More prickly pear, where is the Cactoblastus Beetle? Acknowledged as one of the greatest biological invasions of modern times, the introduction and subsequent spread of prickly pear into Queensland and New South Wales had infested millions of hectares of rural land by the 1920s, rendering it useless for agriculture. Prickly pear proved so difficult and costly to control by chemical and mechanical means that enormous areas were simply abandoned by their owners. The eventual control of this pest, mainly by one insect and in the space of a few short years, is an amazing story, which has encouraged further, successful developments in the field of biological pest control.