praying mantis ID

Gardeners have long appreciated the pest-control benefits of the Carolina praying mantis, which sits patiently on plants, front legs raised as if in prayer, waiting for its next meal. Arguably, they could also be called preying mantises for their voracious appetite. However, the native species Stagmomantis carolina is in decline due to competition and predation by their non-native cousins, the Asian jumping, Chinese, and European mantises.

Photo courtesy of ©Colin Purrington

As its name implies, the Chinese mantis (Tenodera sinensis) is native to Asia and was accidentally introduced to North America at a nursery in Mt. Airy, PA. The insect is twice the size of the native Carolina mantis and is an indiscriminate predator. It feeds on everything from pests to beneficial bugs like Monarch butterflies, bees, small reptiles and amphibians, native praying mantises, and even hummingbirds.

Though smaller than the Asian species, European mantises (Mantis religiosa) are also damaging to the ecology. They were introduced to the U.S. decades ago as a means of controlling another invasive bug, the Gypsy Moth caterpillar.

The narrow-winged mantis (Tenodera angustipennis) is another Asian species and was first noted in Maryland in 1921.

All four species can vary in color from brown to green, making it difficult to distinguish them from one another. Their egg cases—also called oothecae—are somewhat more distinct among the species.

• Carolina mantis:
  Carolina mantises form relatively smooth, elongated, teardrop-shaped oothecae with a central portion that is lightly colored. They can be found on branches, tree trunks, rocks, and even buildings.

  

  Carolina mantis (Stagmomantis carolina) ootheca
  ©Colin Purrington

• Chinese mantis:
  Their oothecae are a little smaller than ping pong balls and roundish in shape. They are uniform in color and their texture is almost like Styrofoam.

  

  Chinese mantis (Tenodera sinensis) ootheca
  Photo by ©Colin Purrington

• European mantis:
  The egg case is similar to that of the Carolina mantis but tends to be uniformly pale in color.

  

  European mantis (Mantis religiosa) ootheca
  Photo by ©Colin Purrington

• Narrow-winged mantis:
  Narrow-winged mantid oothecae are usually elongated. They often have red streaks, though the color seems to be most noticeable after they age a few months.
  

  Narrow-winged mantis (Tenodera angustipennis) ootheca
  Photo by ©Colin Purrington

Natural Lands has been leading Mantis Meadow Walks, which are like scavenger hunts for adults. The volunteer participants are trained to identify the different mantis species’ egg cases and remove the invasive ones they find. Staff then destroy these oothecae.

invasive mantis consuming an Eastern Pond Hawk Dragonfly
Photo by Bill Moses

Colin Purrington, scientist and former teacher of evolutionary biology at Swarthmore College, offers some suggestions on how to dispose of egg cases:

• Give them to a neighbor who has chickens
• Give them to a neighbor who has a pet tarantula, snake, lizard, or fish
• Put them in a freezer for a week
• Step on them
• Burn them

Purrington (who generously provided the images on this webpage) implores, “Whatever you do, do not just relocate oothecae to some nearby field—that just transfers the problem to someplace where you can’t see the problem. If you simply cannot bring yourself to kill the eggs, ask somebody to do so for you.”

It’s important to be tell these species apart, especially if you opt to destroy non-native mantids. Purrington offers this helpful suggestion: “If you need help identifying an ootheca, I highly recommend posting a photograph on iNaturalist. If you post there, feel free to include my iNaturalist username (@colinpurrington) in your caption so that I can have a look. Not only will you get an answer from the iNaturalist community within a day or two, your submission helps scientists track the spread of invasive species.”

Left: Narrow-winged mantis
Center: Chinese mantis
Right: European mantis
Photo by Tianna Godsey