Cockroaches

Cockroaches are one of the most common household pests. Although most cockroach species are tropical in origin the main pest species have adapted their habits so that they are now found living alongside humans in temperate, sub-tropical and tropical climates. They are active mainly at night and hide in cracks and crevices during the day preferring dark moist sites often in basements or sewers. Cockroaches will eat most things including meats and grease, starchy foods, sweets, baked goods, leather, wallpaper paste etc. All cockroaches have dorso-ventrally flattened bodies and in several species the adults are capable of gliding flights.

There is no clear evidence to link cockroaches to disease outbreaks but they are well known to be incidental carriers of micro-organisms because of the habitats in which they live including sewers, heating ducts, waste disposal areas. This incidental transfer of micro-organisms is likely to contaminate foods and produce spoilage and cause gastro-intestinal illness in people. Cockroaches are therefore considered passive disease vectors. Disease organisms found on cockroaches include:

Salmonella (food poisoning)
Mycobacterium tuberculosis (tuberculosis)
Entamoeba histolytica (Ameobic dysentary)
Escherichia coli (Gastro enteritis)
Ancylostoma spp. (Hookworms)
Taenia spp. (Tapeworm).

Cockroaches also produce antigens from their bodies and excretions and these can be important triggers for asthma and other allergies in humans. Up to 60% of asthmatics have an allergic reaction to cockroaches which is only second to the house dust mite in its ability to trigger allergies.

Signs of a cockroach infestation include:

• Cockroach marks. Liquid excreta produced when there is a ready water source. The marks are usually brown in colour and much larger than the marks associated with flies. These marks are usually numerous near the harbourages.

• Faecal pellets. Usually produced when water is in short supply and look similar to mouse droppings but are only 2mm in length and brown to black in colour.

• Ootheca. If the main colony is found egg cases can often be seen.

• Nymphal skins. Often difficult to see unless there are a lot of them.

• Odour. In high densities cockroaches give off a characteristic odour.
  

There are four species of cockroaches that are commonly considered pests:

American Cockroach	German Cockroach	Oriental Cockroach	Brown Banded Cockroach

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