Giant burrowing cockroach

Species of cockroach

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 gramsUnreliable source: date=March 2020 and measure up to 7.5 in length. 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 , 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.

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 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. 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. 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. 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.

Reproductive behaviour between the cockroaches tends to occur at night time, and is based mostly on scent, taste and touch. The male cockroaches attempt to court the females with motions such as hissing, changing posture, motioning with antennas, grooming the female, and pushing the female with their body in an attempt to lift the female. It is unknown if female cockroaches engage in multiple matings and if so, if it occurs with different male cockroaches.

Depending on the temperature, they perform different patterns of eating, carbon dioxide production, and metabolic rates. Macropanesthia rhinoceros can be diagnosed with obesity when there are no changes in its husbandry. When an individual lacks nutrition, they are susceptible to adopting a "thrifty phenotype", which prioritises fat storage over reproductive development to be able to handle dangerous environment conditions. In optimal environmental conditions, this thrifty phenotype has the potential to become maladaptive, thus causing excessive fat storage and metabolic disease. In the future, this may result in obesity or metabolic disease. Obesity can cause, "an atypical body conformation with narrow, elongated abdominal profiles compared to the wide, flat bodies of neighbouring conspecifics." In addition, this exposes a mushy and pale tissue between their abdominal sclerites.

The cockroach is calm and easy to care for making it a common and popular pet. The species cannot move fast or fly. Its large size, sedentary behavioural lifestyle and limited husbandry needs contribute to the increase in popularity for the species as a pet both in Australia and internationally. They are clean, disease free, odourless, do not bite when handled and do not climb or fly. Males can be aggressive towards other males meaning that a larger enclosure would be needed to house more than one cockroach at a time to avoid conflict. There should be more females than males in one enclosure as otherwise conflict may ensue between the males over the females. Enclosures should not be kept in direct sunlight for extended periods of time. The tank or terrarium should have clean, fine to medium grain river sand, with some being wet and the other end of the enclosure dry. The cockroach requires substrate to be up to 100mm deep, which the cockroach use with leaves and sticks to nest and burrow. The substrate is changed regularly after a few months, taking into account the size of the tank and the number of cockroaches present. The giant burrowing cockroach has lived to a maximum of eight years in captivity. Nymphs grow faster when in the wild in comparison to in captivity. Wild nymphs can reach the eighth instar in five months, yet there can be a large variation in growth rates with some nymphs taking up to a year to grow to the ninth instar. It has nine instar stages. Data from laboratories shows that it is a slow growing cockroach with varying growth rates. The cockroach eats dried eucalyptus leaves and can also eat fruit and vegetables.

The largest threat to the giant burrowing cockroach is habitat destruction. Their main habitat includes forests and land in northern Queensland, which has been cleared intensely from the year 2000. Large centipedes find shelter in the burrows of the cockroaches and can prey on young nymphs. Large spiders also consume young nymphs. Neither spiders nor most centipedes are able to consume adults due to their outer shell, however fully grown Ethmostigmus rubripes would likely be capable of preying on the adult cockroaches.