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Professional pest control companies deal with large infestations of German cockroaches on a weekly basis. Mostly it's a commercial business that has let things run a little too far and cockroaches have quickly got out of control.

In some cases the cockroaches are in the walls and appliances and can be very difficult to get rid of even for pest control companies.

What are the tips from ACES? Well straight off the bat, I will admit that a pest controller has the advantage. That is we have access to restricted products. Some of these are very specific to cockroaches and very effective.


(i) Keep your friends close but your enemies closer.

First thing is to work out what type of cockroach it is. By knowing what type of cockroach it is, you can work out a plan of attack. There are two basic types, outdoor (bush) and indoor cockroaches (serious health risk)

(ii) Outdoor cockroaches

There are two types of outdoor (bush) cockroaches. The native (small reddish brown and oval) and the Gisborne cockroach (large dark brown with a tan stripe on its side). The Gisborne cockroach is wrongly named and is actually the Australian cockroach. It first hopped off a ship to NZ in the port of Gisborne.

Both of these roaches prefer cooler outdoor environments e.g. bark in gardens. They mostly come inside your house when it cools down in autumn or winter months. They can set up shop inside your house.

(iii) Indoor cockroaches.

There are two in New Zealand, the German and the American roaches. They are also wrongly named as they both come from Africa. Being from Africa they need to find somewhere like their native home- i.e. HOT!  They are both a considered a health risk.

You will find them in areas of your homes or businesses that are most like Africa e.g. fridge motors, kettle stands.  The American is large and reddish brown. They frequent sewers, and are often a sign that there is problem with sewerage pipes under your house or business. The German cockroach is common in homes and business around Auckland. Smaller and more rectangular than the American it is a light tan colour. It has a black stripe on each side of its head.

Cockroaches are like most insects that is they reproduce quickly. Left untreated you have a serious problem is less than six months.

(iv) Treatment- bush cockroaches

You need to create a barrier around the house to stop them coming in. Spray the base of the house and all entry points (windows and door ways). If you can also spray the inside of windows and doorways to make sure they cannot access the house.  Spray the upper and lower skirtings’ as cockroaches frequent these areas too. Inspect the kitchen. In particular behind the draws and cupboards. Look for oothea from the Gisborne cockroach, as they stick them to these areas. These are brown to whitish and 5mm long. Remove and destroy all of these. Get hold of some bait for cockroaches and place this inside the cupboards away from food and utensils.

NON chemical tip. Trim foliage touching your house and or deck to a 5cm gap. This is how they often access your house.

(v) Treatment - German or American.

Inspect all areas of warmth. Specifically, kettle stands, fridge motors, around and inside dishwasher, microwave, hot water cylinder, portable phones ,  their holders and ADSL modems. Look for cockroach poos because this tells you that the roaches are there! Their poos look like dark black coffee grinds. Example-poos under the microwave tells you there is cockroaches in the microwave. Electronics treat with a bait. If the level of infestation is high OR they are forming “hives”, dome like collections of 100s or 1000s of cockroaches consider using insecticide dust to reduce down the numbers. The most common dust available is a permethrin dust. Some “pesties” just use bait no matter how bad the infestation. Using bait exclusively you have to be patient as it is slow acting.  Spray the inside of the house as above making sure to avoid bait and baited areas as sprays renders bait ineffective.

(vi) It only takes one.

Remember be thorough as it only takes one survivor to start the process over again.

(vii) safety

And always wear a gown,  mask, gloves and protective eyewear at the least. Further safety gear is available at NZ safety.

(viii) Mission Impossible -success!

In some restaurants and bakeries German cockroach infestations can be a challenge even for the experienced pest controller.  In these cases traditional chemicals and approaches do not work. To this extent ACES has successfully eradicated some long well established German cockroach infestations in commercial operations in Auckland.