The giant burrowing cockroach (Macropanesthia rhinoceros) is also known as the rhinoceros cockroach, and Queensland giant cockroach. These cockroaches are native to Australia and mostly found in tropical and subtropical parts of Queensland. They are the world's heaviest species of cockroach and can weigh up to 30-35 grams and measure up to 7.5- in length. It is a member of the family Blaberidae, which contains hundreds of species. It is part of the blaberid subfamily Geoscapheinae. It is prominent in the wild and can also be sold and kept as a pet.
Unlike some other cockroaches, the giant burrowing cockroach does not have wings and is not considered a pest. This species plays a vital part in the ecosystem by consuming dead leaves, eucalyptus in particular, and recycling other matter. They may burrow down in soil to a depth of about , where they make permanent homes and feed on collected dry leaf litter. The giant burrowing cockroach is the only cockroach in the world known to have permanent burrows in the soil. The species play an important ecological role in that it contributes to the recycling of nutrients in the wild.
The cockroach is popular in Brisbane and is frequently sold as a pet.
Description
The giant burrowing cockroach is identifiable by its large size and weight. An adult can reach over 60 mm and up to 75–80 mm, and can weigh up to 30-35 grams. The pronotum is a prominent plate-like structure that covers the first segment of the thorax, has short tubercles at the sides, and can exceed 15 mm. Their pronotum assists with digging, acting as a shovel while its abdomen rests on the ground. The cockroach use their spiny tibiae in order to dig and burrow into the ground. The giant burrowing cockroach is well adapted for burrowing and digging with large back legs and a strong body armour, which offers protection from predators. It is one of few native Australian cockroaches without wings, with a concurrent lack of mobility. It is nocturnal.
Adult males and females can be differentiated by the size of the "scoop" on the pronotum, which covers the head; with the male having a much more pronounced scoop. They grow by moulting several times before reaching full size. When a cockroach moults, it will appear pure white except for the eyes. Individuals have lifespans up to ten years in captivity. Adult males are more commonly-encountered than females.
As in other hemimetabolous insects, the immature stages of the giant burrowing cockroaches are referred to as nymphs. Nymphs are creamy white when born, but soon develop a reddish brown colour. Both adult females and males are dark brown. Nymphs remain with their mothers for five to seven months, and she provides food and cares for them.
Distribution and habitat
The giant burrowing cockroach species are mostly found in Queensland, Australia. It is commonly found along the coastal stretch between Rockhampton and Cooktown. The cockroach can also be located on the islands of the Whitsundays.
The species build burrows that can stretch up to one metre underground, which is where it stores food and lives permanently. Burrow depth appears to change depending on soil type, with burrows ranging from approximately 10 cm underground to 100 cm.
It is prevalent in dry Eucalyptus woodlands in the northeastern territory within Australia. There are 18 known geographical populations of the cockroach along subtropical Queensland. The cockroach has a wide geographical distribution in relation to other burrowing cockroach species. It is present across a one thousand kilometre range. The cockroach can be found in both dry and wet areas of Australia, including rainforests, woodlands and savannas. Common dry areas it inhabits include Maiden Springs, Boonderoo and Alpha. Common wet areas the cockroach is found in include Cooktown, Magnetic island and the Whitsundays. Locations that are in the mid-range between dry and wet regions where the cockroach is present include Coen, Rochford Scrub and Mount Garnet.
Populations of the cockroach can be geographically isolated due to unsuitable ground soil or by water. The species tends to prefer the drier savanna areas west of the Great Dividing Range.
The most common vegetation where the cockroach is found is Eucalyptus woodland and grass.
Behaviour
The cockroach stays underground as it lives permanently in its burrows. The cockroach often surfaces during wet weather, with most activity coinciding with summer rains. During the dry season it remains in its burrows and feed on collected litter. It feeds mostly on dry, decomposing eucalyptus leaves. The cockroach composts the leaves in the burrow with some bark and dry grass.