Queensland releases 2,400 cane toads to control beetles in sugar-cane fields. The beetles remain. Australia acquires one of its most notorious invasive pests.
The biological-control programme produced many toads. That was the problem.
Queensland had a beetle problem.
Cane beetle larvae were damaging the roots of sugar cane, and Australia's sugar industry wanted a biological solution.
The Bureau of Sugar Experiment Stations had heard encouraging reports about a large South American toad being used against agricultural pests elsewhere. In 1935, entomologist Reginald Mungomery travelled to Hawaii and returned to Queensland with a breeding group of cane toads.
They reproduced enthusiastically.
That part of the experiment worked extremely well.
On Monday, 19 August 1935, Mungomery and colleague Robert Buzacott released about 2,400 toads into the Little Mulgrave River and other sites around Gordonvale.
The plan appeared straightforward: toads would eat beetles, and the sugar cane would benefit.
There was a difficulty.
According to the National Museum of Australia, the Bureau had not established that the toads would effectively control the cane beetles under Australian conditions. Nor had it studied how the toads might affect the Australian environment before releasing them.
The cane toads nevertheless proved excellent at one thing.
Being cane toads.
They survived, reproduced and spread. The target beetles did not disappear; the Museum concludes that the toads had no helpful effect on them.
Meanwhile, the imported animals became an ecological problem. Their toxins can kill native predators unfamiliar with them. They compete with native species, eat opportunistically and have spread across northern Australia far beyond their original Queensland release area.
Australian entomologist Walter Froggatt warned early that the introduced toad might become a pest comparable with the country's other notorious invasive species.
That prediction aged better than the beetle-control plan.
Australia had imported an animal to solve an agricultural pest problem.
The agricultural pest remained.
The imported solution became one of the country's most famous pests instead.
Australia released cane toads to control cane beetles without first establishing that the toads would effectively control them. The beetles remained; the toads spread across northern Australia.
The biological control successfully controlled one thing: the geographical distribution of cane toads.