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Entry pointsLow risk

How Do Cockroaches Get Inside?

Written by PestMan Editorial TeamTechnical review pendingPublished Updated

Quick answer

Cockroaches get inside through gaps under doors, weep holes, vents, gaps around pipes and cables, dry floor drains and roof and wall cavities. German cockroaches are usually carried in on boxes, bags, second-hand appliances and furniture. In apartments, they can also travel between units through shared walls, ducts and plumbing.

Why this happens

Adult cockroaches can squeeze through gaps only a few millimetres high. Any opening that connects the outside, the sub-floor or the roof void to living areas can be a route.

Outdoor cockroaches are pushed inside by heat, rain and food shortages, while German cockroaches mostly hitchhike.

What you may be seeing

  • Cockroaches near doors, drains or vents.
  • Activity that starts in one room and spreads.
  • Cockroaches appearing soon after deliveries or moving.

What you can do

  • Fit door sweeps or seals to external doors.
  • Seal gaps around pipes and cables under sinks, behind toilets and in laundries.
  • Keep drain traps wet and grates in place.
  • Screen vents without blocking required ventilation or weep holes (use appropriate weep-hole covers).
  • Inspect and unpack deliveries outside, and recycle cardboard promptly.

What not to do

  • Do not seal weep holes completely; they allow moisture to escape from brick walls.

When professional help may be needed

If you cannot find the entry points, or cockroaches are coming from roof voids or neighbouring units, a professional inspection can identify routes and recommend treatment and exclusion.

Cockroaches

Fast, flat-bodied insects that hide in warm, damp gaps and come out at night to feed. A few introduced species cause most household problems in Australia.

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How to Pest-Proof Your Home

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The Australian Guide to Cockroaches

Everything an Australian household needs to know about cockroaches: which species you are seeing, why they are there, how they get in, the health implications, and how to prevent and manage them.

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Common Brisbane Household Pests

A Brisbane-specific overview of the pests residents meet most often, when they are active, and what the subtropical climate, storms, creeks and Queenslander homes mean for pest pressure.

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Pest Prevention Checklist

A printable seasonal checklist of simple, low-cost tasks that reduce pests around Australian homes, with the reason behind each step and extra lists for renters, apartment residents, pet owners and Queenslander owners.

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Sources & further reading

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