Straying Mantis Insects Adapt To Cold Winters In Moving North

Even insects can’t seem to resist the urge to explore.

Pioneering its way northward, the praying mantis began arriving in southeastern Idaho about 10 years ago.

Stagmomantis californica came from northern Mexico and southern California, adapting to colder winters along the way.

“The large praying mantis that most people are seeing is relatively new to Idaho,” said Robert Anderson, a biology professor at Idaho State University. “It’s moved up from the south along the west side of the Rockies,” he said.

Anderson has noticed the insects’ northward movement.

During the last decade, people have brought him praying mantises to identify from Provo, then Salt Lake City, Ogden and Malad. Then he began finding praying mantises in his back yard.

The 3.5-to 4.5-inch-long insects haven’t arrive sooner because cold weather killed the eggs. About 50 to 150 eggs spend the winter in a protective casing called an ootheca.

“Who knows when or how,” Anderson said, “but through a series of mutations, variant forms of this species have adapted to cold conditions.”

The eggs hatch from the ootheca in April and May.

A praying mantis is a gardener’s best friend becuase of its diet.

As a youngster, it gobbles aphids, scale insects or mites. Five molts later as the montis enlarges, it eats increasingly larger insects, including grasshoppers.

“They do a wonderful job,” said Bill Mayes, nursery manager at Pocatello Greenhouse.

The praying mantises are remarkable, not only for their ability to adapt to colder climates, but for their anatomy, too, Anderson said.

Their head can pivot 180 degrees.

Their most popular trait is their front legs that are always cocked slightly and touching each other, making them look as if they’re in a constant state of prayer.

The mantises’ northward movement isn’t their only mystery. They change colors from green to tan. It’s partially due to sexual dimorphism, Anderson said.