The Prickly Pear Prize

Prickly pear plants were prized as a food source for cochineal insects, which produced a bright red dye when crushed. In the late 18th century, Sir Joseph Banks suggested that New South Wales might prove a suitable climate for establishing a cochineal dye industry.

The insects soon died, but the prickly pear plants survived and thrived, particularly to the west of the Great Dividing Range. 

It overwhelmed native vegetation and farming land and it is estimated that by the early 20th century prickly pear had overrun more than 24 million hectares (60 million acres) across New South Wales and Queensland.

In 1886 the New South Wales Government passed the Prickly-pear Destruction Act. Queensland also went on to pass legislation around the clearing of prickly pear infested land. 

Landowners became responsible for the plant’s destruction, and government-appointed inspectors oversaw the law’s enforcement. However, the Act could not stop the prickly pear infestation. 

In Queensland, the government looked to innovation to solve the problem. A £5,000 reward was offered for an effective method of destroying the plants. 

Suggestions came from around the world and included salt, prairie cattle, steamrollers, arsenic, electricity and a machine that used mirrors to focus the sun’s rays to burn the prickly pear.   

Fortunately, as a result of the  government’s research into the management of cacti in North and South America, a potential solution was found.

The Cactoblastis cactorum moth was introduced in 1926 and by 1933 an estimated 80 per cent of the infested land in Queensland had been cleared of the pear. The release of the moths is regarded as one of the most impressive examples of biological weed control in the world.