By RICK BORCHELT
Courtesy of Bonnie Ott
Look carefully through clumps of goldenrod or asters this month, and you’re likely to find a pair of huge eyes on a triangular head, perched atop wicked-looking, hooked forelegs, calmly taking your measure.
It’s a praying mantis, though truth be told, it would be more accurate to call it a preying mantis. In the fall, mantids (the plural of mantis) are the Tyrannosaurus rexes of the insect world.
A hundred years ago, that mantis you are looking at would have been our only native praying mantis, the Carolina mantis (Stagmomantis carolina). Today, however, you are much more likely to see one of two common invasive mantids: the Chinese mantis (Tenodera sinensis) or European mantis (Mantis religiosa).
The European mantis’s Latin species name, religiosa, best reflects the common name, praying mantis — referencing the prickly forelegs, raised as if in prayer. The word “mantis” in ancient Greek means “soothsayer”; these insects have been considered to have supernatural or mythological connotations across every culture where the 2,500 mantis species are found.
Carolina mantids are the runt of the three species in our area, seldom more than 3 inches long. European mantids can
Courtesy of Jim Moore
be 4 inches, and Chinese mantids max out at 6 inches. All three are ace predators, mostly of other insects and invertebrates. Chinese mantids are large enough to sometimes take vertebrate prey — from small snakes and lizards to the very occasional hummingbird.
Chinese mantids are an introduced species; in 1896, they were released in the Philadelphia suburbs, ostensibly to control other insects. European mantids were introduced just three years later in an effort to prey on another introduced species — the spongy moth, which is better known by its old name, gypsy moth (Lymantria dispar).
But the introduced mantis species proved not to be very coachable — they ate anything they could catch, and often that was the native Carolina mantis. Our native mantid populations have plummeted since the invasives came to our shores, partly from stiff competition from these larger, stronger mantids, and partly from outright cannibalism.
Courtesy of Luc Viatour
In fact, cannibalism is a constant threat in the world of mantids, with males often ending up on the menu of their female sex partners. On the other hand, the common conception of female praying mantids as femmes fatales isn’t entirely accurate either. When a female eats a male, it’s usually the result of a courtship gone wrong.
Female mantids don’t really distinguish between male mantids and other prey items. So, a male mantid typically takes it slow and easy when approaching a female. He’ll usually size her up from a distance and then cautiously — very cautiously, sometimes for hours — stalk her. He’ll freeze in place if she looks his way: Mantids have exceptional eyesight and can turn their heads an astonishing 180 degrees, with the flexibility of Linda Blair in “The Exorcist.” Sometimes the male will sway, camouflaging himself as if he were a branch or leaf in the breeze. Males of some species have an even more elaborate courtship display to calm her down.
Regardless of how he gets there, once the male’s close enough to his female target, he’ll jump on her back like a broncobuster at a rodeo. He’ll use those spiny forelegs to grab and hold on for dear life, quite literally, until he’s able to insert his genitalia into her. The two mantids can stay locked like this for hours, while the female’s abdomen is gripped by waves of sexual contractions. When these contractions start to ease, the male knows it’s time to make himself scarce, and he’ll drop and roll to the ground in hopes of escape.
If the male’s approach is detected or flawed, or if he doesn’t hold her just so to keep her from reaching back for him, or if he doesn’t leave fast enough, he’s dinner. Sometimes she manages to snag his head during the act of copulation — but sex continues while she consumes his head. For our local species, mating ends up being fatal for the males less than 20% of the time.
All three of these Maryland mantid species — and a few other invasive ones that aren’t very common yet — overwinter here as eggs and hatch in the spring. The young mantids grow over the summer and reach sexual maturity in August.
The adult females of our different mantis species are pretty easy to tell apart, though color isn’t a good guide, since all of them can vary from brown to gray to green. An adult female Carolina mantis has wings that are too short to hide the growing bulge of her belly that will be her egg cases; she looks like she’s wearing a jacket that’s several sizes too small. Both Chinese and European mantis females have wings that cover or mostly cover their swelling abdomens. But you can differentiate female European and Chinese mantids by looking at them head-on: European mantids of both sexes have two dark bull’s-eyes on the inside of their spiny forelegs, while Chinese mantids do not.
Courtesy of (clockwise, from left) Jim Brighton, Kevin Fryberger and Tom Potterfield
Mantid egg cases, called oothecae, are even easier to tell apart. Chinese mantis oothecae look like hardened foam from an overly ambitious barista’s cappuccino. Carolina mantis oothecae are oblong, with distinct parallel ridges like a loaf of bread the baker has scored across the top. The oothecae of European mantids look sort of in-between, frothier than those of Carolina, but more formed and longer than they are wide.
All of these egg cases can contain hundreds of mantid young. Many groups, like the Brandywine Conservancy, recommend finding and destroying Chinese and European egg cases in your yard or garden during the winter, when the distinctive lumps show up on branches, fence posts and weed stems.
Whatever you do, don’t bring them inside your warm house — they’ll hatch, and you’ll have swarms of green mini-mantids crawling over your walls and furniture. It’s also a good idea to inspect live-cut Christmas trees for mantis oothecae as well — a mass of mantids would be a holiday surprise you probably won’t want.
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Have questions for Rick about the world of nature in and around the Maryland suburbs or suggestions for future columns? Drop him a note at rborchelt@gmail.com.
