When was the prickly pear introduced

The costs often proved greater than the value of the land. It was indeed a time of heartbreak for many settlers — the hopeless task of keeping prickly pear off their land and, during much of this same period, many rural families were living with the daily fear of knowing their young men were overseas and involved in World War I….

Boiling arsenate mix to kill the pear s NWW Maybe the fumes might have discouraged some of the many death-adders snakes that were prevalent amongst the thick pear. In , the Commonwealth Government with the Governments of NSW and Qld set up a joint Commonwealth Prickly Pear Board to investigate all options for controlling prickly pear- biological and mechanical.

Significantly more funding was put into work on cactoblastis and cochineal biological control agents. It was estimated at the time that the pear was spreading at the rate of one millions acres a year.

Nothing could stop its progress! Tremendous effort went into mechanical and chemical treatment programs, but the pear could not be contained. An interesting piece of NSW history, in its own right! It seems that, even as late as when the pear was virtually out of control in northern NSW, very few NSW state politicians understood the full extent of the problem.

In order to bring about a change in mindset, the then NSW Minister for Lands W E Wearne from Bingara NSW conducted 27 fellow politicians on a train tour to Moree and the Gravesend-Bingara area to demonstrate, first-hand, the impact prickly pear was having on rural areas.

Newspaper items in this section kindly provided by Mr John Wearne, Bingara, grandson of the former Minister for Lands. The NSW Prickly-pear Act provided for the setting up of a Prickly-pear Destruction Commission, with wide powers to deal with the prickly pear problem. Field staff were appointed to enforce the Act. Lessees could eventually own the land — if they cleaned up the pear! Queensland had the bigger share of the prickly pear problem because its climate and land types were more suited.

The Queensland authorities were also the ones responsible for introducing the famous cactoblastis into the equation! Some of the historical information gained from Queensland records makes fascinating reading. For example:. Early model prickly pear spray machine NWW I have no figures for the chemical treatment program undertaken in New South Wales during this same period. Bounty on destruction of birds: the link on the left is an amazing record from the Queensland Prickly Pear Land Commission annual report, , listing bounties paid for the destruction of emus 2 shillings 6 pence head , emu eggs 1 shilling , crows 6 pence and scrub magpies 4 pence head.

Almost immediately, the CPPB sent a group of entomologists to America, under the leadership of Allan P Dodd, to acquire the previously identified biological agents. They simultaneously established a breeding centre for Cactoblastis cactorum moths in Queensland. Female moths lay their eggs on the prickly pear plants. Working as a team, the hatched larvae then eat through the tough outer layer of the cactus pads to get at the edible interior.

There they feast on the soft tissue until they reach around 25 millimetres in length. Once they have reached maturity, the larvae fall from the prickly pear and enter a cocoon stage. The moth hatches from the cocoon, and the cycle starts over again.

The first two attempts to propagate moths in the early s failed, so Cactoblastis cactorum eggs were imported from Argentina. From a population of females, a total of , eggs were hatched. The moth was spectacularly productive. The second generation yielded over 2. In Chinchilla the moths underwent strict breeding and feeding assessments to ensure they would not attack other plants. In the first moth was released. At the height of the operation, Chinchilla was sending out as many as 14 million cactoblastis eggs a day across Queensland and New South Wales.

By most of the overgrown land had been cleared of the pest plants. Although not on the same scale as the s crisis, prickly pear continues to be a problem in New South Wales and Queensland, where new varieties that do not act as hosts for cactoblastis moths have become established. In cactoblastis moths were introduced to the Caribbean, where Opuntia species are indigenous. The moths originated in South America and so the Caribbean plants had previously had no exposure to them.

In the United States there are grave concerns that the moths could destroy ecologically and economically significant Opuntia species right across the south of the country. A prickly invasion, National Museum of Australia. Eradication of prickly pear in Australia, Nature.

Prickly pear history, North West Weeds. The National Museum of Australia acknowledges First Australians and recognises their continuous connection to country, community and culture. Defining Moments Prickly pear eradication. See our classroom resource. Explorer and author Michael Terry standing in a patch of prickly pear. Cactoblastis cactorum, female moth. Photo: Peggy Greb. The rapidity with which these pests have increased is one of the botanical wonders of the world.

Their original home is the coastal sector of Texas and Florida where the mean rainfall is 40—50 in. Yet in Australia the plants have adapted themselves to a very different environment and with a precipitation of only 20—30 in. In an area of about 10,, acres was affected in Queensland and New South Wales. The invasion advanced with such celerity that at the peak, in , the affected area must have been greater than 60,, acres: in some years the annual increase in infested territory exceeded 2,, acres.

The main distribution takes place by seeds, but every broken—off segment of the plant is liable to take root. You can also search for this author in PubMed Google Scholar. Reprints and Permissions. IMMS, A. Nature , — Download citation.