3].
Here's where color comes in. Immediately after a molt, the mantis's new exoskeleton is soft, pale, and extremely vulnerable [citation:3][citation:10]. Over the next few hours or days, it hardens and develops its final pigmentation. During this critical window, environmental cues can influence the colors that develop [citation:2][citation:3].
According to a 2025 study published in Ecology and Evolution, researchers found that mantis nymphs changed color during development in response to their background—those raised in brown containers developed more brownish hues than those in green containers [citation:1][citation:4]. However, the effect was "small and variable," suggesting that while environment matters, it's not the whole story [citation:1][citation:9].
Key point: A mantis cannot change color instantly. The transformation only occurs with a molt, and it takes several days for the new coloration to fully develop [citation:2][citation:3][citation:10].
The Environmental Triggers: Temperature and Humidity
So why do praying mantis turn brown in some conditions and green in others? Researchers and experienced keepers point to two major environmental factors:
| Factor | Effect on Color |
|---|---|
| Humidity | Higher humidity tends to favor green morphs; lower humidity favors brown morphs [citation:2][citation:6]. |
| Temperature | Warmer temperatures often lead to brown coloration; cooler temperatures favor green [citation:2][citation:8]. |
| Light Intensity | Light exposure can indirectly influence color by affecting temperature [citation:2][citation:7]. |
| Background Color | The dominant colors in the environment can influence coloration over successive molts [citation:1][citation:6]. |
On mantis keeper forums, experienced hobbyists debate which factor matters most. Some swear by humidity as the primary driver, while others argue it's more complicated [citation:6]. The scientific consensus is that multiple factors interact, and the result varies by species and even individual [citation:1][citation:6].
The Genetics Factor: Not All Mantises Can Change
Here's an important nuance to why do praying mantis turn brown: not all mantis species have the same color-changing abilities [citation:2].
- Some species are genetically predisposed to be brown regardless of environment [citation:2][citation:3]. The bark mantis, for example, is naturally brown to match tree bark [citation:5][citation:7].
- Other species can readily switch between green and brown depending on conditions [citation:2]. The European mantis (Mantis religiosa) and Chinese mantis (Tenodera sinensis) are known for their color variability [citation:7].
- Still others have a more limited palette and may only show subtle variations [citation:2].
The 2025 study on Stagmomantis limbata found that adults exhibited sexual color dimorphism: males were often heterogeneous in coloration (green body with brown pronotum), while females ranged continuously from green to brown [citation:1][citation:4][citation:9]. This suggests that mobility differences between sexes have led to different camouflage strategies [citation:1].
Age and Maturity: Nymphs vs. Adults
Age also plays a role in why do praying mantis turn brown. Younger mantises often have different coloration than adults [citation:2].
Some species start as green nymphs and gradually turn brown as they mature [citation:2][citation:5]. This change can be linked to the changing vegetation and prey availability throughout their lifecycle [citation:2]. As one source notes, newborn mantises often start mostly brown and develop more green tones as they grow older—or vice versa [citation:5].
Additionally, the exoskeleton naturally darkens with age. Nymphs are often lighter, and with each successive molt, their bodies produce more melanin, deepening their color [citation:5].
When Brown Might Signal a Problem
While color change is usually natural, there are times when it indicates something wrong. Understanding why do praying mantis turn brown also means knowing when to worry.
| Symptom | Possible Cause |
|---|---|
| Entire mantis gradually turns brown after molt | Natural adaptation to environment [citation:3][citation:8] |
| Small brown patches or dots on wings/back | Possible sickness, infection, or injury [citation:3][citation:8] |
| Mantis turning black | Could indicate impending molt, illness, or injury [citation:3] |
| Dull or faded coloration | Possible poor health, malnutrition, or pre-molt [citation:2] |
If your mantis has small brown spots rather than a complete color change, monitor it closely and ensure proper humidity and ventilation [citation:3]. A mantis refusing food after turning brown is normal before and immediately after a molt, but prolonged refusal could indicate a problem [citation:3].
The Pigment Science: What Makes Brown?
On a biological level, why do praying mantis turn brown comes down to pigments. The brown coloration is primarily produced by melanin deposits in the exoskeleton [citation:5].
As mantises develop, melanin granules accumulate in the cuticle—the hard outer layer [citation:5]. The amount of melanin can vary between species and individuals, with some having darker brown due to higher melanin levels [citation:5].
But melanin doesn't work alone. Mantises also produce other pigments, including carotenoids and pterins, which create yellow, orange, and reddish hues [citation:5]. The combination of melanin with these pigments results in the characteristic brown tones and the variation between different shades [citation:5].
What About Other Colors?
While brown and green are most common, some mantis species display stunning color variations [citation:2][citation:7].
- Pink mantises: The orchid mantis (Hymenopus coronatus) mimics orchid flowers, using its pink coloration to attract unsuspecting pollinators [citation:5][citation:7].
- White mantises: Some desert species are white for camouflage in sandy environments [citation:7]. (Note: right after molting, mantises temporarily appear white—this is not albinism, just a vulnerable stage before pigments develop) [citation:10].
- Yellow mantises: Some Southeast Asian species can shift from beige to yellow to brown and green [citation:7].
- Black mantises: Bark mantises from Southeast Asia are often black or dark brown, matching tree bark where they hunt termites [citation:7].
These specialized colors serve the same purpose as brown and green: camouflage in specific habitats [citation:5][citation:7].
Can You Influence Your Pet Mantis's Color?
For mantis keepers wondering why do praying mantis turn brown in their care—and whether they can control it—here's what the experts say:
You can try to influence your mantis's color by manipulating environmental factors [citation:2]. Higher humidity and cooler temperatures may promote green morphs, while lower humidity and warmer temperatures may favor brown [citation:2]. The background color of the enclosure can also play a role—a mantis in a predominantly brown setup may develop brownish hues over time [citation:3][citation:6].
However, there are no guarantees [citation:2][citation:3]. Genetics play a significant role, and some individuals or species are simply predisposed to certain colors [citation:2][citation:6]. Forum discussions among experienced keepers reveal that even with controlled conditions, results can be unpredictable [citation:6].
One keeper reported that an entire generation of Mantis religiosa turned out brown despite green furnishings, sparking debate about whether humidity, background, or random chance was responsible [citation:6].
Get free samples of Nature's Wisdom
Just as you might test a product before committing, you can observe nature's color-changing magic firsthand in your own garden. Think of this guide as free samples of entomological knowledge—a starter kit for understanding the fascinating adaptations of praying mantises. By watching the mantises in your yard throughout the seasons, you're giving yourself free samples of real-world biology lessons, observing how these masters of camouflage shift their colors to match the changing environment.
Conclusion: Nature's Master of Disguise
So, why do praying mantis turn brown? The answer reveals an animal perfectly adapted to its world. They turn brown primarily for camouflage—to blend into dried vegetation, tree bark, and soil [citation:2][citation:5]. This color change happens gradually during molting, influenced by environmental factors like humidity, temperature, and background color [citation:2][citation:3][citation:8]. Genetics, age, and even sex play roles in determining the final shade [citation:1][citation:2].
The next time you see a brown mantis, whether in your garden or your terrarium, appreciate it for the survivor it is. Its color isn't random—it's the result of millions of years of evolution, fine-tuning these predators to disappear into their surroundings. From the green nymph blending into spring leaves to the brown adult vanishing against autumn bark, the praying mantis reminds us that sometimes the best way to succeed is to blend in.