By Phil Mercer
BBC News, Queensland
Scientists in Australia have warned that rising numbers of disease-ravaged feral pigs pose a threat to farmers and the environment.
Feral pigs have caused widespread damage to crops in Queensland
Experts in the northern state of Queensland say that the pig population is out of control.
The pigs are causing untold damage to crops as well as threatening native wildlife, they say.
It is estimated there are 23m wild pigs in Australia. That means there are now more pigs than people.
In Queensland's rain forests, professional hunters are trapping large numbers of these feral scavengers.
The pigs will be shot and buried. They are riddled with disease and cannot be eaten.
Paul Smith runs a hunting business called Boar Busters. He is a former soldier who served in Iraq, East Timor and Somalia.
"It is just like operating in a guerrilla warfare environment," he says.
"I need to utilise the information that I gain from the local population and then to be able to effectively react to that information to respond to the incursions from the feral pigs."
The pigs have caused widespread damage to sugar cane and banana crops.
Government scientists have warned that they are contaminating streams and rivers that run into the Great Barrier Reef.
Doctor James Butler says that the pigs could also spread disease.
"If foot and mouth disease was ever to hit Australia," he says, "pigs would be one of the major vectors. And given that they are almost ubiquitous everywhere and very, very difficult to control, there would be a major problem."
It is thought Australia's wild pigs were brought here by early European settlers.
Like other introduced species such as the red fox and the cane toad, they have been an environmental disaster.