|Belding, David L. Textbook of Parasitology. 3rd ed. Michigan: Appleton-Century-Crofts, 1964.||"In North America north of Mexico there are 40 species of cockroaches...."||40 species
|Cockroach, Microsoft Encarta Online Encyclopedia.||"About 4000 species are known worldwide; most inhabit the warm tropical regions of the globe."||4,000 species
|Johnson, Rolf E., and Nathan E. Kraucunas. Rain Forests of the World. Marshall Cavendish, 2002.||"Over four thousand species of cockroach live on this planet, and a large number are found in tropical rain forests around the world."||4,000 species
|Sims, Calvin. "Insect Census Finds Apartments Infested." The New York Times. 21 January 1986.||"The average low-income apartment in the Southeastern United States is infested with about 26,000 cockroaches, according to a recent survey by the Agriculture Department."||26,000 cockroaches (per apartment)|
|Mosbacker, Linda. Insects-Cockroaches. Utah Education Network.||"There are over 3,500 species of cockroaches in the world."||3,500 species
Cockroaches are little insects who have been on Earth for over 300 million years. They live in a wide range of environments, although most are attracted to warmer conditions such as those found in buildings or any average household.
In general cockroaches are flat and oval shaped with their heads pointing downward. Most species of cockroaches are very sensitive to light and prefer darkness which is usually why they are found in dark corners of a house.
The average life span of a cockroach is one year. Throughout that time, a female cockroach is able to produce eight egg-cases which enables them to have 300-400 offspring per lifetime. Also, it is only necessary for the female cockroach to be impregnated once to produce that number of offspring.
It is nearly impossible to calculate the number of cockroaches that exist worldwide due to the fact that so many already exist and are reproducing at such a fast pace. Scientists believe that there are over 4,000 species around the world and there are at least 40 different species that exist in America. One source suggests that 36,000 cockroaches exist per building in some parts of America.
Larry Yundelson -- 2009