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Why are cockbroaches considered pests?

Apart from the obvious let’s look at a more general picture as to why cockroaches are considered the number one house hold pest. Cockroach species that have established some type of cohabitation with man are widely regarded as pets. While their role in the transmission of diseases to man is the primarily concern, there are many other reasons.

Contamination – Cockroaches may contaminate food products, utensils and various areas with droppings, cast skins, empty egg cases, dead cockroaches and vomit marks on surface.

Annoyance or fear of reaction – May people are annoyed or scared at the sight of cockroaches. This may relate to their fast, unpredictable movements and perhaps very skinny legs.

Odour – Where a substantial cockroach infestation exists an unpleasant odour may develop, owing to secretions from mouth to cuticle.

Allergic reactions – Some people are allergic to cockroaches. Extracts of cockroaches can bring about on skin reactions in sensitive people and may cause an attack of asthma in asthmatics. The allergen may be ingested where foods are contaminated with faeces or inhaled when died faeces becomes a part of house dust.

Disease transmission – Cockroaches carry diseases of man. Although cockroaches have never been irrefutably proven to have transmitted pathogenic diseases to man, several factors point to the likelihood that they play an important role in such disease transmission.

1. Cockroaches often dwell in environments that support the growth of organisms causing diseases harmful to man eg. Sewers, grease traps, other sources of polluted water.
2. The same cockroaches may contact various surfaces including food in kitchens and food processing or handling facilities.
3. Cockroaches are known to carry on their cuticle and in their gut and faeces disease organisms of man. Each cockroach may typically carry several million bacteria on and inside its body. A variety of disease organisms may be carried including salmonella and organisms causing gastroenteritis, dysentery, hepatitis and many other human disorders.
The health threat posed by cockroach population that intimately cohabits with man is considered by most to be serious. The reason by itself entirely justifies the control of cockroaches in premises.

Most frequent types of cockroaches found in the Australian house hold.


German cockroach

The most frequently found cockroach which is small in size and probably most widespread and successful cockroach that coexists with humans in buildings. Adults are light-amber brown with two dark longitudinal stripes on the pronotum (head). Probably the most efficient breeder of all pest cockroach types taking as little as 40 days to develop into adulthood. The female cockroach will carry between 30-40 eggs prior to hatching with 3-4 generations a year. The German cockroach like most cockroaches prefers warm and moist areas. Most infestations are located area kitchens and food preparation areas. During the day they are hidden amongst cracks and crevices. If a large number of cockroaches are found during daylight or if cockroaches are observed in non food handling areas such as living rooms it is very likely that the building is infested with an enormous amount of German cockroaches. It will eat any organic material and in some instances build up of grease. The German cockroach can survive up to a month without food where water is available.

American cockroach

The American cockroach is probably the largest cockroach that we are exposed to in Australian dwellings. Adults are red brown in colour with a pale brown border around the pronotum. Eggs are usually dropped or glued to surfaces within reasonable proximity to food water. Up to 16 eggs may hatch from each egg case and the nymphs may take 6-12 months to develop into adults (unlike the German cockroach which only takes up to 40 days). Lifespan maybe anywhere between 6 to 12 months female may produce up to 50 egg cases. Which means that one cockroach in ideal conditions and life expectancy can produce up to 800 eggs in one lifespan.

Smokeybrown cockroach

The smokeybrown cockroach is similar to the American cockroach in most ways. Egg cases are dropped or attached to surfaces and the female can carry up to 26 eggs in a case with a 6-12 month development into an adult. Adult lifespan is about 6-12 months and during this time a female may produce up to 20 egg cases. Adults are fully winged and can fly short distances in warm conditions often being attracted to light at night.

Australian cockroach

The Australian cockroach is large and in appearance similar to the American cockroach but the body is darker brown. Preferring food of plan origin this cockroach maybe encountered in greenhouses and under dark bark or leaf litter gardens. It is also found in subfloor voids, wall voids and roof voids. The adults unlike the American cockroach seem to have a shorter lifespan of 4-8 months and the female can carry up to 24 eggs in a case producing up to 20 egg cases in a lifespan.

Brownbanded cockroach

Information coming soon...


Information Source:
Gerozisis, John, and Phillip Hadlington. Urban Pest Management in Australia. Sydney: UNSW Press, 2001. N. pag. Print.