Cockroaches belong to the insect order Blattodea of which there are approximately 4,000 species worldwide and 400 species native to Australia. Native species vary in appearance, habitat and feeding habits. All species are thought to have originated in the tropical and sub-tropical areas of Africa around 300 million years ago. They range in size from just a couple of millimetres in length right up to an enormous 70 millimetres in the case of the Giant Burrowing Cockroach (Macropanesthia rhinoceros) from northern Queensland.
No matter the size, they are all based on a similar body plan:
- Oval shaped body which is dorso-ventrally compressed,
- Two pairs of membranous wings when present, with theforewings more sclerotised than the hind wings,
- The thorax protected by a large plate, the pronotum,which extends over the head,
- Strong chewing mouthparts,
- Compound eyes,
- Long whip-like antennae and,
- Prominent leaf shaped cerci at the tip of the abdomen.