Living

Praying mantis bit of nuisance

KENNEWICK -- I noticed a large green mantis hiding among the leaves of my potted herbs.

He was patiently waiting for a large grasshopper to come to him.

The grasshopper came closer and then suddenly, the mantis pounced, trapping the grasshopper with its forelegs and taking a big bite out of the still struggling captive. I couldn't keep watching this gory display, even if the grasshopper had been nibbling on my herbs.

The two species of large green or brown mantises that are sometimes found in local yards and gardens are aliens.

These non-natives, the Chinese mantis and the European mantis, were introduced into this country about 75 years ago to provide natural control of crop insect pests. These vicious predators didn't turn out to be good pest managers, but the mantises have prospered and spread throughout the U.S. and Canada. While not effective in controlling pest populations, gardeners still buy mantis egg clusters for release in their gardens.

Why aren't they effective? As vicious "meat" eaters, the mantises eat insects, but they attack bad guys, like aphid and moth pests, as well as good guys, like bees and spiders. Another reason for their lack of effectiveness is that mantis populations are slow growing, making it difficult for them to keep up with quickly burgeoning pest populations.

Mantis populations grow so slowly because there is only one generation a year. Also, mantises are territorial and cannibalistic. This nasty predilection prevents a buildup of the mantis population. If gardeners try to help by placing numerous egg cases here and there, the mantis numbers still don't seem to grow significantly larger. That's because the hatching mantises either eat each other or quickly move to where there is enough food and places to hide.

Hiding is what mantises do well despite the rather large 3 inch elongated body of the European mantis or the even larger Chinese mantis.

Their lanky green to brown bodies easily blend in with plant leaves and stems.

In the fall, female mantises lay 30 to 300 eggs, enveloping them within a frothy gummy substance and gluing them to plant stems or other objects. The gummy substance turns hard, protecting the eggs over the winter. The adults die a little later, leaving only the eggs to survive the winter. In the spring, the eggs hatch and tiny baby mantises emerge from the tan colored shingled egg cases. The babies or nymphs eat and grow, molting numerous times until they reach maturity.

While the mantises that gardeners like me encounter usually are the introduced aliens, there is a native species found in the wild sagebrush areas of Eastern Washington. The native "ground mantis" is gray and about 1 inch long.

How did mantises get the common name of praying mantis? That's simple.

When they lie in wait for their prey, they hold their front legs together at an angle that makes them look like they're praying. I think they look like they're rubbing their "hands" together in anticipation of dinner. Maybe they should be called preying mantises instead.

* Marianne C. Ophardt is a horticulturist for the Washington State University Benton County Extension Office.

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