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?Cockroaches
Scientific classification
Kingdom: Animalia Phylum: Arthropoda Class: Insecta Subclass: Pterygota Infraclass: Neoptera Superorder: Dictyoptera Order: Blattodea
Families
Blaberidae Blattellidae Blattidae Cryptocercidae Polyphagidae Nocticolidae

Cockroaches are insects of the Order Blattodea. The name of the order is derived from Greek for "cockroach," blatta. There are roughly 3,500 species in 6 families. Cockroaches exist worldwide, with the exception of the polar regions and in elevations above 2,000 m (6,500 ft). Cockroaches are also simply known as "roaches".

The English word cockroach is derived from the Spanish cucaracha, meaning "chafer, beetle".

Among the most well-known species are the American cockroach, Periplaneta americana, which is about 3 cm long, and the German cockroach, Blattella germanica, about 1½ cm long, and the Asian cockroach, Blattella asahinai, also about 1½ cm in length. Tropical cockroaches are often much bigger, and extinct cockroach relatives such as the Carboniferous Archimylacris and the Permian Apthoroblattina were several times as large as these. When infesting buildings, cockroaches are considered pests; out of the thousands of species, however, only a handful fall into this designation.

Contents [hide] 1 Evolutionary history and relationships 2 Biology 3 Selected species 4 Behavior 5 Cockroaches and health risks 6 Habitat 7 Interesting facts 8 Pest control 9 Popular culture 10 History 11 Miscellaneous 12 External links 13 References

Evolutionary history and relationships

The earliest cockroach-like fossils are from the Carboniferous period between 354–295 million years ago. However, these fossils differ from modern cockroaches in having long ovipositors and are apparently the ancestors of mantids as well as modern cockroaches. Current evidence strongly suggests that termites have evolved, in turn, directly from true cockroaches. The first fossils of "modern" cockroaches with short ovipositors appear in the early Cretaceous. Mantodea, Isoptera, and Blattodea are usually combined by entomologists into a higher group called Dictyoptera.

Biology

Cockroaches are generally either scavengers or omnivores. The exception to this is the wood-eating Cryptocercus species found in China and the United States. Although they are incapable of digesting the cellulose themselves, they have a symbiotic relationship with a protozoan that digests the cellulose, allowing them to extract the nutrients. In this, they are similar to termites and current research suggests that the genus Cryptocercus is more closely related to termites than it is to other cockroaches. Cockroaches are most common in tropical and subtropical climates. Some species are in close association with human dwellings and widely found around garbage or in the kitchen.

Female cockroaches are sometimes seen carrying egg cases on the end of their abdomen; the egg case of the German cockroach holds about 30–40 long, thin eggs, packed like frankfurters in the case called an ootheca. The eggs hatch from the combined pressure of the hatchlings gulping air and are initially bright white nymphs that continue inflating themselves with air and harden and darken within about four hours. Their transient white stage while hatching and later while molting has led to many individuals claiming to have seen albino cockroaches.

A female German cockroach carries an egg capsule containing around 40 eggs. She drops the capsule prior to hatching. Development from eggs to adults takes 3-4 months. Cockroaches live up to a year. The female may produce up to eight egg cases in a lifetime; in favorable conditions, it can produce 300-400 offspring. Other species of cockroach, however, can produce an extremely high number of eggs in a lifetime. Laying up to 100 eggs in each egg sac, it only needs to be impregnated once to be able to lay eggs for the rest of its life, allowing one single cockroach to lay over a million eggs during its lifespan.

The world's largest cockroach is the Australian giant burrowing cockroach, which can grow to 9 cm in length and weigh more than 30 grams. Comparable in size is the giant cockroach Blaberus giganteus, which grows to a similar length but is not as heavy.

Cockroaches are mainly nocturnal and will run away when exposed to light. A peculiar exception is the Oriental cockroach, which is attracted to light, thus making it a far more annoying pest. Cockroaches are sometimes called the custodians of nature. They live only in houses where there are crumbs to eat or the garbage can is uncovered. They lay eggs inside the house's hollow walls.

The cockroach is also one of the hardiest insects on the planet, capable of living for a month without food and remaining alive headless for up to a week. It can also hold its breath for 45 minutes and has the ability to slow down its heart rate.

It is popularly suggested that cockroaches will "inherit the earth" after humanity destroys itself in a nuclear war. Cockroaches do indeed have a much higher radiation resistance than vertebrates, with the lethal dose perhaps 6 to 15 times that for humans. However, they are not exceptionally radiation-resistant compared to other insects, such as the fruit fly ^[1].

The cockroach's ability to withstand radiation better than human beings can be explained in terms of the cell cycle. Cells are more vulnerable to effects of radiation when they are dividing. A cockroach's cells only divide once when in its molting cycle, which at most happens weekly. The cells of the cockroach take roughly 48 hours to complete a molting cycle, which would give time enough for radiation to affect it but not all cockroaches would be molting at the same time. This would mean some would be unaffected by the radiation and thus survive. ^[2].

