1935
A cane-toad statuette
The national pest
This is Bruno, now stuffed. He was one of the stars of the film Cane Toads: An Unnatural History and represents a species that has invaded Australia and taken hold of the national consciousness like no other. By far the biggest ecological disaster in Australia has been the introduction of the cane toad.
The prickly pear cactus (Opuntia stricta) was introduced to Australia in 1839. An attractive plant, it’s the core ingredient in making cochineal dye. In less than 25 years it spread from Sydney to Central Queensland, and by 1920 some 24.25 million ha of Australia were covered in it. As fast as farmers burned and chopped the plants away, they came back.
The Queensland government offered 100,000 acres (40 468 ha) reward to anyone who could rid Australia of the troublesome plant. In 1925, the Commonwealth Prickly Pear Board introduced 3000 Cactoblastis moth eggs and larvae from South America. The cactus moth loves the prickly pear. Over 100 000 eggs were hatched. The second generation yielded 2.5 million eggs. It was a spectacular success and by 1933 almost all the cactus was gone.
The larvae of two native species of insect (the greyback cane beetle and French’s cane beetle) eat the roots of sugar cane. Despite the warnings of New South Wales government entomologist W W Froggatt and the Australian Museum’s Roy Kinghorn, the Bureau of Sugar Experiment Stations imported about 100 cane toads from Hawaii to the Meringa Sugar Experiment Station near Cairns in the hope that they would eat the beetles.
The cane toad (Rhinella marina) is native to Central and South America and is not a natural predator for the beetles. It prefers insects but will eat anything, including food scraps, pet food and small animals. Once in an environment, the cane toad is a very aggressive competitor for food. It breeds very fast. Females lay 8000 to 35 000 eggs at a time, twice a year. For all these reasons, cane toads are a serious threat to native fauna.
The milky poison produced by the parotoid glands on the cane toad’s head is fatal to most potential predators, including domestic dogs. The poison is absorbed through mucous membranes such as those in the eyes, mouth and nose. No human deaths have been recorded in Australia but ingestion can cause burning of the eyes and hands, skin irritation, vomiting and shallow breathing. There is an urban myth that cane-toad venom is a hallucinogenic.
The introduced cane toads did attack the larvae but not in sufficient numbers to wipe out the beetles. They steadily expanded their environment. Starting in Far North Queensland in 1935, by 1978 the cane toad had reached well into New South Wales and within a decade had crossed the badlands of Central Queensland into the Northern Territory and, by 2001, the pristine wilderness of Kakadu National Park.
The toad is a significant menace – no ecosystem is unchanged by its arrival – but its sheer resistanqce to being exterminated has led to some people having a grudging respect for it. Queenslanders have adopted the cane toad as a state symbol and proudly refer to themselves as ‘Cane Toads’. Mark Lewis’s multi-award-winning film Cane Toads: An Unnatural History significantly increased the public’s knowledge of the animal, but also went a long way towards transforming it from a pest to a curio.