Common shining cockroach - Drymaplaneta communis.
Image: Alan Henderson
Source: Museum Victoria
Question: What is this huge black cockroach in my house and is it a pest species?
Answer: If your cockroach is shiny black and wingless with a white stripe around the edge of the top half of the body you probably have a species from the genus Drymaplaneta.
Cockroaches from this genus like moist, dark places such as under bark or in deep leaf litter and they can be brought into peoples' homes under the bark of firewood. With all the years of drought that Melbourne has been experiencing and the drive to reduce water use, many of us have been mulching our gardens. This has provided excellent conditions for these insects. Native cockroaches are actually very important insects in the environment and assist in breaking down organic matter.
In Melbourne we have been getting quite a few reports of these cockroaches wandering into peoples’ homes in the last few years, (in fact I had one in my kitchen last night). They may be attracted to water in our homes or may just be increasing in numbers in suburbia. As opposed to the introduced pest species which are very adept at hiding this native species can often be found wandering around in our homes without any obvious concern for its welfare. Given the negative reaction that most people have to cockroaches their presence often causes alarm.
There are hundreds of species of cockroach found in Australia, ranging from very small species to brilliantly coloured species to very large burrowing species from Queensland, capable of hissing. There are a handful of cockroaches which are recognised as pest species; these are all introduced species. The native species of cockroaches shouldn’t cause any problems that we are aware of.
To discourage pest species of cockroach from entering your home it is important to minimise the 3 things that they require, food, water and shelter. Try not to leave piles of newspapers or magazines around that may provide shelter. Avoid leaving crumbs, uneaten pet food or other sources of food and make sure that dripping taps are fixed.