AUGUST
1999

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

8-26-99

Pious Frauds of the Insect World

One insect everyone seems to like is the praying mantis. Few insects are held in such high regard by humans. The reason is that mantids feed on other arthropods. And by most human standards, anything that eats other insects is good!

Mantids also exhibit some interesting biological characteristics. Unlike most insects, they can turn their heads. This allows mantids to gauge the distance of potential meals so that they don't attempt to catch prey outside their reach.

Some female mantids also make a meal of their mate. The male mantid is decapitated by the female—a behavior that some people regard as, well, interesting!

So we like mantids. So much so that some people think that it is against the law to kill them. While no such law exists, there is no reason to kill mantids since they don't harm us, our pets, our plants or our possessions.

But there is more to this insect than meets the eye of the average beholder. Mantids are, as Odgen Nash called them, “pseudo-saintly” bugs. They are “pious frauds,” according to nature writer Harold Bastin in his book “Freaks and Marvels of Insect Life.”

So what is the story of this widely recognized insect? Most mantids are protectively colored. Their color allows them to blend into their environment. Such camouflage is of survival value to the insect.

First, mantids do not chase down and catch their prey. They wait for the potential meal to crawl or fly within range of their forelegs. So the camouflage means that the prey does not see the mantid until too late. Secondly, mantids themselves are prey for birds, lizards and other enemies. So the protective color serves to hide the mantid from mantid-eaters. 

A good example of how this works is exhibited by the common European praying mantis, which has two distinct color forms. One form is green, the other brown. The green form is found on living green foliage, while the brown form hangs around dead and decaying leaves.  

The Italian naturalist Cesnol was curious about colored mantids so he tethered some green mantids on brown foliage and some brown mantids on green foliage and vice versa. He discovered that most of the green mantids on the brown background and the brown mantids on the green background were either destroyed by predators or starved to death. 

On the other hand, when the background colors were reversed the mantids did just fine. The moral of the story is that mantids do better when they don't stand out!

This mantid masquerade is even more highly developed by a Malayan mantis that resembles a pink orchid. So close is the resemblance of the insect to the flower that bees and butterflies mistake the insect for the flower and land on it. Once this happens, the mantid turns the fooled insect into a meal. Mantid deception is even enhanced when the insect periodically sways from side to side as if being caressed by a gentle breeze.

While we humans think praying mantids are wonderful insects, it is obvious the insect is no saint. So maybe we ought to change the name from praying mantid to preying mantid!

 

Writer: Tom Turpin
Editor: Olivia Maddox