FIGHTING PESTS

Hawke's Bay Tribune, Volume XXIII, Issue 210, 18 August 1933, Page 12

FIGHTING PESTS

CONTROL OF INSECTS SCIENJISTS AT WORK. RAGWORT A MAJOR PROBLEM. The control by parasitic insects of ragwort and bidi-bidi, and also of the grass grub and its beetle, are among the researches at present being brought to a practical stage by the Cawthron Institute. Nelson, according to Dr. David Miller, chief of the department of entomology at the institute. Dr. Miller informed a “Pwss” interviewer that the institute had been badly affected by the present financial stringency, and that it was desired to interest the farming community in its work, so that they should realise its importance to them. To that end he had just completed a tour of the south-ern-districts, giving addresses to farmers. Dr. Miller’s work is particularly concerned with the control of insect pests, and with the control of weeds by the use ot insects. His department, he said, had been studying the control of blackberry, gorse, bidi-bidi and ragwort. It seemed now that it would be unwise to go on with the use of insects for the control of blackberry, because all the insects used had a weakness for related plants and fruit trees. With the others, however, there was considerable chance of success, particularly with bidi-bidi and ragwort. BIDI-BIDI AND RAGWORT. “For bidi-bidi we have been working on an insect brought from Chile, winch has adapted itself readily to the New Zealand species of bidi-bidi. At present the research has reached the stage where the insect can be liberated. This will mean obtaining large supplies from South America. “The control of ragwort is very important to dairy farmers, particularly in the North Island and in Southland. At first we experimented with the cinnabar moth, which we liberated. Unfortunately it produces only one generation of caterpillars each year, and that in the spring, with the result that the ragwort, which flowers in the spring, summer and autumn, is checked only in the early stages. “We have now another insect, which I found in Scotland. This produces a generation of caterpillars every six weeks, right through the flowering period of the ragwort, and its maggots destroy the seeds of the plant, Tho value of this will be realised from the fact that the grubs, when they infest a flower-head of destroy 100 per cent, of the seed. We hope to be in a position to liberate this insect some time next January. GRASS GRUB AND BEETLE. “In the interests of the agriculturist we are prying attention to what I consider to be the major insect pest problem of the Dominion—the control of the grass grub and its beetle,” he continued. ‘M consider that a fairly conservative estimate of the damage done in the Dominion each year by the grass grub and its beetle to be about £750,000. For the control of this we are using two parasites, one from Japan to attack the beetle, and the other which I discovered in Chile, to attack the grub. “A few months ago there v a grave possibility that most of these researches would have to be cancelled because our "rants from the Empire Marketing Board and from other sources, apart from the institution’s own endowments, had ceased,” said Dr. Miller in conclusion. “Had it not been for the New Zealand Meat Producers’ Board, which has been standing by in the meantime until other primary producers as a whole can come together to meet the situation, there is no doubt that the work would have been stopped. I may say that the Meat Board and other primary producing bodies have been giving the matter very favourable attention, and there is no doubt that with their aid we shall be able to carry on.”