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Cockroaches as Creatures of the Compost

Written by Angus Stewart

The Australian wood eating Cockroaches are surprisingly beneficial to worm farms and compost bins. If you find one don't be alarmed they are assisting the decomposing process. 

Most people will get a pang of disgust when looking at a cockroach in their worm farm or compost heap. This is because when we see them scuttling around, what comes to mind is the more widely known and encountered German cockroach (Blatella germanica), which is the species of cockroach that generally infests our houses, sometimes in plague proportions! This species is on the smaller side (around 9-10mm in length) and is a pale brown colour and is considered a pest because it can spread harmful germs on and around food, and once it has infested a house, it can be very difficult to get rid of.


Pictured above The Australian wood eating cockroach 

Pictured above are two Australian wood eating cockroach in a worm farm

However, if you do see a cockroach in your worm farm or compost it is not usually the German cockroach, but is more likely to be a species that lives happily in the outdoor and garden environment. There are over 4000 species of cockroaches worldwide with Australia having over 350 species of native cockroaches, some of which are quite fascinating creatures that play a very important role in natural ecosystems and cause no problems to humans. For example, The Australian wood eating cockroach (Panesthia cribrata), as its name suggests, feeds on decaying wood matter, thus helping speed up decomposition and the return of precious humus (and its main ingredient carbon) to the soil where it will do good rather than going into the atmosphere as carbon dioxide if it was burnt for instance. As well as being good waste material converters, cockroaches found in the garden can be a good food source to insect-eating animals such as frogs, birds and lizards, which all helps towards a healthy balanced ecosystem. 


Cockroaches can be a visitor to both compost bins and worm farms, as they are attracted to the organic matter contents. They prefer dark, undisturbed environments, so if you really do not wish to have them in your unit for whatever reason, stirring things up as often as possible to push them out of their comfort zone will help encourage them to scuttle away. It will also aerate the contents of your worm farm or compost, which will in turn provide a more favourable environment for your worms. You can also console yourself that the cockroaches will also help process the organic matter and they are not in your house, but outside in the compost or worm farm. If you keep chickens, they love eating cockroaches, as do huntsmen spiders and visiting birds.


To highlight the concept that cockroaches can actually be a beneficial part of your composting ecosystem, there is actually a form of composting known as “Blatticomposting” that uses cockroaches to process organic matter in the same way that worm farms utilise earthworms. Blatticomposting is being explored in places like the USA as an alternative to worm farming because the cockroaches will tolerate much more variable environmental conditions than worms, and are capable of processing waste even faster than our wriggly buddies. Thanks to the success of worm farming as an alternative composting method, scientists and composting enthusiasts are exploring all sorts of other species to be ‘creatures of the compost’ to expand our array of options for turning what were once considered organic wastes into an incredibly valuable resource that is also helping to turn the tide on human-induced climate change.


Why not eliminate your fear of cockroaches all together and keep one as a pet? The giant burrowing cockroach (Macropanesthia rhinoceros), native to the tropical areas of Queensland and weighing up to 35 grams, lives for up to ten years and can be readily kept and reared as a fascinating way to teach kids about the wonderful world of insects. You can find suppliers of this fascinating species online – who knows, you might even keep it in your compost bin where it will definitely qualify as a beneficial creature of the compost.


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