Cockroaches represent a primitive and highly successful group of animals whose origins extend back at least 300 million years.  Fossil evidence suggests little change in their general body form since that time.
While there are about 3,500 species of cockroach worldwide, only about ten species have seriously exploited human dwellings.

Cockroaches eat virtually everything; animal or human food or beverage plus any dead animal or vegetable material.  These may include cardboard, hair, glue, leather, fabrics, starchy book binding and wallpaper glue to name a few.  Typically, cockroach infestations develop in and around buildings and other structures that provide food, shelter and offer the preferred conditions of temperature and humidity.  A commercial kitchen, and some severely infested domestic homes, may support thousands of cockroaches in various developmental stages.
Cockroaches often dwell in environments that support the growth of organisms causing diseases harmful to humans e.g. sewers, grease traps and other sources of polluted water and refuse, by contaminating food products, utensils and surface areas with their droppings, cast skins, empty egg cases and vomit. 

German Cockroach – Blattella germanica 
Light amber-brown with two dark longitudinal stripes on the pronotum.  12 to 15mm long. 
Commonly infests the interior of buildings, mostly in and around kitchens – domestic and commercial pantries, storerooms and other food handling areas.  They are commonly found in and behind stoves, sinks, refrigerators, water heaters, any electrical appliances, any crack or crevice, all hollow bench, table and chair legs, literally everywhere.  Prefers to be close to water, food and warmth.  Does not fly but is a prolific breeder.

American Cockroach – Periplaneta americana
Reddish brown, pale yellow border around pronotum.  Wings completely cover the abdomen.  35 to 40mm long.
Often found in subfloors, sewers, grease traps, wall voids, cellars, roof voids, in and around refuse tips.  May be a concern around hospitals, bakeries, food stores, warehouses and other foods handling establishments.  Flies in warm weather and often travels for food.

Brownbanded Cockroach – Supella longipalpa
Pale brown with very pale bands across the thorax and abdomen.  Female has reduced wings and male is fully winged.  10 to 14mm long.
Commonly infests houses, offices and other buildings.  Not restricted to kitchen areas – prefers drier areas e.g. bookcases, desks, wardrobes, around picture frames, in stored files, light fittings.  Infestations are often found throughout the building.  Flies when warm or disturbed.

Treatment Methods: successful cockroach treatment is undertaken using a combination of methods and processes.

Initially the client must be informed in IPM (Integrated Pest Management).  This involves a holistic approach to Pest Management including operational items such as staff education, hygiene, maintenance and repairs, stock rotation and stock management.  Once these areas have been addressed a chemical solution may need to be integrated into the program in order to manage the concern/s.

Chemical management may include a mix of the following options:
Dusting of all cracks and crevices using a low volume puffer – behind, under and at the rear of benches, splash backs, hollow table, chair and bench legs/supports etc.
Dusting of roof voids, wall voids and sub-floor voids using a high volume dusting machine
Liquid application to skirting boards/edges of wet areas only – kitchens, toilets, bathrooms, laundry areas etc.- to point of run-off, as per the label

The addition of an IGR (Insect Growth Regulator) to the appropriate liquid application is often used by the technician, particularly in severe infestations.  Compounds that disrupt normal development so that the insect dies or the adults become sterile.

Use of gel baits to electrical appliances – areas where dust and spray applications would be restricted or cause a concern.

Pheromone traps (sticky traps) – sensitive areas (e.g. child care centres) and used as monitoring stations for difficult to control situations.