The Australian Cockroach is a large species of cockroach, winged and growing to a length of 30-35 millimetres. It is brown in colour. It is very similar in appearance to the American Cockroach and may be mistaken for it easily. However, it is slightly smaller than the American cockroach, has a yellow margin on the thorax, yellow streaks at its sides near the wing base.
The Australian cockroach usually invades roof voids, where it finds conditions similar to that found within a tree hole (its natural habitat). Once populations grow large inside these sites, the cockroaches regularly venture down into the home. The occasional cockroach may wander into a home from harbourage outside, but chronic infestations are most always associated with roof void or cavity wall infestations.