The Invincible Cockroach
State: New York
A recent survey indicated that the cockroach was the most despised creature, beating out snakes, rats, bats, and spiders. I was able to observe this insect in its own environment when my father made an arrangement whereby I accompanied a health inspector on a tour of a roach-infested house.
The house I visited was old and not very clean. There was lots of clutter in the corners and the stove was very greasy. The inspector opened the food closet and I came face to face with the dreaded cockroach. In fact, I came face to face with several roaches. When the inspector moved a can, there seemed like hundreds. I was ready to run away.
The inspector explained to the people what they had to do in order to eliminate the problem. They needed to clean everything, remove the clutter, and throw out the old infested food. I never expected I would ever have to do research on the cockroach, but I became curious and wanted to find out what this bug was all about.
The cockroach that I saw is called the German cockroach or Blatella germanica. Humans consider it to be a pest because it invades where we live, eat and sleep. There are between 4,000 to 7,500 different species of roaches. Of this amount, only one percent are considered to be a pest. Some of the other more common species are:
- Oriental Cockroah - Blatta orientalis
- American Cockroach - Periplaneta americana
- Brownbanded Cockroach - Supella longipalpa
They have pathogens or bacteria on their bodies, but none have been known to be transmitted to humans. Their mouths are used for chewing, not biting.
Most roaches are nocturnal, that is, they prefer the night and are sensitive to all forms of light except for the red spectrum. They are most active right after dusk and right before dawn. They seem to appear according to a biological clock. This activity may be a response to a genetic defense because light may indicate the presence of humans, their most dangerous predator. They prefer to live in warm, moist places and are more abundant in tropical areas. However, they can live in almost any environment and they have been found in the North and South Poles.
Cockroaches are thought to be about 350 million years old, making them one of the oldest surviving creatures. They have been able to survive because of their rapid reproductive cycles and adaptability to poisons, environments, and even nuclear bombs. One of the largest is the Madagascar hissing cockroach, which has become a popular pet. Another large roach is Megaloblatta blaberoides, a resident of Central and South America. It has been measured at about 100mm long. Some roaches can fly and one has been measured to have a wing span of about one foot.
Their ability to withstand radiation is very interesting. They have a very hard outer shell or exoskeleton, which is less prone to absorb radiation. Their skin molts, which means shedding, and this removes the radiation. In addition, they have an unusual different chromosome structure, which is difficult for radiation to shatter. The butterfly is similar to the cockroach in this respect.
Although they live in proximity to each other in crevices or harbingers, they are not social insects such as the bee, termite, or the ant. This need to keep in touch with their surroundings is called thigmotaxis. Their immunity extends to poisons, and they are known to survive decapitation. I later read that this is possible because they have two nerve centers-one in the head, the other in the tail. The only way it would eventually die would be from dehydration. They can do without food for over one month, but they need water at least once a week. They will feed on all foods, grease, paint, wallpaper paste, and even bookbinding.
The female will have up to forty babies at one time. Some species will mate only once and they will remain pregnant for the rest of their lives. Adults will live for an average of eight to fifteen months. Cockroaches reproduce on an average of four times per year. Females have a broader abdomen and are more rounded than the male. This constant reproduction adds to their ability to become immune to environment changes or pesticides. The basic structure of the cockroach has, however, remained the same since the middle of the Silurian period almost 365 million years ago. The life cycle of the cockroach is from egg-nymph-adult. This cycle is called simple metamorphosis. It means that the younger nymphs look very similar to the adult and will only differ in size.
The basic anatomy of the cockroach is as follows:
EYE - compound eyes made of 2,000 individual lenses. They see poorly in red light and well in green light.
- ANTENNAE - provides sense of smell while the hairs on the legs give them a sense of touch.
- CERCI - two little hairs on the rear end act as a motion detector. It alerts the roach to run in the opposite direction.
- MOUTH - moves side to side
- REPRODUCTION - female gives off scent to lure male for reproduction purposes.
