Praying mantises are admired insects, known for their distinctive triangular heads and folded forelegs. Their predatory nature often raises questions about their role in various environments, particularly whether certain species are invasive. This article explores the biological criteria for invasive species and examines specific mantis populations of concern.
What Defines an Invasive Species
An invasive species is an organism not native to a particular ecosystem, whose introduction causes or is likely to cause harm to the environment, economy, or human health. While many non-native species are introduced, only a subset become invasive. To be invasive, a species must not only be introduced outside its natural range but also establish a population and spread aggressively.
These species outcompete native organisms for resources like food and habitat. They often lack natural predators or diseases in their new environment, allowing populations to grow unchecked. This ecological imbalance can reduce biodiversity and alter habitats.
Common Non-Native Mantis Species
Two mantis species are widely recognized as non-native in North America: the Chinese Mantis (Tenodera sinensis) and the European Mantis (Mantis religiosa). The Chinese Mantis, originating from Asia, was intentionally introduced to the United States around the late 1890s as a form of biological pest control. The European Mantis, native to Europe, was also brought to North America for similar reasons; both were introduced as biological pest control, intended to manage agricultural insects.
Ecological Impacts of Non-Native Mantises
While introduced with good intentions, the non-native Chinese and European mantises can have negative ecological impacts. These large, generalist predators consume a wide variety of insects, including beneficial native species. They are known to prey on pollinators such as bees and butterflies, important for plant reproduction, and their diet also includes other native insects, potentially disrupting local food webs.
Beyond insects, these larger mantis species have been observed preying on small vertebrates. They can capture and consume hummingbirds, small frogs, lizards, and even small rodents. This broad predatory behavior pressures vulnerable native populations, and their presence alters local ecosystem balance, especially where native predators are scarce.
Distinguishing Native from Non-Native Mantises
Distinguishing native from non-native mantis species involves observing size, color, and specific body features. The Carolina Mantis (Stagmomantis carolina) is a common native species in many parts of North America. It is typically smaller than its non-native counterparts, usually growing to about 2 to 2.5 inches in length, and its coloration can vary from mottled brown to gray, helping it blend into its surroundings.
In contrast, the Chinese Mantis is noticeably larger, often reaching lengths of 3 to 5 inches, and is typically green or brown with a distinct stripe running down its forewings. The European Mantis is medium-sized, generally 2 to 3 inches long, and ranges in color from bright green to light brown. A distinguishing feature of the European Mantis is a small, dark spot with a white center located on the underside of each foreleg, near the joint. These physical characteristics help identify whether a mantis is native or non-native.