A Sanctimonious hypocrite

A Sanctimonious hypocrite

By Robert A. Hedeen, Naturalist

“What’s in a name?” This question is answered by the pietistic praying mantis that holds its forelegs in an attitude of devout prayer while laying in wait for some passing creature that can be captured and eaten. Preying mantis, not praying mantis, would be a more suitable name for this Tyrannosaurus rex of the insect world. The forelegs of the mantis are not used for walking, as with most other insects, but are devoted entirely to the capture of prey; they are large and powerful and armed with sharp, strong spines which are well adapted for grasping and holding. A mantis will attack a wide variety of invertebrate animals and even small vertebrates.

Recently, during a stroll along Pebble Creek in Loves Park, I noticed a large female mantis peering intently at me from her roost on a low shrub. I was reminded that in a few weeks this female would be constructing a styrofoam-like capsule in which she will deposit well over 100 eggs and attach it to a twig where it will pass the winter. When the egg case, or oothecum, is deposited, the female will die, her mate having been killed by her a few weeks earlier.

Well more than 160 years ago, the celebrated French naturalist, Jean-Henri Fabre, observed that before the male mantis would engage in any amorous activity it was necessary for his mate to decapitate him! In more recent times, studies have confirmed that a center in the mantis’s brain inhibits copulation, and to induce her lover to take part in the reproductive act, the female unceremoniously bites off his head. After this necessary chore has been performed, the male is freed from his psychological “hang-ups” in regards to sex, and the mating procedure takes place. The old adage that males are prone to lose their heads over the opposite sex is certainly true of the mantis.

The mantis is indeed an interesting creature. In some countries it is revered, and it is believed the insect always faces to the west when “praying.” It is the only insect, as far as I know, that is capable of rotating its head in a full 360 degrees circle. Some people fear the mantis and call it the “devil’s horse, and many believe the insect, when angered, can literally spit in your eye, causing blindness.

And, the mantis is a tough customer too, being able to hold its own with formidable opponents. A professor of mine at the University of Texas once told me he had observed a confrontation between a mantis and a scorpion. The mantis, apparently desperate for a meal, attacked the dangerous scorpion, deftly dodging the lethal stinger at the tip of the arachnid’s tail-like abdomen. The mantis then grabbed the stinger with its forelegs and nipped it off. Being disarmed, the hapless scorpion became an easy victim and was quickly dispatched and eaten. If you pick up a mantis, the sharp spines of the forelegs may be able to prick the skin and bring a drop of blood, but no permanent damage will be done.

In a very significant way, the praying mantis has contributed to our knowledge of mosquito biology. The most important pestiferous mosquito in the United States is the floodwater species named Aedes vexans. In addition to making life miserable for us at certain times of the year, this species has been found to be a carrier of the West Nile Virus. In order to study a mosquito species in intimate detail, it is necessary to establish a vigorous colony in the laboratory. Biologists tried for years to colonize vexans in the laboratory with no success. They simply would not mate while enclosed in a cage.

Then, Dr.William Horsfall, a famous mosquito biologist at the University of Illinois, Champaign-Urbana, remembered Fabre’s observations on the mating habits of the mantis. He thought, “why not give it a try; everything else has failed to induce them to mate in captivity.” He anesthetized male and female vexans mosquitoes with carbon dioxide, and, under a stereoscopic microscope, skillfully removed the heads of the males. The procedure worked, and the headless males avidly mated with the females when their bodies were approximated. The first self-sustaining lab colony of Aedes vexans was established and, subsequently, has supplied much useful data concerning the biology and life cycle of this notorious mosquito.

The contribution of Fabre, so many years ago, concerning the bizarre mating habits of the praying (preying) mantis is not to be forgotten.

Dr. Robert Hedeen is a former resident of eastern Maryland, with degrees in zoology and botany. He is a former professor of biological science. He has had 30 scientific papers published, has written numerous magazine articles, and is the author of two books on marine biology of Maryland.

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