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An interesting but sanctimonious hypocrite

July 1, 1993

StoryImage( ‘/Images/Story//Auto-img-118229682518130.jpg’, ‘Photo by Dr. Robert A. Hedeen’, ‘The egg case of mantid overwinters and gives rise to about 100 young in the spring.‘);
StoryImage( ‘/Images/Story//Auto-img-118229655314402.jpg’, ‘Photo courtesy of www.freewebs.com‘, ‘The Malaysian Orchid Praying Mantis (pictured) is one of many world varieties of praying manids.‘);
StoryImage( ‘/Images/Story//Auto-img-118229685212527.jpg’, ‘Photo by Dr. Robert A. Hedeen’, ‘A female mantid seems surprised as she stares at the photographer.‘);

The other day, while walking in the wooded area behind my residence, I had the strange feeling that something was closely watching me. Looking around, I saw a female praying mantid (mantis) seemingly staring at me. I was glad I was not another insect, or I would have quickly become a meal for the mantid. Actually, a better name for this denizen of the insect world would be preying mantid. The forelegs of the mantid are not adapted for walking but for the capture of prey. They are large, powerful, and armed with sharp spines capable of piercing the skin on the finger of anyone who picks one up; something to which I can personally attest.

The front legs are usually held in a pious position, as if the insect were praying, hence the official common name of praying mantid. In some countries, the mantid is revered and believed to always face to the west when “praying.” Many fear the animal and call it The Devil’s Horse, and that it can spit in your eye from a distance and cause blindness. Others fear it has a poisonous bite. Neither of these suppositions is true.

Well more than 100 years ago, Jean Henri Fabre, the celebrated French naturalist, observed an unusual phenomenon practiced by the mantid. He noted that before the female mantid could induce the male to mate, she had to decapitate him. Insect physiologists in more recent times have shown that there is a center in the brain of the male that inhibits copulation. When this center is removed by decapitation, the male has no inherent “hang-ups” and freely engages in the reproductive act.

The most important mosquito in the Midwest is arguably the floodwater species, Aedes vexas, and for years mosquito biologists tried unsuccessfully to get this mosquito to mate in captivity so laboratory colonies could be established. One of these workers was Dr. Bill Horsfall of the Department of Entomology at the University of Illinois. Horsfall remembered Fabre’s work with the male mantid and anesthetized male vexans with carbon dioxide and skillfully decapitated them. Lo and behold, it worked. He would bring the genital area of the male with the reproductive end of an anesthetisized female and mating readily took place. Thusly, Horsfall was able to establish a viable laboratory colony of this important mosquito that contributed greatly to our knowledge of them.

After mating in the fall, the female mantid constructs a Styrofoam-like egg case into which she lays about 100 eggs. The egg case, or oothecum, is then attached to a twig, and having fulfilled her biological duty, the female soon dies. The young mantids emerge in the spring and immediately begin feeding on their brothers and sisters and any other creature capable of being overcome.

Certain mail order garden supply companies offer mantid egg cases for sale for those wary of using insecticides to control garden pests. Using one organism to control another is called biological control, and this form of nonchemical control has been used successfully in some situations for many years. The only thing wrong about using mantids for pest control in your garden is that the voracious mantids will probably gobble up just as many beneficial insects as deleterious ones; lady bird beetles and bees being examples..

Another interesting feature about the praying mantid is its ability to rotate its head a full 360 degrees. A neat anatomical trick no other insect can do, and neither can we. This is an advantageous adaptation that the mantid uses to locate prey and for protection against potential enemies.

And, the mantid is a tough customer, too, being able to hold its own with formidable opponents. A professor of mine once told me he had observed mortal combat between an adult mantid and a scorpion. The mantid, desperate for a meal, attacked the venomous scorpion, deftly dodging the lethal stinger at the tip of the scorpion’s tail-like abdomen. In a flash, the mantid was able to grasp the stinger with its forelegs and nip it off. Being disarmed, the scorpion was defenseless and became easy prey for the victorious mantid.

The mantid is primitive in many ways, as far as insects go, but many of its characteristics are certainly unique in the natural world.

Dr. Robert Hedeen is a former resident of Maryland’s eastern shore and resided in the Chicago area from 1960 to 1971. He is a retired professor emeritus of biological sciences in the University of Maryland system. He has published more than 30 scientific papers, has written numerous magazine articles, and is the author of two books on the natural history of the Chesapeake Bay.

from the June 20-26, 2007, issue

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