PRICKLY PEAR PEST.

New Zealand Herald, Volume LXV, Issue 20072, 9 October 1928, Page 9

PRICKLY PEAR PEST.

RAVAGES IN AUSTRALIA. NATURAL ENEMY REMEDY. COCHINEAL AND CATERPILLARS. t. [yftOM OUR OWN COIIItESPONDENX.] SUVA. Sept. 27. From 40 to 50 million acres of the northern parts of Australia were covered with prickly pear eight years ago and the pest was gaining at the rate of 800,000 to a million acres every year. It menaced tlio whole of Australia. To-day the increase each year has been arrested and inroads arc being made on " capital supply" areas. This, in brief, was the story told Ijy Mr. Leilh H. Hitchcock, a passenger, with his wife, on passing through Suva on his return to Australia, after an absenco ill many parts of tho American Continent of two years and nine months. Mr. Hitchcock is the second senior biologist on the staff of the Australian Commonwealth Prickly Pear Board, which is carrying out this successful campaign against the pest. He has been recalled to Australia as a result of the unexpected antics of cochineal, which was being used as one of the enemies of the pear, and which had spread almost everywhere in tho infested area. Suddenly, within a very short, period, it has all but disappeared and tho board has sent for Mr. Hitchcock, who has a very extensive knowledge of it, to discover the reason and the remedy. Speaking from general knowledge Mr. Hitchcock said that tho cochineal's great enemy was wet weather and Queensland had been experiencing very wet seasons. Possibly it would be found that this was the cause of the trouble. During the time that ,he has been in Central America ho and his three Australian assistants, have despatched to Australia 40 different insects to light the prickly pear. Many ot them turned out useless; many would not breed and others were working too slowly. Mr. Hitchcock had on board the Sierra 100 cases of borer caterpillar, which was a very good enemy of prickly pear but, so far, they had not been able to stand the change of climate. Ho was hopeful, however, he would be able to acclimatise those he had with him. They had been shipped in tho full-grown caterpillar stage and were expected to spin a cocoon on the ship. This would be ready on landing in Australia to hatch into a moth. The moth would then start to lay eggs and the, caterpillars would be liberated on the prickly pear. At present tho most successful insect dealing with prickly pear is cactoblastis. It is exceedingly active, so much so, indeed, that many prominent people, among whom was the late Mr. 11. E. Pratten, Australian Minister for Customs, have asked the question, " What the cactoblastis would start to blast when it had blasted all the prickly pear ?" In reply to this Mr. Hitchcock said that they had to take a risk at times, but with such insects evfery precaution humanly possible was taken before they were shipped. They were tested on at least 150 economic plants such as are found in Australia. If it was considered that they would thrive on any one of these plants the insect was immediately rejected. The campaign against- prickly pear in Northern Australia, Mr. Hitchcock said, was the greatest battle, of the kind being waged anywhere -in the \vbrld and the progress being made indicated that it would be a successful one.