The prickly pear is Opuntia: a
genus in the cactus
The genus is named after the
Ancient Greek city of
Opus. There, according to
Theophrastus, an edible plant grew which could be propagated by rooting its leaves.
Prickly pears (mostly Opuntia stricta) were originally imported into
Australia in the 18th century for gardens. They were later used as a natural agricultural fencing.
 They quickly became a widespread
weed. They changed 101,000 sq mi (260,000 km2) of farming land into an impenetrable green jungle of prickly pear, in places 20 ft (6.1 m) high.
In 1919, the
Australian federal government established the Commonwealth Prickly Pear Board to coordinate efforts with state governments to eradicate the weed. Early attempts at mechanical removal and poisonous chemicals failed, so in a last resort,
biological control was attempted.
 There is a
Cactoblastis cactorum, from
South America, whose larvae eat prickly pear. It was introduced in 1925 and rapidly reduced the cactus population. A memorial hall in
Chinchilla (Queensland) commemorates the moth.
 This is one of the earliest known examples of the biological control of