Old, well-matured specimen of a prickly pear cactus (Opuntia sp.) near Weranga, western Darling Downs, Queensland, Australia, one of the epicenters of an infamous prickly pear infestation. Starting about 1870, the prickly pears spread to cover an area larger than Great Britain by 1920, possibly the world's worst plant infestation. This specimen shows dieback from attack by Cactoblastis cactorum moth caterpillars, introduced from Argentina in 1925 for biological control.