FIGHTING PESTS

Hawke's Bay Tribune, Volume XXII, Issue 147, 7 June 1932, Page 11

FIGHTING PESTS

THE LOST LADYBIRD. Sydney, May 25. There have arrived in Australia 81,300 shock troops from 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 the species of beetles, for the 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 parasites follows the successful experiments in Australia with the insect cactoblastis, in keeping down prickly pear. It is pointed out that parasites have hyperparasites, and that these again have tertiary parasites, and that it is for this reason that tho 300 fly eggs 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 eutrustinug them.

Australia is now also experimenting with blowfly parasites from abroad, because there is a natural parasite on tho sheep blowfly in the Commonwealth to-day which is prevented from keeping the blowfly down, since the parasite’s own parasites prey upon it. The interesting fact is recalled that an Australian ladybird was introduced into Now Zealand to exterminate, an orchard pest. It is stated, however, that tho pest took refuge in gorse, where the ladybird would not follow, and that the latter then either died or flew away into the mountains. When a beetle that feeds on a weed pest, such as St. John's Wort, is introduced, a long period of testing in tho 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.