"It is a native and it's not a pest, just a nuisance, so it's really just a matter of us learning to live with our native animals," he said. Roaming 'roaches have kept the phones ringing for pest control companies, but Exopest director and entomologist Simon Dixon says having your yard sprayed with insecticide is unlikely to affect native cockroaches in their hiding places. It's also bad for the environment as it's more likely to kill vital smaller insects.

"Unfortunately, many pest control companies will say yes, they'll spray, but we don't advocate it as it is very ineffective and a waste of money," he said. "You are better to pick them up with a dustpan and shoo them outside." Or get a chook, council permitting. But the "bad" cockroaches are also flourishing in homes and businesses around Melbourne courtesy of the warmer weather. Along with American and Oriental cockroaches, German invaders are the exotic disease-carrying nasties who have adapted to living inside and feasting on our food scraps and other less savoury meals. "They carry a lot of diseases because they can be in sewers one moment and then in the pantry on your Vita-Brits," said Dr Walker.

They will set up home under the fridge or in cupboards and feast from bins or food scraps and seek other places of moisture, such as the bathroom. But it gets much worse. It may change your dental hygiene habits to know your toothbrush is a cockroach's favourite.

"They will go for moisture and unfortunately one of the last things we do at night is clean our teeth, turn off the light and leave the wet toothbrush in a cup, so it's a logical target," Dr Walker said. Touted as the critter most likely to survive a nuclear explosion, cockroaches have many remarkable survival abilities. Even decapitation won't slow them down. And the females of some species can produce up to 20,000 young a year. The drought has also caused other creepy-crawlies such as spiders to join the mass exodus from the garden. Species that are vagrant hunters, such as huntsman, wolf and white-tailed spiders, are shacking up indoors.

"They come inside foraging or just by accident, but they don't know it is a house," said Mr Dixon. "Once they get inside, they can't get out."