Why a failed agricultural experiment created one of the world's most successful invasive pests.

Nature · Published 3 October 2026 Swipe more like this →

In short: In 1935, Australia imported 2,400 cane toads to protect sugarcane crops from beetles. The toads ignored the beetles, thrived in the wild, and multiplied into millions. Today, these toxic, adaptable amphibians are an ecological disaster, spreading across the continent and threatening native wildlife with their potent, heart-stopping poison.

The cane toad (Rhinella marina) is a large, warty amphibian native to South and Central America. While they are just another part of the ecosystem in their original range—where predators like caimans and snakes have evolved to tolerate or avoid their venom—they have become a global menace elsewhere. Their success as an invasive species stems from a combination of extreme hardiness, a voracious appetite, and a rapid reproductive cycle. Females can lay between 5,000 and 30,000 eggs at a time, and the species is capable of breeding in almost any season, provided there is fresh or brackish water available.

The primary defense mechanism of the cane toad is bufotoxin, a milky substance secreted from large parotid glands behind the shoulders. This toxin contains cardioactive steroids that can be fatal to pets and native predators that attempt to lick, bite, or consume the toads. Because they are omnivores, they outcompete native species for food, consuming everything from insects and vegetation to small birds and mammals. Their ability to survive in diverse environments, including urban areas, rainforests, and coastal grasslands, has allowed them to colonize regions as varied as Florida, the Philippines, and Papua New Guinea.

In Australia, the situation remains critical. The population is advancing westward at a rate of 40 to 60 kilometers per year, covering thousands of square miles. Despite the government's efforts to humanely reduce their numbers, the toads continue to flourish. Scientists are now looking to the cane toad's genome to understand how the species adapts so quickly to new environments, hoping that genetic insights might eventually provide a way to halt their march. While their deliberate introduction is now rare, the risk of accidental spread persists through the transport of goods like potted plants and timber.

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