Garden thugs—Chinese, European and Narrow Winged Mantises– are evil alien creatures from Asia. You DO NOT want them in your native plant garden. They are indiscriminate predators of all insects, including beneficial insects. Alien mantises even eat hummingbirds and butterflies.
There are three alien mantis species in Pennsylvania: Chinese mantis (Tenodera sinensis), European mantis (Mantis religiosa), and Narrow-winged mantis (T. angustipennis). Our native Carolina mantis (Stagmomantis carolina) is more common in the south, so if you see a mantis in your Pennsylvania garden, it is most likely an alien.
How to Identify Mantises
Mantises are easy to identify if you know their characteristic markings. But to see these markings, you would have to get up close and personal. The small markings on the legs and wings and the shape of the head are the distinguishing factors.
Chinese mantis is up to 5 inches long and pale green to tan, with a green line along the edges of the forewings. The area in front of the antennae and between the eyes is fairly square and has vertical stripes.
European mantis (Mantis religiosa) grows only to about 3 inches, and its color ranges from tan to light green. Look for a round black dot at the bottom of the forelegs. Sometimes this black dot has a white center, which can be hard to see when their forearms are held together. The lower parts of the front legs have a yellow dot.
Narrow-winged mantis (T. angustipennis) is green or light tan, with a bright green stripe on the wing margin. It is almost identical in appearance to Chinese Mantis. Narrow winged mantis has a bright orange spot on the chest between the forelegs.
Carolina mantis (Stagmomantis carolina), our native mantis, is only about 2½ inches long and is pale green to tan or mottled gray. Wings extend only three-fourths of the way down the abdomen in adult females.
Egg Case Identification
Alien mantis egg cases are different in appearance than native mantis egg cases. Chinese mantis cases are round. Narrow winged mantis egg cases are elongated, wavy, wider and narrower than our native species egg cases. Egg cases can contain up to 400 eggs. Look for them in the fall. You will find cases attached to twigs, shrubs, small trees, rocks, sides of buildings, or fence posts. If you find alien egg cases, destroy them immediately by crushing and then placing the cases in alcohol or water.
Please note: mantis egg cases sold for bio-control are usually those of the Chinese mantis, so do not buy them.
In my research for this article, I discovered there is a misconception about mantises. Many articles, including those from university extension services, state they are beneficial insects. They are not! Protect your hummingbirds, beneficial insects and butterflies. Be on the lookout for Chinese, European and Narrow Winged Mantises. Do not allow them to become established in your garden.