The Toad That Ate Australia
How an ecological cure turned out worse than the disease.
2 min read · from UNINTENDED by Mayank Mehta
In 1935, Australia's sugar cane industry had a beetle problem. Two species of beetle were eating the roots of sugar cane in Queensland, and farmers were losing their crops. Someone suggested a biological solution: the cane toad, a large, hardy amphibian from Central and South America that was known to eat beetles. It had already been used successfully in Hawaiian sugar plantations. The idea was simple. Import the toads, release them into the cane fields, and let nature take its course.
A hundred and two cane toads arrived in Australia. They were bred in captivity until their numbers reached three thousand, and then released into the fields with great optimism.
The toads didn't eat the beetles.
The beetles lived at the top of the cane stalks. The toads lived on the ground. The two species barely encountered each other. But the toads, finding themselves in a warm, predator-free paradise with abundant food, did what any organism does under those conditions. They multiplied. And they ate everything else. Insects, bird eggs, small mammals, native frogs. Anything that fit in their mouths.
Making matters worse, cane toads are toxic. Their skin secretes a poison powerful enough to kill dogs, cats, and native predators that attempt to eat them. Australian wildlife had no evolutionary experience with this toxin, and species that might otherwise have kept the toads in check were killed by their first meal.
Today, cane toads number in the hundreds of millions and have spread across a vast swath of northern Australia. They continue to advance at roughly forty kilometers per year. Native species have declined sharply in areas where the toads have arrived. Billions of dollars have been spent on control efforts. None have worked.
The cane toad didn't save the sugar crops. It became one of the most destructive invasive species on the continent, a permanent reminder that importing a solution from one ecosystem into another isn't a controlled experiment. It's a bet. And in this case, Australia lost.