Nature's Praying Predator

By Bernie Rains, | March 2, 2005
From Missouri Conservationist: Mar 2005

One fall afternoon, as I trimmed a Japanese barberry bush, my wife noticed a tan, walnut-sized glob on a twig near the center of the bush. A few shriveled leaves were attached to one side.

She thought it was some disease or gall. After closely inspecting it, I thought it might be an insect egg pod.

"Let's not disturb it and see what hatches in the spring," I said.

Winter passed, and the late April sun warmed the brick on our south-facing front porch. One afternoon I arrived home from work while it was still light. Instead of my wife greeting me at the back door with her usual kiss, she said, "Well, Mr. Pod Protector, come take a look at your little bundle of joy."

As I approached the bush, I saw the tan-colored glob. Dangling below it on a tiny thread was a swaying, squirming mass of grayish-green nymphs clinging to the thread and to each other. There was no mistaking the little critters with triangular-shaped heads, thin-segmented abdomens, and raptorial front legs for anything but praying mantises.

The next day the tiny mantises were performing gymnastics on the barberry bush branches and prowling on the ground. Observing this "outpouring" of life perked our interest in the insect and "egged" me on to take a closer look at the life history of the praying mantis.

From Eggs to Nymphs

After mating with a male in late autumn, the female mantis lays eggs in a foamy liquid secreted from her abdominal glands. She places the foam on and around a twig or branch, where it quickly hardens to form a protective shell about the size and color of an English walnut. The egg case, or "ootheca," is hard to locate because of its color and often secluded location. A female mantis can produce one or more egg cases. Last winter, our barberry bush held six oothecae.

The baby mantises, or nymphs, hatch on warm days in April. They may hatch all at once or in batches. Two hundred or more mantis nymphs may emerge from a single egg case. The young nymphs hang by a thread from the ootheca until their skins harden. It takes the entire spring and summer for a nymph to mature into adulthood.

As a mantis nymph matures and grows, it periodically replaces the outer covering of its body through a process called molting. It sheds its outer covering, or exoskeleton, and replaces it with a new exterior skeleton that was formed underneath. Depending on the species, mantis nymphs molt five to ten times during the summer. The final molt produces an adult mantis bearing two sets of fully formed wings.

The Perfect Predator

A mantis has three distinct body segments; head, thorax and abdomen. The thorax has an enlarged portion that forms an impressive neck to which legs and wings are attached. The abdomen comprises the hind part of its body. Its head can move 180 degrees from side to side.

On the head are two sets of eyes. One set contains two large, compound eyes with hundreds of facets and two lenses. The second set contains three simple eyes. The compound eyes are on opposite sides of the head, and the three simple eyes are in a triangular pattern between the antennae. Reportedly, mantis eyes are sensitive to slight movements up to 60 feet away.

The most conspicuous body parts of a mantis are its front legs. The front legs of the mantis have rows of strong spikes for grabbing and holding prey. The front of the legs folds back against the middle, making an effective spiked trap for holding prey.

When hunting, the mantis holds these upright in a manner which some say resembles a person in prayer, hence the name "praying" mantis.

A female mantis usually has a heavier abdomen and is larger than the male. In North America, a mantis can have a body length of 2-6 inches. The female's abdomen has six segments. A male has eight. When fully developed, both sexes have two sets of wings. The front pair is thick and narrow. The back pair is thin, and folded like a fan. Mantises do not fly long distances. If undisturbed, males fly more than females, and often at night.

There are three common species of praying mantis in North America. The European, Mantis religiosa, and the Chinese, Tenodera aridifolia sinensis, were introduced in the Northeast around 1900 to control garden insects. The Chinese mantis is tan, except for the outer edges of its forewings, which are pea green. The species considered native to the United States is the Carolina mantis, Stagmomantis carolina.

The closest relatives to the mantis are the grasshopper, cricket, and cockroach.

Fierce Lifestyle

Mantises are commonly found in meadows, gardens, and clearings. They are ideal inhabitants of rose and vegetable gardens, for they voraciously devour aphids, leafhoppers, mites, flies, and grasshoppers.

Because of its hunting ferocity, the praying mantis has been dubbed "the dragon of the insect world." An adult mantis will attack moths, butterflies, horseflies, beetles and other mantises. They have been known to attack animals larger than themselves, including frogs, lizards, and small birds. Such a contest would be exciting to observe.

The mantis hunts mostly by selecting a promising location and waiting motionless for unsuspecting prey to come within striking range. Its varied coloration enables the mantis to sit unnoticed on twigs and stems. Its coloration usually reflects dominant colors of the vegetation in its habitat. Mantises tend to be green in areas of grasses and leafy weeds, and brown in woody areas.

Sometimes a mantis will pursue prey by creeping to within striking range. Although the stalk is stealthy, the attack is incredibly rapid. The mantis starts eating the captured insect alive and almost always starts at the neck to quickly stop any struggle to escape.

Despite its ferocity, the mantis sometimes ends up as food for other creatures. Spiders, ants, lizards, birds, bats, and frogs eat mantis nymph or adults. A mantis can detect high-frequency sounds like those emitted by bats. A mantis will drastically change its flight into an erratic, descending spiral when bats are nearby.

The mating habit of the mantis is consistent with its predaceous disposition. Female mantises are larger than males and sometimes devour them. For mating, a male mantis cautiously approaches the female from behind and climbs onto her back. During the mating process, which may last a day or more, the female may turn and devour the male's head. It usually finishes eating the male after mating.

Insect of Fame

Although they look fierce and dangerous, praying mantises are harmless insects that are beneficial to flower and vegetable gardeners. I'm glad we have them in our yard.

Look closely around your property, you may be lucky enough to discover some of these valuable and fascinating insects, too.

This Issue's Staff

Editor - TomCwynar
Managing Editor - Nichole LeClair
Art Editor - Ara Clark
Artist - Dave Besenger
Artist - Mark Raithel
Photographer - Jim Rathert
Photographer - Cliff White
Staff Writer - Jim Low
Staff Writer - Joan McKee
Circulation - Laura Scheuler