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Weighing in at a hefty 30g, Giant Burrowing Cockroaches are the heaviest cockroaches in the world and they can live up to 10 years!
A member of the Blaberidae Family, they’re unrelated to the much-maligned American or German cockroaches spotted in cupboards across Australia.
Up until 2019 the cockroaches at our Reedy Creek Reserve were mistaken for the more common Macropanesthia rhinoceros also known as the Rhinoceros Cockroach or the Litterbug. These gigantic roaches are endemic to Queensland and prefer life in the compacted sands of forests in north east Australia.
They’re found along the coast from Rockhampton to Cooktown, and on the Whitsunday Islands.
However, a visit in 2019 from renowned cockroach expert Dr Harley Rose from the University of Sydney, revealed that the roaches on Reedy Creek are Macropanesthia rothi – a much rarer species. The difference is marked by a couple of extra spines on the roach’s abdomen.
There are only three specimens of the rothi species known to science and virtually no study has been done on them (though we expect a lot of the traits of the more common Giant Burrowing Cockroaches to apply).
The rothi species at Reedy Creek needs to burrow in loose sandy soils like the ones in the Agnes Water region as part of its lifecycle. We think this species is endemic to a small area and might even be restricted to 10km-12km of the coastline near Reedy Creek.
Giant Burrowing Cockroaches certainly live up to their name. Measuring up to 80mm, they’re giants of the cockroach world and as big as the palm of your hand!
Unlike most insects, Giant Burrowing Cockroaches are wingless as there’s little need for wings when you spend most of your life underground!
During the day they live at the end of their burrows, in a chamber that can be one metre deep in the soil. They dig burrows with their stocky, spade-like legs. Males have a particularly pronounced ‘scoop’ – shields on the top of their heads that are perfectly suited for digging, and fighting with rival males.
Giant Burrowing Cockroaches are most active at night when they surface to gather food from the forest floor. They cart their loot – dry leaves, twigs and bark – underground to eat in the comfort of their chambers.
They’re particularly partial to crispy Eucalyptus leaves. In this way, the species is an important nutrient recycler – converting leaf litter into soil.
Unlike most insects, which lay eggs, the female Giant Burrowing Cockroach gives birth to live young. In each clutch there are up to 30 young (nymphs). The female cares for her offspring in her underground chamber, feeding them the leaf litter she gathers at night.
During this time the nymphs moult (shed their outer layer) up to 12 times, before they’re fully grown. The Giant Burrowing Cockroach is generally solitary, meeting only to mate. After many months the young will eventually leave the family home, venturing out to dig burrows of their own.
The Giant Burrowing Cockroach emits a loud hissing noise if threatened by predators. While the Giant Burrowing Cockroach is not known to be threatened, its habitat is at risk. Habitat destruction from land clearing is the biggest threat for these gentle giants. Like many invertebrates, little is known about their former range, but we do know that their main habitat – forests in northern Queensland – has been dramatically cleared in the last 200 years.
Through our work on Reedy Creek Reserve we’re protecting the habitat of the Giant Burrowing Cockroach.
Reedy Creek Reserve protects an endangered vegetation type: an intact patch of Queensland coastal and riparian forest. This vegetation type has been extensively cleared across its former range to make way for development.
We work with neighbouring land-owners to look after the plant and animal species, like the Giant Burrowing Cockroach, that call Reedy Creek Reserve home. We carefully manage fire on the reserve to look after native species, and to protect nearby homes. We also work with our neighbours to re-vegetate the forest using native plants.
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