How to get rid of large cockroaches

 Adult American cockroach - up to 5cm long Adult American cockroach – up to 5cm long

Large cockroaches certainly have a big “eek” factor. Their large size, fast scurrying movements and ability to fly are all too much for some people. The good news is that if you have a problem with large cockroaches, they are relatively easy to control.

Typically large cockroaches live outside, although they can sometimes set up residence inside the home. More often they come inside “by accident” or when looking for water during dry periods. However, if there is a big population outside, the population overflow is likely to start causing problems inside.

There are 3 key steps to the cockroach control process

1)   Find the source of the infestation

Large cockroaches will often hide outside in drains and sewers, rubbish bins and garden beds. However, they will also congregate in sub-floor areas and basements where it is damp and cool. The somewhat strange hiding place is the roof void where they hide under the insulation – strange in that it is hot and dry!

2)   Apply the correct cockroach treatment


Using a long lasting residual spray (labelled for cockroaches), spray the following outside areas;

  • Perimeter of the home (1m up the wall and 1m out from the wall)
  • Around doors, windows and other openings
  • Known cockroach hiding places

PestXpert Pro-Spray Outdoor Perimeter is ideal for outdoor cockroach treatments.


Use a residual spray which can be used around the perimeter of rooms / cupboards where there may be particular cockroach hotspots. If there are sensitive areas, which you may not be comfortable spraying (or the label does not allow use), placement of cockroach baits can be used.

Targeting cockroach hiding places such as under fridges & dishwashers, under sinks, inside cupboards and in other cracks and crevices. An aerosol with an extendable nozzle is ideal for targeting these hard to reach places (such as PestXpert Pro-Spray Crawling aerosol).

Bombs / Foggers:

If you have an infested room or a particular problem in the roof void / sub-floor consider using a cockroach bomb / fogger. You may need more than one for larger areas, but these deliver a great “fumigation” effect. Make sure you follow all safety directions. 

PestXpert Pro-Fogger contains a unique triple action formulation and stability stand for professional results.

3)   Prevent the cockroach problem returning

For large cockroaches, a regular treatment twice a year to the perimeter of the home and around likely hiding places, will do wonders. However, there are some key preventative measures which will also help;

  • Keep rubbish in sealed bins
  • Make sure insect screens on the windows and doors are in good shape
  • Seal any cracks / openings that may allow cockroach entry
  • Avoid storing goods (especially cardboard boxes) under the house
  • Keep garden beds away from the immediate perimeter of the house

For more information on cockroaches, prevention tips, control techniques and cockroach products, check out our other cockroach blog articles or visit our cockroach control page on our website. 

Key PestXpert Products for cockroach control

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