Des Moines Register
08-31-06
Praying mantis chews into Iowa
Mild winters bring more of the insects further north. Their 'claws of death' devour prey, but don't hurt people.
By MARY CHALLENDER
REGISTER STAFF WRITER
Go outside and take a good look around.
You're likely to spot a long, lean, green, faintly otherworldly creature, staring back at you bug-eyed.
Meet the Chinese praying mantis.
Once scarce this far north, the eye-catching insects with the notorious sexual mythology have been spotted in unusually large numbers in central Iowa this year.
They are the beneficiaries of several mild winters in a row, according to Donald
Lewis, professor of entomology at Iowa State University Extension.
Praying mantids (the plural form) are named for their long front legs, which they fold and clasp "prayer-like" in front of their small, triangular heads.
But don't let the pious act fool you, Lewis says. Praying mantids are cold-blooded killers that snatch crickets, flies, bees, butterflies — even a hummingbird has been reported
— from the air and devour them alive.
The sanctimonious-looking front legs are actually "ferocious claws of death,"
Lewis said, which bear more than a passing resemblance to the medieval torture device, "the iron maiden." Lined on the inside with long and short spines, the claws clamp and impale the mantids' writhing prey until it's devoured.
"They grab it, they squeeze it and they begin to chew it live," he said. "There's no delicacy."
Part of the reason that praying mantids attract our attention is that they don't crawl like most insects but instead seem to walk "upright" on their middle and hind legs, upper abdomen thrust forward proudly.
They also tend to make a lot of noise in the air. Although Chinese mantids are fairly strong fliers, they're not built for grace, Lewis said.

"They're not good aerodynamic acrobats like flies and bees," he said. "They're more like flying bulldozers."
The main reason people are so captivated by praying mantids though - especially now during mating season - is probably morbid fascination.
"Most people seem to believe the popular mythology that all praying mantids practice sexual cannibalism, that it's destined that the male be eaten after mating with a female," Lewis said.
Mythology?
"While it happens in crowded cages, it doesn't seem to be the practice in the natural world," he said.
Even without the risk of being eaten by one's mate, the life span of a mantis can be measured in months, Lewis said.
In late spring, if the winter has been sufficiently mild, the eggs hatch, and hungry nymphs about the length of a trim fingernail emerge.
They spend all summer eating and growing. Then they mate and lay eggs, as many as 200 at a time, in a stiff, foamy case in the fall.
Soon after, the adults die of old age or freezing, and the harshness of the winter decides the size of the next year's population.
Lewis said there is no reason to fear the large insects.
"Praying mantids cannot hurt people," he said. "As long as you keep your fingers away from their front legs or out of their mouths."
Some companies even sell mantis cocoons to gardeners as an organic insecticide, although Lewis doesn't recommend them for this purpose. When mantids feed, he said, they don't discriminate between insects that harm gardens and those that are beneficial."Overall, their impact in the garden and landscape is probably negligible," he said.
Mantis care
If you find a praying mantis egg case:
• Keep it in a box or jar in an unheated garage or porch through the winter.
• In mid-May, bring the egg case in and begin watching for nymph emergence.

• If the eggs hatch, the nymphs can only be kept together for a short amount of time. After a day or two, they will begin to eat each other. Move nymphs to separate cages or relocate them to different parts of your yard.
• Raising nymphs to adulthood in captivity is very difficult.
Source: Donald Lewis, entomologist for Iowa State University Extension