FIGHTING PESTS

Wanganui Chronicle, Volume 75, Issue 142, 18 June 1932, Page 8 (Supplement)

FIGHTING PESTS

THE LOST LADYBIRD. There have arrived in Australia 81,300 shock troops* frmo abroad, not for war in its ordinary grim acceptance, but for an aggressive attack, on a nation-wide front, on two of this country’s biggest pests—the St. John’s Wort and scale on fruit trees. These “shock troops” are actually 81,000 eggs of one of tho species of beetles, for tho purpose of devouring the St. John’s Wort, and 300 eggs of a fly to destroy scale on fruit trees. This effort to fight pests with para sites follows the successful experiments in Australia with the insect cactoblastis, in keeping down prickly pear. It is pointed out that parasites have hyper parasites, and that these again have tertiary parasites, and that it is for this reason that the 300 fly e £gs will, after hatching, be placed in entomological quarantine to free them from their own parasites, and so give them a greater chance to do the work with which Australia is confidently entrusting them. Australia is now also experimenting with blowfly parasites from abroad, because there is a natural parasite on the sheep blowfly in the Commonwealth to-day which is prevented from keeping tho blowfly down, since the parasite’s own parasites prey upon it. The interesting fact is recalled that an Australian ladybird was introduced into New Zealand to exterminate an orchard pest. It is stated, however, that the pest took refuge in gorse, where the ladybird would not follow, and that the latter either died or flew away into the mountains. When a beetle that feeds on a weed pest, as Sti John’s Wort, is introduced, a long period of testing in the laboratory is essential- This is to make sure that it will eat the pest and nothing else. Cactoblastis, for example, it is pointed out, has the virtue of dying 'when its natural food, prickly pear, is all destroyed.