German Cockroach (Blattella Gemanica)
This is one of the smaller cockroaches, amber-brown in colour and with two longitudinal dark stripes on the thorax. It is the most prolific breeder of the pest cockroaches, having three to four generations a year and taking only 40 days to mature from egg to adult during the summer.
German cockroaches are usually found in kitchens behind and under stoves, dishwashers and sinks. During recent years microwave ovens and computers have had their electronic controls damaged by cockroaches that have been attracted to the warmth. When German cockroaches are seen in rooms other than the kitchen, it is likely that the population of the insects is very dense throughout a building.
American Cockroach (Periplaneta Americana)
The adult American cockroach is 35-40mm long, with a pale yellow border around the upper area of the thorax. It is capable of flight. The female may lay up to 50 egg cases, each containing 10-25 eggs. The egg case is often glues to surfaces usually near food. From egg to adult takes 6-12 months.
American cockroaches live both indoors and outside depending on conditions. They inhabit wall cavities, roof areas and sub floors and are often encountered around drains and sewers. They are therefore potential spreaders of disease organisms.
Australian cockroach (Periplaneta Australasiae)
The adult Australian cockroach is 30-35mm long. It has a dark body with pale yellow areas n the upper area of the thorax and on the fore margins of the front wings. The female may produce 29 egg cases each containing 20-24 eggs during her lifetime.
This species favours warmer climates and occurs mostly outside, often where there are plants, wood piles and under garden litter. They also occur in roof voids and walls.
Detection and Prevention
Like most animals, cockroaches need food, water and shelter. These three requirements are present in most houses and buildings where humans live and work. The following preventative measures are recommended:
- Eliminate food and water sources. This is achieved by implementing clean-up procedures at the end of each day so that food is not available at night when cockroaches are active.
- Store food in sealed containers and in refrigerators to reduce accessibility by cockroaches.
- Keep garbage in sealed containers prior to collection.
- Inspect incoming containers from food stores prior to unwrapping within the house.
- Heat-treat appropriate food articles in a microwave to kill egg cases before storage in the kitchen.
- Regularly inspect the motors of washing machines and refrigerators and the areas under and behind stoves as these provide cockroaches with shelter and warmth.
- Monitor microwave ovens, fax machines and computers as these also provide shelter and warmth, particularly in winter. This may help avoid expensive repairs.
- Use vacuum cleaners to remove food waste from floors and cupboards in kitchens. Wiping may leave residues in cracks.
- Fill in cracks and crevices in walls and cupboards to prevent cockroach access.
- Inspect roof cavities as this can often locate populations of otherwise undetected smoky-brown and American cockroaches.