How to get rid of cockroaches

Just when you have everything sorted with your kitchen, along scurries a cockroach!

As a Pest Controller, I specialise in cockroach control. I am often asked how do you get rid of these persistent ‘nasties’.

So I thought I would pass on a few useful tips.

Firstly, to get rid of the cockroaches you have to understand them a little. The cockroach is one of nature’s best survivors!

Here are a few reasons why:

  1. They can go for long periods without food. So when the going gets tough they just hunker down somewhere and wait
  2. The female cockroach can carry 40 young with it. When she gets stressed she lays the young
  3. Cockroaches take around a month to reach sexual maturity.

So if you put these two last facts together ONE MONTH = A SERIOUS PROBLEM!

Secondly, there many different cockroaches in New Zealand. They all behave differently and they need to be treated differently. There are four main types found in homes. Two are bush types being the Native and the Gisborne. These two types live mainly outside and come inside when the weather is cold as they prefer the outside temperature and find it inside. The other two are the German and American. These types both prefer warm areas, such as fridge motors, hot water cylinders etc.

Thirdly, cockroaches living inside need at least two of three things, food, water and warmth. Given these conditions, an infestation can quickly become significant if left unchecked. A sign that an infestation has become significant is cockroaches being seen away from their sources of food and warmth e.g. office next to the kitchen, upstairs bedroom etc.

How to treat cockroaches


Incorrectly applied product may make the situation worse, not better. Remember what the female does when she is stressed? Yes lays her young, 40 of them and then in thirty days, you have 40 times the problem. Typically people tell me they sprayed and the large ones went away, then soon after there were many more small ones. Cockroaches surviving again. Remember that the products available in the supermarket are low toxicity (less effective to cockroaches), have short lengths of action and will not access the difficult to get areas that cockroaches prefer.


You need to get into the areas that the cockroaches prefer. This may not be so hard for fridge motors, but they frequently they prefer areas that you can not access with supermarket products.

Spray the areas cockroaches travel. These areas need to be covered for the entire house or business. Upper and lower skirtings, doorways and window frames. In the case of the bush cockroaches, you need to spray the exterior lower skirting boards, window frames, doorways and garage door.

Leave gel bait for the young that have been laid. In areas where they favour but not where you have sprayed (spray renders the bait ineffective), leave gel bait for the recently laid young. These baits are rich in sugars and have a similar insecticide to that used in cats flea collars.

Monitor the situation. Keep an eye out where the animals like to live.


Remember to be as safe as you can! Always wear a mask, gloves and eye protection!


If I stand on a cockroach it will make the problem worse by releasing it’s young

If you stand on a cockroach you will kill it and its young.

Cockroaches are a sign of a clean house

Cockroaches need food, water and warmth, they don’t mind about the state of your house or business.

I don’t need to worry about cockroaches

Cockroaches carry pathogens harmful to humans. They almost certainly travel over your food preparation surfaces at night. Cockroaches are a health risk.

If you need further information, Questions please email



In recent months (May-June 2010) there has been an ‘explosion’ of enquiries regarding cockroaches and how to get rid of them. Kiwicare cockroach baits, sprays and traps have had record sales in the North Island.

It is likely that the invasion of homes, cafes, restaurants, shops, offices and factories is due to a combination of factors:

Last year was a ‘good’ year for cockroach breeding so the numbers this year started from a high level.

This year has seen a long summer and mild moist autumn which has encouraged cockroach numbers to increase in areas where they survive outdoors.

Increasingly our homes and other buildings are heated, providing conditions where cockroaches can breed all year around.

The recent heavy rains have sent the large numbers of cockroaches outdoors seeking shelter in our buildings.

Have you got cockroaches in your home? You can check using Cockroach Traps available at hardware stores. If you find you have, then you can eliminate them in the manner described below.


Thats Right David, the Gisborne Cockroach is not native to NZ. Also the author of this article Owen Stobart claims on his website to have a degree in Entomology from Victoria University.


Useful tips on dealing with cockroaches.

Thanks for the tips. There are a few things I would add and a few clarifications.

Gisborne cockroaches are not native, they are originally from Australia, like so many pests now established in New Zealand. If you want to identify which cockroach species you have there is a good identification key provided at the Landcare Research cockroach page.

I think you meant to say that the Gisborne and native Bush cockroaches can survive well outside in the North Island and north of the South Island but that the German and American cockroaches prefer to be inside where temperatures do not drop too low for them.

It is true that some supermarket products are less effective than those that professionals would use, but not all. Kiwicare’s NO Cockroaches and NO Bugs Super products are the same as professionals would use; containing the synthetic pyrethroids permethrin and deltamethrin respectively. Both are highly effective against cockroaches and other crawling insects and are effective for periods of three months and more.

Kiwicare also produces: NO Cockroach fumigator for penetration into difficult to access areas and a quick knockdown of adult cockroaches without leaving any residues. NO Cockroach Gel Bait for ongoing control of nymphs and adults. NO Cockroach Traps which are an excellent way of giving control without using insecticide and they provide monitoring for new cockroach infestations.

The difference between professional and DIY pest control is rarely the products used. DIY pest control can be just as effective as employing a professional. You need some knowledge of the pest and how to carry out control. Kiwicare provides excellent advice on the control of pests on the website at

However, a professional should know how to use the products most effectively against any particular pest. Members of the Pest Management Association of NZ (PMANZ) will be qualified to carry out the best pest control. You can find a list of registered technicians here.

You will find information on cockroaches and advice on their control using these and other effective methods at the Kiwicare website. Kiwicare pest control products are available from all good hardware stores, rural supply chains, garden centres and supermarkets,…but hardware stores tend to stock the greatest range of products.


This comment by Kiwicare is incorrect. The invasion of cockroaches into homes this year and recent years is due to a NZ native roach (likes similar to the German one associated with commercial sites) it lives around the exterior of houses and comes inside during cold seasonal changes. They will not breed inside and soon die. They are a beneficial insect outside and do not pose any health risk to humans.