Controversial Cockroaches: Keith McKeown, a noted entomologist once wrote: “Cockroaches are universally detested insects”. He was referring to those cockroaches, which invade our homes and often resist all means of eradication. These home invaders are immigrant species from overseas. Depending on species they are known as American, German and Oriental cockroaches. These migrants are cosmopolitan in their culinary preferences. They will eat anything edible. One author has noted: “That cockroaches will eat cucumber although it disagrees with them horribly”. Perhaps there is a method of control in this message.
We were surprised to read that there are at least 300 native cockroach species. At Yallaroo we have observed three species. Unlike their overseas cousins they avoid human habitation and are happy living outdoors. The only time native cockroaches come inside is when they are accidentally introduced in pieces of firewood.
Introduced cockroaches have wings whilst many native species are wingless. On close inspection, the specimen illustrated appears to have vestiges of wings. There is a theory that in some species the wings are chewed off. Other cockroaches provide this “wing divesting service”.
The specimen illustrated is very common at Yallaroo and we see them frequently during our gardening activities. They reach a length of about four cms. A less common species has yellow stripes on a brown body. This attractive cockroach reaches a length of two cms. The third Yallaroo species is brownish-grey, reaches a length of 1.5 cms, has a flattened body and lives under bark and in rock crevices. This cockroach resembles a miniature version of the fossil trilobite.
When we lived in the Blue Mountains of NSW we often observed a cockroach with eyespots on its rear end. When disturbed it would point its rear-end skywards which resembled the head of a snake or lizard poking its head out of the ground. An interesting defence mechanism.
There is a blind cockroach, which lives in caves under the Nullarbor Plain in South and Western Australia.
Little is known of the life history or dietary preferences of our native cockroaches. As with many other Australian insects there is scope for the amateur naturalist to add to our knowledge of our fascinating insects.
We welcome native cockroaches to the environment of Yallaroo. They don’t bother us and we try not to bother them. The home invading exotic cockroaches are viewed somewhat differently.