What are cockroaches?

Cockroaches are insects of the order Blattaria, and are one of the most common household pests. In the wild, cockroaches perform a useful role by consumption of decaying organic material. There are about 4,000 species of cockroach, of which 30 are associated with human habitation - where they are regarded as pests. The best-known pest species are:

 American cockroach (Periplaneta americana) - 30 millimetres long

 German cockroach (Blattella germanica) - 15 millimetres long

 Asian cockroach (Blattella asahinai) - 15 millimetres long

 Oriental cockroach (Blatta orientalis) - 25 millimetres long

American cockroach

German cockroach

Asian cockroach

Oriental cockroach

New Zealand varieties include both native bush cockroaches and black cockroaches. The black or brown cockroaches commonly encountered by people in their homes are usually introduced pests species (pictured above).

Behaviour and location

Pest species of cockroaches adapt readily to a variety of environments, but prefer moist, warm conditions found within buildings. Their flattened bodies and rapid reactions enable them to quickly disperse into inaccessible locations. They are mainly nocturnal, and like to avoid light by hiding in cracks and crevices. They eat almost anything, including cardboard, and come out to feed at dusk. They like to stay together in groups, and within the home are mainly found in kitchens and bathrooms, especially behind kitchen appliances, in laundry baskets  and at the backs of cupboards. They travel along water pipes and air ducts. Tower blocks, and buildings joined to other buildings, are particularly vulnerable to re-infestation because of the ease with which cockroaches can move either through ducts in a building or between buildings.

Cockroaches and health effects

Cockroaches are implicated in the transfer of disease. They are bearers of pathogens such as salmonella, E. coli, hepatitis E, diarrhoea, dysentery and staphylococcus. They have been linked to outbreaks of gastroenteritis, typhus and skin diseases, and are particularly associated with the transfer of bacteria on their legs from dirty areas to food and food preparation surfaces. Contact with cockroaches can lead to a number of allergic illnesses, including dermatitis, rhinitis, bronchitis and asthma.

Cockroach control

The best control method is to deny them access to the home, by mending any holes and cracks in walls, and sealing off entry points with steel wool, cement or putty. Cockroaches need food, water and shelter to survive. Good hygiene is essential in preventing or limiting infestation. These tips should help prevent infestation:

 In the kitchen, dishes should be washed promptly, food stored in tightly sealed containers, working surfaces kept clean, and all scraps food waste cleared away.

 Rubbish should be kept in containers with tight lids, and bags properly sealed when moved outside.  Carpets should be vacuumed regularly.

 Water spills should be mopped up and all water leaks repaired.

 Remove any clutter where cockroaches might live (e.g. in drawers, cupboards)

If used correctly, cockroach pesticide sprays, gel bait and bait traps are effective in the control of cockroaches. Follow the instructions carefully before applying them around the home. Pesticides containing hydramethylnon, fipronil, deltamethrin, cypermethrin and pyrethrin are effective at killing cockroaches. If infestation persists, then a professional pest controller should be consulted. Cockroaches are great survivors and are difficult to eliminate completely, particularly when they live in places to which there is limited access for treatment. The essence of cockroach control is to use chemical insecticides with residual properties so that the active ingredient will continue to kill hatchings of subsequent generations. Further information.

Cockroaches transmit diseases, contaminate food, and induce allergies. If someone in your building has them, Guess what? You Have Them Too! Some female cockroaches mate once and are pregnant for the rest of their lives.

Your home is an ideal breeding ground for most species of cockroaches. With plenty of food, warmth, water and nesting sites,They can remain active all year round.

Cockroaches have existed for millions of years and there are thousands of species throughout the world today. Some of the more common species include the German cockroach, the American cockroach, the asian cockroach and the gisborne cockroach. The German cockroach and the gisborne cockroach are the two most common roaches in the Bay of plenty area.

. Can survive a month or more without food, but less than two weeks without water.

. Have an acrid odor that may permeate items with which they come in contact.

. Can transmit bacteria and organisms responsible for diseases in humans including food poisoning, cholera,     dysentery, salmonellosis and strep.

. A study by the National Institute of Allergy and Infectious Diseases and a report in the New England Journal of   Medicine indicate that exposure to cockroach allergens is a major health concern for asthmatic children.


They are active mostly at night, and hide in dark crevices during the day. If cockroaches are seen during the day, the population may be high and the available harborage is full, or food and moisture are in short supply resulting in daytime foraging. Cockroaches prefer to stay close to moisture and food and are generally found in the kitchens and bathrooms. LIFE CYCLE : Cockroaches are highly successful due to the high rate of reproduction. The female carries the egg capsule protruding from the rear of her abdomen until the eggs are ready to hatch. Each egg capsule will contain 30-48 nymphs (young). It takes 28 days from the initial formation of the egg capsule until it hatches. Formation of the next egg capsule usually begins within 2 weeks. Nymphs require as little as 40 days to become a mature adult. Adult cockroaches of most species can live up to one year.

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 The Bug Stops Here!