According to The Advocate, “The prickly pear cactus was a scourge in outback regions of Australia until the Cactoblastus moth was introduced in 1926 as a biological method to eradicate this introduced plant pest.
A consignment of 3,000 Cactoblastus moth eggs reproduced and the next generation numbered in excess of two and a half million eggs. These were distributed to selected areas from which eggs were gathered and scattered over an increasing area until about 300 million moth eggs had been successfully translocated. By 1932 most of the infested country had been reduced to soggy masses of decaying yellow pulp and by 1934 the cactus had been brought under control.
This cactus was first introduced into Australia in the early colonial days by the English West India Company who wanted to set up a dye manufacturing industry. Captain Arthur Phillip on his voyage to Australia in 1788, called in at Rio de Janeiro and took aboard prickly pear cactus plants containing colonies of the Cochineal insects for this purpose. Sadly, the insects died out before an industry could get off the ground. But, unfortunately the prickly pear cactus went on to become a devastating environmental weed.
The Cochineal insects, which produce a deep maroon pigment stored in their body fluids and tissues, make the prickly pear cactus their home where they feed off the plant’s moisture and nutrients with their beak-like mouthparts.
The source of this much prized dye had been known from ancient times and was used and revered by the Aztecs before the Spanish Conquest not only for its brilliant colour but also for the fact that it’s one of the few water-soluble colorants to resist fading.”