- ESOPHAGUS - (throat) food travels down to stomach.
- CROP - section of esophagus used to store food. There is a second set of teeth in the digestive tract.
- GASTRIC CAECA - provides enzymes to help in digestion.
- MALPIGHIAN TUBULES - cleans out wastes.
- COLON - produces excrement.
- RESPIRATORY - breathes through spiracles on side of the body, supplies oxygen to rest of the body.
The cockroach that I observed is more important as a pest problem than as an important link in the food chain. Other species do provide nourishment for certain insects. In particular, spiders are its natural enemy. However, they are too sluggish to really inflict harm. Frogs, toads, and salamanders are more effective predators. Lizards are also very successful in catching the roach. In some parts of the world the lizard is kept as a pet just to keep the house clean of roaches. Humans have also used the cockroach as a source of nourishment and for its medicinal value.
The roach, as a pest, is responsible for millions of dollars of spoiled food, pesticides, and damage to the environment from these pesticides. The non-deadly diseases they cause such as Salmonella, staph. and strep. have contributed to its being such a despised insect. Recent discoveries have suggested that the skin molts of the cockroach have caused allergic reactions and asthmatic conditions in some children who live in poor urban areas. If the roach were to disappear, humans would not have to spend millions of dollars trying to get rid of them. In addition, I feel that the chemicals that kill the roaches are doing more harm to people, animals, and plants than the roaches do themselves.
On one of the web sites, there was information from Rachel Carson's book, "Silent Spring," which was written over thirty years ago. It tells about the increasing and dangerous amounts of pesticides that are being used in America.
It drew much attention and many laws were enacted to decrease the use of chemicals meant to control insects and keep them from contaminating food and invading our homes. I was very surprised to find out the following information:
|1964 Chemical Usage||245 million kilograms|
|1995 Chemical Usage||567 million kilograms|
The reasons for this increase may be the pest's increasing resistance to pesticides, adverse climate factors and advertising, leading to greater user acceptance of pesticides. I think that we must find alternative means of controlling these insectsÑwe cannot allow them to destroy our food supply, but we are only harming ourselves by using so many chemicals.
After studying this insect, I have become less afraid of it than when I went on the inspection tour. The more you learn about something, the less you fear it. I have seen how the insect's body works in many ways like ours: It chews and digests its food. It can reproduce. It will produce excrement to rid itself of waste. It is part of the world's ecosystem. Only a small portion of the thousands of species are considered pests with little value in the food chain. In a tropical rain forest, cockroaches live on the forest floor or high in trees where they are part of the food web. They also frequently inhabit caves where they are a source of food for bats. They are not as destructive as other insects, such as the termite. They don't spread deadly germs like the mosquito has been found to do. They are not as dangerous as the black widow spider or the killer bee. If the roach would disappear, the species I observed would not affect the ecosystem in a negative way because there are many other species which can be a source of food without being such a problem for humans. If people would study it some more, then maybe the cockroach will not rank as the number one hated creature in the next survey.
Biodiversity Forum. www.worldcorp.com/biodiversity
Environmental Protection Agency.www.epa.gov
Kids Web: Biology and Life Science. www.infomall.org/kidsweb/biology.html
Gaede, G. General and Comparative Endocrinology 75(2) 1989: 287-300.
Gordon, David. "The Complete Cockroach," excerpts from Website. Interview, 1997.
Morrell, Matthew. Illustrations. January 1998.
McKittrick, F.A. "A contribution to the understanding of cockroaches." Annals of the Entomological Society of America, 58 (1965): 18-22.National Geographic Society. www.nationalgeographic.com
New Jersey Online: Roach Anatomy. www.newjerseyonline.com
More About This Resource...
Less than 1 period.
Supplement a study of biology with an activity drawn from this winning student essay.
- Survey the class to find out if students despise cockroaches more than snakes, rats, bats, and spiders.
- Send students to this online article, or print copies of the essay for them to read.
- Have them write a one-page response to the article, explaining whether or not it changed their opinion of cockroaches.
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