The Chinese Mantis (Tenodera sinensis) is a common, large insect frequently encountered in North American gardens and yards. This imposing predator can reach lengths of up to five inches. The dilemma regarding its presence arises because this species is not native to the continent and poses an established threat to local ecosystems.
Identifying the Chinese Mantis vs. Native Species
Correct identification is the first step in deciding whether to intervene, as North America has native mantis species that should be protected. The Chinese Mantis is the largest mantid found in North America, typically measuring between three and five inches as an adult. This is significantly larger than the native Carolina Mantis (Stagmomantis carolina), which rarely exceeds three inches. Its coloration can be pale green or tan, often with a slender build.
A key distinguishing feature is the color on the forewings: the Chinese Mantis often has a green line only along the edge, while the rest of the wing is tan or brown. Unlike the European Mantis, the Chinese Mantis lacks a prominent black or white spot on the inside of its front legs. Female Chinese Mantids also have wings that extend the full length of their abdomen, unlike the native Carolina female whose wings only cover about three-quarters of the abdomen.
The Status of Tenodera sinensis in North America
The Chinese Mantis is not indigenous to North America; its native range includes China, Japan, and other parts of East Asia. This species was first introduced to the United States around 1896, likely arriving accidentally with a shipment of plants to a nursery in Pennsylvania. It was later deliberately distributed across the continent, often marketed for use in gardens as a biological control agent.
Although it has been established and naturalized for over a century, the species is classified as non-native or exotic. The term “invasive species” is applied to T. sinensis because its introduction causes environmental harm by negatively impacting native species and ecosystem balance.
Specific Ecological Concerns
The large size and generalist predatory nature of Tenodera sinensis negatively impact native ecosystems. It is an indiscriminate ambush predator, consuming almost any organism it can subdue, regardless of whether the prey is a pest or a beneficial native species. This non-selective diet includes pollinators like native bees and butterflies, such as the Monarch, which are already facing population declines.
The Chinese Mantis poses a direct threat to the smaller, native Carolina Mantis by competing for food and frequently preying upon it. The mantis’s robust size has also led to documented instances of predation on small vertebrates. These attacks include small reptiles, amphibians, and predation on hummingbirds, especially near feeders or flowering plants. The ability of this insect predator to take down a small vertebrate highlights its disruptive role in the ecosystem.
Recommended Actionable Steps
Given the threat Tenodera sinensis poses to native biodiversity, targeted removal is encouraged to protect local wildlife populations. Since adult mantises are mobile, the most effective control point is the destruction of their overwintering egg cases, known as oothecae. Chinese Mantis oothecae are distinct: they appear large, round, or cube-shaped with a foamy texture, contrasting with the native Carolina Mantis’s smaller, elongated, and smoother egg case.
Searching for and destroying these oothecae during late fall, winter, and early spring prevents the hatching of up to 400 nymphs per case. Once located on a twig or structure, the egg case can be scraped off and destroyed by crushing, freezing, or submerging it in water. Removing and killing a Chinese Mantis is an ethical choice focused on protecting vulnerable native species from this introduced predator.