The Key with any cockroach treatments is the correct identification of the species.

German Cockroaches

What they look like:

Adult German cockroaches are light tan to medium brown except for the shield behind the head marked with two dark stripes (separated by a lighter stripe), which run lengthwise on the body. Adults are small, about 12-15mm long, and have wings but rarely fly. Wings cover the entire abdomen of females and all except the abdominal tip in males. Young roaches (nymphs) are wingless and nearly black.

Where you will see them:

They are most often found in kitchens, hot water cupboards and laundries where they infest appliance motors. Commonly found in the back of fridges, washing machines and microwaves or other such dark, warm, moist areas. They are nocturnal so will seldom be seen during the day except where there is a heavy infestation. 

Best treatment methods:

We use a combination of gel baits, glue boards and surface treatments.  Baiting is the most effective method as they take the bait back to the nest where they eat it and die, and then other members of the nest use the dead cockroaches as a food sources, hence creating a domino affect of the poisoning.  Glueboards also attract the cockroaches and they walk on them and become stuck. They are excellent monitoring tools and work well in conjunction with baits. It is best not to disturb the cockroaches prior to the treatment. It will take at least four weeks to eliminate all cockroaches depending on the severity of the problem.
Wood Cockroaches

There are two types of wood cockroaches: Native Black and Gisborne.
What they look like:

Native Black is a wingless cockroach that is native to New Zealand. Black or dark brown in colour, this cockroach has a broad, flattened body with no wings.

Gisborne cockroach is an Australian species but was first found in New Zealand in Gisborne during the 1960s, hence the name.  This cockroach is dark red/ brown to black in colour with distinctive white bands down the thorax.  Its flat body is smooth, shiny and wingless.  Adults grow up to 45mm in length and 12-15 mm wide. 

Where you will see them:

Both of these cockroach species normal habitats is outdoors in timber or bark chips, in leaf litter, under loose bark, in rotten wood and amongst stones on the ground. They eat decaying plant material and will not usually establish themselves inside houses.
Neither species become a huge problem inside, however you might see them in odd places and probably only one at a time ie. on a bedroom or on a windowsill. 

Best treatment methods:

A synthetic pyrethroid spray is required on the outside of the home, around all entry points such as walls and doors as well as walls up to and around the windows. Ant Stop Granules will also be used in garden areas where cockroaches are likely to be located.

American Cockroaches

What they look like:

Adult American cockroaches are reddish-brown to dark brown (except for a pale yellow area on the head); about 40mm long, and have wings that completely cover the body.  Nymphs are wingless and also reddish-brown. 

Where you will see them:

They live in dark moist places such as bathtubs, clothes hampers and sewerage system.  Not that common in domestic residences.