If you are strolling in the outdoors these days, you may notice a styrofoam-like structure attached to a twig or an upright piece of grass. This is the egg case or ootheca of a praying mantid. A female mantid secreted the egg case last fall and deposited about 200 fertilized eggs within.
An interesting project for the junior naturalist is to bring one of these eggs cases into a warm house and observe the young insects when they hatch in late winter or early spring. However, if they are not frequently fed a small bit of raw meat, they will feed on each other until only one remains.
Mantids are very interesting animals and have contributed considerably to insect folklore. They are highly predaceous insects and are called praying mantids because they usually lie in wait for their prey with the front legs upraised in an attitude of prayer. A more appropriate name would be preying mantids as they are vicious predators and will attack and devour any animal they can overpower.
Mantids are about the only insect known to overcome and gobble up vertebrate animals such as small mice and humming birds.
Creatures with formidable defense mechanisms do not intimidate them. A biologist once described to me an observation he made of a mantid attacking a scorpion .The mantid cautiously circled the scorpion, keeping just out of range of the lethal stinger in the tip end of the tail-like abdomen of his foe. Then, with the speed of a striking rattlesnake, the mantid darted in and nipped off the segment of the scorpion that bore the stinger, rendering it defenseless. The mantid then leisurely proceeded to enjoy its meal.
A famous French naturalist, Jean Henri Fabre, made an interesting observation in the mid-1700s concerning the mating habits of the praying mantid. A male and female mantid was observed to approach each other, but the male steadfastly refused to engage in the mating process. The female then unceremoniously decapitated the male. Apparently there is a copulatory inhibition center in the males brain that prevents him from engaging in the act of mating. Once decapitated, the headless male proceeded to mate with the female without any evident hang-ups. After mating had been accomplished, the female added insult to the males injury by having him for lunch.
Mantids have such a voracious appetite for other insects that they are sometimes touted as the ideal solution for insect control, so-called biological control, or using one living thing to control another.
In the classified section of garden magazines one can frequently find mantid egg cases for sale, with the idea being if you can establish a colony of mantids in the garden, they will solve all of your pest control problems. The efficacy of this practice is, however, suspect.
As far as I can determine there has never been a detailed study made of the food habits of mantids under different conditions. In the absence of such information, I must assume that beneficial insects are just as tasty to mantids as harmful ones.
My grandmother greatly feared a praying mantid and always kept a considerable distance between herself and one residing in her yard. She called mantids, devilhorses (others have referred to them as mule killers, soothsayers, and other uncomplimentary names), and she firmly believed that mantids could spit for a long distance and always aimed for your eyes. She also believed if the spit got into your eyes, severe pain and possible blindness would occur.
The truth of the matter is that mantids are quite harmless to humans. The spitting at your eyes story probably originated because mantids are sometimes confused with another insect. Walking sticks are large insects that resemble mantids, and may be mistaken for them, even by trained biologists.
As a defense mechanism, some walking sticks have been observed to eject an irritating fluid for several inches, and the few people who have gotten this substance into their eyes have suffered intense pain. Walking sticks, however, do not spit the irritating fluid but secrete it from special glands located along the sides of the body.
There is one species of praying mantid in which males are unknown. Progeny are presumably produced by parthenogenesis, the development of an egg without the benefit of fertilization. Could it be that the females of this species went too far with the decapitation technique and deprived themselves of male companionship?
Dr. Robert Hedeen is a former resident of Marylands eastern shore and resided in the Chicago area from 1960-1971. 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.