Harrisia Cactus (Harrisia martinii) was introduced to Australia as a garden plant in the 1890s. Before long it had escaped into the natural environment and was first recognised as a weed in 1935 at Collinsville QLD. By the 1950s Goondiwindi was battling its own infestation of Harrisia which began east of Goondiwindi.
The mid 1970s saw the biological control "The Mealy Bug" released into the area and forty years on, it has failed to become the silver bullet many had hoped for. The Mealy Bug does not handle the cold or dry times well and is limited in the distance it will travel between plants.
The core infestation has now spread from East of Goondiwindi to Moonie, North Star, Toobeah & Yelarbon. Harrisia cactus is primarily spread by seed, however its fleshy stem segments do readily take root when they come into contact with soil. The seeds are spread by birds and other animals (e.g. foxes, emus, pigs, goannas and ants) that eat the fruit.