All cacti originate from the New World (the Americas), but some of them also introduced at many points of the world. On some places which were similar to their natural habitat they became invasive. The most famous story is the invasion of Opuntia sticta in Australia. By the first part of the 20th century, the problem became severe thus a resolution was needed. Cactus moth was introduced in 1923 which removed most of the Opuntia population until 1933. In South Africa, Opuntia stricta also means a great ecological problem, the solution is, nevertheless, far more difficult as Opuntia ficus-indica also widely cultivated plant important in the agronomy, in the country. Nowadays, Opuntia aurantiaca is also dispersing in Australia and South Africa. Cactus moth is not infecting this species thus new method for thinning is needed. In Africa, Harrisi martinii is also spreading. This species is sensitive against Hypogeococcus festerianus, an aphid species, thus biological control is possible.
