She sits on a leaf near the ground and flexes her abdomen, exposing her pheromone glands. A football field away, he catches her siren call and flies to meet her. He is cautious, approaching from the front, wiggling his abdomen, showing off his prowess. They come together, and while he’s lost in ecstasy, she may, if she’s hungry, eat his head. He keeps going anyway, hoping to ensure his paternity. (Can you hope without a head?) When he’s done, she may finish him off and then give the come hither to another potential partner. This one she may not eat—she’s not greedy, just making sure she has the protein she needs to create those eggs. Monogamy is not her thing, so her eggs may have multiple fathers. If one escapes her ultimate expression of love, he’ll try again with another temptress. Her name is Chinese praying mantis (Tenodera aridifolia sinensis).
Chinese praying mantises are native to East Asia. They were introduced to North America in 1896 because gardeners hoped they would eat garden pests. They did, and still do, and a lot more besides. Today, the Chinese praying mantis is one of the two species of mantises found in Iowa. The other species is the North American native Carolina mantis (Stagmomantis carolina).
Growing to a whopping four to five inches, the Chinese praying mantis is our largest insect. She lives in the grass and other low vegetation. She is a stealth hunter, ambushing her prey. She sits up on her back four legs, sometimes rocking a bit from side to side, watching for prey with her large, compound insect eyes. She swivels her small, triangular head up to 180 degrees in either direction on her long flexible neck. This gives her a 360-degree view of her surroundings. She gets her name because of the way she holds her strong front legs up in front of her as if in prayer. What she’s praying for is a meal to come along. When it does—an insect, a small amphibian, a little lizard, a mouse—basically anything smaller than she is, she grabs it with those powerful front legs and holds it tight while she eats it.
It’s not all one way, of course. In her food web, she eats, but may also be eaten by larger predators like birds, snakes, bats and spiders. Danger is most acute just after she molts and before her new outer skin hardens. She has some strategies that help her survive, including being the color of grass.
Our mantis hatched in the spring along with 100-200 brothers and sisters. She immediately started hunting. If food was scarce, she was not averse to eating her siblings. What is it about these guys? A nymph, she looked like her parents without wings. She shed her hard outer skin twelve times, growing bigger with each molt until she reached adulthood. After her final molt, she got her wings. Throughout this process, she captured and ate everything she could get those “praying” arms around. By fall she was ready to lure a mate to her position on the ground. She never learned to fly, so she sent out pheromones to get the males to fly to her. When she was done mating, she set about laying her eggs. She climbed onto a twig or leaf and deposited a foamy mass that included 100-200 eggs. The foam dried and hardened into a styrofoam-like blob reminiscent of a toasted marshmallow. Called an ootheca, this egg case will protect the eggs through the winter. With her job complete, she and her sisters, and any males they allowed to live, would hang around hunting and eating until the first hard frost. The eggs would survive the freeze, but the adults wouldn’t. If they lived where it doesn’t frost, they would just die of old age.
People continue to introduce these striking insects into their gardens. Egg-cases are sold by a number of commercial suppliers, although caveats persist that the praying mantises will eat anything, including beneficial insects like bees. Since they’ll eat anything they can catch, the invasive mantis will readily eat one of her native cousins given half a chance.
So, is she macabre and scary, or just practical and efficient? And as for him …?
Photo by Author. Alt text: Slender green insect with triangular head and heavy forelegs stands head down on the side of a red farm building. Praying mantis sub adult nymph, wings are not yet present.