The Northern Territory government is offering A$15,000 (pounds 6,150) to the inventor of the most effective trap. Cane toads secrete a deadly toxin and have killed even dingoes and freshwater crocodiles. They have a voracious appetite and a rampant libido, and breed rapidly.
Andrew Arthur, a Northern Territory musician near Darwin, has tested his "Toad Blaster", a battery-powered loudspeaker that replicates their mating call. "I got an immediate reaction," he said: "All the males in the area started arching up and calling. Males and females were drawn to it, and started moving towards the sound."
A businessman, Harry Maschke, has built a trap with circular swinging doors that drop the toads into buried buckets. It also has lights, to attract insects and increase its appeal to toads. And zoologists are searching gene technology to prevent the pests developing into sexually mature adults.
Originally from Venezuela, the toads were first released in Gordonvale, south of Cairns, but ignored the cane beetles and ate almost everything else. Then they fanned out, covering up to 30 miles a year, reaching the Northern Territory in the late 1990s. They have also hopped down to northern New South Wales.
On rainy days in northern Queensland, cane toads the size of dinner plates carpet roads and pavements. Drivers will weave across the highway, squashing them with their tyres. On warm evenings, the toads gather in suburban backyards, stealing pet food and snacking on insects. Spearing them with a garden fork appears only to irritate them, and whacking them with a golf club only lets off steam. Even the massacre on the roads makes a minuscule dent in an estimated population of 100 million.
But Cairns pubs stage cane toad races. Their skins are made into purses and handbags. And there are devotees of the hallucinogenic powers of their venom. There was an epidemic of toad-licking in the 1970s, and two Queensland dogs have been recorded as addicts.