Prickly pears (Genus Opuntia) include a number of plant species that were introduced and have become invasive in Australia. Prickly pears (mostly Opuntia stricta) were imported into Australia in the 19th century for use as a natural agricultural fence and in an attempt to establish a cochineal dye industry. Many of these, especially the Tiger Pear, quickly became widespread invasive species, rendering 40,000 km2 (15,000 sq mi) of farming land unproductive. The moth Cactoblastis cactorum from South America, whose larvae eat prickly pear, was introduced in 1925 and almost wiped out the population. This case is often cited as an example of successful biological pest control.