There are approximately 4000-plus species of cockroaches out of which 30 are linked with human habitats. There are 4 regular household roaches/household pests that need governance are – German Cockroach, American Cockroach, Australian Cockroach and the Oriental Cockroach.
Cockroaches come in both small and large sizes (3-70 mm in length); broad, flattened body with the pronotum as the shield generally overhanging the body on the sides and fairly the head. Certain cockroaches have membranous and toughened wings that assist in flying and all of them have legs that are extended, adapted and spined for running.
Certain species of cockroaches, such as the gregarious German cockroach, have a rich social structure that involves common shelter, social dependence, kin recognition and information transfer. The American cockroach is huge with a shiny red color and Australian cockroach (which originated in Asia) can be identified by a yellow band across the base of the pronotum and yellow slashes along the base of the forewings. India is mainly dominated by German cockroaches.
Disease-causing organisms like bacteria, protozoa, and viruses are found in the body of cockroaches. Different kind of gastroenteritis (food poisoning, diarrhea, dysentery, etc.) happens to be those principal diseases spread by these cockroaches. Their efficient daytime hiding and their skill to fly into new territory makes it difficult to eradicate them. You would need specific Cockroach killers to ensure maximum reach to every nook and corner of your house.
A field guide to insects in Australia - third edition - Paul Zborowski and Ross Storey - New Holand publishers,