Dr Rentz, the former orthopteroid insect curator at CSIRO’s Australian National Insect Collection, has debunked many of the myths associated with the creatures in his new book A Guide to the Cockroaches of Australia, launched at the Discovery Centre on Monday.

While Canberra may only have about 20 or 30 types of cockroaches braving the cool climate, there are close to 100 varieties in the Queensland rainforest where Dr Rentz has lived since he retired.

“[Cockroaches] are important from two aspects, one they’re eating vegetation matter so they’re returning a lot of leaves and branches back into the soil … they’re recyclers,” he said.

“Also because they’re so common they must serve as food for birds, other insects and lizards in that habitat.

“[But] aside from the ecology angle when you see them up close they’re really very colourful … with some species most people say ‘they’re not cockroaches, they’re beetles’.”

Cockroaches are rarely welcome guests at home and finding a roach in the kitchen could spell disaster for a restaurant, but Dr Rentz said few native varieties sought the comforts of home.

“They don’t live very long in the dry atmosphere and most have specialised feeding habits, they eat things that you don’t find in a house,” he said

“If you see a dead cockroach on the windowsill it doesn’t mean it’s infested, it probably means [the house] is too dry.”

But Dr Rentz said the pest varieties including the American, German and Australasian cockroaches were of economic concern for restaurants and hospitals and should be controlled to avoid the transmission of bacteria like E. coli and disease.

“Around Canberra, in some eating places, I’ve seen some really decent infestations,” he said.

“It’s not on and must be dealt with [but] for the most part the other 500-odd species belong here and they must be important because there are so many different kinds.”

Although the cockroaches grossly exagerrated ability to survive nuclear radiation may have earned them a place in folklore, Dr Rentz said different species were able to occupy most habitats – from the treetops to the soil.

“They’ve been around for 300 million years and they looked pretty much the same as they do now so they’re great survivors,” he said.

The book is pitched at insect-lovers interesting in collecting and preserving cockroaches, but also as a resource for pest-controllers, students and researchers to identify pest and non-pest species.

The catalogue shows the diversity of the 500 species of cockroaches scuttling around Australia thanks to photographic contributions from more than 50 people, Dr Rentz said.

While insects may not be everyone’s cup of tea for Dr Rentz some are particularly striking. “There’s a beautiful translucent green one up here [in Queensland],” he said.

“They range in size from five millimetres long to really heavy ones that are 30 grams in weight.

“Desert [cockroaches] can be kept in a terrarium under a light, they’re sort of a good lab animal."