N.Z. SCIENCE CONGRESS.

Auckland Star, Volume LVII, Issue 24, 29 January 1926, Page 9

N.Z. SCIENCE CONGRESS.

150 PRESENT. SIX SECTIONS AT WORK. (By Telegraph.—Press Association.) DUNEDIN, this day. The fourth science congress in connection with New Zealand Institute opened here to-day, being attended by some 150 representative scientists of the Dominion. The congress is divided for the purpose of hearing papers and discussions into six different sections, comprising agriculture (presided over by Mr. A. H. Cockayne), biology (Dr. Tillyard), geology (Mr. J. A. Bartrum). chemistry, physics, and engineering ( Dr. C. C. Fa'rr), anthropology (Dr. P. H. Buck), and social science and economics (Professor J. Shelley). Sectional meetings will be held in the mornings, and each evening a public lecture will be delivered. Various papers on matters of scientific interest were read in the agricultural, biological, anl anthropological sections, and Dr. Marshall delivered his presidential address. Fighting Plant Pests. The progress of economic entomology in Australia and New Zealand was the subject of the address by Dr. J. R. Tillyard, at the meeting of the biology section. In the course of his address. Dr. Tillyard outlined the recent history of control of woolly aphis in New Zealand and Australia, and dealt extensively with the three types of insects concerned in its natural control, namely, certain eyrphid flies, the ladybird (hippodamia convergens), and the chalcid wasp (aphelinus niali). He said all the evidence was in favour of the hippodamia, which had a wonderful record in California, and was rightly looked upon as one of the most valuable of known beneficial insects. Aphelinus mali, on the other hand, was not greatly esteemed, but when it was introduced from two or three localities with widely different climates and the biological races received from these were crossed, it was very successful in New Zealand. At present, woolly aphis was well under control in New Zealand, owing to the work of this parasite, which had proved of the greatest help to orchardists throughout the Dominion. Hippodamia, on the other hand, although liberated in thousands throughout the Nelson province, had not since been seen or reported. Discussing the codlin moth. Dr. Tillyard said only the most Tigid attention to the spraying schedule would ensure to an orchardist freedom of his crop from injury by it. Two entomolosists in Colorado University discovered a few years ago that codlin moth could easily be trapped by means of fermented apple juice placed in jars hung in the upper third of the trees. The experiment had been repeated recently in Nelson and by a South Australian grower with remarkably successful results. Control of Noxious Weeds. The control of noxious weeds by insects was also dealt with by the speaker, who summariecd the course of events which led up to the present system of prickly pear control by moans of its insect and fungus enemies judiciously released. The general opinion at the present time in Australia was that the problem was in course of solution by the utilisation of insect enemies alone. A few years ago the then Minister of Lands in New South Walee, visiting the prickly pear laboratory in the northwest of that State, and seeing the work that was beginning there with the insects, remarked that it was the one bright spot in an otherwise hopeless situation. In 1025, the officer in charge of the principal laboratory in Queensland was able to write as follows:—"There is now no doubt at all in our opinion that in time, by biological means, we shall surely control the prickly pear pest iv Australia."