Selected species

• Periplaneta americana, American cockroach
• Eurycotis floridana, Florida woods cockroach
• Blatta orientalis, Oriental cockroach
• Blattella germanica, German cockroach
• Blattella asahinai, Asian cockroach
• Pycnoscelus surinamensis, Surinam cockroach
• Supella longipalpa, brown-banded cockroach
• Periplaneta australasiae, Australian cockroach
• Periplaneta fuliginosa, smokybrown cockroach
• Parcoblatta pennsylvanica, Pennsylvania woods cockroach
• Periplaneta brunnea, brown cockroach
• Blatta marimantaringisis, large-headed stink cockroach
• Blaberus discoidalis, discoid cockroach or false death's head
• Blaberus craniifer, true death's head cockroach
• Gromphadorhina portentosa, Madagascar hissing cockroach

Behavior

Cockroaches have been shown to make group decisions ^[3].

New research being conducted at the University of Florida shows that cockroaches leave chemical trails in their feces. Other cockroaches will follow these trails to discover sources of food, water, and where other cockroaches are hiding. One of the major implications of this research is a new technique in cockroach pest control. Cockroaches could be potentially removed from a home by leaving a chemical trail that leads away from the home.

Research has shown that group-based decision making is responsible for more complex behavior such as resource allocation. A study where 50 cockroaches were placed in a dish with three shelters with a capacity for 40 insects in each, the insects arranged themselves in two shelters with 25 insects in each, leaving the third shelter empty. When the capacity of the shelters was increased to more than 50 insects per shelter, all of the cockroaches arranged themselves in one shelter. Researchers found a balance between cooperation and competition exists in group decision-making behavior found in cockroaches. The models used in this research can also explain the group dynamics of other insects and animals.

Cockroaches and health risks

A 2005 national study on factors that affect asthma in inner-city children shows that cockroach allergens appear to worsen asthma symptoms more than other known triggers. This study, funded by the US National Institute of Environmental Health Sciences (NIEHS) and the US National Institute of Allergy and Infectious Diseases (NIAID), is the first large-scale study to rank asthma triggers according to severity.

Additionally, a 2005 research study, sponsored by the National Pest Management Association (NPMA), shows a disparity in homeowner knowledge about this link. Only 10% of homeowners nationwide feel that cockroaches are a threat to their family’s health.

Habitat

Cockroaches live in a wide range of environments around the world. Pest species of cockroaches adapt readily to a variety of environments, but prefer warm conditions such as found within buildings. Many tropical species prefer even warmer environments and do not fare well in the average household. Only a small handful of the 3,500 or so species of cockroach are suited to thrive in the typical home.

Interesting facts

Why do most cockroaches die on their backs? First, few cockroaches die on their backs in the wild. Natural death of cockroaches probably occurs in the stomach of a bird, bat or other small animal. Second, cockroaches are not used to living on a polished marble or vinyl floor. They are more used to a rugous living plane including leaves and sticks and other vegetable debris. Thus when a cockroach finds itself on its back (by some mistake in its orienteering) it may have trouble righting itself if there is not debris around to grab hold of with its legs. (Try it, put a cockroach on its back on a polished floor with and without some crinkled paper.) Third, often we come across dead cockroaches in buildings that have died of insecticide. Most of these insecticides are pyrethroid nerve poisons ^[4]. The nerve poison induces muscular spasms which often result in the cockroach flipping on its back. Without muscular coordination the cockroach cannot right itself and eventually dies in its upside-down position.

Pest control

There are numerous parasites and predators of cockroaches, but few of them have proven to be highly effective for biological control. Wasps in the family Evaniidae are perhaps the most effective insect predators, as they attack the egg cases, and wasps in the family Ampulicidae are predators on adult and nymphal cockroaches (e.g., Ampulex compressa). The house centipede, however, is probably the most effective control agent of cockroaches, though most homeowners find the centipedes themselves objectionable. Preventative measures include keeping all food stored away in sealed containers, using garbage cans with a tight lid, frequent cleaning in the kitchen, and regular vacuuming. Any water leaks, such as dripping taps, should also be repaired. It is also helpful to seal off any entry points, such as holes around baseboards, pipes, doors, and windows with some steel wool and some cement or putty. Once a cockroach infestation occurs, chemical controls may help alleviate the problem. Bait stations, gels containing hydramethylnon, as well as boric acid powder, are toxic to cockroaches. A simple homemade Vegas cockroach trap is reported to be successful. Additionally, pest control products containing deltamethrin are very effective.

