Iguanas were once considered trendy household pets, shipped to California from Central and South America in the early 1990s.

BBC: News | Americas | LA's lizard crisis

In some cases, said the researchers, viruses could be spread by household pets such as cats and dogs that are injected with the tags to help identify their owner.

BBC: NEWS | Technology | Viruses leap to smart radio tags

To eradicate the thriving possum population (70 million at last count), authorities airdrop carrots laced with sodium monofluoroacetate, a rodenticide banned in the U.S. The poisoned veggies snuff not only possums but also bunnies, deer and household pets.

FORBES: It's Not Easy Being Green