CONTROL OF PESTS.

Manawatu Herald, Volume XLV, Issue 2531, 18 January 1923, Page 4

CONTROL OF PESTS.

PRESERVING FOOD SUPPLY. ADDRESS BY DR. R, J. TILLYARD. Wellington, January 13.' “The Control of Injurious Pests” was the subject of an address delivered in the Town H.-.VI on Saturday evening by Dr. R. J. Tillyard, F.L.S. who lectured under the auspices of the Australian Association for the Advancement of Science. Dr. Tillyard said that man, in his effort to improve his own food suplily, was always unwittingly making new opportunities for his enemies. \s an example of this, the lecturer mentioned the well-known pest, the •odlin moth, which had attacked the apples before the era of civilisation. This little moth lived l in the thickets and forests of the northern hemisphere, and this catterpillar bored its way inside of the wild crab apple, and lived on its contents. AVith the improvement of trade in the apple by man, the oo'dlin moth got its opportunity, and quickly seized the chance to spread and damage all the beautiful varieties of apples which man had produced. Man was thus faced in all directions with problems of his own making, and of the very greatest importance to his future welfare, the control of the various insect pests which interferred with his food supply.

The lecturer then went on to deal with the various methods by which sometimes with signal success, sometimes with disappointing failure. These methods might lie classed roughly as mechanical, chemical and biological. Under the heading of mechanical methods the lecturer gave illustrations of a number of interesting devices which had been made use of particularly in America, with great success. Two of (he most striking of these were tarred paper discs used to control 11m cabbage-root maggot and ingenious cases for the control of the pine weevil. In the chemical division there were numerous sprays, vapours, dusts, and gases for fumigation. The lecturer passed these over fairly rapidly as he said they would he mostly familiar lo the audience, hut lie mentioned particularly t lie highpower spraying used for valuable forest trees in America and the recent development of spraying from an aeroplane. lie also mentioned recent developments of (he use of chemicals in soil, which vapourised and gave off gases which repelled certain insects. The chief portion of the lecture dealt with biological methods, which were being improved and brought into use and which consisted broadly in careful, scientific study of an insect pest and its own numerous enemies, and the utilisation of these enemies to control the pest. In this connection he gave a detailed account of the wonderful work which has been done in America in control of the gipsy moth. This moth was introduced from Europe and rapidly

began to attack all kinds of forest trees, threatening colossal destruction in Eastern States. Huge sums of money had been spent in controlling it and from 20 to 30 different natural enemies, both predatory and parasitic, were now being liberated in countless numbers to help to check the pest. . Before giving other striking examples of the successes achieved by the Americans, who he said, were undoubtedly far ahead of the rest of the world in this branch of work, the lecturer went on to give a short account of the more modest efforts which are being undertaken in New Zealand by Government biological laboratories in Wellington, and by the Cawthorn Institute in Nelson. Of considerable interest in this connection was a detailed account of the introduction, acclimatisation, and distribution to all parts of New Zealand of a valuable liflle parasite of the woolly aphis, known as aphef linus mali. The lecturer concluded by giving some instances of urgent problems not yet evolved in New Zealand and stressed the point that only by continuous.,application by devoted bands of scientists could they hope to cope with these extremely difficult problems, which were of far more importance than the people generally realised.