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Grades 6-8: catching up with cockroaches. (ScientificNotations).

"Humans consider them the `rats of the insect world,' yet cockroaches could be considered one of the most successful creatures on earth," Newton's Apple notes. "Entomologists have found fossilized cockroaches that are more than 300 million years old. Amazingly enough, these fossilized cockroaches look very similar to the ones scurrying around in our yards and homes today.

"There are over 4,000 species of cockroaches. As one of nature's recyclers, they are often found eating natural forest debris. A few find their way into our kitchens, basements, and bathrooms, coming up through the drains, sneaking in through cracks, or carded in on grocery bags. These cockroaches are usually looking for warm, moist, dark places to call home.

"Cockroaches, by design, are survivors. They are nocturnal, making them hard to spot. If they are discovered, their flat bodies make it easy for them to escape into small crevices. Their antennae and cerci help them detect changes in vibrations and air pressure, making it difficult to even step on them. Cockroaches are omnivorous. They eat anything from dog food to plaster. Internal bacteria help cockroaches digest these unusual meals. If necessary, cockroaches can live for three months without food and one month without water.

"Although cockroaches preen regularly, they are still suspected of transmitting diseases such as salmonella, dysentery, and typhus. They are also suspected of causing allergic reactions in half of the 17 million people afflicted with asthma."

Trap 'em: In the following activity, developed with the assistance of the National Science Teachers Association, students will construct a roach trap. They will need a wide-mouth container, a container lid with holes, masking tape (or black paint, or black construction paper), petroleum jelly, a cardboard strip (or a wooden tongue depressor), and food for cockroach bait.

Coat the outside of your container with masking tape, black paint, or construction paper to make the inside dark and inviting to a cockroach. Smear a wide band of petroleum jelly around the inside of the container just below the neck. Add bits of food to the container for cockroach bait.

Where in your school, home, or community might cockroaches be hiding? Select a site, get permission, then go and set up your trap. Place the trap on its side. Create a miniature ramp using the cardboard strip or tongue depressor, extending the ramp from the floor to the container.

If you catch a few cockroaches, quickly screw the lid on tightly. You don't want any cockroaches to escape. Notify the building authorities of your discovery.

Discussion questions: What plan would you suggest to help get rid of the cockroaches at your specific site? What experiments can you devise to see how well your plan works?

Compare your cockroaches with those caught by your classmates. Are they the same types of cockroaches or are they different? Try to identify them.

What repels a cockroach? Experiment by putting a piece of bread in one end of a box and adding a cockroach. How long does it take for the cockroach to start eating the bread? Then, place a piece of peeled garlic into the box. Observe. Is the cockroach attracted to the garlic or repelled by it? Try bay leaves or cucumbers. Does your cockroach say "No thanks!" to these? Experiment with other foods.

Get out the calculators. A female German cockroach reproduces four to eight times in its life cycle, laying seven to eight egg cases, each case containing 35 to 40 eggs. About how many offspring might one female German cockroach have? Divide students into groups to solve the problem. Give each group a package of kidney beans to predict how many cockroaches their female would produce. Put all the beans together to see the effects of cockroach reproduction.

Find out how smart a cockroach can be. Design a cockroach maze. Start with a baking pan half-filled with water. Build a maze using several 6-oz. cans and strips of cardboard. Arrange the cans in the pan and place the cardboard strips on top of the cans to create two pathways. One pathway leads to the cockroach's home; the other leads to a dead-end. Put your cockroach at the start of the maze and observe.

Lesson vocabulary:

Antennae, a pair of sensory feelers on the head of an Insect

Bacteria, microscopic organisms that, in this case, aid in a cockroach's digestion.

Boric acid, a medical antiseptic; a powder that acts as an insecticide for cockroaches

Entomologists, scientists who study insects

Cerci, small nerve on the back of a cockroach that can detect changes in air pressure and movement

Nocturnal, active at night

Omnivorous, eating both animals and plants; in the case of cockroaches, eating almost anything

Palpi, sensitive appendages attached to the oral part of a cockroach enabling it to pre-taste food
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Publication:Curriculum Review
Article Type:Brief Article
Date:Dec 1, 2001
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