Cockroaches: A bane of mankind

StoryImage( ‘/Images/Story//Auto-img-11605898032282.jpg’, ‘Photo courtesty of‘, ‘The largest complete fossil of a cockroach was found in a Columbiana County, Ohio coal mine. Measureing 3.5 inches, the fossil is 300 million years old. An American cockroach stands atop the fossil measuring 1.5 inches.’);
StoryImage( ‘/Images/Story//Auto-img-11605898982282.jpg’, ‘Photo by Robert A. Hedeen’, ‘Be thankful this 3-inch long hissing cockroach is native to Madagascar and not the United States. (Speciman from the Burpee Museum of Natural History)’);

If nuclear bombs ever obliterate life on earth, in all probability the last surviving animal will be a cockroach. If a human is exposed to 1,000 rads (units of radiation), he will die within two weeks. Laboratory experiments have demonstrated that cockroaches can survive 6,400 rads, and after an exposure to 9,600 rads, some lived for 35 days.

Cockroaches appear in fossils that are approximately 350 million years old, and over the eons of time they have changed very little. They could appropriately be called living fossils. One of the evolutionary developments that made insects such a successful group was the development of wings, and roaches were the first known winged insects. That they were and are a successful group is evidenced by the fact that there are more than 3,100 different species of cockroaches on a worldwide basis, but, fortunately, only a very few have become domesticated and invade our homes.

Cockroaches are oval, flattened creatures that vary in size from less than an inch in size to several inches. Their antennae, or feelers, are long and threadlike, and the head is not obvious from above, being covered by a plate called the pronotum. They are very fast runners, as anyone who has ever attempted to step on one soon discovers. Though most are winged, they very seldom fly.

Cockroaches are arguably the most detested domestic insects by residents of the United States. They eat the same food as we do and can become serious pests when large infestations occur. In addition to processed foodstuffs they may damage books by eating the paste in the binding and have been known to cause wallpaper to loosen and fall by eating the paste used in hanging it. They were said to have the repulsive habit of nibbling at the toenails and fingernails of sleeping sailors of infested ships of yore.

They emit a foul odor, and, in general, they are unpleasant creatures if found in your home. Though they have filthy habits, they have never been incriminated as a specific vector of a disease. But, as they move about, harmful microorganisms may become attached to their bodies and then be transferred to our food.

Several species invade our homes in the U.S., but four are the most cosmopolitan: the American cockroach, the German cockroach, the oriental cockroach, and the brown banded cockroach.

The American roach is the large, reddish-brown one that may be 1.5 inches long. The oriental is about an inch in length and is much darker in color. The German roach is usually the one we most frequently have to deal with, and it is about a half inch or less in length It is pale yellowish in color and has two dark bars on the pronotum. The brown banded roach is similar to its German cousin but lacks the two dark bars on the pronotum.

An infestation of roaches is very difficult to alleviate, and is probably the most difficult job the pest control technician has to tackle. Sanitation must be practiced before roaches can be eliminated from your home. Garbage and food scraps must not be allowed to accumulate. Suitable insecticides are usually required to achieve a successful control program. In the past, Chlordane, Malathion, Dursban and a host of other materials were used successfully for roach control, but the bugs quickly developed resistance to them, and the chemicals also were found to be dangerous to man. The pest control industry now uses less toxic and somewhat less effective insecticides for roach control.

But there is more than one way “to skin a cat” in regard to roach control. Years ago, while serving as a medical entomologist in the U.S. Army, I was assigned to the Walter Reed Army Institute of Research in Washington, D. C., to work on the mosquito-transmitted disease termed Japanese B encephalitis. Jap B, as it was called, was a serious disease found in Japan, Korea, and Southeast Asia.

When I arrived at Walter Reed, I was stunned to find our laboratory was heavily infested with cockroaches. Insecticides could not be used as we maintained several colonies of living mosquitoes that were suspected to be the vectors of the viral disease. Thinking about the problem, I remembered an article I had read in a farmer’s almanac concerning how to safely get rid of roaches around the home. You were to mix equal amounts of flour and plaster of paris (calcium sulfate) and place the concoction in a small container next to another container of water. The roaches would eat the mixture and then take a sip of water. The plaster of Paris would then harden in the insect’s gut, causing an obstruction that would eventually kill it—not quickly, but surely.

I gave this method a try, and after about a week, I would have to summon the janitor each morning to sweep the dead roaches out of our laboratory.

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 Oct. 11-17, 2006, issue

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