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CockroachesThere are nearly 4,000 species of cockroaches in the world. Cockroaches have been on the earth for at least 250 million years, and it is possible that in the late carboniferous period cockroaches outnumbered (in terms of number of individuals) all other flying insects.
Cockroaches have an oval, somewhat flattened head that is partially concealed by the pronotum, and a mouth that points backwards between the fore coax (leg segments that are attached to the body). The antennae are long and thin and located below the middle of the eyes. Their mouthparts are adapted for biting, chewing, and licking, and their compound eyes are usually large. The forewings are typically hardened and opaque, while the hind wings are membranous. The legs are almost equal in length and depressed beneath the body. The abdomen has ten segments but only 7 or 8 are visible from above. Males and nymphs carry two smaller appendages that are thinner than and located below the cerci (finger-like appendages). Cockroach eggs are laid in an ootheca (nature’s answer to the polystyrene egg box). The ootheca can contain 14 to 28 eggs. Incubation time for the eggs is temperature dependant; hatching takes approximately 35 days at 30 degrees C and 59 days at 20 degrees C. Nymphs take between 4.5 and 15 months or longer to reach maturity depending on the temperature and the availability of food. Life expectancy ranges from 2 to 4 years and a female can produce 30 oothecae, resulting in 1000 young, before dying of old age.
Cockroaches can carry a number of diseases that can be passed on to people, including: dysentery, gastroenteritis, diarrhoea, typhoid, poliomyelitis and salmonella. They can also damage buildings, vegetation, and fabrics.
Photo courtesy of Clemson University Department of Entomology, Soils & Plant Sciences, Cooperative Extension Service.
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