Popular culture

In popular culture, cockroaches are often regarded as vile and very resilient pests, contrary to their fastidious habits, shine along their exoskeleton which makes them look slimy and their size for a scavenging insect. For example, English translations of Franz Kafka's The Metamorphosis generally read that the protagonist found himself transformed into a giant cockroach.

Movies which feature cockroaches include:

• Joe's Apartment — The bugs are cheerful, swinging party-goers who help the titular human hero.
• Creepshow — Swarms of them terrorize a cantankerous and verminophobic old man.
• Damnation Alley — A post-apocalyptic Las Vegas is infected with a flesh-eating mutant variety.
• Men in Black — A giant cockroach-like alien's actions threaten to lead to the destruction of the Earth.
• Mimic — Diseased cockroaches are the target of the genetically-altered titular species.
• Indiana Jones and the Temple of Doom — Cockroaches are among the many items served in a banquet scene.
• Team America: World Police — After his apparent death, a coachroach crawls out of Kim Jong-il's mouth and flies away in a rocket ship, in parody of Men in Black.
• Quest for Glory IV: Shadow of Darkness — Form the Thieve's Guild leader takes after touching a cursed statue in the monastery.

In the classic William Burroughs epic, Naked Lunch (and its film adaptation), one of the main themes is an abundance of cockroaches, and some of the characters resemble cockroaches.

In the X-Files episode "War of The Coprophages", cockroaches are seen to group together to murder people. The character Dr. Berenbaum (based on the University of Illinois entomologist) suggests that it is actually swarms of flying cockroaches that are responsible for most UFO sightings (they generate an electro-static field which can be illuminated dependent on atmospheric conditions). In one of the scenes, a cockroach that escaped can be seen crawling over the camera, making it appear that the viewer's television has become infested. Though the shot was not planned, the producers decided to leave it in the episode.

In the television show ALF, Alf inadvertantly releases a Melmacian cockroach in the house. When it is sprayed with insecticide, it grows bigger until it is large enough to eat him. He discovers that a bottle of perfume will kill the cockroach.

The famous Mexican folk song, La Cucaracha, means "The Cockroach" in Spanish, and refers to cockroaches in some of its lines.

The cult computer game Bad Mojo deals with a person turned into a cockroach.

Archy is a cockroach in a series of columns by Don Marquis.

Megalon is a 50 meter tall cockroach.

Along with rats, cockroaches are frequently seen infesting various locations in sam and max comics, and one storyline features a race of gigantic cockroaches living on the moon.

In the Discworld novel The Last Continent, Ponder Stibbons is horrified to learn that the cockroach is actually the most highly evolved and advanced creature in the world, and not mankind as he had assumed.

In the early 2000s, a pest control company ran a series of television commercials which initially appeared to be for products such as fabric softener or furniture polish, until a cockroach came scurrying across the screen. The bug was digitally edited so that it would actually appear to be on the viewer's television screen, rather than as part of the tape. Many viewers mistook it for an actual cockroach and tried to swat it. Some damaged their sets and wanted the company to fix them. The company declined.

History

Some of the earliest writings with regards to cockroaches encourage their use as medicine. Pedanius Dioscorides (1st century), Kamal al-Din al-Damiri and Abu Hanifa ad-Dainuri (9th century) all offered medicines that either suggest grinding them up with oil or boiling. The list of ailments included earaches, open wounds and "gynaecological disorders".

Miscellaneous

• The largest known cockroach by wingspan is a Megaloblatta longipennis, with an 18cm wingspan.
• The largest by weight is a 50g Macropanesthia rhinoceros.
• The smallest species is Attaphila fungicola, reaching only 4mm.

External links

• Cockroach health threats
• Cockroach pictures shares pictures and facts on cockroaches and their behavior, feeding habits and life cycle.
• UC Davis on cockroaches
• Online book about cockroaches
• Transitional Species in Insect Evolution discusses the evolution of termites from cockroach ancestors
• The cockroach FAQ
• Allpet Roaches for cockroach enthusiasts
• Cockroach gallery
• Russian cockroach
• An illustration by George Rolleston published in 1870 showing the internal organs of a cockroach

References

1. ^ Cockroaches & Radiation. Retrieved on 10 June 2006.
2. ^ Joseph G. Kunkel. Are cockroaches resistant to radation?. Retrieved on 10 June 2006.
3. ^ Jennifer Viegas. Cockroaches Make Group Decisions. Discovery Channel. Retrieved on 10 June 2006.
4. ^ Hadlington & Gerozisis, 1995, Urban Pest Control in Australia, University of New South Wales Press Ltd.

• Firefly Encyclopedia of Insects and Spiders, edited by Christopher O'Toole, ISBN 1-55297-612-2, 2002
• Insects: Their Biology and Cultural History, Bernhard Klausnitzer, ISBN 0-87663-666-0, 1987